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, Available online ,
doi: 10.11883/bzycj-2026-0273
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This study aims to clarify the influence of external turbulence on ethylene-air explosion characteristics. Experiments were performed in a constant-volume combustion chamber equipped with a fan-generated turbulence system, high-speed schlieren imaging, and pressure acquisition devices. The effects of turbulence intensity (u′ = 0.00-0.60 m/s) and equivalence ratio (Φ = 0.6-2.0) on flame morphology, propagation velocity, explosion overpressure, and pressure rise rate were systematically investigated. The results indicate that increasing turbulence intensity promotes flame surface wrinkling and accelerates flame propagation, with the most significant enhancement observed at u′ = 0.44-0.60 m/s. The normalized turbulent flame propagation velocity exhibits self-similar behavior with increasing turbulent Reynolds number, and Ka- and Da-based correlations accurately describe the acceleration process with R2 values above 0.91. Moreover, higher turbulence intensity increases the maximum explosion overpressure and pressure rise rate by enhancing fuel-air mixing and reducing heat loss. A physics-guided neural network model incorporating initial condition, peak, and smoothness constraints was further developed to predict overpressure evolution, achieving improved physical consistency and prediction accuracy compared with the XGBoost model. These findings provide quantitative insights into turbulence-enhanced ethylene explosion hazards and support safety assessment of ethylene-related industrial processes.
This study aims to clarify the influence of external turbulence on ethylene-air explosion characteristics. Experiments were performed in a constant-volume combustion chamber equipped with a fan-generated turbulence system, high-speed schlieren imaging, and pressure acquisition devices. The effects of turbulence intensity (u′ = 0.00-0.60 m/s) and equivalence ratio (Φ = 0.6-2.0) on flame morphology, propagation velocity, explosion overpressure, and pressure rise rate were systematically investigated. The results indicate that increasing turbulence intensity promotes flame surface wrinkling and accelerates flame propagation, with the most significant enhancement observed at u′ = 0.44-0.60 m/s. The normalized turbulent flame propagation velocity exhibits self-similar behavior with increasing turbulent Reynolds number, and Ka- and Da-based correlations accurately describe the acceleration process with R2 values above 0.91. Moreover, higher turbulence intensity increases the maximum explosion overpressure and pressure rise rate by enhancing fuel-air mixing and reducing heat loss. A physics-guided neural network model incorporating initial condition, peak, and smoothness constraints was further developed to predict overpressure evolution, achieving improved physical consistency and prediction accuracy compared with the XGBoost model. These findings provide quantitative insights into turbulence-enhanced ethylene explosion hazards and support safety assessment of ethylene-related industrial processes.
, Available online ,
doi: 10.11883/bzycj-2026-0114
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There are a large number of irregular distributed joints in rock mass, which usually show high energy accumulation characteristics, so it is very important to study the crack propagation behaviour of non-persistent joined rock mass containing a hole and to evaluate the strain failure of rock samples caused by stress concentration under different impact loads, which is very important for specifying effective prevention and control measures. In this paper, through laboratory experiments and theoretical derivation, based on DIC digital image correlation technology, the dynamic mechanical properties, damage evolution law and fracture failure characteristics of non-interpenetrated jointed rock mass with hole are studied. The test results show that the existence of the structural plane significantly changes the dynamic mechanical properties of the specimen with different hole. And the dynamic strength and elastic modulus of the specimens increase with the increase of impact load. Peak strain and energy dissipation density show an obvious strain-rate dependence. With the increase of strain rate, the damage degree of the specimens increase continuously. Under the same strain rate, the relationship between the damage degree of the specimens is D-shaped hole specimen>rectangular hole specimen>circular hole specimen. The damage evolution of rock with composite cracks takes into account the energy dissipation and dynamic load effect, and the damage curve increases in an L-shaped manner during the loading process. The structural plane in the sample has obvious strain localization and blocking effect. The stress concentration and plastic zone are mainly located at both ends of the structural plane and the rock bridge area. The tensile strain occurs after the shear strain, and the final failure mode of the rock changes from main shear to mixed tensile shear failure. Considering the maximum hoop stress criterion, the effects of impact load and different hole on the initiation and propagation of
There are a large number of irregular distributed joints in rock mass, which usually show high energy accumulation characteristics, so it is very important to study the crack propagation behaviour of non-persistent joined rock mass containing a hole and to evaluate the strain failure of rock samples caused by stress concentration under different impact loads, which is very important for specifying effective prevention and control measures. In this paper, through laboratory experiments and theoretical derivation, based on DIC digital image correlation technology, the dynamic mechanical properties, damage evolution law and fracture failure characteristics of non-interpenetrated jointed rock mass with hole are studied. The test results show that the existence of the structural plane significantly changes the dynamic mechanical properties of the specimen with different hole. And the dynamic strength and elastic modulus of the specimens increase with the increase of impact load. Peak strain and energy dissipation density show an obvious strain-rate dependence. With the increase of strain rate, the damage degree of the specimens increase continuously. Under the same strain rate, the relationship between the damage degree of the specimens is D-shaped hole specimen>rectangular hole specimen>circular hole specimen. The damage evolution of rock with composite cracks takes into account the energy dissipation and dynamic load effect, and the damage curve increases in an L-shaped manner during the loading process. The structural plane in the sample has obvious strain localization and blocking effect. The stress concentration and plastic zone are mainly located at both ends of the structural plane and the rock bridge area. The tensile strain occurs after the shear strain, and the final failure mode of the rock changes from main shear to mixed tensile shear failure. Considering the maximum hoop stress criterion, the effects of impact load and different hole on the initiation and propagation of
, Available online ,
doi: 10.11883/bzycj-2026-0250
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An integration-point reformulation method is proposed for the adiabatic shear band (ASB) initiation criterion. The original criterion uses shear strain measured from a grid marked on the specimen surface. This strain cannot be used directly in finite-element integration-point calculations. The maximum plastic shear strain is calculated using Mohr’s circle for strain and the J2 associated flow rule. Its increment is used as the weight. The weighting is applied only to the stress-state history used to calculate the critical shear strain. An integration point meets the ASB initiation condition when the ratio of the maximum plastic shear strain to the weighted critical shear strain is not less than unity. The calculation procedure is implemented in LS-DYNA through a user-defined material subroutine. Shear-compression specimens with different notch angles are used for evaluation. The results show that the ASB initiation site generally shifts from the center of the shear zone toward a notch tip as the notch angle increases. This trend agrees with experimental observations. The increment-weighted scheme reduces the effect of early stress-state fluctuations on the critical shear strain. It also produces a more concentrated high-ratio region than the instantaneous and arithmetic-mean schemes. The potential initiation sites and orientations of the high-ratio regions remain generally consistent across different mesh sizes. The integration-point reformulation allows the critical shear strain variable derived from experimental measurements to be calculated directly at finite-element integration points. The resulting criterion provides a numerical method for identifying ASB initiation sites under complex loading.
An integration-point reformulation method is proposed for the adiabatic shear band (ASB) initiation criterion. The original criterion uses shear strain measured from a grid marked on the specimen surface. This strain cannot be used directly in finite-element integration-point calculations. The maximum plastic shear strain is calculated using Mohr’s circle for strain and the J2 associated flow rule. Its increment is used as the weight. The weighting is applied only to the stress-state history used to calculate the critical shear strain. An integration point meets the ASB initiation condition when the ratio of the maximum plastic shear strain to the weighted critical shear strain is not less than unity. The calculation procedure is implemented in LS-DYNA through a user-defined material subroutine. Shear-compression specimens with different notch angles are used for evaluation. The results show that the ASB initiation site generally shifts from the center of the shear zone toward a notch tip as the notch angle increases. This trend agrees with experimental observations. The increment-weighted scheme reduces the effect of early stress-state fluctuations on the critical shear strain. It also produces a more concentrated high-ratio region than the instantaneous and arithmetic-mean schemes. The potential initiation sites and orientations of the high-ratio regions remain generally consistent across different mesh sizes. The integration-point reformulation allows the critical shear strain variable derived from experimental measurements to be calculated directly at finite-element integration points. The resulting criterion provides a numerical method for identifying ASB initiation sites under complex loading.
, Available online ,
doi: 10.11883/bzycj-2026-0156
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Addressing the inherent defects of traditional body-centered cubic (BCC) lattices, which are highly prone to rapid, global catastrophic failure and dangerous stress localizations under dynamic impact, and profoundly inspired by the naturally occurring, highly toughened cross-layered microstructures found in seashells, this paper aims to develop a novel class of protective metamaterials that seamlessly combine extreme lightweight characteristics with highly efficient dynamic energy absorption capabilities. Based on the utilization of advanced high-toughness resin materials, a single-layer bionic structure featuring node-constrained spatial gradients and a sophisticated three-layer bionic cross-layered metamaterial employing an orthogonal stacking strategy were meticulously designed, with the traditional uniform BCC lattice serving as the baseline control group. Low-velocity dynamic impact tests were rigorously conducted using an advanced drop-weight impact testing system. This experimental approach was systematically combined with in-situ high-speed photography and highly detailed explicit dynamic finite element simulations to comprehensively compare and analyze the complex deformation responses, stress wave propagation patterns, and progressive failure evolution processes of the three distinct topologies under transient dynamic loading. The multifaceted results reveal that the traditional lattice exhibited rapidly penetrating global shear bands and highly destructive rigid bottoming phenomena, severely limiting its protective utility; the single-layer bionic structure significantly enhanced the initial impact-bearing capacity through engineered mechanical heterogeneity, but an overall structural softening still inevitably occurred in the later stages of large deformation; conversely, the three-layer bionic structure, precisely through interlayer orthogonal rotation, successfully constructed a macroscopic artificial interface, effectively triggering a profound interface-blocking effect and greatly increasing the tortuosity of crack propagation pathways. The study concludes that this multidimensional bionic collaborative design fundamentally transforms the failure mode of the three-layer metamaterial into a highly desirable progressive crushing mechanism, distinctly characterized by a beneficial interlayer deformation lag. Ultimately, this hierarchical structure effectively eliminates hazardous bottoming peaks and reliably maintains a prolonged, stable load plateau even under extreme compression, exhibiting exceptional impact kinetic energy dissipation performance and providing a robust new paradigm for the future design of advanced, lightweight impact-resistant and energy-absorbing structural systems.
Addressing the inherent defects of traditional body-centered cubic (BCC) lattices, which are highly prone to rapid, global catastrophic failure and dangerous stress localizations under dynamic impact, and profoundly inspired by the naturally occurring, highly toughened cross-layered microstructures found in seashells, this paper aims to develop a novel class of protective metamaterials that seamlessly combine extreme lightweight characteristics with highly efficient dynamic energy absorption capabilities. Based on the utilization of advanced high-toughness resin materials, a single-layer bionic structure featuring node-constrained spatial gradients and a sophisticated three-layer bionic cross-layered metamaterial employing an orthogonal stacking strategy were meticulously designed, with the traditional uniform BCC lattice serving as the baseline control group. Low-velocity dynamic impact tests were rigorously conducted using an advanced drop-weight impact testing system. This experimental approach was systematically combined with in-situ high-speed photography and highly detailed explicit dynamic finite element simulations to comprehensively compare and analyze the complex deformation responses, stress wave propagation patterns, and progressive failure evolution processes of the three distinct topologies under transient dynamic loading. The multifaceted results reveal that the traditional lattice exhibited rapidly penetrating global shear bands and highly destructive rigid bottoming phenomena, severely limiting its protective utility; the single-layer bionic structure significantly enhanced the initial impact-bearing capacity through engineered mechanical heterogeneity, but an overall structural softening still inevitably occurred in the later stages of large deformation; conversely, the three-layer bionic structure, precisely through interlayer orthogonal rotation, successfully constructed a macroscopic artificial interface, effectively triggering a profound interface-blocking effect and greatly increasing the tortuosity of crack propagation pathways. The study concludes that this multidimensional bionic collaborative design fundamentally transforms the failure mode of the three-layer metamaterial into a highly desirable progressive crushing mechanism, distinctly characterized by a beneficial interlayer deformation lag. Ultimately, this hierarchical structure effectively eliminates hazardous bottoming peaks and reliably maintains a prolonged, stable load plateau even under extreme compression, exhibiting exceptional impact kinetic energy dissipation performance and providing a robust new paradigm for the future design of advanced, lightweight impact-resistant and energy-absorbing structural systems.
, Available online ,
doi: 10.11883/bzycj-2026-0247
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Hovercraft are potentially vulnerable to underwater explosion threats, while the mechanisms by which the pressurized air cushion beneath the hull affects explosion-bubble evolution and blast-load transmission remain insufficiently understood. In this study, a plate structure incorporating a pressurized air cushion is established as a simplified representation of the bottom structure of a hovercraft. Numerical simulations of underwater explosions under free-field conditions and beneath air-cushioned structures with different initial pressures are performed using the coupled Eulerian–Lagrangian (CEL) method. Particular attention is devoted to the effects of the initial air-cushion pressure on bubble expansion, contraction, migration, and collapse, as well as on the propagation and transmission of shock-wave and bubble-pulsation loads. The numerical results demonstrate that the pressurized air cushion significantly suppresses the dynamic evolution of the underwater explosion bubble. Compared with the free-field condition, bubble deformation, migration, expansion, and contraction are strongly constrained, and the overall pulsation characteristics are substantially altered. Nevertheless, although the air cushion restricts bubble motion, it intensifies both the peak shock-wave load and the subsequent bubble-pulsation load acting on the structure, thereby increasing the global structural response and potential for structural damage. These findings indicate that a pressurized air cushion does not necessarily mitigate underwater explosion loads; instead, its compressibility and pressure-dependent response may enhance load transmission under certain conditions. Furthermore, bubble evolution and load-transmission characteristics under free structural boundary conditions are investigated, and the influence of structural motion on the coupled interaction among the explosion bubble, surrounding water, pressurized gas, and structure is discussed. The results provide further insight into the fluid–gas–structure interaction mechanisms associated with underwater explosions beneath air-cushioned structures. This study provides a theoretical and numerical basis for evaluating the blast and impact resistance of hovercraft and offers technical support for the design and optimization of protective structures subjected to underwater explosion loading.
Hovercraft are potentially vulnerable to underwater explosion threats, while the mechanisms by which the pressurized air cushion beneath the hull affects explosion-bubble evolution and blast-load transmission remain insufficiently understood. In this study, a plate structure incorporating a pressurized air cushion is established as a simplified representation of the bottom structure of a hovercraft. Numerical simulations of underwater explosions under free-field conditions and beneath air-cushioned structures with different initial pressures are performed using the coupled Eulerian–Lagrangian (CEL) method. Particular attention is devoted to the effects of the initial air-cushion pressure on bubble expansion, contraction, migration, and collapse, as well as on the propagation and transmission of shock-wave and bubble-pulsation loads. The numerical results demonstrate that the pressurized air cushion significantly suppresses the dynamic evolution of the underwater explosion bubble. Compared with the free-field condition, bubble deformation, migration, expansion, and contraction are strongly constrained, and the overall pulsation characteristics are substantially altered. Nevertheless, although the air cushion restricts bubble motion, it intensifies both the peak shock-wave load and the subsequent bubble-pulsation load acting on the structure, thereby increasing the global structural response and potential for structural damage. These findings indicate that a pressurized air cushion does not necessarily mitigate underwater explosion loads; instead, its compressibility and pressure-dependent response may enhance load transmission under certain conditions. Furthermore, bubble evolution and load-transmission characteristics under free structural boundary conditions are investigated, and the influence of structural motion on the coupled interaction among the explosion bubble, surrounding water, pressurized gas, and structure is discussed. The results provide further insight into the fluid–gas–structure interaction mechanisms associated with underwater explosions beneath air-cushioned structures. This study provides a theoretical and numerical basis for evaluating the blast and impact resistance of hovercraft and offers technical support for the design and optimization of protective structures subjected to underwater explosion loading.
, Available online ,
doi: 10.11883/bzycj-2026-0239
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To investigate the damage characteristics, residual axial load-carrying performance, and post-blast axial compression failure modes of concrete-filled stainless steel tubular (CFSST) columns subjected to blast loading, field blast tests, post-blast axial compression tests, and axial compression tests on intact specimens were conducted. The specimens had a square cross-section of 250 mm × 250 mm, a total length of 3000 mm, and a stainless steel tube thickness of 3 mm. In the blast test, a 6 kg TNT charge was detonated at a standoff distance of 300 mm from the mid-height blast-facing surface, while an initial axial compression ratio of 0.2 was applied. An LS-DYNA finite element model based on the multi-material arbitrary Lagrangian-Eulerian method was then established and validated to reproduce blast-wave propagation, fluid-structure interaction, structural damage, and the subsequent axial compression response. The results show that the blast-induced damage was mainly concentrated in the mid-height blast-facing region, where local indentation and lateral outward buckling developed in the stainless steel tube, while the overall integrity of the column was maintained. The maximum indentation depth measured in the test was 37 mm. The validated numerical model reasonably reproduced the damage pattern, displacement response, acceleration response, and post-blast axial load-displacement behavior. The errors between the experimental and numerical peak displacement, peak acceleration, and peak axial load were 1.5%, 5.6%, and 5.0%, respectively. The blast-damaged specimen reached a peak axial load of 1572.2 kN, which was 50.4% lower than that of the intact specimen. As the scaled distance decreased, the failure mode gradually changed from overall flexural failure to a combined failure mode involving local indentation, lateral outward buckling, and overall flexural deformation. The residual flexural deformation generated additional bending moments during subsequent axial compression, while the initial blast damage weakened the composite action between the stainless steel tube and the core concrete. As the initial damage decreased, the axial compression failure mode of the blast-damaged columns gradually changed from mid-height buckling to combined loading-end and mid-height buckling, and ultimately to loading-end buckling in the intact column. These findings provide a basis for the blast-resistant design and post-blast safety assessment of CFSST columns.
To investigate the damage characteristics, residual axial load-carrying performance, and post-blast axial compression failure modes of concrete-filled stainless steel tubular (CFSST) columns subjected to blast loading, field blast tests, post-blast axial compression tests, and axial compression tests on intact specimens were conducted. The specimens had a square cross-section of 250 mm × 250 mm, a total length of 3000 mm, and a stainless steel tube thickness of 3 mm. In the blast test, a 6 kg TNT charge was detonated at a standoff distance of 300 mm from the mid-height blast-facing surface, while an initial axial compression ratio of 0.2 was applied. An LS-DYNA finite element model based on the multi-material arbitrary Lagrangian-Eulerian method was then established and validated to reproduce blast-wave propagation, fluid-structure interaction, structural damage, and the subsequent axial compression response. The results show that the blast-induced damage was mainly concentrated in the mid-height blast-facing region, where local indentation and lateral outward buckling developed in the stainless steel tube, while the overall integrity of the column was maintained. The maximum indentation depth measured in the test was 37 mm. The validated numerical model reasonably reproduced the damage pattern, displacement response, acceleration response, and post-blast axial load-displacement behavior. The errors between the experimental and numerical peak displacement, peak acceleration, and peak axial load were 1.5%, 5.6%, and 5.0%, respectively. The blast-damaged specimen reached a peak axial load of 1572.2 kN, which was 50.4% lower than that of the intact specimen. As the scaled distance decreased, the failure mode gradually changed from overall flexural failure to a combined failure mode involving local indentation, lateral outward buckling, and overall flexural deformation. The residual flexural deformation generated additional bending moments during subsequent axial compression, while the initial blast damage weakened the composite action between the stainless steel tube and the core concrete. As the initial damage decreased, the axial compression failure mode of the blast-damaged columns gradually changed from mid-height buckling to combined loading-end and mid-height buckling, and ultimately to loading-end buckling in the intact column. These findings provide a basis for the blast-resistant design and post-blast safety assessment of CFSST columns.
, Available online ,
doi: 10.11883/bzycj-2026-0245
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A simplified algorithm for internal blast wave propagation in multi-room buildings was developed based on forward ray tracing, aiming to rapidly predict the propagation range of blast waves in buildings partitioned by masonry infill walls. The algorithm emitted ray bundles from the explosion source into space and generated uniformly distributed rays by performing triangulation on the spherical blast wavefront, ensuring that the ray density adequately represented the energy distribution of the incident wave. The algorithm simulated both the direct propagation of blast waves and their reflection off wall surfaces, and employed a time-stepping method to track the propagation paths of each ray within rooms and their interactions with wall boundaries. To address the blocking effect of infill walls on blast wave propagation, the walls were discretized into regularly arranged masonry units using a grid model with dimensions consistent with the actual masonry units. Based on the bond failure criterion of individual masonry units and the overall shear failure criterion of the wall, the opening state of the wall was determined at each time step; when a masonry unit reached the failure condition, it was removed from the grid, allowing rays to penetrate through the damaged region into adjacent rooms, thus enabling the simulation of continuous blast propagation across multiple rooms. The proposed model was validated through comprehensive comparisons with experimental data and finite element simulations under both single-room and multi-room configurations, focusing on key metrics including wall surface overpressure time histories and overall damage ranges. Good agreement is achieved across all test cases, confirming the model's capability in rapid assessment of internal blast loads in buildings. It should be noted that the model is specifically developed for buildings partitioned by masonry infill walls; for scenarios involving rigid walls or structural components with openings such as doors and windows, the current formulation requires further refinement and additional treatment of diffraction effects.
A simplified algorithm for internal blast wave propagation in multi-room buildings was developed based on forward ray tracing, aiming to rapidly predict the propagation range of blast waves in buildings partitioned by masonry infill walls. The algorithm emitted ray bundles from the explosion source into space and generated uniformly distributed rays by performing triangulation on the spherical blast wavefront, ensuring that the ray density adequately represented the energy distribution of the incident wave. The algorithm simulated both the direct propagation of blast waves and their reflection off wall surfaces, and employed a time-stepping method to track the propagation paths of each ray within rooms and their interactions with wall boundaries. To address the blocking effect of infill walls on blast wave propagation, the walls were discretized into regularly arranged masonry units using a grid model with dimensions consistent with the actual masonry units. Based on the bond failure criterion of individual masonry units and the overall shear failure criterion of the wall, the opening state of the wall was determined at each time step; when a masonry unit reached the failure condition, it was removed from the grid, allowing rays to penetrate through the damaged region into adjacent rooms, thus enabling the simulation of continuous blast propagation across multiple rooms. The proposed model was validated through comprehensive comparisons with experimental data and finite element simulations under both single-room and multi-room configurations, focusing on key metrics including wall surface overpressure time histories and overall damage ranges. Good agreement is achieved across all test cases, confirming the model's capability in rapid assessment of internal blast loads in buildings. It should be noted that the model is specifically developed for buildings partitioned by masonry infill walls; for scenarios involving rigid walls or structural components with openings such as doors and windows, the current formulation requires further refinement and additional treatment of diffraction effects.
, Available online ,
doi: 10.11883/bzycj-2026-0219
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Impact cratering is a fundamental geological process that shapes the surface morphology of planets and small bodies. The morphological characteristics of impact craters and the distribution of ejecta record key information about impact conditions and target properties. Classical impact-cratering theories are mainly based on idealized assumptions, such as vertical impact, homogeneous targets, and flat surfaces. However, natural impact events are generally oblique and commonly occur on targets with complex topography and heterogeneous structures. Impact angle, topographic features, and target heterogeneity jointly affect shock-wave propagation, energy deposition, material failure, ejecta motion, and crater collapse, resulting in pronounced asymmetry and complex structural characteristics of natural impact craters. This paper reviews recent progress in the formation mechanisms of impact craters under complex impact conditions, with emphasis on the effects of oblique impact, topography, porous media, layered structures, and joints and fractures on the cratering process, ejecta distribution, and scaling-law models. First, impact-cratering experiments, numerical simulation methods, and classical scaling laws are summarized. Then, the basic theories of ejecta motion under vertical and oblique impact conditions are introduced. The controlling effects of impact angle on the shock-pressure field, transient-crater evolution, final crater morphology, and scaling laws are analyzed. Furthermore, changes in shock-wave attenuation, energy dissipation, and material deformation mechanisms under complex target conditions are discussed. Existing studies still face several challenges, including insufficient experiments on multi-factor coupling, lack of unified characterization of complex target parameters, difficulties in scaling among experimental, numerical, and natural impact conditions, and unclear applicability limits of current scaling laws. Future research should focus on systematic experiments under coupled oblique-impact and complex-target conditions, high-resolution three-dimensional numerical simulations, and planetary observations, so as to develop cratering theories and quantitative prediction models that are more applicable to natural impact scenarios.
Impact cratering is a fundamental geological process that shapes the surface morphology of planets and small bodies. The morphological characteristics of impact craters and the distribution of ejecta record key information about impact conditions and target properties. Classical impact-cratering theories are mainly based on idealized assumptions, such as vertical impact, homogeneous targets, and flat surfaces. However, natural impact events are generally oblique and commonly occur on targets with complex topography and heterogeneous structures. Impact angle, topographic features, and target heterogeneity jointly affect shock-wave propagation, energy deposition, material failure, ejecta motion, and crater collapse, resulting in pronounced asymmetry and complex structural characteristics of natural impact craters. This paper reviews recent progress in the formation mechanisms of impact craters under complex impact conditions, with emphasis on the effects of oblique impact, topography, porous media, layered structures, and joints and fractures on the cratering process, ejecta distribution, and scaling-law models. First, impact-cratering experiments, numerical simulation methods, and classical scaling laws are summarized. Then, the basic theories of ejecta motion under vertical and oblique impact conditions are introduced. The controlling effects of impact angle on the shock-pressure field, transient-crater evolution, final crater morphology, and scaling laws are analyzed. Furthermore, changes in shock-wave attenuation, energy dissipation, and material deformation mechanisms under complex target conditions are discussed. Existing studies still face several challenges, including insufficient experiments on multi-factor coupling, lack of unified characterization of complex target parameters, difficulties in scaling among experimental, numerical, and natural impact conditions, and unclear applicability limits of current scaling laws. Future research should focus on systematic experiments under coupled oblique-impact and complex-target conditions, high-resolution three-dimensional numerical simulations, and planetary observations, so as to develop cratering theories and quantitative prediction models that are more applicable to natural impact scenarios.
, Available online ,
doi: 10.11883/bzycj-2026-0198
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With the widespread application of ultra-high strength steel in warheads and protective structures, accurately characterizing its failure behavior under high-speed impact loading is crucial for projectile structural optimization and protection design. Firstly, three classical fracture criteria, Johnson-Cook (J-C), Bao-Wierzbicki (B-W) and Modified Mohr-Coulomb (MMC) were selected, and the effects of strain rate and temperature were introduced into the B-W and MMC fracture criteria. Besides, the J-C strength model was modified based on the Ludwik-Voce strain hardening law. Then, the constitutive model parameters of ultra-high strength steel were determined from the existing static and dynamic test data, and the constitutive model was implemented into Abaqus/Explicit program via a VUMAT user-defined subroutine. The reliability of the proposed fracture criteria and strength model parameters was validated by comparing the deformations and failure modes of specimens in Taylor bar impact tests. Finally, numerical simulations were conducted for typical projectile broken scenarios, including the ultra-high strength steel projectiles penetrating steel plates, armored steel composite structures, and corundum rubble concrete target. By comparing the projectile/target failure modes and the instantaneous contours of stress state parameters, the prediction accuracy of the above three fracture criteria was quantitatively evaluated, revealing the influence mechanisms of stress triaxiality and Lode angle parameters on the failure behavior of ultra-high strength steel projectile/target. The results show that the penetration failure behavior of projectile/target is affected by the coupled high strain rate, multiaxial stress state and local shear mechanism. The J-C criterion only depends on the stress triaxiality, which makes it difficult to characterize the shear-dominated failure mode. Although the B-W criterion accounts for the piecewise characteristics of stress triaxiality, it exhibits large prediction deviations under the tension/compression-shear coupling stress state. The MMC criterion accurately reproduces the failure characteristics of the projectile nose shear sharpening, shell fragmentation, target plate tearing failure and shear plugging during penetration by coupling the Lode angle parameter and the stress triaxiality.
With the widespread application of ultra-high strength steel in warheads and protective structures, accurately characterizing its failure behavior under high-speed impact loading is crucial for projectile structural optimization and protection design. Firstly, three classical fracture criteria, Johnson-Cook (J-C), Bao-Wierzbicki (B-W) and Modified Mohr-Coulomb (MMC) were selected, and the effects of strain rate and temperature were introduced into the B-W and MMC fracture criteria. Besides, the J-C strength model was modified based on the Ludwik-Voce strain hardening law. Then, the constitutive model parameters of ultra-high strength steel were determined from the existing static and dynamic test data, and the constitutive model was implemented into Abaqus/Explicit program via a VUMAT user-defined subroutine. The reliability of the proposed fracture criteria and strength model parameters was validated by comparing the deformations and failure modes of specimens in Taylor bar impact tests. Finally, numerical simulations were conducted for typical projectile broken scenarios, including the ultra-high strength steel projectiles penetrating steel plates, armored steel composite structures, and corundum rubble concrete target. By comparing the projectile/target failure modes and the instantaneous contours of stress state parameters, the prediction accuracy of the above three fracture criteria was quantitatively evaluated, revealing the influence mechanisms of stress triaxiality and Lode angle parameters on the failure behavior of ultra-high strength steel projectile/target. The results show that the penetration failure behavior of projectile/target is affected by the coupled high strain rate, multiaxial stress state and local shear mechanism. The J-C criterion only depends on the stress triaxiality, which makes it difficult to characterize the shear-dominated failure mode. Although the B-W criterion accounts for the piecewise characteristics of stress triaxiality, it exhibits large prediction deviations under the tension/compression-shear coupling stress state. The MMC criterion accurately reproduces the failure characteristics of the projectile nose shear sharpening, shell fragmentation, target plate tearing failure and shear plugging during penetration by coupling the Lode angle parameter and the stress triaxiality.
, Available online ,
doi: 10.11883/bzycj-2026-0173
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Abstract:
High-entropy alloys (HEAs) exhibit pronounced strength–ductility synergy under extreme conditions such as high strain rates and cryogenic temperatures. However, existing crystal plasticity models, although capable of capturing macroscopic dynamic responses, rarely quantify strain-rate effects at the mechanistic level, and their critical parameters often lack explicit physical meaning. This limits the in-depth understanding of the physical mechanisms behind the excellent mechanical performance of HEAs. To address this issue, a physics-informed crystal plasticity finite element (CPFE) model was developed for equiatomic CrMnFeCoNi HEAs over a wide strain-rate range from 10−2 to 104 s−1. Multiple deformation mechanisms were integrated into the model, and the model was implemented in a finite element environment. Based on a thermo-elasto-viscoplastic theory, strain-rate-sensitive crystallographic formulations were derived for the plastic deformation mechanisms, including dislocation slip, deformation twinning, and martensitic phase transformation. Two dislocation mechanisms, i.e., dislocation slip and viscous drag, were considered to describe rate-controlled dislocation activity. Discrete internal state variables, updated at each time step, were introduced to track the evolution of dislocation density and dislocation-motion resistance on individual slip systems. In addition, the model incorporated the temperature dependence of stacking fault energy (SFE), adiabatic temperature rise, and the temperature dependence of the Hall Petch relation. These components enabled quantitative characterization of the kinetic features of microstructural evolution and established a direct link between mesoscale microstructural evolution and macroscopic mechanical properties. Numerical simulations were performed for equiatomic CrMnFeCoNi HEAs across this wide strain-rate range. The model reasonably predicted the macroscopic plastic flow behavior and maintained consistent predictions of stress–strain responses and microstructural evolution. The results show that the nonlinear evolution of strength–ductility synergy under dynamic loading is jointly governed by strain-rate-dominated dislocation dynamics and SFE-regulated competition among dislocation slip, twinning, and transformation, which ultimately dictates the macroscopic mechanical responses of the alloy. By analyzing strain-rate sensitivity and work-hardening rate, the plastic stability during dynamic deformation was revealed. The simulation results validated the reliability of the model in capturing dynamic deformation mechanisms. It is concluded that the proposed framework provides a quantitative physical model for describing extreme deformation mechanisms in the Cantor (CrMnFeCoNi) alloy. It also offers a physically sound and transferable modeling framework for other face-centered cubic (FCC) HEAs and for the investigation and design of multi-principal element alloy systems with complex deformation mechanisms under dynamic deformation and temperature variation.
High-entropy alloys (HEAs) exhibit pronounced strength–ductility synergy under extreme conditions such as high strain rates and cryogenic temperatures. However, existing crystal plasticity models, although capable of capturing macroscopic dynamic responses, rarely quantify strain-rate effects at the mechanistic level, and their critical parameters often lack explicit physical meaning. This limits the in-depth understanding of the physical mechanisms behind the excellent mechanical performance of HEAs. To address this issue, a physics-informed crystal plasticity finite element (CPFE) model was developed for equiatomic CrMnFeCoNi HEAs over a wide strain-rate range from 10−2 to 104 s−1. Multiple deformation mechanisms were integrated into the model, and the model was implemented in a finite element environment. Based on a thermo-elasto-viscoplastic theory, strain-rate-sensitive crystallographic formulations were derived for the plastic deformation mechanisms, including dislocation slip, deformation twinning, and martensitic phase transformation. Two dislocation mechanisms, i.e., dislocation slip and viscous drag, were considered to describe rate-controlled dislocation activity. Discrete internal state variables, updated at each time step, were introduced to track the evolution of dislocation density and dislocation-motion resistance on individual slip systems. In addition, the model incorporated the temperature dependence of stacking fault energy (SFE), adiabatic temperature rise, and the temperature dependence of the Hall Petch relation. These components enabled quantitative characterization of the kinetic features of microstructural evolution and established a direct link between mesoscale microstructural evolution and macroscopic mechanical properties. Numerical simulations were performed for equiatomic CrMnFeCoNi HEAs across this wide strain-rate range. The model reasonably predicted the macroscopic plastic flow behavior and maintained consistent predictions of stress–strain responses and microstructural evolution. The results show that the nonlinear evolution of strength–ductility synergy under dynamic loading is jointly governed by strain-rate-dominated dislocation dynamics and SFE-regulated competition among dislocation slip, twinning, and transformation, which ultimately dictates the macroscopic mechanical responses of the alloy. By analyzing strain-rate sensitivity and work-hardening rate, the plastic stability during dynamic deformation was revealed. The simulation results validated the reliability of the model in capturing dynamic deformation mechanisms. It is concluded that the proposed framework provides a quantitative physical model for describing extreme deformation mechanisms in the Cantor (CrMnFeCoNi) alloy. It also offers a physically sound and transferable modeling framework for other face-centered cubic (FCC) HEAs and for the investigation and design of multi-principal element alloy systems with complex deformation mechanisms under dynamic deformation and temperature variation.
, Available online ,
doi: 10.11883/bzycj-2026-0115
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Abstract:
Boron carbide ceramic is an important strategic material for aerospace and nuclear facilities. Its thermomechanical coupling behavior under transient thermal shocks determines structural service safety. Classical thermomechanical models neglect microscale local thermal diffusion, leading to obvious errors in predicting thermal shock responses. To solve this problem, this study improved the Green-Lindsay model based on dual-phase relaxation theory and established a thermomechanical coupling model incorporating four relaxation items: heat flux vector, stress, strain rate and temperature gradient. Laplace transform was used to obtain frequency-domain analytical solutions. A finite difference scheme with nonlinear iteration was constructed to numerically solve the coupling fields, and the consistency between analytical and numerical results was verified. The dynamic evolution of temperature, displacement, stress and velocity fields was systematically analyzed. The quantitative influences of various relaxation coefficients on coupling responses and stress wave propagation were clarified, and the size effect of thermal waves and stress waves was revealed. Thermal waves together with elastic waves dominated field evolution at the micro-nano scale, while thermal waves decayed rapidly at the macroscale and stress waves became the dominant factor. High-energy electron beam thermal shock experiments with Polyvinylidene Fluoride (PVDF) piezoelectric sensors verified the reliability and applicability of the proposed model. The results show that all four relaxation coefficients are negatively correlated with stress wave amplitude. The relaxation coefficients of stress and temperature gradient govern the pulse width, the heat flux relaxation coefficient determines wave speed, and the temperature gradient relaxation term eliminates the strong discontinuity of stress waves, making the model more consistent with microscale thermomechanical characteristics. The established model provides a theoretical method for predicting the thermomechanical responses of boron carbide ceramic under transient thermal shocks, and offers guidance for structural design and service safety assessment of thermal-shock-resistant ceramics.
Boron carbide ceramic is an important strategic material for aerospace and nuclear facilities. Its thermomechanical coupling behavior under transient thermal shocks determines structural service safety. Classical thermomechanical models neglect microscale local thermal diffusion, leading to obvious errors in predicting thermal shock responses. To solve this problem, this study improved the Green-Lindsay model based on dual-phase relaxation theory and established a thermomechanical coupling model incorporating four relaxation items: heat flux vector, stress, strain rate and temperature gradient. Laplace transform was used to obtain frequency-domain analytical solutions. A finite difference scheme with nonlinear iteration was constructed to numerically solve the coupling fields, and the consistency between analytical and numerical results was verified. The dynamic evolution of temperature, displacement, stress and velocity fields was systematically analyzed. The quantitative influences of various relaxation coefficients on coupling responses and stress wave propagation were clarified, and the size effect of thermal waves and stress waves was revealed. Thermal waves together with elastic waves dominated field evolution at the micro-nano scale, while thermal waves decayed rapidly at the macroscale and stress waves became the dominant factor. High-energy electron beam thermal shock experiments with Polyvinylidene Fluoride (PVDF) piezoelectric sensors verified the reliability and applicability of the proposed model. The results show that all four relaxation coefficients are negatively correlated with stress wave amplitude. The relaxation coefficients of stress and temperature gradient govern the pulse width, the heat flux relaxation coefficient determines wave speed, and the temperature gradient relaxation term eliminates the strong discontinuity of stress waves, making the model more consistent with microscale thermomechanical characteristics. The established model provides a theoretical method for predicting the thermomechanical responses of boron carbide ceramic under transient thermal shocks, and offers guidance for structural design and service safety assessment of thermal-shock-resistant ceramics.
, Available online ,
doi: 10.11883/bzycj-2026-0130
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Abstract:
An underwater explosion bubble contains enormous energy, which can cause severe localized damage to structures in near-field scenarios. To fully utilize the damage potential of such bubbles, this paper proposes a synergistic impact method based on spatiotemporal control of two out-of-phase underwater explosions. The total charge is divided into two independent explosive sources. By precisely adjusting their relative spatial configuration and initiation delay time, the interaction between the shock waves and bubble oscillations is used to achieve an enhanced and synergistic impact on the target structure. A series of experiments are conducted to compare a reference single-charge underwater explosion with three specially designed two-charge configurations. The results demonstrate that the proposed two-charge scheme with an unequal charge distribution significantly amplifies the jetting and collapse loads exerted by the primary bubble on the structure. Under the same total charge mass, this out-of-phase two-bubble configuration achieves a markedly superior impact effect compared to the traditional single-charge explosion. These findings provide theoretical insights and experimental references for the development of novel bubble control techniques in underwater explosions.
An underwater explosion bubble contains enormous energy, which can cause severe localized damage to structures in near-field scenarios. To fully utilize the damage potential of such bubbles, this paper proposes a synergistic impact method based on spatiotemporal control of two out-of-phase underwater explosions. The total charge is divided into two independent explosive sources. By precisely adjusting their relative spatial configuration and initiation delay time, the interaction between the shock waves and bubble oscillations is used to achieve an enhanced and synergistic impact on the target structure. A series of experiments are conducted to compare a reference single-charge underwater explosion with three specially designed two-charge configurations. The results demonstrate that the proposed two-charge scheme with an unequal charge distribution significantly amplifies the jetting and collapse loads exerted by the primary bubble on the structure. Under the same total charge mass, this out-of-phase two-bubble configuration achieves a markedly superior impact effect compared to the traditional single-charge explosion. These findings provide theoretical insights and experimental references for the development of novel bubble control techniques in underwater explosions.
, Available online ,
doi: 10.11883/bzycj-2026-0113
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Abstract:
A theoretical study was conducted on the design method of simulated loads based on plane charge explosion technique. Based on the assumptions of one-dimensional strain and quasi-static cavity pressure, combined with the rigid-perfectly plastic-locking model and the theory of plastic wave propagation, a theoretical model of dynamic response for planar charge explosion experiments was established. An analytical solution for load prediction considering overburden compression and overall movement was proposed, and the effects of various parameters, including the mechanical properties of overburden, overburden thicknesses, and cavity heights, on the characteristics of the simulated load were analyzed. The results show that under different charge densities, overburden thicknesses, and overburden types, the theoretical predictions are in good agreement with the numerical results. Thus, the proposed model offers a reliable theoretical framework for the load design of planar charge simulation experiments. The characteristics of the simulated load are closely related to the mechanical properties of overburden, overburden thicknesses and initial cavity heights, which affect the characteristics at the early loading stage, the late loading stage and the whole loading process, respectively. The more compressible the overburden material, the thicker the overburden, or the smaller the initial cavity height, the faster the simulated pressure time-history curve attenuates. In load design, a small initial cavity height should be prioritized to reduce experimental cost and improve experimental reliability.
A theoretical study was conducted on the design method of simulated loads based on plane charge explosion technique. Based on the assumptions of one-dimensional strain and quasi-static cavity pressure, combined with the rigid-perfectly plastic-locking model and the theory of plastic wave propagation, a theoretical model of dynamic response for planar charge explosion experiments was established. An analytical solution for load prediction considering overburden compression and overall movement was proposed, and the effects of various parameters, including the mechanical properties of overburden, overburden thicknesses, and cavity heights, on the characteristics of the simulated load were analyzed. The results show that under different charge densities, overburden thicknesses, and overburden types, the theoretical predictions are in good agreement with the numerical results. Thus, the proposed model offers a reliable theoretical framework for the load design of planar charge simulation experiments. The characteristics of the simulated load are closely related to the mechanical properties of overburden, overburden thicknesses and initial cavity heights, which affect the characteristics at the early loading stage, the late loading stage and the whole loading process, respectively. The more compressible the overburden material, the thicker the overburden, or the smaller the initial cavity height, the faster the simulated pressure time-history curve attenuates. In load design, a small initial cavity height should be prioritized to reduce experimental cost and improve experimental reliability.
, Available online ,
doi: 10.11883/bzycj-2026-0229
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Abstract:
Fuel tanks of vehicles are vulnerable to both hydrodynamic ram (HRAM) and fuel explosion when subjected to high-speed projectile impacts. To mitigate this coupled mechanical-activational damage, a novel protection method was proposed, in which load-reducing hollow spheres (LRHS) and explosion-proof spheres (EPS) are filled in a hybrid manner inside the tank. The attenuation effect of these fillers on HRAM was investigated experimentally. A series of comparative tests were conducted using a 25 mm two-stage light gas gun. A 12.7 mm spherical steel projectile with a mass of about 8.45 g was launched at approximately 1100 m/s to impact a fluid-filled container under five different filling conditions : fully water-filled (T1, baseline), 94% water-filled with a free surface (T2), fully water-filled with EPS (T3, about 5% in volume), fully water-filled with 36 preset LRHS (T4, about 1% in volume), and mixed filling with both LRHS and EPS (T5, about 6% in volume). The impact velocity was measured by laser screens, the cavitation evolution inside the container was recorded by a high-speed camera, and the pressure-time histories were recorded by underwater free-field pressure sensors. After the tests, the failure modes of the two fillers were examined, and the maximum deformations of the front and rear panels were obtained by three-dimensional scanning. The results demonstrate that the mixed filling scheme (T5) achieves the most significant attenuation: the peak pressure of the shock wave is reduced by 92.9%, and the maximum deformations of the front and rear panels are decreased by 53.6% and 65.3%, respectively, compared to the baseline. In contrast, the free surface condition (T2) shows negligible effects. The EPS alone (T3) and LRHS alone (T4) also provide considerable attenuation, with peak pressure reductions of 87~90% and 79~85%, respectively. The analysis indicates that the LRHS attenuates the HRAM loading via reflect shock wave and provides expansion space, while the EPS dissipates energy through plastic deformation and restricts cavitation development by compartmentalizing the fluid domain. Their combination yields a synergistic effect. The proposed method provides a promising integrated design for enhancing the survivability of fuel tank against coupled HRAM and explosion threats at a low volumetric penalty.
Fuel tanks of vehicles are vulnerable to both hydrodynamic ram (HRAM) and fuel explosion when subjected to high-speed projectile impacts. To mitigate this coupled mechanical-activational damage, a novel protection method was proposed, in which load-reducing hollow spheres (LRHS) and explosion-proof spheres (EPS) are filled in a hybrid manner inside the tank. The attenuation effect of these fillers on HRAM was investigated experimentally. A series of comparative tests were conducted using a 25 mm two-stage light gas gun. A 12.7 mm spherical steel projectile with a mass of about 8.45 g was launched at approximately 1100 m/s to impact a fluid-filled container under five different filling conditions : fully water-filled (T1, baseline), 94% water-filled with a free surface (T2), fully water-filled with EPS (T3, about 5% in volume), fully water-filled with 36 preset LRHS (T4, about 1% in volume), and mixed filling with both LRHS and EPS (T5, about 6% in volume). The impact velocity was measured by laser screens, the cavitation evolution inside the container was recorded by a high-speed camera, and the pressure-time histories were recorded by underwater free-field pressure sensors. After the tests, the failure modes of the two fillers were examined, and the maximum deformations of the front and rear panels were obtained by three-dimensional scanning. The results demonstrate that the mixed filling scheme (T5) achieves the most significant attenuation: the peak pressure of the shock wave is reduced by 92.9%, and the maximum deformations of the front and rear panels are decreased by 53.6% and 65.3%, respectively, compared to the baseline. In contrast, the free surface condition (T2) shows negligible effects. The EPS alone (T3) and LRHS alone (T4) also provide considerable attenuation, with peak pressure reductions of 87~90% and 79~85%, respectively. The analysis indicates that the LRHS attenuates the HRAM loading via reflect shock wave and provides expansion space, while the EPS dissipates energy through plastic deformation and restricts cavitation development by compartmentalizing the fluid domain. Their combination yields a synergistic effect. The proposed method provides a promising integrated design for enhancing the survivability of fuel tank against coupled HRAM and explosion threats at a low volumetric penalty.
, Available online ,
doi: 10.11883/bzycj-2026-0076
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Abstract:
Paper-based carbon fiber honeycombs exhibit advantages such as low density, high specific strength, and high specific stiffness. However, owing to the brittle nature of the cell-wall material, they are prone to local buckling and sudden failure under impact loading, which limits further improvement in their cushioning and energy-absorption performance. To address this issue, a shear thickening fluid-filled paper-based carbon fiber honeycomb (STF-CFH) composite structure is proposed in this study, in which a corn starch-based shear thickening fluid is introduced into the honeycomb cells. Drop-weight impact tests, high-speed photography, and coupled Eulerian–Lagrangian (CEL) finite element simulations were conducted to investigate the dynamic mechanical response, failure mode, and fluid–structure interaction enhancement mechanism of the composite structure. The results show that STF filling significantly improves the crushing stability of the paper-based carbon fiber honeycomb, transforming the failure mode from localized brittle failure to a more uniform global progressive crushing mode. Under an impact energy of 40 J, the mean crushing force and crushing force efficiency of the STF-CFH composite structure increase to 1.62 and 1.39 times those of the unfilled honeycomb, respectively. Under an impact energy of 80 J, the peak force decreases to 0.76 times that of the unfilled honeycomb, while the mean crushing force and crushing force efficiency increase to 1.81 and 2.38 times, respectively, demonstrating enhanced energy-absorption efficiency. Numerical results further indicate that, during impact, the STF inside the cells undergoes a sharp increase in viscosity under high shear, suppressing local instability of the honeycomb walls through lateral constraint and pressure transmission, and thereby promoting the participation of more cells in deformation and energy dissipation. The findings provide guidance for the design of lightweight adaptive honeycomb structures for impact protection.
Paper-based carbon fiber honeycombs exhibit advantages such as low density, high specific strength, and high specific stiffness. However, owing to the brittle nature of the cell-wall material, they are prone to local buckling and sudden failure under impact loading, which limits further improvement in their cushioning and energy-absorption performance. To address this issue, a shear thickening fluid-filled paper-based carbon fiber honeycomb (STF-CFH) composite structure is proposed in this study, in which a corn starch-based shear thickening fluid is introduced into the honeycomb cells. Drop-weight impact tests, high-speed photography, and coupled Eulerian–Lagrangian (CEL) finite element simulations were conducted to investigate the dynamic mechanical response, failure mode, and fluid–structure interaction enhancement mechanism of the composite structure. The results show that STF filling significantly improves the crushing stability of the paper-based carbon fiber honeycomb, transforming the failure mode from localized brittle failure to a more uniform global progressive crushing mode. Under an impact energy of 40 J, the mean crushing force and crushing force efficiency of the STF-CFH composite structure increase to 1.62 and 1.39 times those of the unfilled honeycomb, respectively. Under an impact energy of 80 J, the peak force decreases to 0.76 times that of the unfilled honeycomb, while the mean crushing force and crushing force efficiency increase to 1.81 and 2.38 times, respectively, demonstrating enhanced energy-absorption efficiency. Numerical results further indicate that, during impact, the STF inside the cells undergoes a sharp increase in viscosity under high shear, suppressing local instability of the honeycomb walls through lateral constraint and pressure transmission, and thereby promoting the participation of more cells in deformation and energy dissipation. The findings provide guidance for the design of lightweight adaptive honeycomb structures for impact protection.
, Available online ,
doi: 10.11883/bzycj-2025-0265
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Abstract:
The propagation of blast waves in urban buildings is influenced by architectural configurations, as the blast waves undergo complex reflection and diffraction phenomena on building surfaces, rendering empirical formulas inadequate for estimating surface loads. To investigate the propagation characteristics of near-field blast waves in urban buildings, an experimental study was conducted. Initially, a scaled test platform was established in a laboratory environment to measure blast wave loading within building clusters. Pressure sensors were employed to obtain pressure-time curves at multiple locations, including building surfaces and the ground gauges, under representative building configurations. Key characteristic parameters were acquired, including shock wave arrival time, positive duration time, peak pressure, and positive impulse. The distribution patterns of these parameters were systematically analyzed across various building surfaces and ground gauges, followed by quantitative comparisons with empirical formulas. Experimental results indicate that urban buildings exert significant attenuation and obstruction effects on blast wave propagation. The degree of parameter attenuation correlates not only with scaled distance but also with specific measurement locations and architectural arrangement patterns. The research results can provide guidance for the rapid assessment of the distribution of blast loads in urban buildings.
The propagation of blast waves in urban buildings is influenced by architectural configurations, as the blast waves undergo complex reflection and diffraction phenomena on building surfaces, rendering empirical formulas inadequate for estimating surface loads. To investigate the propagation characteristics of near-field blast waves in urban buildings, an experimental study was conducted. Initially, a scaled test platform was established in a laboratory environment to measure blast wave loading within building clusters. Pressure sensors were employed to obtain pressure-time curves at multiple locations, including building surfaces and the ground gauges, under representative building configurations. Key characteristic parameters were acquired, including shock wave arrival time, positive duration time, peak pressure, and positive impulse. The distribution patterns of these parameters were systematically analyzed across various building surfaces and ground gauges, followed by quantitative comparisons with empirical formulas. Experimental results indicate that urban buildings exert significant attenuation and obstruction effects on blast wave propagation. The degree of parameter attenuation correlates not only with scaled distance but also with specific measurement locations and architectural arrangement patterns. The research results can provide guidance for the rapid assessment of the distribution of blast loads in urban buildings.
, Available online ,
doi: 10.11883/bzycj-2026-0228
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Abstract:
Shale gas, as an important unconventional clean energy resource, plays a significant role in ensuring energy security and promoting low-carbon energy transition. Perforation is a key preliminary process for shale reservoir stimulation, and the quality of the perforation channel and the associated damage characteristics directly affect subsequent fracturing performance. To clarify the influence of bedding angle on shaped-charge jet penetration and fracture response in deep shale, a three-dimensional coupled numerical model consisting of a perforating charge, air domain, and shale target was established using ANSYS/LS-DYNA. A DP46HMX42-Y perforating charge was adopted, and numerical cases with non-bedded shale and bedded shale at angles of 0°, 15°, 30°, 45°, 60°, 75°, and 90° were considered. The ALE fluid-structure coupling algorithm was used to simulate the dynamic penetration process of the shaped-charge jet into shale. The jet velocity and morphology evolution, perforation-channel formation, damage distribution, and crack-inducing behavior were systematically analyzed. The results show that the bedding angle has a significant effect on jet penetration. At the same moment, the jet-head velocity generally increases with increasing bedding angle, and the 90° bedded shale exhibits the greatest penetration depth, approximately 10% higher than that of the non-bedded shale. The channel-volume results indicate that bedding structures promote the formation of larger perforation channels, with the most pronounced improvement observed in the 0° and 90° bedding cases. The damage-evolution results show that the total damage volume of bedded shale is generally smaller than that of non-bedded shale, and decreases with increasing bedding angle. Bedding planes exert a clear guiding effect on damage propagation, causing the damage zone to extend along the bedding direction and inducing secondary cracks near bedding interfaces. Further cross-sectional damage analysis indicates that the radius of the compression-shear damage zone is negatively correlated with penetration depth, while the maximum crack length decreases in a fluctuating manner as penetration depth increases. The cross-sectional damage area and fractal dimension also generally decrease with increasing penetration depth. These findings provide numerical guidance for optimizing perforation parameters and improving subsequent fracturing stimulation in deep shale reservoirs.
Shale gas, as an important unconventional clean energy resource, plays a significant role in ensuring energy security and promoting low-carbon energy transition. Perforation is a key preliminary process for shale reservoir stimulation, and the quality of the perforation channel and the associated damage characteristics directly affect subsequent fracturing performance. To clarify the influence of bedding angle on shaped-charge jet penetration and fracture response in deep shale, a three-dimensional coupled numerical model consisting of a perforating charge, air domain, and shale target was established using ANSYS/LS-DYNA. A DP46HMX42-Y perforating charge was adopted, and numerical cases with non-bedded shale and bedded shale at angles of 0°, 15°, 30°, 45°, 60°, 75°, and 90° were considered. The ALE fluid-structure coupling algorithm was used to simulate the dynamic penetration process of the shaped-charge jet into shale. The jet velocity and morphology evolution, perforation-channel formation, damage distribution, and crack-inducing behavior were systematically analyzed. The results show that the bedding angle has a significant effect on jet penetration. At the same moment, the jet-head velocity generally increases with increasing bedding angle, and the 90° bedded shale exhibits the greatest penetration depth, approximately 10% higher than that of the non-bedded shale. The channel-volume results indicate that bedding structures promote the formation of larger perforation channels, with the most pronounced improvement observed in the 0° and 90° bedding cases. The damage-evolution results show that the total damage volume of bedded shale is generally smaller than that of non-bedded shale, and decreases with increasing bedding angle. Bedding planes exert a clear guiding effect on damage propagation, causing the damage zone to extend along the bedding direction and inducing secondary cracks near bedding interfaces. Further cross-sectional damage analysis indicates that the radius of the compression-shear damage zone is negatively correlated with penetration depth, while the maximum crack length decreases in a fluctuating manner as penetration depth increases. The cross-sectional damage area and fractal dimension also generally decrease with increasing penetration depth. These findings provide numerical guidance for optimizing perforation parameters and improving subsequent fracturing stimulation in deep shale reservoirs.
, Available online ,
doi: 10.11883/bzycj-2026-0170
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Abstract:
The initiation delay time is one of the key parameters in engineering blasting and plays a significant role in regulating the fragmentation size. Accurately predicting the fragmentation size under different initiation delay times is of great importance for guiding blasting engineering. To investigate the influence of initiation delay time on fragmentation size and to achieve fragmentation prediction, field tests with different inter-hole delay times were conducted in the graded aggregate blasting operation at the Lianghekou Hydropower Station. The fragmentation size distribution characteristics under different delay times were obtained. The results indicate that the effect of initiation delay time on fragmentation size exhibits zonal characteristics: the variation in small-sized fragments is not obvious, while the mean fragment size changes significantly, initially decreasing and then increasing with the increase in initiation delay time. The optimal delay per meter is approximately 3.3 ms/m. On this basis, numerical simulations of different inter-hole delay times were carried out using the finite element method, and the results were compared with the experimental data. The variation patterns obtained from both methods were in strong agreement. Analysis of the stress wave propagation characteristics under different initiation delays reveals that the intrinsic mechanical mechanism affecting the mean fragment size is the superposition effect of stress waves caused by different inter-hole delays and the reflection from new free surfaces. Finally, based on the fragmentation size distribution characteristics under different delay times, mathematical relationships between delay time and both mean fragment size and uniformity coefficient were established. A time term was introduced into the KUZ-RAM model, and a blast fragmentation prediction model considering delay time was proposed. The modified KUZ-RAM model overcomes the limitation of existing fragmentation prediction models in accounting for the influence of delay time on fragmentation size, thereby improving the accuracy of fragmentation size distribution prediction under electronic detonator delay initiation conditions.
The initiation delay time is one of the key parameters in engineering blasting and plays a significant role in regulating the fragmentation size. Accurately predicting the fragmentation size under different initiation delay times is of great importance for guiding blasting engineering. To investigate the influence of initiation delay time on fragmentation size and to achieve fragmentation prediction, field tests with different inter-hole delay times were conducted in the graded aggregate blasting operation at the Lianghekou Hydropower Station. The fragmentation size distribution characteristics under different delay times were obtained. The results indicate that the effect of initiation delay time on fragmentation size exhibits zonal characteristics: the variation in small-sized fragments is not obvious, while the mean fragment size changes significantly, initially decreasing and then increasing with the increase in initiation delay time. The optimal delay per meter is approximately 3.3 ms/m. On this basis, numerical simulations of different inter-hole delay times were carried out using the finite element method, and the results were compared with the experimental data. The variation patterns obtained from both methods were in strong agreement. Analysis of the stress wave propagation characteristics under different initiation delays reveals that the intrinsic mechanical mechanism affecting the mean fragment size is the superposition effect of stress waves caused by different inter-hole delays and the reflection from new free surfaces. Finally, based on the fragmentation size distribution characteristics under different delay times, mathematical relationships between delay time and both mean fragment size and uniformity coefficient were established. A time term was introduced into the KUZ-RAM model, and a blast fragmentation prediction model considering delay time was proposed. The modified KUZ-RAM model overcomes the limitation of existing fragmentation prediction models in accounting for the influence of delay time on fragmentation size, thereby improving the accuracy of fragmentation size distribution prediction under electronic detonator delay initiation conditions.
, Available online ,
doi: 10.11883/bzycj-2026-0068
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Abstract:
Rapid and accurate prediction of blast loads on urban buildings is of great importance for post-disaster assessment following accidental urban explosions, including terrorist attacks and industrial explosion accidents, and for improving the comprehensive disaster-prevention and mitigation capability of cities. To enable rapid calculation of blast loads on the blast-facing surface of rigid buildings subjected to far-field explosions, an analytical calculation method was developed based on Hudson’s theoretical blast loading model incorporating rarefaction wave propagation. The original Hudson method was improved for moderate-intensity shock waves by revising the calculations of the incident wave wavelength and rarefaction wave propagation velocity. An incident pressure approximation was further introduced for long duration shock waves to correct the overestimated clearing effect once the calculated surface pressure fell below the incident pressure. In addition, symbolic regression, a supervised machine learning method, was employed to approximate the clearing pressure relation obtained from the Dewitt integral equation. An explicit expression for calculating the pressure-time history on the blast-facing surface was consequently established, avoiding repeated numerical evaluation of the original integral equation and improving the convenience of engineering calculations. The accuracy of the proposed method was evaluated through comparisons with numerical simulations and existing calculation methods. The method was then applied to investigate the spatial distribution of positive impulse over the blast-facing surface and to examine the effects of incident-wave characteristics and building dimensions on the impulse distribution. The results show that, for incident peak overpressures of approximately 100-500 kPa and positive-phase durations of approximately 0.5-2.0 s, the proposed method provides more accurate predictions of blast-facing surface pressure-time histories and impulses than the current standard method and the original Hudson method under most of the investigated conditions. Near the boundary of the investigated applicability range, corresponding to a peak overpressure of approximately 100 kPa, a positive phase duration of approximately 0.5 s, and a relatively large building, the prediction error of the proposed method can be greater than that of the original Hudson method; nevertheless, its deviation from the numerical simulation remains within 20 %. The method therefore provides a reliable calculation tool for rapid damage assessment and blast-resistant design of buildings subjected to far-field explosions.
Rapid and accurate prediction of blast loads on urban buildings is of great importance for post-disaster assessment following accidental urban explosions, including terrorist attacks and industrial explosion accidents, and for improving the comprehensive disaster-prevention and mitigation capability of cities. To enable rapid calculation of blast loads on the blast-facing surface of rigid buildings subjected to far-field explosions, an analytical calculation method was developed based on Hudson’s theoretical blast loading model incorporating rarefaction wave propagation. The original Hudson method was improved for moderate-intensity shock waves by revising the calculations of the incident wave wavelength and rarefaction wave propagation velocity. An incident pressure approximation was further introduced for long duration shock waves to correct the overestimated clearing effect once the calculated surface pressure fell below the incident pressure. In addition, symbolic regression, a supervised machine learning method, was employed to approximate the clearing pressure relation obtained from the Dewitt integral equation. An explicit expression for calculating the pressure-time history on the blast-facing surface was consequently established, avoiding repeated numerical evaluation of the original integral equation and improving the convenience of engineering calculations. The accuracy of the proposed method was evaluated through comparisons with numerical simulations and existing calculation methods. The method was then applied to investigate the spatial distribution of positive impulse over the blast-facing surface and to examine the effects of incident-wave characteristics and building dimensions on the impulse distribution. The results show that, for incident peak overpressures of approximately 100-500 kPa and positive-phase durations of approximately 0.5-2.0 s, the proposed method provides more accurate predictions of blast-facing surface pressure-time histories and impulses than the current standard method and the original Hudson method under most of the investigated conditions. Near the boundary of the investigated applicability range, corresponding to a peak overpressure of approximately 100 kPa, a positive phase duration of approximately 0.5 s, and a relatively large building, the prediction error of the proposed method can be greater than that of the original Hudson method; nevertheless, its deviation from the numerical simulation remains within 20 %. The method therefore provides a reliable calculation tool for rapid damage assessment and blast-resistant design of buildings subjected to far-field explosions.
, Available online ,
doi: 10.11883/bzycj-2026-0211
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Abstract:
To investigate the stress wave propagation mechanisms within curved shell structures during the separation of curved shell specimens by a ring-shaped detonation cord in an underwater environment, this study combines experimental testing and numerical simulation to systematically investigate the dynamic response of light-cured resin curved shell specimens with integrated skirts subjected to underwater explosion loading. Particular emphasis is placed on elucidating the propagation mechanisms of stress waves within the curved shell when a ring-shaped detonation cord embedded in the skirt is synchronously initiated using multiple initiation points. By comparing the stress wave propagation processes under different initiation configurations, the influence of the initiation mode on stress wave evolution, stress concentration behavior, and the dynamic response of the curved shell is comprehensively analyzed. Numerical simulations are further employed to reveal the transient evolution of the stress field and to clarify the underlying mechanisms governing stress wave propagation and convergence within the curved shell. The results demonstrate that different initiation modes significantly affect the propagation characteristics of stress waves within the curved shell, resulting in the formation of different numbers of stress concentration points. A distinct geometric relationship is observed among the apex of the curved shell, the stress concentration points, and the corresponding convergence points of the detonation waves generated by the ring-shaped detonation cord, all of which are consistently located on the same plane. This finding indicates a strong correlation between the locations of stress concentration and the initiation mode. Furthermore, as the number of initiation points increases, the number of stress concentration points increases correspondingly, whereas the peak stress at these locations decreases significantly. These findings provide a deeper understanding of stress wave propagation and stress concentration mechanisms in curved shell structures subjected to underwater explosion loading and offer valuable guidance for the design of explosive initiation networks for underwater blast-resistant structures and underwater separation devices with similar structural configurations.
To investigate the stress wave propagation mechanisms within curved shell structures during the separation of curved shell specimens by a ring-shaped detonation cord in an underwater environment, this study combines experimental testing and numerical simulation to systematically investigate the dynamic response of light-cured resin curved shell specimens with integrated skirts subjected to underwater explosion loading. Particular emphasis is placed on elucidating the propagation mechanisms of stress waves within the curved shell when a ring-shaped detonation cord embedded in the skirt is synchronously initiated using multiple initiation points. By comparing the stress wave propagation processes under different initiation configurations, the influence of the initiation mode on stress wave evolution, stress concentration behavior, and the dynamic response of the curved shell is comprehensively analyzed. Numerical simulations are further employed to reveal the transient evolution of the stress field and to clarify the underlying mechanisms governing stress wave propagation and convergence within the curved shell. The results demonstrate that different initiation modes significantly affect the propagation characteristics of stress waves within the curved shell, resulting in the formation of different numbers of stress concentration points. A distinct geometric relationship is observed among the apex of the curved shell, the stress concentration points, and the corresponding convergence points of the detonation waves generated by the ring-shaped detonation cord, all of which are consistently located on the same plane. This finding indicates a strong correlation between the locations of stress concentration and the initiation mode. Furthermore, as the number of initiation points increases, the number of stress concentration points increases correspondingly, whereas the peak stress at these locations decreases significantly. These findings provide a deeper understanding of stress wave propagation and stress concentration mechanisms in curved shell structures subjected to underwater explosion loading and offer valuable guidance for the design of explosive initiation networks for underwater blast-resistant structures and underwater separation devices with similar structural configurations.
, Available online ,
doi: 10.11883/bzycj-2026-0214
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Abstract:
The dynamic response, damage characteristics, and energy evolution of high-strength steel/aramid fiber-reinforced polymer (AFRP) composite target plates under close-in blast loading are important for understanding blast-resistance enhancement mechanisms and improving structural protective performance. In this study, close-in blast tests were conducted on Q460 high-strength steel/AFRP composite plates with different AFRP backing thicknesses. A single-camera stereo three-dimensional digital image correlation system was used to measure the full-field transient out-of-plane deformation of the rear surface, while three-dimensional scanning was employed to quantify the residual deformation and final damage morphology. Based on the experiments, an ALE fluid–structure interaction model was established in LS-DYNA and validated against the measured displacement fields, residual deflections, and AFRP tearing characteristics. Parametric analyses were further performed to investigate the effects of the front steel layer (FSL) yield strength and aramid backing layer (ABL) thickness on the blast response. The results showed that the unbacked high-strength steel plate underwent central petalling perforation, whereas the introduction of AFRP backing effectively suppressed perforation and changed the failure mode to non-perforated localized bulging. Increasing the AFRP backing thickness reduced both the residual deformation and damage extent of the composite target. Energy evolution analysis indicated that the structural energy was mainly concentrated in the FSL, while the ABL accounted for only a relatively small proportion of the total energy. Thus, the blast-resistance enhancement provided by the AFRP backing was mainly associated with constraining the localized large deformation and tearing development of the steel plate. For multilayer AFRP-backed configurations, the inner aramid layers adjacent to the steel plate accounted for a larger proportion of the total ABL energy than the outer layers. In addition, increasing the FSL yield strength and ABL thickness improved the blast resistance of the composite plates, whereas the incremental benefit of further increasing the backing thickness gradually diminished. These findings provide a reference for material selection and optimization of high-strength steel/AFRP composite blast-resistant structures.
The dynamic response, damage characteristics, and energy evolution of high-strength steel/aramid fiber-reinforced polymer (AFRP) composite target plates under close-in blast loading are important for understanding blast-resistance enhancement mechanisms and improving structural protective performance. In this study, close-in blast tests were conducted on Q460 high-strength steel/AFRP composite plates with different AFRP backing thicknesses. A single-camera stereo three-dimensional digital image correlation system was used to measure the full-field transient out-of-plane deformation of the rear surface, while three-dimensional scanning was employed to quantify the residual deformation and final damage morphology. Based on the experiments, an ALE fluid–structure interaction model was established in LS-DYNA and validated against the measured displacement fields, residual deflections, and AFRP tearing characteristics. Parametric analyses were further performed to investigate the effects of the front steel layer (FSL) yield strength and aramid backing layer (ABL) thickness on the blast response. The results showed that the unbacked high-strength steel plate underwent central petalling perforation, whereas the introduction of AFRP backing effectively suppressed perforation and changed the failure mode to non-perforated localized bulging. Increasing the AFRP backing thickness reduced both the residual deformation and damage extent of the composite target. Energy evolution analysis indicated that the structural energy was mainly concentrated in the FSL, while the ABL accounted for only a relatively small proportion of the total energy. Thus, the blast-resistance enhancement provided by the AFRP backing was mainly associated with constraining the localized large deformation and tearing development of the steel plate. For multilayer AFRP-backed configurations, the inner aramid layers adjacent to the steel plate accounted for a larger proportion of the total ABL energy than the outer layers. In addition, increasing the FSL yield strength and ABL thickness improved the blast resistance of the composite plates, whereas the incremental benefit of further increasing the backing thickness gradually diminished. These findings provide a reference for material selection and optimization of high-strength steel/AFRP composite blast-resistant structures.
, Available online ,
doi: 10.11883/bzycj-2026-0131
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Abstract:
Abstract: To systematically characterize the dynamic mechanical behavior of 30CrMnSiNi2A ultra-high-strength steel under different stress states, strain rates, and temperatures, and to evaluate its ballistic resistance and failure characteristics under flat-nosed projectile impact, a comprehensive experimental and numerical investigation was conducted. A modified Johnson-Cook (MJC) plasticity model was employed to describe the plastic response, in which the strain-hardening term was represented by a linear combination of the Ludwik and Voce laws, together with strain-rate hardening and temperature-softening terms. An extended Xue-Wierzbicki (XW) fracture criterion incorporating stress triaxiality, the normalized third invariant of the deviatoric stress tensor (Lode parameter), strain rate, and temperature was adopted to characterize ductile fracture. The material parameters were calibrated using a combined experimental and finite-element-based identification procedure. Quasi-static tests on smooth round-bar, notched round-bar, flat shear, and plane-strain specimens were performed to cover different stress states. Split Hopkinson pressure bar compression tests at strain rates of 1063.8~4753.8 s⁻¹, high-rate tensile tests at 25~1000 s⁻¹, and elevated-temperature tensile tests from 200 to 800 °C were further conducted to characterize strain-rate and temperature effects. Digital image correlation was used to measure local deformation and strain fields in the shear, plane-strain, and high-rate tensile specimens. The quasi-static hardening parameters were determined from the smooth round-bar tensile response, with one weighting parameter identified through inverse optimization by coupling Isight with ABAQUS. The strain-rate and thermal-softening parameters were calibrated from the measured yield stresses at different strain rates and temperatures. For fracture calibration, finite element simulations of the smooth and notched round-bar, shear, and plane-strain tests were used to extract the histories of equivalent plastic strain, stress triaxiality, and Lode parameter at the fracture location, from which the stress-state-dependent fracture locus was established. The strain-rate- and temperature-dependent fracture parameters were subsequently determined from the high-rate and elevated-temperature tensile tests. Ballistic resistance was evaluated through 13 impact tests using nominally 6-mm-diameter flat-nosed projectiles against 4-mm-thick steel targets at impact velocities of 196.2~413.9 m/s. The ballistic limit was obtained by fitting the initial–residual velocity data using the Lambert-Jonas relationship. Axisymmetric finite element simulations were finally performed in ABAQUS to evaluate the predictive capability of the calibrated material model and to quantify the influence of local element size. The results show pronounced strain-rate strengthening and thermal softening of 30CrMnSiNi2A steel. As the strain rate increased from the quasi-static regime to 4547.8 s⁻¹, the yield strength increased from 1095.6 to 1497.0 MPa, whereas a marked loss of strength occurred at temperatures of 600 °C and above. The ductile fracture response exhibited a pronounced dependence on stress state and the Lode parameter. Relative to uniaxial tension, the fracture strains under shear and plane-strain tension decreased by 35.8% and 63.9%, respectively. The Lambert-Jonas fit to the ballistic-test data yielded a ballistic limit of 209.9 m/s, and shear plugging was identified as the dominant target failure mode. The numerical ballistic limit showed significant mesh-size dependence: local element sizes of 75 and 50 μm resulted in predicted ballistic limits of 213.7 and 205.0 m/s, corresponding to deviations of +1.8% and −2.4% from the experimental fit, respectively. The dominant shear-plugging failure mode was also reproduced numerically. The results demonstrate that the systematically calibrated MJC plasticity model combined with the extended XW fracture criterion provides an effective description of the dynamic plasticity and stress-state-dependent ductile fracture of 30CrMnSiNi2A steel. With an appropriately refined local mesh, the modeling framework can reasonably predict the ballistic limit and dominant shear-plugging failure of thin 30CrMnSiNi2A steel targets subjected to flat-nosed projectile impact.
Abstract: To systematically characterize the dynamic mechanical behavior of 30CrMnSiNi2A ultra-high-strength steel under different stress states, strain rates, and temperatures, and to evaluate its ballistic resistance and failure characteristics under flat-nosed projectile impact, a comprehensive experimental and numerical investigation was conducted. A modified Johnson-Cook (MJC) plasticity model was employed to describe the plastic response, in which the strain-hardening term was represented by a linear combination of the Ludwik and Voce laws, together with strain-rate hardening and temperature-softening terms. An extended Xue-Wierzbicki (XW) fracture criterion incorporating stress triaxiality, the normalized third invariant of the deviatoric stress tensor (Lode parameter), strain rate, and temperature was adopted to characterize ductile fracture. The material parameters were calibrated using a combined experimental and finite-element-based identification procedure. Quasi-static tests on smooth round-bar, notched round-bar, flat shear, and plane-strain specimens were performed to cover different stress states. Split Hopkinson pressure bar compression tests at strain rates of 1063.8~4753.8 s⁻¹, high-rate tensile tests at 25~1000 s⁻¹, and elevated-temperature tensile tests from 200 to 800 °C were further conducted to characterize strain-rate and temperature effects. Digital image correlation was used to measure local deformation and strain fields in the shear, plane-strain, and high-rate tensile specimens. The quasi-static hardening parameters were determined from the smooth round-bar tensile response, with one weighting parameter identified through inverse optimization by coupling Isight with ABAQUS. The strain-rate and thermal-softening parameters were calibrated from the measured yield stresses at different strain rates and temperatures. For fracture calibration, finite element simulations of the smooth and notched round-bar, shear, and plane-strain tests were used to extract the histories of equivalent plastic strain, stress triaxiality, and Lode parameter at the fracture location, from which the stress-state-dependent fracture locus was established. The strain-rate- and temperature-dependent fracture parameters were subsequently determined from the high-rate and elevated-temperature tensile tests. Ballistic resistance was evaluated through 13 impact tests using nominally 6-mm-diameter flat-nosed projectiles against 4-mm-thick steel targets at impact velocities of 196.2~413.9 m/s. The ballistic limit was obtained by fitting the initial–residual velocity data using the Lambert-Jonas relationship. Axisymmetric finite element simulations were finally performed in ABAQUS to evaluate the predictive capability of the calibrated material model and to quantify the influence of local element size. The results show pronounced strain-rate strengthening and thermal softening of 30CrMnSiNi2A steel. As the strain rate increased from the quasi-static regime to 4547.8 s⁻¹, the yield strength increased from 1095.6 to 1497.0 MPa, whereas a marked loss of strength occurred at temperatures of 600 °C and above. The ductile fracture response exhibited a pronounced dependence on stress state and the Lode parameter. Relative to uniaxial tension, the fracture strains under shear and plane-strain tension decreased by 35.8% and 63.9%, respectively. The Lambert-Jonas fit to the ballistic-test data yielded a ballistic limit of 209.9 m/s, and shear plugging was identified as the dominant target failure mode. The numerical ballistic limit showed significant mesh-size dependence: local element sizes of 75 and 50 μm resulted in predicted ballistic limits of 213.7 and 205.0 m/s, corresponding to deviations of +1.8% and −2.4% from the experimental fit, respectively. The dominant shear-plugging failure mode was also reproduced numerically. The results demonstrate that the systematically calibrated MJC plasticity model combined with the extended XW fracture criterion provides an effective description of the dynamic plasticity and stress-state-dependent ductile fracture of 30CrMnSiNi2A steel. With an appropriately refined local mesh, the modeling framework can reasonably predict the ballistic limit and dominant shear-plugging failure of thin 30CrMnSiNi2A steel targets subjected to flat-nosed projectile impact.
, Available online ,
doi: 10.11883/bzycj-2026-0224
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Abstract:
This study fabricates origami-inspired sandwich panels using 3D printing technology and investigates their blast resistance through explosion experiments. By examining different core layers, panel thicknesses, and equivalent loads, it is found that increasing the number of core layers enhances the specific energy absorption of the sandwich panel, while ribbed designs improve the stiffness of the core layer, thereby effectively enhancing the panel's resistance to deformation. Compared with uniformly distributed structures, gradient-designed cores significantly improve energy absorption capacity, offering an effective approach to enhance blast resistance. Overall, a gradient design with higher density in the upper layer of the origami core provides optimal protective performance under blast loading. This research offers a novel approach for applying origami structures in blast-resistant protective panels.
This study fabricates origami-inspired sandwich panels using 3D printing technology and investigates their blast resistance through explosion experiments. By examining different core layers, panel thicknesses, and equivalent loads, it is found that increasing the number of core layers enhances the specific energy absorption of the sandwich panel, while ribbed designs improve the stiffness of the core layer, thereby effectively enhancing the panel's resistance to deformation. Compared with uniformly distributed structures, gradient-designed cores significantly improve energy absorption capacity, offering an effective approach to enhance blast resistance. Overall, a gradient design with higher density in the upper layer of the origami core provides optimal protective performance under blast loading. This research offers a novel approach for applying origami structures in blast-resistant protective panels.
, Available online ,
doi: 10.11883/bzycj-2026-0117
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Abstract:
When subjected to bridge-deck contact explosions, reinforced concrete (RC) box girders with closed cross-sections are exposed not only to external blast loads but also to internal loads generated by shock waves entering the cell after deck perforation. To investigate the propagation mechanism of these inflowing shock waves and the resulting distribution of internal blast loads, the adopted finite element method was first validated against existing RC slab contact-explosion tests and confined internal-explosion tests by comparing both local damage characteristics and shock-wave propagation behavior. The validated method was then used to investigate shock-wave evolution and bottom-slab blast load distributions in a prototype box girder under four representative threat levels, as well as the influence of end boundary conditions. The results show that shock-wave propagation comprises four stages: leakage into the cell, regular reflection, irregular reflection, and planar-wave propagation. The blast loads on the inner surfaces of the box girder generally decrease with increasing propagation distance. Transversely, wave convergence significantly amplifies the loads near the cell corners. Longitudinally, multiple reflections and wavefront reshaping transform the shock wave into an approximately planar wave, producing a propagation pattern similar to that observed in tunnel explosions. Compared with the open-end condition, the closed-end condition causes full cross-sectional reflection of the planar wave at the end plate, thereby increasing the load intensity in the adjacent region. Finally, empirical predictive models for the peak overpressure and positive impulse on the bottom slab were developed through regression analysis, enabling rapid estimation of internal blast loads on RC box girders subjected to bridge-deck contact explosions.
When subjected to bridge-deck contact explosions, reinforced concrete (RC) box girders with closed cross-sections are exposed not only to external blast loads but also to internal loads generated by shock waves entering the cell after deck perforation. To investigate the propagation mechanism of these inflowing shock waves and the resulting distribution of internal blast loads, the adopted finite element method was first validated against existing RC slab contact-explosion tests and confined internal-explosion tests by comparing both local damage characteristics and shock-wave propagation behavior. The validated method was then used to investigate shock-wave evolution and bottom-slab blast load distributions in a prototype box girder under four representative threat levels, as well as the influence of end boundary conditions. The results show that shock-wave propagation comprises four stages: leakage into the cell, regular reflection, irregular reflection, and planar-wave propagation. The blast loads on the inner surfaces of the box girder generally decrease with increasing propagation distance. Transversely, wave convergence significantly amplifies the loads near the cell corners. Longitudinally, multiple reflections and wavefront reshaping transform the shock wave into an approximately planar wave, producing a propagation pattern similar to that observed in tunnel explosions. Compared with the open-end condition, the closed-end condition causes full cross-sectional reflection of the planar wave at the end plate, thereby increasing the load intensity in the adjacent region. Finally, empirical predictive models for the peak overpressure and positive impulse on the bottom slab were developed through regression analysis, enabling rapid estimation of internal blast loads on RC box girders subjected to bridge-deck contact explosions.
, Available online ,
doi: 10.11883/bzycj-2026-0154
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Abstract:
Acetylene, as a fundamental raw material for industrial processing and the synthesis of organic products, is highly prone to explosion accidents when exposed to open flames. To investigate the inhibitory effects of carbonates on the explosion characteristics of acetylene, sodium carbonate and sodium bicarbonate powders were selected as explosion inhibitors. The 20 L spherical explosion device and the 5 L dust explosion flame propagation testing device were employed respectively to study the inhibitory effects of sodium carbonate and sodium bicarbonate powders on the explosion overpressure and flame propagation characteristics of acetylene. Combined with the results of Chemkin numerical simulations, the explosion suppression mechanisms of these two powders on acetylene explosions were elucidated. The experimental results show that when the concentrations of sodium carbonate and sodium bicarbonate are both 1500 g/m3, the explosion pressure of acetylene is reduced by 34.88% and 32.56% respectively, the explosion pressure rise rate is reduced by 51.35% and 54.9% respectively, and the continuity of the acetylene explosion flame structure is significantly decreased. The time for the flame to reach the top of the pipeline is extended by 120% and 130% respectively, and the average propagation speed is reduced by 54.54% and 56.52% respectively. The inhibitory effects of both powders are remarkable.The numerical simulation results indicate that as pyrolytic endothermic powders, sodium carbonate and sodium bicarbonate can effectively reduce the temperature of the reaction system. Meanwhile, the generated NaOH can combine with the high - activity free radicals in the reaction system to form stable products, thus achieving the explosion suppression effect. However, due to the difference in the concentration of NaOH generated by the pyrolysis of the two powders, the inhibitory effect of sodium bicarbonate is ultimately better than that of sodium carbonate.The research results are of great significance for a deeper understanding of the essence of acetylene explosions. They can contribute to the optimization of acetylene explosion suppression technology and further ensure the safe and efficient industrial production in China.
Acetylene, as a fundamental raw material for industrial processing and the synthesis of organic products, is highly prone to explosion accidents when exposed to open flames. To investigate the inhibitory effects of carbonates on the explosion characteristics of acetylene, sodium carbonate and sodium bicarbonate powders were selected as explosion inhibitors. The 20 L spherical explosion device and the 5 L dust explosion flame propagation testing device were employed respectively to study the inhibitory effects of sodium carbonate and sodium bicarbonate powders on the explosion overpressure and flame propagation characteristics of acetylene. Combined with the results of Chemkin numerical simulations, the explosion suppression mechanisms of these two powders on acetylene explosions were elucidated. The experimental results show that when the concentrations of sodium carbonate and sodium bicarbonate are both 1500 g/m3, the explosion pressure of acetylene is reduced by 34.88% and 32.56% respectively, the explosion pressure rise rate is reduced by 51.35% and 54.9% respectively, and the continuity of the acetylene explosion flame structure is significantly decreased. The time for the flame to reach the top of the pipeline is extended by 120% and 130% respectively, and the average propagation speed is reduced by 54.54% and 56.52% respectively. The inhibitory effects of both powders are remarkable.The numerical simulation results indicate that as pyrolytic endothermic powders, sodium carbonate and sodium bicarbonate can effectively reduce the temperature of the reaction system. Meanwhile, the generated NaOH can combine with the high - activity free radicals in the reaction system to form stable products, thus achieving the explosion suppression effect. However, due to the difference in the concentration of NaOH generated by the pyrolysis of the two powders, the inhibitory effect of sodium bicarbonate is ultimately better than that of sodium carbonate.The research results are of great significance for a deeper understanding of the essence of acetylene explosions. They can contribute to the optimization of acetylene explosion suppression technology and further ensure the safe and efficient industrial production in China.
, Available online ,
doi: 10.11883/bzycj-2026-0065
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Abstract:
Abstract: High-intensity impact loads experienced by a projectile during high-speed water entry can induce pronounced dynamic structural responses and deformation, and may further lead to structural damage or failure. Therefore, investigating this process is of great significance. To reveal the fluid–structure interaction characteristics and the deformation mechanism of the tail structure of a projectile equipped with a tail fairing, a numerical simulation based on the arbitrary Lagrangian–Eulerian (ALE) method was conducted for its water-entry process at a velocity of 40 m/s. The reliability and accuracy of the numerical model were validated through comparisons with experimental results and grid-independence verification. In the model, the water and air domains were described using an Eulerian formulation, while the projectile structure was modeled using a Lagrangian formulation. The compressibility of water and air was considered through corresponding equations of state, and the projectile material was defined using an elastoplastic constitutive model. The fluid–structure interaction between the projectile and the surrounding fluid was realized using a penalty-based coupling algorithm. To improve the stability and reliability of the coupling calculation, different penalty factors were compared, and the acceleration response and sliding interface energy were analyzed to determine an appropriate coupling parameter. A three-dimensional computational domain containing both water and air was established, and local mesh refinement was applied to the impact region and key structural regions of the tail fairing. The reliability of the numerical model was validated by comparing the simulated cavity morphology, projectile displacement, and projectile velocity with experimental results. Meanwhile, a grid-independence study was conducted to balance computational accuracy and efficiency. Based on the validated numerical model, the effects of entry angle and angle of attack on cavity evolution, impact load, stress-wave transmission, and deformation of the tail fairing were systematically investigated. The results indicate that, as the entry angle decreases, the cavity becomes increasingly asymmetric, accompanied by more complex free-surface deformation and cavitation phenomena, while the overall impact load on the projectile decreases accordingly. The deformation of the tail fairing is jointly governed by stress-wave propagation and cavitation effects, exhibiting a non-monotonic dependence on the entry angle: it first decreases and then increases, reaching a minimum at an entry angle of 60°. For oblique entry with a positive angle of attack, the cavity asymmetry is stronger than that under a negative angle of attack, and the peak acceleration decreases with increasing angle of attack. Under negative angles of attack, the peak acceleration first decreases and then increases as the absolute value of the angle of attack grows. A sufficiently large angle of attack can trigger secondary tail re-entry, producing a “tail-slap effect” and a second acceleration peak, which is more pronounced for positive angles of attack. In addition, a positive angle of attack markedly increases the deformation of the tail fairing, whereas a small negative angle of attack can reduce the deformation; however, the deformation increases again as the magnitude of the negative angle of attack further increases.
Abstract: High-intensity impact loads experienced by a projectile during high-speed water entry can induce pronounced dynamic structural responses and deformation, and may further lead to structural damage or failure. Therefore, investigating this process is of great significance. To reveal the fluid–structure interaction characteristics and the deformation mechanism of the tail structure of a projectile equipped with a tail fairing, a numerical simulation based on the arbitrary Lagrangian–Eulerian (ALE) method was conducted for its water-entry process at a velocity of 40 m/s. The reliability and accuracy of the numerical model were validated through comparisons with experimental results and grid-independence verification. In the model, the water and air domains were described using an Eulerian formulation, while the projectile structure was modeled using a Lagrangian formulation. The compressibility of water and air was considered through corresponding equations of state, and the projectile material was defined using an elastoplastic constitutive model. The fluid–structure interaction between the projectile and the surrounding fluid was realized using a penalty-based coupling algorithm. To improve the stability and reliability of the coupling calculation, different penalty factors were compared, and the acceleration response and sliding interface energy were analyzed to determine an appropriate coupling parameter. A three-dimensional computational domain containing both water and air was established, and local mesh refinement was applied to the impact region and key structural regions of the tail fairing. The reliability of the numerical model was validated by comparing the simulated cavity morphology, projectile displacement, and projectile velocity with experimental results. Meanwhile, a grid-independence study was conducted to balance computational accuracy and efficiency. Based on the validated numerical model, the effects of entry angle and angle of attack on cavity evolution, impact load, stress-wave transmission, and deformation of the tail fairing were systematically investigated. The results indicate that, as the entry angle decreases, the cavity becomes increasingly asymmetric, accompanied by more complex free-surface deformation and cavitation phenomena, while the overall impact load on the projectile decreases accordingly. The deformation of the tail fairing is jointly governed by stress-wave propagation and cavitation effects, exhibiting a non-monotonic dependence on the entry angle: it first decreases and then increases, reaching a minimum at an entry angle of 60°. For oblique entry with a positive angle of attack, the cavity asymmetry is stronger than that under a negative angle of attack, and the peak acceleration decreases with increasing angle of attack. Under negative angles of attack, the peak acceleration first decreases and then increases as the absolute value of the angle of attack grows. A sufficiently large angle of attack can trigger secondary tail re-entry, producing a “tail-slap effect” and a second acceleration peak, which is more pronounced for positive angles of attack. In addition, a positive angle of attack markedly increases the deformation of the tail fairing, whereas a small negative angle of attack can reduce the deformation; however, the deformation increases again as the magnitude of the negative angle of attack further increases.
, Available online ,
doi: 10.11883/bzycj-2026-0103
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Abstract:
To address the adverse effects of contaminants generated by mixing and combustion in the hydrogen-air contact region of the shock tube on both the effective test time and test gas quality in a hydrogen-driven shock tunnel, a nitrogen isolation operating mode was proposed. Numerical simulations were conducted to investigate the flow field under typical operating conditions of the shock tunnel. The quasi-one-dimensional thermochemical non-equilibrium Navier-Stokes equations were solved, where a cubic equation of state was employed to evaluate the thermodynamic properties of high-temperature gases. The wall friction and heat transfer along the tube, as well as the thermochemical non-equilibrium effects, were comprehensively considered. The flow field characteristics under two configurations, namely direct hydrogen-air contact operation and isobaric nitrogen isolation operation, were compared, covering incident shock Mach number, onset and evolution of mixing-induced combustion, as well as pressure, temperature and species distribution in the stagnation chamber of the shock tube. On this basis, the influence of the nitrogen isolation mode on the flow field characteristics of the shock tunnel was clarified. The results show that nitrogen isolation has little effect on the incident shock Mach number at the end of the shock tube, and exerts no notable impact on the tunnel’s capability to reproduce total temperature and total pressure in terms of shock strength. The oscillation amplitude of the gas pressure curve in the stagnation chamber is reduced, and the pressure stabilizes earlier, which slightly prolongs the effective test time. The addition of a nitrogen isolation section effectively suppresses combustion inside the shock tunnel. This is mainly manifested in a significant reduction in both the concentration and axial distribution width of water species along the shock tube, as well as a marked decrease in water species concentration at the monitoring point in the stagnation chamber at the end of the shock tube. Meanwhile, it effectively inhibits the sudden rise in the stagnation chamber temperature curve caused by combustion heat release. Under the typical condition of hydrogen at 50 MPa driving air at 0.1 MPa, setting the nitrogen isolation length to approximately one-third of the total length of the low-pressure driven section can achieve satisfactory suppression of hydrogen-oxygen combustion while avoiding excessive loss of available test air caused by an overly long nitrogen isolation section. Keywords: shock tunnel; shock tube; quasi-one-dimensional numerical simulation; mixing and combustion
To address the adverse effects of contaminants generated by mixing and combustion in the hydrogen-air contact region of the shock tube on both the effective test time and test gas quality in a hydrogen-driven shock tunnel, a nitrogen isolation operating mode was proposed. Numerical simulations were conducted to investigate the flow field under typical operating conditions of the shock tunnel. The quasi-one-dimensional thermochemical non-equilibrium Navier-Stokes equations were solved, where a cubic equation of state was employed to evaluate the thermodynamic properties of high-temperature gases. The wall friction and heat transfer along the tube, as well as the thermochemical non-equilibrium effects, were comprehensively considered. The flow field characteristics under two configurations, namely direct hydrogen-air contact operation and isobaric nitrogen isolation operation, were compared, covering incident shock Mach number, onset and evolution of mixing-induced combustion, as well as pressure, temperature and species distribution in the stagnation chamber of the shock tube. On this basis, the influence of the nitrogen isolation mode on the flow field characteristics of the shock tunnel was clarified. The results show that nitrogen isolation has little effect on the incident shock Mach number at the end of the shock tube, and exerts no notable impact on the tunnel’s capability to reproduce total temperature and total pressure in terms of shock strength. The oscillation amplitude of the gas pressure curve in the stagnation chamber is reduced, and the pressure stabilizes earlier, which slightly prolongs the effective test time. The addition of a nitrogen isolation section effectively suppresses combustion inside the shock tunnel. This is mainly manifested in a significant reduction in both the concentration and axial distribution width of water species along the shock tube, as well as a marked decrease in water species concentration at the monitoring point in the stagnation chamber at the end of the shock tube. Meanwhile, it effectively inhibits the sudden rise in the stagnation chamber temperature curve caused by combustion heat release. Under the typical condition of hydrogen at 50 MPa driving air at 0.1 MPa, setting the nitrogen isolation length to approximately one-third of the total length of the low-pressure driven section can achieve satisfactory suppression of hydrogen-oxygen combustion while avoiding excessive loss of available test air caused by an overly long nitrogen isolation section. Keywords: shock tunnel; shock tube; quasi-one-dimensional numerical simulation; mixing and combustion
, Available online ,
doi: 10.11883/bzycj-2026-0191
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Abstract:
Far-field shock waves induced by large-scale powerful explosions are characterized by long positive pressure duration, large impulse and high dynamic pressure. Under the action of such long-duration explosion waves, structures are not only subjected to overpressure, but the effect of dynamic pressure (explosion-induced wind) should also be taken into consideration. Columnar structures and members with rectangular cross-sections are widely applied in engineering practice, yet their load characteristics and flow field features under the action of long-duration explosion waves remain unclear. Aiming at the diffraction problem of long-duration explosion waves around rectangular columns, this paper adopts a numerical simulation method, incorporates the influences of positive pressure duration (<italic>td</italic> = 50 ms~2000 ms) and the width-to-height ratio of rectangular columns (<italic>B</italic>/<italic>D</italic> = 0.5~2.5), investigates the variation law of the drag force of rectangular columns and the time history of their impulse, analyzes the distribution characteristics of reflected overpressure on the surface of rectangular columns, and clarifies the evolution process and interaction mechanism of explosion waves and flow field structures. The research results show that the drag coefficient of rectangular columns differs significantly from the empirical values in the field of wind engineering, and it is less affected by the width-to-height ratio but more significantly influenced by the positive pressure duration. With the increase of positive pressure duration, the drag coefficient of rectangular columns under all width-to-height ratio conditions shows a variation trend of decreasing first, then increasing, and finally tending to be stable. The flow field structure around the rectangular column exhibits diverse configurations under different positive pressure durations, evolving from a symmetric wake to a distinctly asymmetric distribution as the duration increases.
Far-field shock waves induced by large-scale powerful explosions are characterized by long positive pressure duration, large impulse and high dynamic pressure. Under the action of such long-duration explosion waves, structures are not only subjected to overpressure, but the effect of dynamic pressure (explosion-induced wind) should also be taken into consideration. Columnar structures and members with rectangular cross-sections are widely applied in engineering practice, yet their load characteristics and flow field features under the action of long-duration explosion waves remain unclear. Aiming at the diffraction problem of long-duration explosion waves around rectangular columns, this paper adopts a numerical simulation method, incorporates the influences of positive pressure duration (<italic>td</italic> = 50 ms~2000 ms) and the width-to-height ratio of rectangular columns (<italic>B</italic>/<italic>D</italic> = 0.5~2.5), investigates the variation law of the drag force of rectangular columns and the time history of their impulse, analyzes the distribution characteristics of reflected overpressure on the surface of rectangular columns, and clarifies the evolution process and interaction mechanism of explosion waves and flow field structures. The research results show that the drag coefficient of rectangular columns differs significantly from the empirical values in the field of wind engineering, and it is less affected by the width-to-height ratio but more significantly influenced by the positive pressure duration. With the increase of positive pressure duration, the drag coefficient of rectangular columns under all width-to-height ratio conditions shows a variation trend of decreasing first, then increasing, and finally tending to be stable. The flow field structure around the rectangular column exhibits diverse configurations under different positive pressure durations, evolving from a symmetric wake to a distinctly asymmetric distribution as the duration increases.
, Available online ,
doi: 10.11883/bzycj-2026-0122
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Abstract:
To address the engineering problem of tubing-string and downhole-tool failures induced by transient pressure fluctuations during perforating operations in ultra-deep wells, this study moves beyond the limitation of analyses based on a single peak load. On the basis of transient pressure evolution simulation throughout the entire perforation process, a dynamic model of the perforating string is established by coupling the full-cycle effects of detonation pressure and dynamic underbalance pressure. Field test data from Well X1 in the Junggar Basin are used to validate the model accuracy. The relative error between the calculated and measured acceleration peaks is 8.62%, indicating that the model can effectively capture the acceleration peak and main oscillation characteristics during the early strong-impact stage of perforation. Taking an ultra-deep well in the Sichuan Basin as an example, the propagation and evolution characteristics of stress waves in the perforating string, the acceleration response behavior, and their sensitivity to key operating parameters are systematically analyzed. The results show that the detonation pressure peak directly governs the axial compressive stress level of the string, whereas the dynamic underbalance pressure trough plays a decisive role in axial tensile stress. Strong reflection and superposition of stress waves occur at the fixed packer end, making the packer and adjacent connection regions high-risk zones for tensile peak amplification, threaded-connection failure, and packer mandrel damage. This study establishes a relatively complete analytical framework from load evolution and dynamic response to failure-risk identification, providing a theoretical basis for tubing-string integrity evaluation throughout the entire perforation process.
To address the engineering problem of tubing-string and downhole-tool failures induced by transient pressure fluctuations during perforating operations in ultra-deep wells, this study moves beyond the limitation of analyses based on a single peak load. On the basis of transient pressure evolution simulation throughout the entire perforation process, a dynamic model of the perforating string is established by coupling the full-cycle effects of detonation pressure and dynamic underbalance pressure. Field test data from Well X1 in the Junggar Basin are used to validate the model accuracy. The relative error between the calculated and measured acceleration peaks is 8.62%, indicating that the model can effectively capture the acceleration peak and main oscillation characteristics during the early strong-impact stage of perforation. Taking an ultra-deep well in the Sichuan Basin as an example, the propagation and evolution characteristics of stress waves in the perforating string, the acceleration response behavior, and their sensitivity to key operating parameters are systematically analyzed. The results show that the detonation pressure peak directly governs the axial compressive stress level of the string, whereas the dynamic underbalance pressure trough plays a decisive role in axial tensile stress. Strong reflection and superposition of stress waves occur at the fixed packer end, making the packer and adjacent connection regions high-risk zones for tensile peak amplification, threaded-connection failure, and packer mandrel damage. This study establishes a relatively complete analytical framework from load evolution and dynamic response to failure-risk identification, providing a theoretical basis for tubing-string integrity evaluation throughout the entire perforation process.
, Available online ,
doi: 10.11883/bzycj-2026-0089
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Abstract:
To overcome the long-standing trade-off between strength and ductility in copper alloys, this study proposes the construction of a gradient-grained layered heterostructure using explosive welding. Three plates of a Cu-Ni-Si-Cr alloy with distinct grain sizes—fine, medium, and coarse—were prepared by solution treatment and subsequently bonded into a three-layer composite plate through two successive explosive welding processes. The microstructure, mechanical properties, and deformation behavior of the composite were systematically characterized using optical microscopy, scanning electron microscopy, electron backscatter diffraction, and digital image correlation. The results show that the bonding interfaces exhibit a typical wavy morphology, accompanied by localized melted zones and adiabatic shear bands. The composite achieves a yield strength of 402.5 MPa, which exceeds the value of 304.0 MPa predicted by the rule of mixtures, while maintaining an elongation to fracture of 16.8%. Quantitative strengthening analysis reveals that dislocation strengthening contributes the most to the yield strength, primarily due to the high-density dislocations introduced by the intense impact and deformation during explosive welding. Fracture analysis indicates significant interlayer deformation incompatibility, with crack initiation occurring at interface 2. Shear bands and thickness reduction are observed in the fine- and medium-grained layers, but not in the coarse-grained layer. Digital image correlation confirms the presence of a pronounced strain gradient and strain localization along the thickness direction during tensile loading, which ultimately drives crack initiation and propagation at interface 2. This study elucidates the critical role of hetero-interfaces in governing interlayer deformation partitioning and failure in gradient-grained heterogeneous Cu-Ni-Si-Cr alloy composites, and provides a viable approach for fabricating high-performance layered gradient heterogeneous copper alloys via explosive welding.
To overcome the long-standing trade-off between strength and ductility in copper alloys, this study proposes the construction of a gradient-grained layered heterostructure using explosive welding. Three plates of a Cu-Ni-Si-Cr alloy with distinct grain sizes—fine, medium, and coarse—were prepared by solution treatment and subsequently bonded into a three-layer composite plate through two successive explosive welding processes. The microstructure, mechanical properties, and deformation behavior of the composite were systematically characterized using optical microscopy, scanning electron microscopy, electron backscatter diffraction, and digital image correlation. The results show that the bonding interfaces exhibit a typical wavy morphology, accompanied by localized melted zones and adiabatic shear bands. The composite achieves a yield strength of 402.5 MPa, which exceeds the value of 304.0 MPa predicted by the rule of mixtures, while maintaining an elongation to fracture of 16.8%. Quantitative strengthening analysis reveals that dislocation strengthening contributes the most to the yield strength, primarily due to the high-density dislocations introduced by the intense impact and deformation during explosive welding. Fracture analysis indicates significant interlayer deformation incompatibility, with crack initiation occurring at interface 2. Shear bands and thickness reduction are observed in the fine- and medium-grained layers, but not in the coarse-grained layer. Digital image correlation confirms the presence of a pronounced strain gradient and strain localization along the thickness direction during tensile loading, which ultimately drives crack initiation and propagation at interface 2. This study elucidates the critical role of hetero-interfaces in governing interlayer deformation partitioning and failure in gradient-grained heterogeneous Cu-Ni-Si-Cr alloy composites, and provides a viable approach for fabricating high-performance layered gradient heterogeneous copper alloys via explosive welding.
, Available online ,
doi: 10.11883/bzycj-2026-0118
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Abstract:
The earth penetrating weapon (EPW) employs a precision guidance system to achieve accurate emplacement at a predetermined depth, after which a cylindrical explosive charge is detonated to induce damage and failure to the protective structure. Within a layered protective structure, the concrete shelter serves as a sacrificial layer; consequently, the critical perforation thickness, i.e., the minimum thickness required to prevent complete penetration followed by catastrophic failure under combined projectile impact and subsequent charge detonation, constitutes the primary design control parameter. To enable engineering-level prediction, the coupled penetration-explosion process induced by EPW was rationally idealized as a pre-drilled charge explosion. Building upon this simplification, a computational method for predicting the penetration depth of the penetrator prior to detonation was first formulated; then, the calculation formula for the peak stress of the blast wave in the concrete beneath the cylindrical charge and the analytical model for the wavelength of the blast wave were established, respectively; on this basis, corresponding calculation methods for the crushed depth and spall depth of the concrete shelter induced by the charge explosion of EPW were proposed; finally, a practical and iterative calculation framework for determining the critical perforation thickness of the concrete shelter subjected to projectile penetration followed by charge explosion was developed and rigorously validated against a comprehensive database of controlled blast experiments. Variations in striking velocity, depth of burial, charge mass, charge length-to-diameter ratio, concrete compressive strength and shelter thickness were encompassed by the validation. Results demonstrate strong agreement between model predictions and experimental measurements across all test configurations, confirming the method’s reliability and broad applicability. Leveraging the validated framework, critical perforation thicknesses were systematically determined for five representative EPWs impacting concrete shelters across a compressive strength range of 30–150 MPa and initial striking velocities of 300–400 m/s. The research results can provide an important reference for the design of protective structures against EPWs.
The earth penetrating weapon (EPW) employs a precision guidance system to achieve accurate emplacement at a predetermined depth, after which a cylindrical explosive charge is detonated to induce damage and failure to the protective structure. Within a layered protective structure, the concrete shelter serves as a sacrificial layer; consequently, the critical perforation thickness, i.e., the minimum thickness required to prevent complete penetration followed by catastrophic failure under combined projectile impact and subsequent charge detonation, constitutes the primary design control parameter. To enable engineering-level prediction, the coupled penetration-explosion process induced by EPW was rationally idealized as a pre-drilled charge explosion. Building upon this simplification, a computational method for predicting the penetration depth of the penetrator prior to detonation was first formulated; then, the calculation formula for the peak stress of the blast wave in the concrete beneath the cylindrical charge and the analytical model for the wavelength of the blast wave were established, respectively; on this basis, corresponding calculation methods for the crushed depth and spall depth of the concrete shelter induced by the charge explosion of EPW were proposed; finally, a practical and iterative calculation framework for determining the critical perforation thickness of the concrete shelter subjected to projectile penetration followed by charge explosion was developed and rigorously validated against a comprehensive database of controlled blast experiments. Variations in striking velocity, depth of burial, charge mass, charge length-to-diameter ratio, concrete compressive strength and shelter thickness were encompassed by the validation. Results demonstrate strong agreement between model predictions and experimental measurements across all test configurations, confirming the method’s reliability and broad applicability. Leveraging the validated framework, critical perforation thicknesses were systematically determined for five representative EPWs impacting concrete shelters across a compressive strength range of 30–150 MPa and initial striking velocities of 300–400 m/s. The research results can provide an important reference for the design of protective structures against EPWs.
, Available online ,
doi: 10.11883/bzycj-2026-0157
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Abstract:
Compressible multi-material and multi-species flows involving shock waves and chemical reactions are central to explosion mechanics and shock dynamics. Machine learning approaches for solving multi-material Riemann problems and capturing interface coupling effects have emerged as an active research area. However, existing neural network-based approaches generally assume calorically perfect gases with constant specific heat ratios, and are therefore incapable of handling variations in the specific heat ratio arising from compositional changes or from the excitation of molecular vibrational energy modes under high-temperature conditions. Such variations are frequently encountered in realistic detonation and reactive flow problems. To address this limitation, an unsupervised physics-constrained neural network model, termed PCNN-RS-γ, was proposed, which extended the previously developed Physics-Constrained Neural Network framework for multi-material Riemann Solvers (PCNN-RS) from calorically perfect gases to thermally perfect gases with variable specific heat ratios. Parameters characterizing the specific heat ratios on both sides of the material interface were incorporated into the input layer, enabling the model to effectively account for variations induced by chemical reactions or by high-temperature vibrational excitation. The Rankine-Hugoniot jump conditions and the thermally perfect gas equation of state were embedded in the loss function, thereby establishing an unsupervised learning framework requiring no labeled training data. The trained model was further integrated into the modified ghost fluid method (MGFM), enabling effective coupling with computational fluid dynamics solvers for multi-species reactive flow simulations. Comprehensive numerical experiments demonstrate that the proposed model exhibits strong generalization capability, high fidelity, and high computational efficiency. In terms of generalization, the model establishes a unified framework applicable to various gaseous material with specific heat ratios ranging from 1.2 to 1.7, accurately capturing variable specific heat ratio effects while remaining fully applicable to conventional two-gas flows with constant specific heat ratios. In terms of fidelity, the predictions of the model agree closely with those of standard implicit iterative methods, and the model faithfully resolves complex flow structures such as detonation waves and shock-bubble interactions involving chemical reactions. In terms of efficiency, the model eliminates the need for iterative interface prediction, and its computational cost is significantly lower than that of traditional implicit iterative approaches. These results indicate that the proposed model provides a reliable and efficient numerical tool for multi-species reactive flow simulations with variable specific heat ratio effects in explosion mechanics and shock dynamics.
Compressible multi-material and multi-species flows involving shock waves and chemical reactions are central to explosion mechanics and shock dynamics. Machine learning approaches for solving multi-material Riemann problems and capturing interface coupling effects have emerged as an active research area. However, existing neural network-based approaches generally assume calorically perfect gases with constant specific heat ratios, and are therefore incapable of handling variations in the specific heat ratio arising from compositional changes or from the excitation of molecular vibrational energy modes under high-temperature conditions. Such variations are frequently encountered in realistic detonation and reactive flow problems. To address this limitation, an unsupervised physics-constrained neural network model, termed PCNN-RS-γ, was proposed, which extended the previously developed Physics-Constrained Neural Network framework for multi-material Riemann Solvers (PCNN-RS) from calorically perfect gases to thermally perfect gases with variable specific heat ratios. Parameters characterizing the specific heat ratios on both sides of the material interface were incorporated into the input layer, enabling the model to effectively account for variations induced by chemical reactions or by high-temperature vibrational excitation. The Rankine-Hugoniot jump conditions and the thermally perfect gas equation of state were embedded in the loss function, thereby establishing an unsupervised learning framework requiring no labeled training data. The trained model was further integrated into the modified ghost fluid method (MGFM), enabling effective coupling with computational fluid dynamics solvers for multi-species reactive flow simulations. Comprehensive numerical experiments demonstrate that the proposed model exhibits strong generalization capability, high fidelity, and high computational efficiency. In terms of generalization, the model establishes a unified framework applicable to various gaseous material with specific heat ratios ranging from 1.2 to 1.7, accurately capturing variable specific heat ratio effects while remaining fully applicable to conventional two-gas flows with constant specific heat ratios. In terms of fidelity, the predictions of the model agree closely with those of standard implicit iterative methods, and the model faithfully resolves complex flow structures such as detonation waves and shock-bubble interactions involving chemical reactions. In terms of efficiency, the model eliminates the need for iterative interface prediction, and its computational cost is significantly lower than that of traditional implicit iterative approaches. These results indicate that the proposed model provides a reliable and efficient numerical tool for multi-species reactive flow simulations with variable specific heat ratio effects in explosion mechanics and shock dynamics.
, Available online ,
doi: 10.11883/bzycj-2026-0093
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Abstract:
, Available online ,
doi: 10.11883/bzycj-2026-0063
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Abstract:
Secondary dust explosion is a typical and hazardous disaster phenomenon in industrial dust safety, which is defined as the secondary combustion and explosion behavior of suspended combustible dust clouds excited and induced by the shock wave and thermal effect of the primary explosion. The inert powder suppression technology is recognized as one of the most efficient and feasible measures to mitigate and restrain dust explosion hazards. To reveal effective suppression routes for secondary explosions of high-reactivity metal dust, three typical inert suppressants including sodium bicarbonate (NaHCO₃), ammonium dihydrogen phosphate (NH₄H₂PO₄) and sodium chloride (NaCl) were selected. A series of contrastive experiments were carried out to investigate the suppression characteristics of four different mass fractions (33.3 wt%, 50 wt%, 60 wt%, and 75 wt%) of inert powders on hydrogen deflagration-induced secondary explosion of accumulated zirconium dust in an open space. The explosion overpressure, flame morphology evolution, flame propagation velocity and flame temperature duration characteristics were systematically analyzed. Experimental results demonstrate that inhibitors dominated by physical effects such as NaCl are more efficient and reliable for active zirconium dust. In contrast, chemically based inhibitors exhibit inconsistent concentration-dependent suppression performance. Specifically, NaCl powder relies on pure physical suppression mechanisms including heat absorption and flame blocking; it does not participate in chemical combustion reactions or generate secondary harmful by-products, thereby delivering outstanding suppression stability. The 60 wt% NaCl condition achieves the optimal comprehensive suppression effect, which can markedly reduce explosion overpressure, limit flame propagation range, lower flame temperature and shorten the duration of high-temperature zones. The suppression capacities of NaHCO₃ and NH₄H₂PO₄ cannot be continuously enhanced with the increase of doping mass fraction. Moreover, thermal decomposition products of NH₄H₂PO₄ even exert a certain catalytic effect on the combustion of zirconium dust. By comparison, 50–60 wt% NaHCO₃ presents relatively balanced suppression performance, whereas NH₄H₂PO₄ is not applicable to the suppression of zirconium dust explosion. Distinctions between physical and chemical inhibition mechanisms governing zirconium dust secondary explosions are identified, supplying reliable experimental datasets and technical support for explosion prevention and safety control of highly reactive metal dust in industrial production and storage processes.
Secondary dust explosion is a typical and hazardous disaster phenomenon in industrial dust safety, which is defined as the secondary combustion and explosion behavior of suspended combustible dust clouds excited and induced by the shock wave and thermal effect of the primary explosion. The inert powder suppression technology is recognized as one of the most efficient and feasible measures to mitigate and restrain dust explosion hazards. To reveal effective suppression routes for secondary explosions of high-reactivity metal dust, three typical inert suppressants including sodium bicarbonate (NaHCO₃), ammonium dihydrogen phosphate (NH₄H₂PO₄) and sodium chloride (NaCl) were selected. A series of contrastive experiments were carried out to investigate the suppression characteristics of four different mass fractions (33.3 wt%, 50 wt%, 60 wt%, and 75 wt%) of inert powders on hydrogen deflagration-induced secondary explosion of accumulated zirconium dust in an open space. The explosion overpressure, flame morphology evolution, flame propagation velocity and flame temperature duration characteristics were systematically analyzed. Experimental results demonstrate that inhibitors dominated by physical effects such as NaCl are more efficient and reliable for active zirconium dust. In contrast, chemically based inhibitors exhibit inconsistent concentration-dependent suppression performance. Specifically, NaCl powder relies on pure physical suppression mechanisms including heat absorption and flame blocking; it does not participate in chemical combustion reactions or generate secondary harmful by-products, thereby delivering outstanding suppression stability. The 60 wt% NaCl condition achieves the optimal comprehensive suppression effect, which can markedly reduce explosion overpressure, limit flame propagation range, lower flame temperature and shorten the duration of high-temperature zones. The suppression capacities of NaHCO₃ and NH₄H₂PO₄ cannot be continuously enhanced with the increase of doping mass fraction. Moreover, thermal decomposition products of NH₄H₂PO₄ even exert a certain catalytic effect on the combustion of zirconium dust. By comparison, 50–60 wt% NaHCO₃ presents relatively balanced suppression performance, whereas NH₄H₂PO₄ is not applicable to the suppression of zirconium dust explosion. Distinctions between physical and chemical inhibition mechanisms governing zirconium dust secondary explosions are identified, supplying reliable experimental datasets and technical support for explosion prevention and safety control of highly reactive metal dust in industrial production and storage processes.
, Available online ,
doi: 10.11883/bzycj-2026-0174
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Abstract:
Hypervelocity space debris poses a serious threat to the surfaces of on-orbit spacecraft, and impacts can cause severe damage. To ensure the safety and long-term operation of spacecraft in orbit, it is urgent to enhance their protective capabilities against such hypervelocity impacts. Numerical investigations on the impact failure behavior of metal debris against bio-inspired honeycomb sandwich structures were conducted using the finite element-smoothed particle hydrodynamics (FE-SPH) adaptive coupling method. This numerical approach converts failed finite element meshes into smoothed particle hydrodynamics particles that inherit the original physical properties of the elements, which effectively avoids energy non-conservation caused by element deletion and achieves high-fidelity reproduction of the entire impact process with large deformation and material fragmentation. First, by integrating gradient cell configurations with spiderweb-inspired topologies, a refined numerical model of a double-layer bio-inspired honeycomb sandwich panel composed of alternating layers of CFRP face sheets and honeycomb cores was established, and the reliability of the numerical model and algorithm in simulating impact damage and fragment cloud evolution was verified. Subsequently, it was demonstrated that the dual-gradient design offers significant overall advantages over conventional single-layer structures in effectively attenuating impact loads, controlling fragment cloud morphology, and improving energy absorption efficiency. Then, the dynamic damage mechanisms and failure modes of the double-layer sandwich panel under hypervelocity impact at 5818 m/s were revealed, clarifying how different cellular topologies regulate shock wave propagation paths and structural failure processes. Finally, through systematic analysis of the effects of impact velocity within the range of 2000-5000 m/s on structural mechanical response, damage evolution, fragment cloud characteristics, and energy absorption performance, it was confirmed that the double-layer spiderweb honeycomb sandwich panel exhibits optimal comprehensive protective performance. Results show that the designed bio-inspired gradient honeycomb sandwich panel significantly enhances overall protection capability under hypervelocity impact by inducing progressive layer-by-layer crushing of the core and effectively controlling fragment cloud dispersion. The findings provide important theoretical foundations and references for future lightweight impact-resistant structural designs in spacecraft.
Hypervelocity space debris poses a serious threat to the surfaces of on-orbit spacecraft, and impacts can cause severe damage. To ensure the safety and long-term operation of spacecraft in orbit, it is urgent to enhance their protective capabilities against such hypervelocity impacts. Numerical investigations on the impact failure behavior of metal debris against bio-inspired honeycomb sandwich structures were conducted using the finite element-smoothed particle hydrodynamics (FE-SPH) adaptive coupling method. This numerical approach converts failed finite element meshes into smoothed particle hydrodynamics particles that inherit the original physical properties of the elements, which effectively avoids energy non-conservation caused by element deletion and achieves high-fidelity reproduction of the entire impact process with large deformation and material fragmentation. First, by integrating gradient cell configurations with spiderweb-inspired topologies, a refined numerical model of a double-layer bio-inspired honeycomb sandwich panel composed of alternating layers of CFRP face sheets and honeycomb cores was established, and the reliability of the numerical model and algorithm in simulating impact damage and fragment cloud evolution was verified. Subsequently, it was demonstrated that the dual-gradient design offers significant overall advantages over conventional single-layer structures in effectively attenuating impact loads, controlling fragment cloud morphology, and improving energy absorption efficiency. Then, the dynamic damage mechanisms and failure modes of the double-layer sandwich panel under hypervelocity impact at 5818 m/s were revealed, clarifying how different cellular topologies regulate shock wave propagation paths and structural failure processes. Finally, through systematic analysis of the effects of impact velocity within the range of 2000-5000 m/s on structural mechanical response, damage evolution, fragment cloud characteristics, and energy absorption performance, it was confirmed that the double-layer spiderweb honeycomb sandwich panel exhibits optimal comprehensive protective performance. Results show that the designed bio-inspired gradient honeycomb sandwich panel significantly enhances overall protection capability under hypervelocity impact by inducing progressive layer-by-layer crushing of the core and effectively controlling fragment cloud dispersion. The findings provide important theoretical foundations and references for future lightweight impact-resistant structural designs in spacecraft.
, Available online ,
doi: 10.11883/bzycj-2026-0183
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Abstract:
Damage assessment serves as a pivotal link bridging target selection, operational planning, and combat feedback. It encompasses both pre-strike weapon damage effectiveness assessment oriented toward damage probability, target vulnerability, and weapon-target matching, and post-strike battlefield damage effect assessment oriented toward target state, functional degradation, and mission effectiveness. With advances in machine learning, multi-source sensing, numerical simulation, and intelligent computing, damage assessment is transitioning from static evaluation reliant on empirical rules, manual interpretation, and single-source data toward intelligent assessment that integrates perceptual recognition, data-driven modeling, knowledge reasoning, multi-source fusion, and closed-loop decision-making. This paper presents a review of research on artificial intelligence (AI)-driven damage assessment. After clarifying the connotation of damage assessment and the enabling logic of AI, we summarize key technical progress from five perspectives: perception and feature extraction, data-driven assessment models, knowledge-driven assessment methods, multi-source fusion, and intelligent decision-making and optimization. We further discuss the application chain covering pre-strike prediction, post-strike assessment, system-of-systems target assessment, and assessment-driven re-decision-making. The results indicate that AI can substantially improve the efficiency of damage information acquisition, feature extraction, effect prediction, state estimation, and action feedback. Nevertheless, challenges persist, including insufficient real-world samples, simulation bias, unclear functional mapping, multi-source information conflicts, inadequate model generalization and trustworthy verification, and the difficulty of stably incorporating assessment results into decision-making workflows. Future research should concentrate on data credibility, mechanism constraints, knowledge enhancement, multi-source fusion, explainable verification, and human-machine collaboration, so as to construct an intelligent damage assessment system tailored for complex combat environments.
Damage assessment serves as a pivotal link bridging target selection, operational planning, and combat feedback. It encompasses both pre-strike weapon damage effectiveness assessment oriented toward damage probability, target vulnerability, and weapon-target matching, and post-strike battlefield damage effect assessment oriented toward target state, functional degradation, and mission effectiveness. With advances in machine learning, multi-source sensing, numerical simulation, and intelligent computing, damage assessment is transitioning from static evaluation reliant on empirical rules, manual interpretation, and single-source data toward intelligent assessment that integrates perceptual recognition, data-driven modeling, knowledge reasoning, multi-source fusion, and closed-loop decision-making. This paper presents a review of research on artificial intelligence (AI)-driven damage assessment. After clarifying the connotation of damage assessment and the enabling logic of AI, we summarize key technical progress from five perspectives: perception and feature extraction, data-driven assessment models, knowledge-driven assessment methods, multi-source fusion, and intelligent decision-making and optimization. We further discuss the application chain covering pre-strike prediction, post-strike assessment, system-of-systems target assessment, and assessment-driven re-decision-making. The results indicate that AI can substantially improve the efficiency of damage information acquisition, feature extraction, effect prediction, state estimation, and action feedback. Nevertheless, challenges persist, including insufficient real-world samples, simulation bias, unclear functional mapping, multi-source information conflicts, inadequate model generalization and trustworthy verification, and the difficulty of stably incorporating assessment results into decision-making workflows. Future research should concentrate on data credibility, mechanism constraints, knowledge enhancement, multi-source fusion, explainable verification, and human-machine collaboration, so as to construct an intelligent damage assessment system tailored for complex combat environments.
, Available online ,
doi: 10.11883/bzycj-2026-0138
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Abstract:
To address the limitations of traditional segmented empirical formulas for underwater explosion shock wave loads, namely, insufficient near-field accuracy and physical discontinuities at partition boundaries, this paper establishes an improved unified continuous calculation model for near-field shock wave loads based on the Chapman-Jouguet (CJ) detonation model, post-shock approximate isentropic flow assumption, and Kirkwood-Bethe (K-B) theory. By introducing the K-B equation in the form of second-order Mach accuracy and an improved pressure attenuation time constant, the theoretical application range is extended to the dimensionless detonation distance of 2 to 20, eliminating the discontinuities inherent in conventional piecewise approximations. The model is validated against multi-scale spherical charge tests, unified bubble dynamics high-fidelity theory, Arbitrary Lagrangian-Eulerian (ALE) numerical simulation, and classical empirical formulas, with the peak pressure calculation error controlled within 10 % and the accuracy of impulse and energy flux significantly superior to Cole’s empirical formula. Calculation results show that the peak pressure and energy flux of the shock wave rapidly and nonlinearly decay in the near field, while the decay rate decreases markedly in the middle and far fields. In the near field (2-10 charge radii), geometric diffusion contributes approximately 89 % to the peak pressure attenuation, and the energy flux decay is almost entirely dominated by geometric diffusion. The impulse decays slowly with detonation distance at a rate much lower than that of the peak pressure. The systematic overestimation of impulse and energy flux by Cole’s formula in the middle and far fields stems from its constant time constant assumption, which neglects the unsteady nature of bubble expansion. The proposed model possesses both analytical efficiency and numerical accuracy, providing an effective theoretical tool for underwater weapon warhead design and ship anti-blast protection.
To address the limitations of traditional segmented empirical formulas for underwater explosion shock wave loads, namely, insufficient near-field accuracy and physical discontinuities at partition boundaries, this paper establishes an improved unified continuous calculation model for near-field shock wave loads based on the Chapman-Jouguet (CJ) detonation model, post-shock approximate isentropic flow assumption, and Kirkwood-Bethe (K-B) theory. By introducing the K-B equation in the form of second-order Mach accuracy and an improved pressure attenuation time constant, the theoretical application range is extended to the dimensionless detonation distance of 2 to 20, eliminating the discontinuities inherent in conventional piecewise approximations. The model is validated against multi-scale spherical charge tests, unified bubble dynamics high-fidelity theory, Arbitrary Lagrangian-Eulerian (ALE) numerical simulation, and classical empirical formulas, with the peak pressure calculation error controlled within 10 % and the accuracy of impulse and energy flux significantly superior to Cole’s empirical formula. Calculation results show that the peak pressure and energy flux of the shock wave rapidly and nonlinearly decay in the near field, while the decay rate decreases markedly in the middle and far fields. In the near field (2-10 charge radii), geometric diffusion contributes approximately 89 % to the peak pressure attenuation, and the energy flux decay is almost entirely dominated by geometric diffusion. The impulse decays slowly with detonation distance at a rate much lower than that of the peak pressure. The systematic overestimation of impulse and energy flux by Cole’s formula in the middle and far fields stems from its constant time constant assumption, which neglects the unsteady nature of bubble expansion. The proposed model possesses both analytical efficiency and numerical accuracy, providing an effective theoretical tool for underwater weapon warhead design and ship anti-blast protection.
, Available online ,
doi: 10.11883/bzycj-2026-0151
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Abstract:
Zr-based amorphous alloy has excellent mechanical properties such as high strength and high hardness. It has important application value as a warhead fragment damage element. To investigate the dispersion characteristics and deformation behavior of Zr-based amorphous alloy fragments driven by detonation of a circumferentially focusing charge, the static explosion tests of Zr-based amorphous alloy fragments driven by cylinder and trumpet-shaped circumferentially focusing warheads were carried out, and the spatial distribution characteristics of fragments under two charge structures were obtained. Using the fragment recovery device, the detonation-driven Zr-based amorphous alloy fragments were recovered. Combined with numerical simulations, the influence of the charge generatrix shape on the dispersion behavior of the fragments was analyzed, and the effect of the flameproof layer thickness on the fragmentation behavior of the fragments was investigated. The results show that, compared with the cylinder charge structure, the trumpet-shaped circumferentially focusing charge significantly reduces the fragment scattering angle. When the focusing radius of curvature is 600 mm, the width of the focusing band containing 70% of the fragments is reduced of 38.4%. Moreover, at the flameproof layer thickness of 8 mm, slight fragmentation occurs, but the main-body fragments can penetrate and damage a 3 mm thick Q235 steel target. Within a certain range, reducing the curvature radius of the focusing generatrix facilitates fragment convergence; However, if the radius is too small, it will cause excessive squeezing and fragmentation of the fragments. Appropriately reducing the diameter of the upper end of the charge can not only shift the focusing band toward the central area of the target, but also improve the uniformity of fragment distribution within the focusing band. Because Zr-based amorphous alloy fragments are prone to fragmentation under detonation loading, the degree of fragmentation can be controlled by adjusting the thickness of the flameproof layer. The optimal flameproof layer thickness for achieving relatively intact driving of Zr-based amorphous alloy fragments is 8 mm. If the thickness is less than this value, the fragments will be severely fragmented; If the thickness is greater than this value, velocity loss will increase. The research results in this paper provide data and technical support for the engineering application of Zr-based amorphous alloy materials in blast-fragmentation warheads.
Zr-based amorphous alloy has excellent mechanical properties such as high strength and high hardness. It has important application value as a warhead fragment damage element. To investigate the dispersion characteristics and deformation behavior of Zr-based amorphous alloy fragments driven by detonation of a circumferentially focusing charge, the static explosion tests of Zr-based amorphous alloy fragments driven by cylinder and trumpet-shaped circumferentially focusing warheads were carried out, and the spatial distribution characteristics of fragments under two charge structures were obtained. Using the fragment recovery device, the detonation-driven Zr-based amorphous alloy fragments were recovered. Combined with numerical simulations, the influence of the charge generatrix shape on the dispersion behavior of the fragments was analyzed, and the effect of the flameproof layer thickness on the fragmentation behavior of the fragments was investigated. The results show that, compared with the cylinder charge structure, the trumpet-shaped circumferentially focusing charge significantly reduces the fragment scattering angle. When the focusing radius of curvature is 600 mm, the width of the focusing band containing 70% of the fragments is reduced of 38.4%. Moreover, at the flameproof layer thickness of 8 mm, slight fragmentation occurs, but the main-body fragments can penetrate and damage a 3 mm thick Q235 steel target. Within a certain range, reducing the curvature radius of the focusing generatrix facilitates fragment convergence; However, if the radius is too small, it will cause excessive squeezing and fragmentation of the fragments. Appropriately reducing the diameter of the upper end of the charge can not only shift the focusing band toward the central area of the target, but also improve the uniformity of fragment distribution within the focusing band. Because Zr-based amorphous alloy fragments are prone to fragmentation under detonation loading, the degree of fragmentation can be controlled by adjusting the thickness of the flameproof layer. The optimal flameproof layer thickness for achieving relatively intact driving of Zr-based amorphous alloy fragments is 8 mm. If the thickness is less than this value, the fragments will be severely fragmented; If the thickness is greater than this value, velocity loss will increase. The research results in this paper provide data and technical support for the engineering application of Zr-based amorphous alloy materials in blast-fragmentation warheads.
, Available online ,
doi: 10.11883/bzycj-2026-0164
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Abstract:
High-velocity fragment penetration into a liquid-filled container induces hydrodynamic ram (HRAM) and produces an elongated cavity that expands and contracts within the liquid. Container confinement strongly affects cavity evolution, whereas dimensional variables alone cannot clearly distinguish the effect of container size from that of the confinement condition. A dimensionless framework was therefore developed to characterize the peak features of confined cavities in containers of different sizes. A cylindrical-cavity cross-sectional model was adopted, and the fragment kinetic-energy loss per unit penetration length was used to represent the initial energy input. Liquid compression and elastic container expansion were treated as two volume springs connected in series, and a system equivalent bulk modulus was introduced to describe their combined resistance to cavity expansion. The initial inner radius of the container, liquid density, and system equivalent bulk modulus were selected as repeating variables. The fragment energy input, initial pressure difference, elastic volume partitioning, wall inertia, and initial geometric scale were then organized into a dimensionless parameter group. Fragment-impact experiments were conducted using three structurally similar water-filled containers of different sizes. Cavity contours were extracted from high-speed images, and a pixel-slice method was used to obtain the radius history, maximum radius, and time to maximum radius at selected valid cross-sections in the central region of each container. The square cross-sections were converted into equal-area circular cross-sections. The container equivalent bulk modulus was identified by matching the calculated and measured radius histories, and the system equivalent bulk modulus was then determined from the liquid and container moduli. The experimental confined-cavity results were also compared with reference values obtained from an unconfined cylindrical-cavity model. The results show that the dimensionless maximum radius increases approximately linearly with the dimensionless kinetic-energy input. A larger initial pressure-difference ratio produces a smaller dimensionless maximum radius under a comparable energy input because the relative contribution of the initial pressure difference to the total pressure difference increases. The sensitivity of the maximum radius to energy input, represented by the slopes of the grouped linear fits, decreases rapidly at first and then approaches a relatively stable level as the initial pressure-difference ratio increases. In contrast, the dimensionless time to maximum radius exhibits substantially greater dispersion and does not form a stable monotonic relation with energy input. Its variation depends not only on the maximum radius but also on the radial-velocity decay history, including the effects of pressure evolution, wall inertia, and geometric scale. Comparison with the unconfined reference shows that confinement reduces both the maximum radius and the time to maximum radius, but the relative reduction in time is greater. Consequently, the dimensionless average expansion rate is higher under confined conditions, and the difference becomes more pronounced as the container size decreases. The proposed dimensionless framework provides a consistent basis for comparing peak cavity characteristics under different container sizes and confinement conditions and supports similarity analysis of hydrodynamic ram and damage assessment of liquid-filled structures.
High-velocity fragment penetration into a liquid-filled container induces hydrodynamic ram (HRAM) and produces an elongated cavity that expands and contracts within the liquid. Container confinement strongly affects cavity evolution, whereas dimensional variables alone cannot clearly distinguish the effect of container size from that of the confinement condition. A dimensionless framework was therefore developed to characterize the peak features of confined cavities in containers of different sizes. A cylindrical-cavity cross-sectional model was adopted, and the fragment kinetic-energy loss per unit penetration length was used to represent the initial energy input. Liquid compression and elastic container expansion were treated as two volume springs connected in series, and a system equivalent bulk modulus was introduced to describe their combined resistance to cavity expansion. The initial inner radius of the container, liquid density, and system equivalent bulk modulus were selected as repeating variables. The fragment energy input, initial pressure difference, elastic volume partitioning, wall inertia, and initial geometric scale were then organized into a dimensionless parameter group. Fragment-impact experiments were conducted using three structurally similar water-filled containers of different sizes. Cavity contours were extracted from high-speed images, and a pixel-slice method was used to obtain the radius history, maximum radius, and time to maximum radius at selected valid cross-sections in the central region of each container. The square cross-sections were converted into equal-area circular cross-sections. The container equivalent bulk modulus was identified by matching the calculated and measured radius histories, and the system equivalent bulk modulus was then determined from the liquid and container moduli. The experimental confined-cavity results were also compared with reference values obtained from an unconfined cylindrical-cavity model. The results show that the dimensionless maximum radius increases approximately linearly with the dimensionless kinetic-energy input. A larger initial pressure-difference ratio produces a smaller dimensionless maximum radius under a comparable energy input because the relative contribution of the initial pressure difference to the total pressure difference increases. The sensitivity of the maximum radius to energy input, represented by the slopes of the grouped linear fits, decreases rapidly at first and then approaches a relatively stable level as the initial pressure-difference ratio increases. In contrast, the dimensionless time to maximum radius exhibits substantially greater dispersion and does not form a stable monotonic relation with energy input. Its variation depends not only on the maximum radius but also on the radial-velocity decay history, including the effects of pressure evolution, wall inertia, and geometric scale. Comparison with the unconfined reference shows that confinement reduces both the maximum radius and the time to maximum radius, but the relative reduction in time is greater. Consequently, the dimensionless average expansion rate is higher under confined conditions, and the difference becomes more pronounced as the container size decreases. The proposed dimensionless framework provides a consistent basis for comparing peak cavity characteristics under different container sizes and confinement conditions and supports similarity analysis of hydrodynamic ram and damage assessment of liquid-filled structures.
, Available online ,
doi: 10.11883/bzycj-2026-0139
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Abstract:
Blast-induced ground shock is considered as the primary design load for underground protective structures, especially those that are shallow-buried. A shallow-buried rigid structure and its overlying soil are regarded as an equivalent structure supported on an elastic foundation and an analytical blast-resistant model based on one-dimensional wave theory is established. By solving the nonlinear wave equation with the separation of variables methods and orthogonal inner product methods, the standing wave solution for normal displacement at the soil-shallow buried rigid structure interface is derived, and the effects of load characteristics and structure-overlying soil compression wave ratio on the structural dynamic response are examined. Results indicate the dynamic displacement of shallow-buried structures can be expressed as the structural displacement yielded by static load being equivalent to peak blast load multiplied by a dynamic function according to one-dimensional wave theory. This method provides a justification for various experimental phenomena, achieves favorable calculation accuracy for underground structure with high rigid, and offers clear physical interpretation, making it well-suited for practical engineering applications. Amplification of structure dynamic response is observed with a shorter rise time and longer duration of blast load, indicating the significant influence of temporal parameters on the dynamic function. The dynamic response of shallow-buried structures is significantly influenced by the ratio of the compression wave between the structure and the ground layer, indicating that the dynamic behavior of the structure is determined by the capacity of the structure and soil to resist volumetric deformation. It is shown the relative errors between the analytical results and measured data for the solid pressure and the structural displacement are varied from 13.57% to 18.22% and from 9.86% to 13.22% respectively and thus the reliability and prediction accuracy of proposed model are validated. Consequently, it is demonstrated that the dynamic behavior of underground structures under blast loading can be reasonably depicted by the soil-structure interaction based on one-dimensional wave theory. The blast-resistance of such structures can be reasonably estimated by taking the interaction between soil and structure into account. It provides an effective tool for the analysis of shallow-buried.structure subjected to blast loading.
Blast-induced ground shock is considered as the primary design load for underground protective structures, especially those that are shallow-buried. A shallow-buried rigid structure and its overlying soil are regarded as an equivalent structure supported on an elastic foundation and an analytical blast-resistant model based on one-dimensional wave theory is established. By solving the nonlinear wave equation with the separation of variables methods and orthogonal inner product methods, the standing wave solution for normal displacement at the soil-shallow buried rigid structure interface is derived, and the effects of load characteristics and structure-overlying soil compression wave ratio on the structural dynamic response are examined. Results indicate the dynamic displacement of shallow-buried structures can be expressed as the structural displacement yielded by static load being equivalent to peak blast load multiplied by a dynamic function according to one-dimensional wave theory. This method provides a justification for various experimental phenomena, achieves favorable calculation accuracy for underground structure with high rigid, and offers clear physical interpretation, making it well-suited for practical engineering applications. Amplification of structure dynamic response is observed with a shorter rise time and longer duration of blast load, indicating the significant influence of temporal parameters on the dynamic function. The dynamic response of shallow-buried structures is significantly influenced by the ratio of the compression wave between the structure and the ground layer, indicating that the dynamic behavior of the structure is determined by the capacity of the structure and soil to resist volumetric deformation. It is shown the relative errors between the analytical results and measured data for the solid pressure and the structural displacement are varied from 13.57% to 18.22% and from 9.86% to 13.22% respectively and thus the reliability and prediction accuracy of proposed model are validated. Consequently, it is demonstrated that the dynamic behavior of underground structures under blast loading can be reasonably depicted by the soil-structure interaction based on one-dimensional wave theory. The blast-resistance of such structures can be reasonably estimated by taking the interaction between soil and structure into account. It provides an effective tool for the analysis of shallow-buried.structure subjected to blast loading.
, Available online ,
doi: 10.11883/bzycj-2026-0066
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Abstract:
Ultra-high-pressure (UHP) water jetting is widely applied in ship rust removal due to their high energy density and eco-friendly characteristics. However, the influence of nozzzle’s rotating motion on the impact characteristics of water jetting requires further investigation. Based on the numerical simulation scheme incorporating cavitation and sliding mesh models, and considering liquid compressibility and nozzle rotating speed, a straight conical convergent nozzle model was constructed. The variations in key parameters, including flow field morphology, turbulent kinetic energy, shear stress, were investigated under different nozzle rotating speeds. The results indicate that nozzle rotation induces varying degrees of asymmetry in the jet flow field, causing the jet core to deviate, accompanied by shear layer thickening and an expanded turbulence range. As the nozzle rotating speed increases, the peak shear stress of the jet impact gradually decreases. To maximize operational efficiency, an evaluation method based on the "sweep time-sweep length-moving speed" relationship was established. By introducing a minimum sweep time constraint, this method quantitatively analyzes the non-linear relationship between nozzle rotating speed and translation speed. Using the theoretical maximum translation speed as a criterion, the optimal nozzle rotating range was obtained. These findings provide a theoretical basis for the design of process parameters in UHP water-jets cleaning systems.
Ultra-high-pressure (UHP) water jetting is widely applied in ship rust removal due to their high energy density and eco-friendly characteristics. However, the influence of nozzzle’s rotating motion on the impact characteristics of water jetting requires further investigation. Based on the numerical simulation scheme incorporating cavitation and sliding mesh models, and considering liquid compressibility and nozzle rotating speed, a straight conical convergent nozzle model was constructed. The variations in key parameters, including flow field morphology, turbulent kinetic energy, shear stress, were investigated under different nozzle rotating speeds. The results indicate that nozzle rotation induces varying degrees of asymmetry in the jet flow field, causing the jet core to deviate, accompanied by shear layer thickening and an expanded turbulence range. As the nozzle rotating speed increases, the peak shear stress of the jet impact gradually decreases. To maximize operational efficiency, an evaluation method based on the "sweep time-sweep length-moving speed" relationship was established. By introducing a minimum sweep time constraint, this method quantitatively analyzes the non-linear relationship between nozzle rotating speed and translation speed. Using the theoretical maximum translation speed as a criterion, the optimal nozzle rotating range was obtained. These findings provide a theoretical basis for the design of process parameters in UHP water-jets cleaning systems.
, Available online ,
doi: 10.11883/bzycj-2026-0155
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Abstract:
The cyclic blasting in tunnel excavation inevitably causes cumulative damage to the surrounding rock. In view of the deficiency that the explosive load is almost simplified as an impact load in the current numerical simulation studies, the Bandaki micro-blasting test was first numerically reproduced based on the LS-DYNA software, which verified the rationality of the RHT constitutive model, ALE coupling algorithm and material parameters adopted in the numerical model. Secondly, the real explosion process of 88 blast holes in a certain tunnel section was truly simulated by this software, which overcame the shortcomings of the current methods that failed to consider the effect of blast gas and simplification errors, and improved the calculation accuracy. At the same time, the complete restart technology and the initial in-situ stress application method were adopted to well simulate the cumulative damage mechanism of the surrounding rock of the tunnel under the coupling effect of cyclic blasting and initial in-situ stress. Finally, based on the above numerical model, the cumulative damage mechanism of the surrounding rock of the tunnel under different in-situ stress conditions caused by cyclic blasting was studied. It was found that with the increase of the number of cyclic blasting, the damage range of the surrounding rock gradually expanded, and the cumulative damage effect was obvious. The initial in-situ stress had a significant inhibitory effect on the damage of the surrounding rock of the tunnel, and the damage range decreased with the increase of in-situ stress. Taking the third cyclic blasting as an example, when the initial in-situ stress gradually increased from 0 MPa to 10 MPa, 20 MPa and 30 MPa, the average damage range of the surrounding rock gradually decreased from 64.05 cm to 20.99 cm, 13.34 cm and 7.01 cm, with the reduction rates of 67.2%, 36.4% and 47.45% respectively, that is, the reduction rate generally showed a gradually slowing trend. The research results can provide useful references for tunnel blasting excavation engineering.
The cyclic blasting in tunnel excavation inevitably causes cumulative damage to the surrounding rock. In view of the deficiency that the explosive load is almost simplified as an impact load in the current numerical simulation studies, the Bandaki micro-blasting test was first numerically reproduced based on the LS-DYNA software, which verified the rationality of the RHT constitutive model, ALE coupling algorithm and material parameters adopted in the numerical model. Secondly, the real explosion process of 88 blast holes in a certain tunnel section was truly simulated by this software, which overcame the shortcomings of the current methods that failed to consider the effect of blast gas and simplification errors, and improved the calculation accuracy. At the same time, the complete restart technology and the initial in-situ stress application method were adopted to well simulate the cumulative damage mechanism of the surrounding rock of the tunnel under the coupling effect of cyclic blasting and initial in-situ stress. Finally, based on the above numerical model, the cumulative damage mechanism of the surrounding rock of the tunnel under different in-situ stress conditions caused by cyclic blasting was studied. It was found that with the increase of the number of cyclic blasting, the damage range of the surrounding rock gradually expanded, and the cumulative damage effect was obvious. The initial in-situ stress had a significant inhibitory effect on the damage of the surrounding rock of the tunnel, and the damage range decreased with the increase of in-situ stress. Taking the third cyclic blasting as an example, when the initial in-situ stress gradually increased from 0 MPa to 10 MPa, 20 MPa and 30 MPa, the average damage range of the surrounding rock gradually decreased from 64.05 cm to 20.99 cm, 13.34 cm and 7.01 cm, with the reduction rates of 67.2%, 36.4% and 47.45% respectively, that is, the reduction rate generally showed a gradually slowing trend. The research results can provide useful references for tunnel blasting excavation engineering.
Method for Calculating the Pressure of Oblique Reflection of Shock Waves at the Water-Soil Interface
, Available online ,
doi: 10.11883/bzycj-2026-0108
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Abstract:
The theoretical framework for calculating the oblique reflection pressure of shock waves at the soil-water interface remains incomplete. In this study, building upon previous theoretical derivations, we established an analytical equation for the oblique reflection pressure of shock waves at the soil-water interface. Based on this, we conducted underwater explosion tests and developed a fluid-structure interaction numerical model, using the experimental data to validate both the theoretical model and the numerical model. To investigate the influence of different parameters on the normal reflection pressure coefficient, explosions were conducted using explosives with varying TNT equivalents at a distance of 0.52 m from the water-soil interface (with a proportional blast distance ranging from 0.326 to 2.936 m/kg¹/³). Based on the incident pressure obtained from empirical formulas for underwater explosions, the calculated normal reflection pressure coefficient ranged from 1.26 to 1.50. At a distance of 0.3 m from the water-soil interface, with the air content of saturated soil varying between 0% and 10%, the reflected pressure ranged from 64.15 to 81.77 MPa, and the reflected pressure coefficient ranged from 1.19 to 1.52. To investigate the influence of different parameters on the oblique reflection pressure calculation model, the results of numerical simulations with varying blast distances and incident angles (0°-40°) were analyzed, clarifying the applicability range of the theoretical model: When the incident angle is ≤20°, the model’s prediction error is generally below 10%, demonstrating high engineering accuracy; when the incident angle is >30° and the blast distance is small, the model error increases significantly, providing clear boundary conditions for practical applications. The derived calculation method for the shock wave reflection pressure at the water-soil interface has clear physical significance and high computational accuracy, providing a theoretical foundation for assessing the damage caused by underwater explosions to engineering structures in subaquatic soil.
The theoretical framework for calculating the oblique reflection pressure of shock waves at the soil-water interface remains incomplete. In this study, building upon previous theoretical derivations, we established an analytical equation for the oblique reflection pressure of shock waves at the soil-water interface. Based on this, we conducted underwater explosion tests and developed a fluid-structure interaction numerical model, using the experimental data to validate both the theoretical model and the numerical model. To investigate the influence of different parameters on the normal reflection pressure coefficient, explosions were conducted using explosives with varying TNT equivalents at a distance of 0.52 m from the water-soil interface (with a proportional blast distance ranging from 0.326 to 2.936 m/kg¹/³). Based on the incident pressure obtained from empirical formulas for underwater explosions, the calculated normal reflection pressure coefficient ranged from 1.26 to 1.50. At a distance of 0.3 m from the water-soil interface, with the air content of saturated soil varying between 0% and 10%, the reflected pressure ranged from 64.15 to 81.77 MPa, and the reflected pressure coefficient ranged from 1.19 to 1.52. To investigate the influence of different parameters on the oblique reflection pressure calculation model, the results of numerical simulations with varying blast distances and incident angles (0°-40°) were analyzed, clarifying the applicability range of the theoretical model: When the incident angle is ≤20°, the model’s prediction error is generally below 10%, demonstrating high engineering accuracy; when the incident angle is >30° and the blast distance is small, the model error increases significantly, providing clear boundary conditions for practical applications. The derived calculation method for the shock wave reflection pressure at the water-soil interface has clear physical significance and high computational accuracy, providing a theoretical foundation for assessing the damage caused by underwater explosions to engineering structures in subaquatic soil.
, Available online ,
doi: 10.11883/bzycj-2026-0124
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Abstract:
To investigate the damage evolution mechanism, meso-crack propagation law, and strain rate effect of white sandstone under static and dynamic loads, fine-grained white sandstone was selected as the research object. Taking fine-grained white sandstone as the research object, a three-dimensional discrete element model based on the parallel bond model (PBM) is established using PFC3D software to numerically analyze the mechanical behavior of white sandstone under three loading conditions: uniaxial compression, Brazilian splitting, and three-dimensional split Hopkinson pressure bar (SHPB). Meanwhile, corresponding laboratory experiments are carried out to conduct a comparative analysis of the macroscopic mechanical characteristics and failure modes of white sandstone under static and dynamic loads. The macroscopic mechanical characteristics and failure modes of white sandstone under static and dynamic loads were compared and analyzed. The process of crack initiation, propagation, and coalescence, the evolution law of force chains, and the energy transformation characteristics were explored from a mesoscopic perspective. The dynamic increase factor (DIF) was introduced to quantitatively characterize the strain rate strengthening effect. The results indicate that the established discrete element model effectively represents the macroscopic mechanical behavior of white sandstone, with relative errors of compressive strength and tensile strength between numerical analysis and laboratory results both below 2%, and the failure modes are in good agreement. Under uniaxial compression, Brazilian split, and dynamic impact, the crack propagation patterns of white sandstone differ, but all share a common basis: shear cracks initiate the fracture, tensile cracks guide the propagation, and the coupled development of the two types of cracks forms the fracture surface. The proportions of shear cracks are 61.8%, 52.7%, and 54.5%, respectively. The initiation and propagation of cracks are closely related to the breakage, reorganization, and concentration of force chains, with the concentrated regions of tensile force chains serving as the main paths for crack propagation. Under different strain rate loading conditions, the crack propagation mode and fragmentation morphology of white sandstone do not change significantly. Under high strain rate impact conditions, it can absorb more energy and exhibit better load-bearing capacity. This is because the number of internal cracks in the specimen increases significantly under high strain rate impact, and the penetrating crack zone becomes more pronounced, resulting in the white sandstone absorbing more energy under high strain rate impact conditions. The research findings can provide a theoretical reference for stability evaluation and disaster prevention in deep rock engineering under coupled static-dynamic loads.
To investigate the damage evolution mechanism, meso-crack propagation law, and strain rate effect of white sandstone under static and dynamic loads, fine-grained white sandstone was selected as the research object. Taking fine-grained white sandstone as the research object, a three-dimensional discrete element model based on the parallel bond model (PBM) is established using PFC3D software to numerically analyze the mechanical behavior of white sandstone under three loading conditions: uniaxial compression, Brazilian splitting, and three-dimensional split Hopkinson pressure bar (SHPB). Meanwhile, corresponding laboratory experiments are carried out to conduct a comparative analysis of the macroscopic mechanical characteristics and failure modes of white sandstone under static and dynamic loads. The macroscopic mechanical characteristics and failure modes of white sandstone under static and dynamic loads were compared and analyzed. The process of crack initiation, propagation, and coalescence, the evolution law of force chains, and the energy transformation characteristics were explored from a mesoscopic perspective. The dynamic increase factor (DIF) was introduced to quantitatively characterize the strain rate strengthening effect. The results indicate that the established discrete element model effectively represents the macroscopic mechanical behavior of white sandstone, with relative errors of compressive strength and tensile strength between numerical analysis and laboratory results both below 2%, and the failure modes are in good agreement. Under uniaxial compression, Brazilian split, and dynamic impact, the crack propagation patterns of white sandstone differ, but all share a common basis: shear cracks initiate the fracture, tensile cracks guide the propagation, and the coupled development of the two types of cracks forms the fracture surface. The proportions of shear cracks are 61.8%, 52.7%, and 54.5%, respectively. The initiation and propagation of cracks are closely related to the breakage, reorganization, and concentration of force chains, with the concentrated regions of tensile force chains serving as the main paths for crack propagation. Under different strain rate loading conditions, the crack propagation mode and fragmentation morphology of white sandstone do not change significantly. Under high strain rate impact conditions, it can absorb more energy and exhibit better load-bearing capacity. This is because the number of internal cracks in the specimen increases significantly under high strain rate impact, and the penetrating crack zone becomes more pronounced, resulting in the white sandstone absorbing more energy under high strain rate impact conditions. The research findings can provide a theoretical reference for stability evaluation and disaster prevention in deep rock engineering under coupled static-dynamic loads.
, Available online ,
doi: 10.11883/bzycj-2026-0120
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Abstract:
To address the flame jetting problem occurring during the detonation-driven dispersal of the fuel-air explosive (FAE) mixture by the central dispersion charge in an FAE warhead, this study combines charge structural design with the incorporation of flame suppressants. The selected explosive was pressed passivated RDX, with varying mass fractions of sodium chloride (NaCl) as a suppressant, to form the dispersion charge. A comprehensive experimental investigation was carried out to evaluate the inhibition of high temperature and flame in the post-detonation fireball, as well as the corresponding detonation performance. High-speed video imaging and calibrated infrared thermography were used to capture the temporal and spatial evolution of the explosion fireball, enabling quantification of peak temperature and the duration of elevated temperature. In parallel, an explosive detonation velocity measurement technique employing ionization probes positioned at multiple axial locations along the cylindrical charge was adopted to systematically study the detonation velocity variation at different positions within the charge body after adding different NaCl proportions, and the relevant variation patterns were derived. The experimental results demonstrate a clear monotonic trend: with increasing NaCl content, the detonation velocity, heat of detonation, and fireball temperature all decrease monotonically. In particular, for a fixed total charge mass, when the NaCl content was increased to 10% by weight, the detonation velocity decreased by 4.1%, the heat of detonation dropped by 8.4%, the maximum fireball temperature was reduced by 30.7%, and the duration for which the fireball temperature exceeded 200℃ was shortened by 70.9% compared with the pure RDX baseline. The multi-point detonation velocity measurements further revealed that the detonation wave remained steady along the charge axis, and the velocity reduction was uniform. indicating that NaCl does not disrupt the detonation propagation stability. To validate the practical efficacy, full-scale verification tests were conducted using a FAE mixture integrated with a central dispersion charge containing 5% NaCl. This indicates that adding NaCl as a flame suppressant to the dispersion charge in FAE munitions can effectively prevent flashback during the explosive dispersal of the fuel-air cloud.
To address the flame jetting problem occurring during the detonation-driven dispersal of the fuel-air explosive (FAE) mixture by the central dispersion charge in an FAE warhead, this study combines charge structural design with the incorporation of flame suppressants. The selected explosive was pressed passivated RDX, with varying mass fractions of sodium chloride (NaCl) as a suppressant, to form the dispersion charge. A comprehensive experimental investigation was carried out to evaluate the inhibition of high temperature and flame in the post-detonation fireball, as well as the corresponding detonation performance. High-speed video imaging and calibrated infrared thermography were used to capture the temporal and spatial evolution of the explosion fireball, enabling quantification of peak temperature and the duration of elevated temperature. In parallel, an explosive detonation velocity measurement technique employing ionization probes positioned at multiple axial locations along the cylindrical charge was adopted to systematically study the detonation velocity variation at different positions within the charge body after adding different NaCl proportions, and the relevant variation patterns were derived. The experimental results demonstrate a clear monotonic trend: with increasing NaCl content, the detonation velocity, heat of detonation, and fireball temperature all decrease monotonically. In particular, for a fixed total charge mass, when the NaCl content was increased to 10% by weight, the detonation velocity decreased by 4.1%, the heat of detonation dropped by 8.4%, the maximum fireball temperature was reduced by 30.7%, and the duration for which the fireball temperature exceeded 200℃ was shortened by 70.9% compared with the pure RDX baseline. The multi-point detonation velocity measurements further revealed that the detonation wave remained steady along the charge axis, and the velocity reduction was uniform. indicating that NaCl does not disrupt the detonation propagation stability. To validate the practical efficacy, full-scale verification tests were conducted using a FAE mixture integrated with a central dispersion charge containing 5% NaCl. This indicates that adding NaCl as a flame suppressant to the dispersion charge in FAE munitions can effectively prevent flashback during the explosive dispersal of the fuel-air cloud.
, Available online ,
doi: 10.11883/bzycj-2026-0083
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Abstract:
Downhole liquid-phase discharge plasma rock breaking and wire explosion are the two primary implementations of high-voltage pulsed discharge technology for rock fragmentation. The aim of this study is to systematically compare the rock fragmentation performance and energy dissipation between the two methods. Homogeneous cubic cement mortar specimens, each with a side length of 200 mm and a prefabricated central borehole measuring 20 mm in diameter and 120 mm in depth, were used to simulate soft rock in laboratory experiments. A test system was constructed, consisting of a high-voltage pulse discharge device, a discharge-parameter measurement module, and a high-speed photography module. The high-voltage pulse discharge device features a 250 μF capacitor with an adjustable charging voltage range of 0-100 kV, which was used to apply high-voltage pulses to the specimens. Concurrently, the discharge-parameter measurement module recorded current and voltage waveforms, enabling comparison of the differences in energy transfer processes between the two methods. Simultaneously, the high-speed photography module captured the dynamic failure process of the specimens under shock wave loading, facilitating analysis of differences in crack propagation. In the tests, needle-needle electrodes with a fixed electrode spacing of 10 mm were inserted into boreholes and served as the discharge electrodes for generating high-voltage pulses. Four charging voltages of 7 kV, 8 kV, 9 kV, and 10 kV were used as experimental variables to compare the characteristics of soft rock fragmentation between downhole liquid-phase discharge plasma and wire explosion. High-speed photography was employed to analyze and compare crack propagation behaviors between the two methods. Quantitative assessments of surface crack density and fractal dimension were conducted to characterize crack morphology differences in the processed specimens. Statistical analysis of fragment size distribution and specific surface area further revealed distinctive fragmentation characteristics. Additionally, on the basis of the dynamic processes of energy release and transfer in rock fragmentation via high-voltage pulse discharge and the relationship between newly created surface area and fragmentation energy in fracture mechanics, time-history current and voltage data were utilized to quantify the downhole deposited energy distribution and fragmentation energy allocation efficiency. The results show that, for rock fragmentation by liquid-phase discharge plasma, the surface crack density and newly created surface area increase monotonically with the increase of charging voltage, while the average fragment size presents a monotonically decreasing trend. For rock fragmentation by wire explosion, however, the surface crack density and newly created surface area increase first and then decrease, with the average fragment size showing an inverse trend. The fractal dimension of specimen surface cracks increases with the rising voltage for both methods, with wire explosion generating a more complex crack network. As charging voltage increases from 7 kV to 10 kV, the energy deposition efficiency for rock fragmentation by liquid-phase discharge plasma increases from 55.37% to 69.43%, whereas for rock fragmentation by wire explosion, it rises from 59.78% at 7 kV to a peak of 67.47% at 9 kV before sharply dropping to 52.96% at 10 kV. Meanwhile, the fraction of rock fragmentation energy within deposited energy declines from 7.53% to 4.77% for liquid-phase discharge plasma, which accounts for 3.32%–4.17% of the total energy stored in the capacitor. For wire explosion, the fraction declines from 8.08% to 6.62%. The corresponding value accounts for 2.98%–4.83% of the total energy stored in the capacitor. This demonstrates that the wire explosion technique delivers a higher conversion efficiency from deposited energy to rock fragmentation energy. At 10 kV, the insufficient deposited energy generated by wire explosion directly degrades its rock-breaking performance at this voltage, which deviates from the consistent upward trend of rock fragmentation efficacy observed in liquid-phase discharge plasma as the applied voltage rises. The findings offer valuable guidance for the method selection and parameter optimization of high-voltage pulse discharge for rock fragmentation.
Downhole liquid-phase discharge plasma rock breaking and wire explosion are the two primary implementations of high-voltage pulsed discharge technology for rock fragmentation. The aim of this study is to systematically compare the rock fragmentation performance and energy dissipation between the two methods. Homogeneous cubic cement mortar specimens, each with a side length of 200 mm and a prefabricated central borehole measuring 20 mm in diameter and 120 mm in depth, were used to simulate soft rock in laboratory experiments. A test system was constructed, consisting of a high-voltage pulse discharge device, a discharge-parameter measurement module, and a high-speed photography module. The high-voltage pulse discharge device features a 250 μF capacitor with an adjustable charging voltage range of 0-100 kV, which was used to apply high-voltage pulses to the specimens. Concurrently, the discharge-parameter measurement module recorded current and voltage waveforms, enabling comparison of the differences in energy transfer processes between the two methods. Simultaneously, the high-speed photography module captured the dynamic failure process of the specimens under shock wave loading, facilitating analysis of differences in crack propagation. In the tests, needle-needle electrodes with a fixed electrode spacing of 10 mm were inserted into boreholes and served as the discharge electrodes for generating high-voltage pulses. Four charging voltages of 7 kV, 8 kV, 9 kV, and 10 kV were used as experimental variables to compare the characteristics of soft rock fragmentation between downhole liquid-phase discharge plasma and wire explosion. High-speed photography was employed to analyze and compare crack propagation behaviors between the two methods. Quantitative assessments of surface crack density and fractal dimension were conducted to characterize crack morphology differences in the processed specimens. Statistical analysis of fragment size distribution and specific surface area further revealed distinctive fragmentation characteristics. Additionally, on the basis of the dynamic processes of energy release and transfer in rock fragmentation via high-voltage pulse discharge and the relationship between newly created surface area and fragmentation energy in fracture mechanics, time-history current and voltage data were utilized to quantify the downhole deposited energy distribution and fragmentation energy allocation efficiency. The results show that, for rock fragmentation by liquid-phase discharge plasma, the surface crack density and newly created surface area increase monotonically with the increase of charging voltage, while the average fragment size presents a monotonically decreasing trend. For rock fragmentation by wire explosion, however, the surface crack density and newly created surface area increase first and then decrease, with the average fragment size showing an inverse trend. The fractal dimension of specimen surface cracks increases with the rising voltage for both methods, with wire explosion generating a more complex crack network. As charging voltage increases from 7 kV to 10 kV, the energy deposition efficiency for rock fragmentation by liquid-phase discharge plasma increases from 55.37% to 69.43%, whereas for rock fragmentation by wire explosion, it rises from 59.78% at 7 kV to a peak of 67.47% at 9 kV before sharply dropping to 52.96% at 10 kV. Meanwhile, the fraction of rock fragmentation energy within deposited energy declines from 7.53% to 4.77% for liquid-phase discharge plasma, which accounts for 3.32%–4.17% of the total energy stored in the capacitor. For wire explosion, the fraction declines from 8.08% to 6.62%. The corresponding value accounts for 2.98%–4.83% of the total energy stored in the capacitor. This demonstrates that the wire explosion technique delivers a higher conversion efficiency from deposited energy to rock fragmentation energy. At 10 kV, the insufficient deposited energy generated by wire explosion directly degrades its rock-breaking performance at this voltage, which deviates from the consistent upward trend of rock fragmentation efficacy observed in liquid-phase discharge plasma as the applied voltage rises. The findings offer valuable guidance for the method selection and parameter optimization of high-voltage pulse discharge for rock fragmentation.
, Available online ,
doi: 10.11883/bzycj-2026-0084
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Abstract:
To establish a simplified calculation method for the explosion stress wave time-history curve induced by cylindrical charge explosions in concrete considering the influence of aspect ratio, this paper presents a numerical simulation study on cylindrical charges with varying aspect ratios detonated in concrete. The study is based on an enhanced version of the Kong-Fang concrete constitutive model and the multi-material ALE algorithm, following validation of the model’s reliability against existing experimental data. The analysis focuses on the attenuation law of peak stress, the rise time, and the evolution of the constant impulse action time under different scaled distances. Results reveal that the peak stress follows a power-law decay pattern across various damage zones. With increasing aspect ratio, the attenuation index increases significantly, the attenuation coefficient decreases, and the extent of the cracked zones expands. In the proximity of the explosion, the stress rising time of the explosion stress wave increases linearly with distance, and the rate of this increase becomes more pronounced as the aspect ratio grows. Once the stress wave enters the cracked zone, its waveform is influenced by reflections and scatterings at crack interfaces, leading to a gradual flattening of the waveform and a subsequent stabilization in stress rising time. The equivalent impulse duration increases linearly with distance in the near zone but exhibits a decreasing trend within the fracture zone, reflecting the modulating effect of concrete damage on explosion stress wave propagation. Based on the principle of impulse equivalence, a simplified triangular explosion stress wave model is proposed, suitable for engineering-level anti-explosion analysis. Through segmented regression analysis, practical formulas are derived to estimate the peak stress, stress rising time, and equivalent impulse duration, explicitly incorporating the aspect ratio as a key parameter. These formulas offer a parametric tool for engineering calculations of explosion stress waves generated by internal cylindrical charge explosions in concrete structures.
To establish a simplified calculation method for the explosion stress wave time-history curve induced by cylindrical charge explosions in concrete considering the influence of aspect ratio, this paper presents a numerical simulation study on cylindrical charges with varying aspect ratios detonated in concrete. The study is based on an enhanced version of the Kong-Fang concrete constitutive model and the multi-material ALE algorithm, following validation of the model’s reliability against existing experimental data. The analysis focuses on the attenuation law of peak stress, the rise time, and the evolution of the constant impulse action time under different scaled distances. Results reveal that the peak stress follows a power-law decay pattern across various damage zones. With increasing aspect ratio, the attenuation index increases significantly, the attenuation coefficient decreases, and the extent of the cracked zones expands. In the proximity of the explosion, the stress rising time of the explosion stress wave increases linearly with distance, and the rate of this increase becomes more pronounced as the aspect ratio grows. Once the stress wave enters the cracked zone, its waveform is influenced by reflections and scatterings at crack interfaces, leading to a gradual flattening of the waveform and a subsequent stabilization in stress rising time. The equivalent impulse duration increases linearly with distance in the near zone but exhibits a decreasing trend within the fracture zone, reflecting the modulating effect of concrete damage on explosion stress wave propagation. Based on the principle of impulse equivalence, a simplified triangular explosion stress wave model is proposed, suitable for engineering-level anti-explosion analysis. Through segmented regression analysis, practical formulas are derived to estimate the peak stress, stress rising time, and equivalent impulse duration, explicitly incorporating the aspect ratio as a key parameter. These formulas offer a parametric tool for engineering calculations of explosion stress waves generated by internal cylindrical charge explosions in concrete structures.
, Available online ,
doi: 10.11883/bzycj-2026-0097
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Abstract:
To address the safety operation issues of in-service buried bolted flange pipelines subjected to repeated blasting vibrations, a combined approach of refined model testing and numerical simulation was adopted. A model test system for investigating the blasting dynamic response of bolted flange cast iron pipelines was established, and ten blasting tests were conducted. The axial strain characteristics of the bolts, as well as the strain characteristics of the pipe body and flange, were analyzed. Based on the model tests and their results, a numerical model for the blasting dynamic response of buried bolted flange pipelines was established using the LS-DYNA dynamic finite element software. The wear theory model was employed to simulate bolt loosening, enabling multiple blasting cycle calculations. The response characteristics of vibration velocity, stress, and flange rotation angle of the buried bolted flange pipelines were analyzed. The results indicated that the peak vibration velocity along the pipeline axis gradually increase from the two ends toward the center. The blasting vibrations cause bolt loosening, with the peak resultant velocity of the bolts increasing slightly as the number of blasting cycles increase. Furthermore, increasing the preload is observed to decrease the peak resultant velocity of the bolts. Stress concentration occurs at the connection between the pipe body and the flange, with a maximum effective stress of 157.5 MPa. Stress concentration is also observed at the connection between the nuts, bolts, and flanges, with a maximum effective stress of 151.4 MPa. A marked stress redistribution in the bolts is observed after blasting. The stress on the opposite side of the bolts is significantly lower than that on the blasting side. The axial pressure on the blasting side of the spacer increase, while that on the opposite side decrease. Flange rotation manifests as compression on the blasting side and tension on the opposite side. The flange at Bolt 1# on the blasting side exhibits the largest rotation, with a flange rotation angle of 0.029°.
To address the safety operation issues of in-service buried bolted flange pipelines subjected to repeated blasting vibrations, a combined approach of refined model testing and numerical simulation was adopted. A model test system for investigating the blasting dynamic response of bolted flange cast iron pipelines was established, and ten blasting tests were conducted. The axial strain characteristics of the bolts, as well as the strain characteristics of the pipe body and flange, were analyzed. Based on the model tests and their results, a numerical model for the blasting dynamic response of buried bolted flange pipelines was established using the LS-DYNA dynamic finite element software. The wear theory model was employed to simulate bolt loosening, enabling multiple blasting cycle calculations. The response characteristics of vibration velocity, stress, and flange rotation angle of the buried bolted flange pipelines were analyzed. The results indicated that the peak vibration velocity along the pipeline axis gradually increase from the two ends toward the center. The blasting vibrations cause bolt loosening, with the peak resultant velocity of the bolts increasing slightly as the number of blasting cycles increase. Furthermore, increasing the preload is observed to decrease the peak resultant velocity of the bolts. Stress concentration occurs at the connection between the pipe body and the flange, with a maximum effective stress of 157.5 MPa. Stress concentration is also observed at the connection between the nuts, bolts, and flanges, with a maximum effective stress of 151.4 MPa. A marked stress redistribution in the bolts is observed after blasting. The stress on the opposite side of the bolts is significantly lower than that on the blasting side. The axial pressure on the blasting side of the spacer increase, while that on the opposite side decrease. Flange rotation manifests as compression on the blasting side and tension on the opposite side. The flange at Bolt 1# on the blasting side exhibits the largest rotation, with a flange rotation angle of 0.029°.
, Available online ,
doi: 10.11883/bzycj-2026-0070
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Abstract:
Due to the low flash point and high vapor pressure of ethanol, serious combustion and explosion accidents are readily triggered during industrial storage and transportation. Explosion venting is therefore regarded as a critical safety protection measure. To reveal the explosion venting characteristics of ethanol mist and provide experimental guidance for industrial venting design, a comprehensive experimental platform was established based on a 20 L spherical explosion vessel, integrating mist dispersion, ignition, pressure and flame acquisition, and explosion venting units. Explosion and venting experiments of ethanol were conducted under a concentration range of 0~800 g/m³, with three different vent diameters and six distinct static activation pressures. The results show that an ethanol mist concentration of 500 g/m³ produces the most severe explosion under the experimental conditions investigated, with a maximum explosion pressure of 0.79 MPa and a peak explosion index of 34.8 MPa·m/s. It is clearly found that increasing the static activation pressure and reducing the venting diameter lead to higher explosion pressures and suppressed flame propagation. When the static activation pressure is increased from 320.22 kPa to 426.96 kPa, the maximum explosion pressure is increased by 31.9%, while the average flame propagation velocity is reduced by 25.5%. When the venting diameter is enlarged from 60 mm to 100 mm, the maximum flame propagation velocity is increased by 15.3%. A smaller venting diameter results in a more elongated flame jet with concentrated sparks, whereas a higher static activation pressure delays the flame appearance time and increases spark generation. Based on the experimental data, the venting area equation specified in the NFPA 68 standard is modified, and a venting area model applicable to ethanol mist explosions is established. The findings provide valuable experimental evidence and data support for the optimization and design of explosion venting systems in the industrial storage and transportation of ethanol.
Due to the low flash point and high vapor pressure of ethanol, serious combustion and explosion accidents are readily triggered during industrial storage and transportation. Explosion venting is therefore regarded as a critical safety protection measure. To reveal the explosion venting characteristics of ethanol mist and provide experimental guidance for industrial venting design, a comprehensive experimental platform was established based on a 20 L spherical explosion vessel, integrating mist dispersion, ignition, pressure and flame acquisition, and explosion venting units. Explosion and venting experiments of ethanol were conducted under a concentration range of 0~800 g/m³, with three different vent diameters and six distinct static activation pressures. The results show that an ethanol mist concentration of 500 g/m³ produces the most severe explosion under the experimental conditions investigated, with a maximum explosion pressure of 0.79 MPa and a peak explosion index of 34.8 MPa·m/s. It is clearly found that increasing the static activation pressure and reducing the venting diameter lead to higher explosion pressures and suppressed flame propagation. When the static activation pressure is increased from 320.22 kPa to 426.96 kPa, the maximum explosion pressure is increased by 31.9%, while the average flame propagation velocity is reduced by 25.5%. When the venting diameter is enlarged from 60 mm to 100 mm, the maximum flame propagation velocity is increased by 15.3%. A smaller venting diameter results in a more elongated flame jet with concentrated sparks, whereas a higher static activation pressure delays the flame appearance time and increases spark generation. Based on the experimental data, the venting area equation specified in the NFPA 68 standard is modified, and a venting area model applicable to ethanol mist explosions is established. The findings provide valuable experimental evidence and data support for the optimization and design of explosion venting systems in the industrial storage and transportation of ethanol.
, Available online ,
doi: 10.11883/bzycj-2026-0090
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Abstract:
In rock excavation engineering, presplit blasting serves as a core technology to protect the integrity and long-term stability of surrounding rock masses, while the initiation delay between presplit holes and main blast holes is the dominant parameter that directly determines blasting contour quality, stress wave transmission law and retained rock damage degree. To reveal the intrinsic dynamic regulation mechanism of initiation delay on presplit blasting process, this study adopted a coupled method of Digital Laser Dynamic Caustics (DLCS) test system and AUTODYN nonlinear dynamic numerical simulation. A series of dynamic blasting tests were conducted on polymethyl methacrylate (PMMA) specimens with prefabricated primary cracks under multiple typical delay conditions, to systematically analyze presplit crack propagation characteristics, blast stress field evolution, and initiation and propagation response of primary cracks in retained rock masses.Results show that detonating main blast holes during the dynamic propagation of presplit cracks changes the stress state at the crack tip, leading to a fracture mode transition from pure tensile Mode I to mixed Mode I-II tensile-shear fracture. This causes significant deflection of crack paths, reduces the straightness and continuity of presplit fractures, and weakens the stress wave isolation effect. When main blast holes are initiated after presplit cracks have completely arrested, the fully formed continuous presplit cracks can effectively block the transmission of main blast stress waves, with the final crack morphology almost consistent with that of single presplit blasting, realizing optimal fracture formation quality. For surrounding rock stability, presplit hole detonation compresses and closes pre-existing primary cracks through stress wave superposition and detonation gas effects. With the increase of delay time, the attenuation of main blast stress waves is significantly enhanced, which effectively suppresses the initiation and secondary propagation of primary cracks in retained rock, thus improving surrounding rock stability. Numerical results are in good agreement with DLCS test data, verifying the reliability of conclusions. This work clarifies the delay regulation mechanism of presplit blasting, providing theoretical support and practical guidance for precise optimization of blasting parameters in rock excavation engineering.
In rock excavation engineering, presplit blasting serves as a core technology to protect the integrity and long-term stability of surrounding rock masses, while the initiation delay between presplit holes and main blast holes is the dominant parameter that directly determines blasting contour quality, stress wave transmission law and retained rock damage degree. To reveal the intrinsic dynamic regulation mechanism of initiation delay on presplit blasting process, this study adopted a coupled method of Digital Laser Dynamic Caustics (DLCS) test system and AUTODYN nonlinear dynamic numerical simulation. A series of dynamic blasting tests were conducted on polymethyl methacrylate (PMMA) specimens with prefabricated primary cracks under multiple typical delay conditions, to systematically analyze presplit crack propagation characteristics, blast stress field evolution, and initiation and propagation response of primary cracks in retained rock masses.Results show that detonating main blast holes during the dynamic propagation of presplit cracks changes the stress state at the crack tip, leading to a fracture mode transition from pure tensile Mode I to mixed Mode I-II tensile-shear fracture. This causes significant deflection of crack paths, reduces the straightness and continuity of presplit fractures, and weakens the stress wave isolation effect. When main blast holes are initiated after presplit cracks have completely arrested, the fully formed continuous presplit cracks can effectively block the transmission of main blast stress waves, with the final crack morphology almost consistent with that of single presplit blasting, realizing optimal fracture formation quality. For surrounding rock stability, presplit hole detonation compresses and closes pre-existing primary cracks through stress wave superposition and detonation gas effects. With the increase of delay time, the attenuation of main blast stress waves is significantly enhanced, which effectively suppresses the initiation and secondary propagation of primary cracks in retained rock, thus improving surrounding rock stability. Numerical results are in good agreement with DLCS test data, verifying the reliability of conclusions. This work clarifies the delay regulation mechanism of presplit blasting, providing theoretical support and practical guidance for precise optimization of blasting parameters in rock excavation engineering.
, Available online ,
doi: 10.11883/bzycj-2026-0127
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Abstract:
For the protection requirements of shipborne cabinets subjected to multidirectional shock and multidirectional vibration, a corrugated honeycomb buffer with both multidirectional shock resistance and vibration isolation capability was designed based on corrugated honeycomb and porous rubber. The proposed buffer consists of a corrugated honeycomb, porous rubber, a metal casing, connectors, and spacers. The corrugated honeycomb serves as the primary energy-absorbing component for shock mitigation, while the porous rubber acts as the key vibration-isolation element. Through the interaction of these components, the buffer achieves integrated shock absorption and vibration isolation. A prototype of the corrugated honeycomb buffer was also fabricated. In accordance with the shock test standards for shipborne environments, shock tests were conducted on the cabinet equipped with the proposed buffer under both horizontal and inclined installation conditions. Acceleration responses of the cabinet in the lateral and vertical directions were measured under different test conditions, and the peak acceleration reduction ratio together with the shock transmissibility in different directions were calculated to evaluate the shock mitigation performance of the buffer. In addition, according to the vibration test standards for shipborne environments,sweep-frequency vibration tests were carried out in three orthogonal directions (X, Y, and Z). The vibration transmissibility in each direction was obtained, and the three-dimensional vibration-isolation performance of the corrugated honeycomb buffer was assessed systematically. The shock test results show that the cabinet fitted with the corrugated honeycomb buffer exhibits a low shock transmissibility of 0.091 under the horizontal installation condition, indicating an effective attenuation of shock. Under the inclined installation condition, the lateral and vertical shock transmissibility values are 0.132 and 0.083, respectively, which also remain at relatively low levels. These results demonstrate that the proposed buffer can maintain favorable shock-resistance performance under different installation configurations and loading directions. The vibration test results further indicate that, under typical shipborne vibration environments, the average vibration transmissibility values in the X, Y, and Z directions are 0.129, 0.085, and 0.180, respectively. The cabinet therefore maintains desirable vibration-isolation performance in all three directions, confirming the effectiveness of the proposed design in suppressing multidirectional vibration responses.Overall, the proposed corrugated honeycomb buffer can effectively reduce the dynamic response of shipborne cabinets subjected to multidirectional shock and vibration excitations. Owing to its stable shock attenuation capability and favorable three-dimensional vibration-isolation performance, the buffer provides a feasible protective solution for shipborne equipment and can serve as a reference for the design of protective structures for shipborne cabinets operating in complex mechanical environments.
For the protection requirements of shipborne cabinets subjected to multidirectional shock and multidirectional vibration, a corrugated honeycomb buffer with both multidirectional shock resistance and vibration isolation capability was designed based on corrugated honeycomb and porous rubber. The proposed buffer consists of a corrugated honeycomb, porous rubber, a metal casing, connectors, and spacers. The corrugated honeycomb serves as the primary energy-absorbing component for shock mitigation, while the porous rubber acts as the key vibration-isolation element. Through the interaction of these components, the buffer achieves integrated shock absorption and vibration isolation. A prototype of the corrugated honeycomb buffer was also fabricated. In accordance with the shock test standards for shipborne environments, shock tests were conducted on the cabinet equipped with the proposed buffer under both horizontal and inclined installation conditions. Acceleration responses of the cabinet in the lateral and vertical directions were measured under different test conditions, and the peak acceleration reduction ratio together with the shock transmissibility in different directions were calculated to evaluate the shock mitigation performance of the buffer. In addition, according to the vibration test standards for shipborne environments,sweep-frequency vibration tests were carried out in three orthogonal directions (X, Y, and Z). The vibration transmissibility in each direction was obtained, and the three-dimensional vibration-isolation performance of the corrugated honeycomb buffer was assessed systematically. The shock test results show that the cabinet fitted with the corrugated honeycomb buffer exhibits a low shock transmissibility of 0.091 under the horizontal installation condition, indicating an effective attenuation of shock. Under the inclined installation condition, the lateral and vertical shock transmissibility values are 0.132 and 0.083, respectively, which also remain at relatively low levels. These results demonstrate that the proposed buffer can maintain favorable shock-resistance performance under different installation configurations and loading directions. The vibration test results further indicate that, under typical shipborne vibration environments, the average vibration transmissibility values in the X, Y, and Z directions are 0.129, 0.085, and 0.180, respectively. The cabinet therefore maintains desirable vibration-isolation performance in all three directions, confirming the effectiveness of the proposed design in suppressing multidirectional vibration responses.Overall, the proposed corrugated honeycomb buffer can effectively reduce the dynamic response of shipborne cabinets subjected to multidirectional shock and vibration excitations. Owing to its stable shock attenuation capability and favorable three-dimensional vibration-isolation performance, the buffer provides a feasible protective solution for shipborne equipment and can serve as a reference for the design of protective structures for shipborne cabinets operating in complex mechanical environments.
, Available online ,
doi: 10.11883/bzycj-2026-0032
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Abstract:
The bilge structure of a ship's hull is a typical vulnerable area in resisting underwater explosions, and the rapid assessment of its dynamic response and damage is crucial for ship survivability design. To overcome the high computational cost bottleneck of traditional finite element methods, this paper proposes an integrated assessment and prediction framework that combines parametric modeling and machine learning. First, a fluid-structure interaction numerical model based on the Coupled Eulerian-Lagrangian (CEL) method was established and validated through experimental data. Subsequently, parametric modeling of the bilge grillage was conducted, systematically considering six key variables such as curvature radius, stiffener spacing, and plate thickness, resulting in a dataset of 2304 working conditions. Based on this, a two-stage machine learning prediction model was developed: initially, a random forest algorithm was employed to classify deformation and rupture damage modes; then, a conditional generative adversarial network (CGAN) was used to establish an end-to-end mapping relationship from design parameters to full-field stress, strain, and deformation contour maps. The research results indicate that this integrated framework achieves an order-of-magnitude improvement in computational efficiency while maintaining high prediction accuracy, thereby providing an efficient and reliable new approach for the rapid assessment of underwater explosion damage and the optimization of explosion resistance performance in ship hull structures.
The bilge structure of a ship's hull is a typical vulnerable area in resisting underwater explosions, and the rapid assessment of its dynamic response and damage is crucial for ship survivability design. To overcome the high computational cost bottleneck of traditional finite element methods, this paper proposes an integrated assessment and prediction framework that combines parametric modeling and machine learning. First, a fluid-structure interaction numerical model based on the Coupled Eulerian-Lagrangian (CEL) method was established and validated through experimental data. Subsequently, parametric modeling of the bilge grillage was conducted, systematically considering six key variables such as curvature radius, stiffener spacing, and plate thickness, resulting in a dataset of 2304 working conditions. Based on this, a two-stage machine learning prediction model was developed: initially, a random forest algorithm was employed to classify deformation and rupture damage modes; then, a conditional generative adversarial network (CGAN) was used to establish an end-to-end mapping relationship from design parameters to full-field stress, strain, and deformation contour maps. The research results indicate that this integrated framework achieves an order-of-magnitude improvement in computational efficiency while maintaining high prediction accuracy, thereby providing an efficient and reliable new approach for the rapid assessment of underwater explosion damage and the optimization of explosion resistance performance in ship hull structures.
, Available online ,
doi: 10.11883/bzycj-2026-0059
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Abstract:
To reveal the failure characteristics and performance degradation mechanisms of lithium-ion batteries under different mechanical abuse conditions, comparative tests of quasi-static planar compression, dynamic plate impact, and dynamic hemispherical impact were conducted on commercial pouch lithium-ion batteries. Real-time voltage monitoring, post-impact voltage tracking, electrochemical performance tests, and disassembly analysis were combined to investigate the effects of loading mode on failure threshold, electrical performance degradation, and internal damage mechanism. The results show that the loading mode significantly affects the safety boundary and failure mode of the battery. Failure occurs after a deformation energy of approximately 115 J under quasi-static compression, whereas plate impact and hemispherical impact induce failure at input energies of approximately 50 J and 10 J, respectively, indicating that dynamic impact, especially localized hemispherical impact, markedly narrows the safety boundary of the battery. At the same load level, quasi-static compression mainly causes an increase in internal resistance, while plate impact leads to more pronounced capacity loss. Under critical failure conditions, plate impact causes only slight capacity loss and internal resistance variation, whereas hemispherical impact results in a capacity loss of 17.4% and an internal resistance up to three times that of the fresh battery. This indicates that the transient voltage disturbance does not necessarily correspond to the actual degradation degree. Disassembly analysis further reveals two distinct failure mechanisms under dynamic impact: localized separator tearing and internal short circuit induced by hemispherical impact, and aluminum-plastic film rupture with electrolyte leakage induced by plate impact. This study provides experimental evidence for battery safety risk assessment under complex collision scenarios.
To reveal the failure characteristics and performance degradation mechanisms of lithium-ion batteries under different mechanical abuse conditions, comparative tests of quasi-static planar compression, dynamic plate impact, and dynamic hemispherical impact were conducted on commercial pouch lithium-ion batteries. Real-time voltage monitoring, post-impact voltage tracking, electrochemical performance tests, and disassembly analysis were combined to investigate the effects of loading mode on failure threshold, electrical performance degradation, and internal damage mechanism. The results show that the loading mode significantly affects the safety boundary and failure mode of the battery. Failure occurs after a deformation energy of approximately 115 J under quasi-static compression, whereas plate impact and hemispherical impact induce failure at input energies of approximately 50 J and 10 J, respectively, indicating that dynamic impact, especially localized hemispherical impact, markedly narrows the safety boundary of the battery. At the same load level, quasi-static compression mainly causes an increase in internal resistance, while plate impact leads to more pronounced capacity loss. Under critical failure conditions, plate impact causes only slight capacity loss and internal resistance variation, whereas hemispherical impact results in a capacity loss of 17.4% and an internal resistance up to three times that of the fresh battery. This indicates that the transient voltage disturbance does not necessarily correspond to the actual degradation degree. Disassembly analysis further reveals two distinct failure mechanisms under dynamic impact: localized separator tearing and internal short circuit induced by hemispherical impact, and aluminum-plastic film rupture with electrolyte leakage induced by plate impact. This study provides experimental evidence for battery safety risk assessment under complex collision scenarios.
, Available online ,
doi: 10.11883/bzycj-2026-0077
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Abstract:
To effectively suppress noise interference in blasting vibration signals, a denoising method combining Gaussian mutation multi‑verse optimizer (GMVO) and variational mode decomposition (VMD) was proposed. In this method, a Gaussian mutation strategy was introduced into the standard multi‑verse optimizer to improve its global exploration and local exploitation capabilities by adding normally distributed perturbations to individuals after wormhole transmission. The enhanced GMVO was then employed to adaptively determine the optimal VMD parameters, i.e., the penalty factor alpha and the number of modes K, using the minimum envelope entropy as the fitness function. The optimization process aimed at minimizing the envelope entropy, which reflects the complexity of the signal envelope and indicates better decomposition performance. With the optimized parameters, the noisy signal was decomposed via VMD into a series of intrinsic mode functions (IMFs). To distinguish noise‑dominant components from effective ones, multi‑scale permutation entropy (MPE) and variance contribution rate were calculated for each IMF. MPE quantifies the complexity of time series at multiple scales, with noise‑dominated components generally exhibiting higher entropy values. A dual‑threshold criterion was established: IMFs with MPE values exceeding 0.6 or variance contribution rates below 1% were rejected as noise or invalid modes. The retained IMFs were reconstructed to obtain the denoised signal.For validation, a clean blasting vibration signal was simulated using a prediction model previously developed, which incorporates modulated white noise and a Gamma envelope to faithfully reproduce the nonstationary characteristics of real blasting vibrations. Gaussian white noise at different signal‑to‑noise ratios (SNR) of 3, 5, 7, 10, and 15 dB was added to generate noisy signals. The denoising experiments demonstrated that the GMVO‑VMD method outperformed MVO‑VMD, wavelet thresholding, empirical mode decomposition with MPE (EMD‑MPE), and ensemble EMD‑MPE (EEMD‑MPE) in terms of SNR, root mean square error (RMSE), correlation coefficient, and smoothness index. The robustness indices remained above 0.8 even under strong noise interference. Application to field blasting vibration signals from an underground mine showed that the method effectively suppressed high‑frequency noise and corrected baseline drift, with smoothness indices below 0.0009 for cut holes and 0.0035 for perimeter holes. Compared with the four classical methods, the proposed approach exhibits superior overall performance in smoothness, energy ratio, and spectral similarity, confirming its effectiveness and applicability in practical engineering.
To effectively suppress noise interference in blasting vibration signals, a denoising method combining Gaussian mutation multi‑verse optimizer (GMVO) and variational mode decomposition (VMD) was proposed. In this method, a Gaussian mutation strategy was introduced into the standard multi‑verse optimizer to improve its global exploration and local exploitation capabilities by adding normally distributed perturbations to individuals after wormhole transmission. The enhanced GMVO was then employed to adaptively determine the optimal VMD parameters, i.e., the penalty factor alpha and the number of modes K, using the minimum envelope entropy as the fitness function. The optimization process aimed at minimizing the envelope entropy, which reflects the complexity of the signal envelope and indicates better decomposition performance. With the optimized parameters, the noisy signal was decomposed via VMD into a series of intrinsic mode functions (IMFs). To distinguish noise‑dominant components from effective ones, multi‑scale permutation entropy (MPE) and variance contribution rate were calculated for each IMF. MPE quantifies the complexity of time series at multiple scales, with noise‑dominated components generally exhibiting higher entropy values. A dual‑threshold criterion was established: IMFs with MPE values exceeding 0.6 or variance contribution rates below 1% were rejected as noise or invalid modes. The retained IMFs were reconstructed to obtain the denoised signal.For validation, a clean blasting vibration signal was simulated using a prediction model previously developed, which incorporates modulated white noise and a Gamma envelope to faithfully reproduce the nonstationary characteristics of real blasting vibrations. Gaussian white noise at different signal‑to‑noise ratios (SNR) of 3, 5, 7, 10, and 15 dB was added to generate noisy signals. The denoising experiments demonstrated that the GMVO‑VMD method outperformed MVO‑VMD, wavelet thresholding, empirical mode decomposition with MPE (EMD‑MPE), and ensemble EMD‑MPE (EEMD‑MPE) in terms of SNR, root mean square error (RMSE), correlation coefficient, and smoothness index. The robustness indices remained above 0.8 even under strong noise interference. Application to field blasting vibration signals from an underground mine showed that the method effectively suppressed high‑frequency noise and corrected baseline drift, with smoothness indices below 0.0009 for cut holes and 0.0035 for perimeter holes. Compared with the four classical methods, the proposed approach exhibits superior overall performance in smoothness, energy ratio, and spectral similarity, confirming its effectiveness and applicability in practical engineering.
, Available online ,
doi: 10.11883/bzycj-2026-0062
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Abstract:
In recent years, there have been frequent explosions of aluminum dust in the industrial and commercial enterprises, seriously threatening the personnel safety and economic development. To investigate the explosion characteristics of aluminum powder and the efficacy of explosion suppressant in industrial dust removal pipelines, a medium-to-large-scale transparent pipeline explosion testing system was constructed, and experiments on aluminum powder explosion and explosion suppression were carried out. Various parameters were measured under different influencing factors, including the explosion pressure, maximum free-field pressure rise rate, and the flame propagation speed. Through the analysis of pressure curves and deflagration flame propagation characteristics, the results showed that aluminum powder with a concentration below 100 g/m³ had a relatively low explosive destructive power in medium-to-large-scale pipeline. With increasing aluminum powder concentration, the mass of aluminum powder per unit volume rose. Consequently, more heat was released upon combustion. The flame propagated rapidly after passing through the second and third sections of the pipeline. The explosion pressure at each measurement point in the pipeline increased accordingly. Simultaneously, the free‑field pressure and its rise rate outside the pipeline increased significantly. A MgAl‑CO₃ bimetallic supramolecular suppressant suppresses aluminum powder explosion via physicochemical synergy. At a suppressant concentration of 500 g/m³, the free-field pressure of aluminum powder explosion decreased across all tested powder concentrations. Furthermore, the suppressant exhibited better performance for 300 g/m³ aluminum powder than for 200 g/m³, in terms of reducing both the maximum free-field pressure rise rate and flame propagation speed. At an aluminum powder concentration of 200 g/m³, the suppression effect remained almost unchanged with increasing suppressant concentration. However, an excessively high suppressant concentration reduced the suppression effect on the explosion free‑field pressure. The suppression effect of the suppressant interacts with the reaction acceleration caused by its high concentration, thereby reducing the overall suppression efficacy. Based on the engineering-scale pipeline testing system, these findings can provide scientific and theoretical support for the risk assessment and explosion suppression of aluminum powder explosions in industrial dust removal systems.
In recent years, there have been frequent explosions of aluminum dust in the industrial and commercial enterprises, seriously threatening the personnel safety and economic development. To investigate the explosion characteristics of aluminum powder and the efficacy of explosion suppressant in industrial dust removal pipelines, a medium-to-large-scale transparent pipeline explosion testing system was constructed, and experiments on aluminum powder explosion and explosion suppression were carried out. Various parameters were measured under different influencing factors, including the explosion pressure, maximum free-field pressure rise rate, and the flame propagation speed. Through the analysis of pressure curves and deflagration flame propagation characteristics, the results showed that aluminum powder with a concentration below 100 g/m³ had a relatively low explosive destructive power in medium-to-large-scale pipeline. With increasing aluminum powder concentration, the mass of aluminum powder per unit volume rose. Consequently, more heat was released upon combustion. The flame propagated rapidly after passing through the second and third sections of the pipeline. The explosion pressure at each measurement point in the pipeline increased accordingly. Simultaneously, the free‑field pressure and its rise rate outside the pipeline increased significantly. A MgAl‑CO₃ bimetallic supramolecular suppressant suppresses aluminum powder explosion via physicochemical synergy. At a suppressant concentration of 500 g/m³, the free-field pressure of aluminum powder explosion decreased across all tested powder concentrations. Furthermore, the suppressant exhibited better performance for 300 g/m³ aluminum powder than for 200 g/m³, in terms of reducing both the maximum free-field pressure rise rate and flame propagation speed. At an aluminum powder concentration of 200 g/m³, the suppression effect remained almost unchanged with increasing suppressant concentration. However, an excessively high suppressant concentration reduced the suppression effect on the explosion free‑field pressure. The suppression effect of the suppressant interacts with the reaction acceleration caused by its high concentration, thereby reducing the overall suppression efficacy. Based on the engineering-scale pipeline testing system, these findings can provide scientific and theoretical support for the risk assessment and explosion suppression of aluminum powder explosions in industrial dust removal systems.
, Available online ,
doi: 10.11883/bzycj-2026-0061
PDF(132)
Abstract:
In order to investigate the penetration performance of tungsten fiber / metallic glass matrix (WF/MG) composite long rods onto ceramic targets as well as the deformation and failure characteristics of both projectile and target materials, the adaptive coupling algorithm with finite element method and smoothed particle hydrodynamics (FE-SPH) is employed to conduct related simulations integrated with the corresponding experiments, and comparative analysis is conducted between the ballistic performances of tungsten alloy long rods impacting onto ceramic targets and WF/MG composite long rods onto steel targets, and the corresponding similarities and differences in the deformation and failure features of long rods and targets are discussed. Furthermore, the effects of several factors, including impact velocity, rod nose shape, and mechanical properties of ceramic materials, on the ballistic characteristics and damage evolution features of ceramic targets, are analyzed in detail. Related analysis demonstrates that during the impact onto ceramic targets, severe dispersion of tungsten fibers occurs in the rod nose region, and thus the penetration capability of WF/MG composite long rods is significantly lower than that regarding to metallic targets, and it is also lower than that of tungsten alloy long rods against ceramic targets. Impact velocity, rod nose shape, and the strength of ceramic material all have significant influences on the dynamic response characteristics of composite long rod and ceramic target. Increasing the impact velocity helps to suppress the dispersion of tungsten fibers, thereby enhances the penetration capability of composite long rod; the flat-nosed long rod can induce broader region of crack initiation and propagation within the ceramic target; lower ceramic strength leads to wider inner damage regions within the target caused by the impact of composite long rod. Related research is beneficial to predicting and evaluating the penetration performance of WF/MG composite long rods against high-strength brittle targets such as ceramic targets, and also to recognize the applicable scenarios for this new kind of long rod.
In order to investigate the penetration performance of tungsten fiber / metallic glass matrix (WF/MG) composite long rods onto ceramic targets as well as the deformation and failure characteristics of both projectile and target materials, the adaptive coupling algorithm with finite element method and smoothed particle hydrodynamics (FE-SPH) is employed to conduct related simulations integrated with the corresponding experiments, and comparative analysis is conducted between the ballistic performances of tungsten alloy long rods impacting onto ceramic targets and WF/MG composite long rods onto steel targets, and the corresponding similarities and differences in the deformation and failure features of long rods and targets are discussed. Furthermore, the effects of several factors, including impact velocity, rod nose shape, and mechanical properties of ceramic materials, on the ballistic characteristics and damage evolution features of ceramic targets, are analyzed in detail. Related analysis demonstrates that during the impact onto ceramic targets, severe dispersion of tungsten fibers occurs in the rod nose region, and thus the penetration capability of WF/MG composite long rods is significantly lower than that regarding to metallic targets, and it is also lower than that of tungsten alloy long rods against ceramic targets. Impact velocity, rod nose shape, and the strength of ceramic material all have significant influences on the dynamic response characteristics of composite long rod and ceramic target. Increasing the impact velocity helps to suppress the dispersion of tungsten fibers, thereby enhances the penetration capability of composite long rod; the flat-nosed long rod can induce broader region of crack initiation and propagation within the ceramic target; lower ceramic strength leads to wider inner damage regions within the target caused by the impact of composite long rod. Related research is beneficial to predicting and evaluating the penetration performance of WF/MG composite long rods against high-strength brittle targets such as ceramic targets, and also to recognize the applicable scenarios for this new kind of long rod.
, Available online ,
doi: 10.11883/bzycj-2026-0036
PDF(97)
Abstract:
The widespread deployment of Explosive Reactive Armor (ERA) has qualitatively enhanced the battlefield survivability of modern main battle tanks and heavy infantry fighting vehicles. The conventional Explosively Formed Projectile (EFP) warhead, which generate a single projectile, is insufficient to effectively destroy armor targets equipped with ERA. This limitation has created a significant performance gap in existing anti-armor systems. In response to the threat posed by ERA, the Collinear Explosively Formed Projectiles (CEFP) warhead has been developed as a novel, high-efficiency warhead designed to meet this operational requirement. The CEFP warhead employs a multi-layered liner structure. Upon detonation, it forms multiple EFPs that separate sequentially along the axis, each retaining penetrative capability. The leading EFP is intended to perforate the front plate or initiate the ERA, while the trailing EFP consecutively penetrates the primary armor. This mechanism significantly enhances the destructive potential against composite "ERA + Primary Armor" configurations. However, a critical challenge for this type of warhead lies in the suboptimal kinetic energy matching between the leading and trailing damage elements. To address this challenge and effectively defeat the composite protection system of ERA and primary armor, a coaxial double-layer liner EFP warhead featuring an "externally thin, internally thick" asymmetric liner structure is proposed. A comprehensive investigation into its formation mechanism and penetration characteristics was conducted through theoretical analysis, numerical simulation, and experimental validation. This study elucidated the influence of the liner thickness ratio on the kinetic energy of the leading and trailing EFPs. Research findings indicate that a single detonation of this warhead generates two axially separated EFPs with a significant velocity differential, both possessing penetration capability. It thereby achieves a sequential attack function: the leading EFP triggers the ERA, and the trailing EFP penetrates the primary armor. Under the constraint of a constant total liner mass, the velocity differential between the leading EFP and the trailing EFP can be continuously adjusted within a range of 78 m/s to 357 m/s by varying the thickness ratio of the outer and inner liners. Concurrently, the kinetic energy distribution ratio between the two projectiles can be flexibly configured within the range of 1:5.5 to 4.2:1. The feasibility of this innovative design has been successfully verified through static detonation testing of the warhead prototype.
The widespread deployment of Explosive Reactive Armor (ERA) has qualitatively enhanced the battlefield survivability of modern main battle tanks and heavy infantry fighting vehicles. The conventional Explosively Formed Projectile (EFP) warhead, which generate a single projectile, is insufficient to effectively destroy armor targets equipped with ERA. This limitation has created a significant performance gap in existing anti-armor systems. In response to the threat posed by ERA, the Collinear Explosively Formed Projectiles (CEFP) warhead has been developed as a novel, high-efficiency warhead designed to meet this operational requirement. The CEFP warhead employs a multi-layered liner structure. Upon detonation, it forms multiple EFPs that separate sequentially along the axis, each retaining penetrative capability. The leading EFP is intended to perforate the front plate or initiate the ERA, while the trailing EFP consecutively penetrates the primary armor. This mechanism significantly enhances the destructive potential against composite "ERA + Primary Armor" configurations. However, a critical challenge for this type of warhead lies in the suboptimal kinetic energy matching between the leading and trailing damage elements. To address this challenge and effectively defeat the composite protection system of ERA and primary armor, a coaxial double-layer liner EFP warhead featuring an "externally thin, internally thick" asymmetric liner structure is proposed. A comprehensive investigation into its formation mechanism and penetration characteristics was conducted through theoretical analysis, numerical simulation, and experimental validation. This study elucidated the influence of the liner thickness ratio on the kinetic energy of the leading and trailing EFPs. Research findings indicate that a single detonation of this warhead generates two axially separated EFPs with a significant velocity differential, both possessing penetration capability. It thereby achieves a sequential attack function: the leading EFP triggers the ERA, and the trailing EFP penetrates the primary armor. Under the constraint of a constant total liner mass, the velocity differential between the leading EFP and the trailing EFP can be continuously adjusted within a range of 78 m/s to 357 m/s by varying the thickness ratio of the outer and inner liners. Concurrently, the kinetic energy distribution ratio between the two projectiles can be flexibly configured within the range of 1:5.5 to 4.2:1. The feasibility of this innovative design has been successfully verified through static detonation testing of the warhead prototype.
, Available online ,
doi: 10.11883/bzycj-2026-0081
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Abstract:
Research on the underwater motion of shaped charge jets (SCJs) remains limited, leaving the evolution patterns and influencing factors of jet velocity and morphology in this medium insufficiently understood. Furthermore, established kinematic equations describing jet motion in water remain scarce. To address these gaps, a combined numerical and experimental approach was employed to investigate the evolution behavior of jets formed from five distinct metallic liner materials—aluminum, titanium, zirconium, iron, and copper—in both air and water. A three-dimensional Arbitrary Lagrangian-Eulerian (ALE) model of jet flight was established based on ANSYS finite element software to investigate the velocity and stress variations of jets in air and water. Concurrently, an experimental platform for jet flight was constructed, and the dynamic evolution processes in both media were recorded using high-speed imaging. The results demonstrate that jet velocity undergoes significant and rapid attenuation in water, decreasing by approximately 80% within 4 times the standoff distance, and the attenuation rate is negatively correlated with material density. Moreover, based on experimental and simulation results, combined with hydromechanics theory, a mathematical model was developed to predict jet velocity attenuation in water, achieving a Mean Absolute Relative Error (MARE) of 9.8%. Based on this model, the primary material factors influencing the jet velocity attenuation process are identified, with the weighted influence ranked as melting point, strength, and density. Additionally, the density, strength, and plasticity of the liner are the key factors governing jet evolution behavior in water. Specifically, high density and high plasticity effectively enhance the jet's fracture resistance and significantly delay its dispersion process. Notably, the resistance force acting on the jet tip in water can reach up to 2000 MPa, which intensifies jet fracture, leading to an increase of over 41.4% in the degree of jet dispersion compared to that in air. Furthermore, water significantly inhibits the oxidation energy release of the reactive materials via oxygen isolation and cooling effects, rendering their energy release characteristics similar to those of inert materials. These findings elucidate the influence of material properties on jet deceleration, fracture, and dispersion in water, providing a theoretical basis for the optimized design of underwater shaped charge warheads.
Research on the underwater motion of shaped charge jets (SCJs) remains limited, leaving the evolution patterns and influencing factors of jet velocity and morphology in this medium insufficiently understood. Furthermore, established kinematic equations describing jet motion in water remain scarce. To address these gaps, a combined numerical and experimental approach was employed to investigate the evolution behavior of jets formed from five distinct metallic liner materials—aluminum, titanium, zirconium, iron, and copper—in both air and water. A three-dimensional Arbitrary Lagrangian-Eulerian (ALE) model of jet flight was established based on ANSYS finite element software to investigate the velocity and stress variations of jets in air and water. Concurrently, an experimental platform for jet flight was constructed, and the dynamic evolution processes in both media were recorded using high-speed imaging. The results demonstrate that jet velocity undergoes significant and rapid attenuation in water, decreasing by approximately 80% within 4 times the standoff distance, and the attenuation rate is negatively correlated with material density. Moreover, based on experimental and simulation results, combined with hydromechanics theory, a mathematical model was developed to predict jet velocity attenuation in water, achieving a Mean Absolute Relative Error (MARE) of 9.8%. Based on this model, the primary material factors influencing the jet velocity attenuation process are identified, with the weighted influence ranked as melting point, strength, and density. Additionally, the density, strength, and plasticity of the liner are the key factors governing jet evolution behavior in water. Specifically, high density and high plasticity effectively enhance the jet's fracture resistance and significantly delay its dispersion process. Notably, the resistance force acting on the jet tip in water can reach up to 2000 MPa, which intensifies jet fracture, leading to an increase of over 41.4% in the degree of jet dispersion compared to that in air. Furthermore, water significantly inhibits the oxidation energy release of the reactive materials via oxygen isolation and cooling effects, rendering their energy release characteristics similar to those of inert materials. These findings elucidate the influence of material properties on jet deceleration, fracture, and dispersion in water, providing a theoretical basis for the optimized design of underwater shaped charge warheads.
, Available online ,
doi: 10.11883/bzycj-2026-0050
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Abstract:
Underwater two-point explosions are commonly encountered in engineering fields such as underwater blasting. The cooperative effects of multiple explosive sources result in more complex shockwave load characteristics compared to single-source underwater explosions. Based on the open-source software OpenFOAM, this paper establishes a multi-physics coupled numerical model for underwater multi-point explosions in a limited water domain with a free surface and a rigid bottom. Numerical investigations are conducted on the complex evolution of shockwave loads generated by multiple underwater explosive sources under different spatial distributions and initiation sequences. It is found that the spacing between explosive sources and the initiation phase difference are key parameters governing shockwave superposition. Variations in the spacing between two explosive sources have little effect on the pressure fields on the left and right sides along the horizontal direction of the two-source system, but significantly influence the pressure field in the region perpendicular to the line connecting the centers of the two sources. Within a certain range, a larger initiation spacing can increase the positive pressure duration of the shockwave. Delayed initiation with a certain time interval can significantly enhance the peak overpressure of the initial superimposed wave. A noticeable pressure truncation phenomenon occurs near the free surface, while multiple reflections and superposition of shockwaves in the rigid bottom boundary region significantly increase the nearby pressure field, producing a reflected wave enhancement effect.
Underwater two-point explosions are commonly encountered in engineering fields such as underwater blasting. The cooperative effects of multiple explosive sources result in more complex shockwave load characteristics compared to single-source underwater explosions. Based on the open-source software OpenFOAM, this paper establishes a multi-physics coupled numerical model for underwater multi-point explosions in a limited water domain with a free surface and a rigid bottom. Numerical investigations are conducted on the complex evolution of shockwave loads generated by multiple underwater explosive sources under different spatial distributions and initiation sequences. It is found that the spacing between explosive sources and the initiation phase difference are key parameters governing shockwave superposition. Variations in the spacing between two explosive sources have little effect on the pressure fields on the left and right sides along the horizontal direction of the two-source system, but significantly influence the pressure field in the region perpendicular to the line connecting the centers of the two sources. Within a certain range, a larger initiation spacing can increase the positive pressure duration of the shockwave. Delayed initiation with a certain time interval can significantly enhance the peak overpressure of the initial superimposed wave. A noticeable pressure truncation phenomenon occurs near the free surface, while multiple reflections and superposition of shockwaves in the rigid bottom boundary region significantly increase the nearby pressure field, producing a reflected wave enhancement effect.
, Available online ,
doi: 10.11883/bzycj-2026-0116
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Abstract:
To investigate the injury effects of cloud detonation shock waves on biological targets, a cloud detonation model and a finite element model of the goat thorax were established. Shock wave pressure-time histories at different locations were obtained through numerical simulation of cloud detonation and were applied as input loads to the external air-domain boundary on the blast-facing side of the goat thoracic model. The interaction process between the shock wave and the goat thorax was simulated using a fluid-structure coupling method between the air domain and thoracic tissue structures. Mesh independence verification was performed for both the cloud detonation model and the goat thoracic finite element model, and model validity was analyzed by comparison with field test results. On this basis, chest wall displacement velocity, thoracic compression process, and stress responses at different lung locations were extracted to investigate the dynamic response of the goat thoracic model under shock wave loading. By varying load parameters, including peak overpressure, impulse, and pressure rise time, the effects of different shock wave parameters on thoracic deformation characteristics and pulmonary stress propagation were analyzed. The applicability of cloud-detonation-induced lung injury evaluation indexes was further assessed by combining the maximum thoracic compression rate criterion with the pulmonary stress criterion. The results show that, under shock wave loading, chest wall motion compresses the lung and induces stress wave propagation within the pulmonary tissue. As impulse and pressure rise time increase, the sustained compression effect of the shock wave on the chest wall is enhanced, while the reflection characteristics of stress waves propagating in the lung are weakened. Therefore, the maximum thoracic compression rate alone cannot fully evaluate lung injury. Using the maximum thoracic compression rate as an evaluation index for lung injury under cloud detonation conditions has certain limitations and may underestimate lung injury severity under high-impulse and long-rise-time loading conditions. Chest compression and the maximum compression rate can be used together as auxiliary criteria for evaluating lung injury under cloud detonation conditions.
, Available online ,
doi: 10.11883/bzycj-2026-0058
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Abstract:
To ensure safe production in coal mines and effectively mitigate casualties as well as economic losses caused by coal dust explosions, the overpressure propagation laws following explosions of coal dust with varying concentrations in a pipeline were investigated. Based on the positive feedback mechanism between the shock wave and the flame wave during coal dust explosions in a horizontal pipeline—realized specifically through heating and compression effects, a rigorous dimensional analysis method was employed. This method allowed a comprehensive consideration of a series of dynamic and static factors affecting the overpressure propagation of coal dust explosions, including energy of the explosive coal dust mixture, accumulated volume of the explosive coal dust mixture, pipeline cross-sectional area, hydraulic diameter, distance from the measuring point to the explosion source, initial air pressure before explosion, air density, coal dust concentration, flame propagation velocity at the measuring point, coal dust particle size, and pipeline friction coefficient. By incorporating experimental data, a dynamic-static coupling mathematical model was established to describe the unidirectional propagation of overpressure from coal dust explosions in a semi-closed straight pipeline. The model was subsequently validated and subjected to further comprehensive comparisons. The results clearly indicate that the energy of the explosive mixture, the distance between the measuring point and the explosion source, coal dust concentration, flame propagation velocity, and coal dust particle size constitute the main factors influencing the overpressure propagation of coal dust explosions. A strong positive correlation exists between coal dust explosion overpressure and flame propagation velocity. In practical hazard assessments of coal dust explosions, particular attention should be paid to factors that promote flame acceleration, such as turbulence and obstacles. The established dynamic-static coupling model demonstrates high reliability. Compared with existing overpressure prediction methods, this model offers lower operational thresholds and the capability to resolve the dynamic overpressure propagation process, thereby presenting overall comprehensive advantages.
To ensure safe production in coal mines and effectively mitigate casualties as well as economic losses caused by coal dust explosions, the overpressure propagation laws following explosions of coal dust with varying concentrations in a pipeline were investigated. Based on the positive feedback mechanism between the shock wave and the flame wave during coal dust explosions in a horizontal pipeline—realized specifically through heating and compression effects, a rigorous dimensional analysis method was employed. This method allowed a comprehensive consideration of a series of dynamic and static factors affecting the overpressure propagation of coal dust explosions, including energy of the explosive coal dust mixture, accumulated volume of the explosive coal dust mixture, pipeline cross-sectional area, hydraulic diameter, distance from the measuring point to the explosion source, initial air pressure before explosion, air density, coal dust concentration, flame propagation velocity at the measuring point, coal dust particle size, and pipeline friction coefficient. By incorporating experimental data, a dynamic-static coupling mathematical model was established to describe the unidirectional propagation of overpressure from coal dust explosions in a semi-closed straight pipeline. The model was subsequently validated and subjected to further comprehensive comparisons. The results clearly indicate that the energy of the explosive mixture, the distance between the measuring point and the explosion source, coal dust concentration, flame propagation velocity, and coal dust particle size constitute the main factors influencing the overpressure propagation of coal dust explosions. A strong positive correlation exists between coal dust explosion overpressure and flame propagation velocity. In practical hazard assessments of coal dust explosions, particular attention should be paid to factors that promote flame acceleration, such as turbulence and obstacles. The established dynamic-static coupling model demonstrates high reliability. Compared with existing overpressure prediction methods, this model offers lower operational thresholds and the capability to resolve the dynamic overpressure propagation process, thereby presenting overall comprehensive advantages.
, Available online ,
doi: 10.11883/bzycj-2026-0039
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Abstract:
This study investigates the dynamic and quasi-static mechanical behaviors of a single-phase body-centered cubic (BCC) WNbMoTaV refractory high-entropy alloy (RHEA) fabricated by vacuum arc melting, over a temperature range of 77.15–1373.15 K and strain rates of 0.001–7300 s⁻¹. The microstructural evolution mechanisms under thermo-mechanical coupling were explored. Based on experimental data, the Johnson–Cook (J–C) constitutive model was fitted and analyzed. Results indicate significant deviations in the strain-rate hardening stage, with pronounced temperature dependence of mechanical responses: the flow stress at 77.15 K was only 68.5% of that at 1373.15 K under certain conditions. Therefore, a modified J–C model was proposed by introducing regression coefficients and a coupled temperature–strain rate correction term for both strain-rate hardening and thermal softening. Finite element numerical simulations verified that the error range of the modified model lies between 8.0% and 12.5%. Furthermore, microstructural characterization via scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and high-resolution transmission electron microscopy (HRTEM) revealed that on cleavage surfaces of quasi-static tensile fracture, tough tear ridges and river patterns exhibited distinct distributions, along with varying degrees of grain refinement. Fracture and crack propagation modes showed notable evolution. Under combined temperature and impact loading, the high proportion of high-angle grain boundaries (HAGBs) was identified as the core factor for the wide-temperature stability of the WMoTaNbV RHEA. At low temperatures, sub-grain refinement and dislocation walls enhanced dynamic strength, whereas at high temperatures, reduced lattice distortion and dynamic recrystallization jointly promoted the formation of HAGBs.
This study investigates the dynamic and quasi-static mechanical behaviors of a single-phase body-centered cubic (BCC) WNbMoTaV refractory high-entropy alloy (RHEA) fabricated by vacuum arc melting, over a temperature range of 77.15–1373.15 K and strain rates of 0.001–7300 s⁻¹. The microstructural evolution mechanisms under thermo-mechanical coupling were explored. Based on experimental data, the Johnson–Cook (J–C) constitutive model was fitted and analyzed. Results indicate significant deviations in the strain-rate hardening stage, with pronounced temperature dependence of mechanical responses: the flow stress at 77.15 K was only 68.5% of that at 1373.15 K under certain conditions. Therefore, a modified J–C model was proposed by introducing regression coefficients and a coupled temperature–strain rate correction term for both strain-rate hardening and thermal softening. Finite element numerical simulations verified that the error range of the modified model lies between 8.0% and 12.5%. Furthermore, microstructural characterization via scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and high-resolution transmission electron microscopy (HRTEM) revealed that on cleavage surfaces of quasi-static tensile fracture, tough tear ridges and river patterns exhibited distinct distributions, along with varying degrees of grain refinement. Fracture and crack propagation modes showed notable evolution. Under combined temperature and impact loading, the high proportion of high-angle grain boundaries (HAGBs) was identified as the core factor for the wide-temperature stability of the WMoTaNbV RHEA. At low temperatures, sub-grain refinement and dislocation walls enhanced dynamic strength, whereas at high temperatures, reduced lattice distortion and dynamic recrystallization jointly promoted the formation of HAGBs.
, Available online ,
doi: 10.11883/bzycj-2026-0064
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Abstract:
The composite protective structure consists of a shield layer, a distribution layer, and a structure layer. Compared with traditional monolithic protective structure made of high strength materials, the composite protective structure is more economical and effective to resist the combined penetration and explosion of earth-penetrating weapons. To establish a design method for composite protective structures against combined penetration and explosion, the integrated design concept and process were first proposed based on the protective requirements of shield layer, distribution layer, and structure layer. Subsequently, a high-fidelity numerical simulation method was established and validated to analyze the resistance of composite protective structures against combined penetration and explosion. Furthermore, a composite protective structure was designed against the penetration of a 105 mm projectile and explosion of 7 kg of HMX explosive as example. The results indicated that shield layer is non-perforated and the load transmitted to the structure layer attenuated by distribution layer is less than local dynamic bearing capacity of structure layer, so the composite protective structure can meet the protective requirements by using the proposed design method. Finally, under the constraints of equal combined penetration and explosion and thickness of each layer, comparative analysis was conducted on the dynamic response and damage of composite protective structures consisting of three types of shield layers—normal strength concrete (NSC), ultra-high performance concrete (UHPC), and corundum rubble concrete (CRC), and two types of distribution layers—C3 foam concrete and sand. The results indicated that: (1) The NSC shield layer is perforated by projectile and the peak reflected stress at the top of structure layer in “UHPC shield layer + sand distribution layer + NSC structure layer” composite protective structure is larger than local dynamic bearing capacity, both fail to meet protective requirements; “UHPC/CRC shield layer + C3 foam concrete distribution layer + NSC structure layer” exhibit localized yielding at the bottom of distribution layer, with peak reflected stresses at the top of structure layer is less than local dynamic capacity, both meet protective requirements. (2) The compression ratios of the distribution layers in both “UHPC shield layer + C3 foam concrete/sand distribution layer + NSC structure layer” are similar (approximately 30%), but the peak stresses at both the top and bottom of C3 foam concrete distribution layer are only 16% and 13% of those in the sand distribution layer. The impedance mismatch effect of composite structure with C3 foam concrete distribution layer is more pronounced than sand distribution layer `and exhibits better wave attenuation performance. (3) The “CRC shield layer + C3 foam concrete distribution layer + NSC structure layer” exhibits the best resistance against combined penetration and explosion, with penetration depth in shield layer, as well as compression ratio, peak stress and strain at the top, and peak strain at the bottom of distribution layer are 87%, 29%, 55%, 47%, and 21% respectively of those in the corresponding UHPC shield layer configuration.
The composite protective structure consists of a shield layer, a distribution layer, and a structure layer. Compared with traditional monolithic protective structure made of high strength materials, the composite protective structure is more economical and effective to resist the combined penetration and explosion of earth-penetrating weapons. To establish a design method for composite protective structures against combined penetration and explosion, the integrated design concept and process were first proposed based on the protective requirements of shield layer, distribution layer, and structure layer. Subsequently, a high-fidelity numerical simulation method was established and validated to analyze the resistance of composite protective structures against combined penetration and explosion. Furthermore, a composite protective structure was designed against the penetration of a 105 mm projectile and explosion of 7 kg of HMX explosive as example. The results indicated that shield layer is non-perforated and the load transmitted to the structure layer attenuated by distribution layer is less than local dynamic bearing capacity of structure layer, so the composite protective structure can meet the protective requirements by using the proposed design method. Finally, under the constraints of equal combined penetration and explosion and thickness of each layer, comparative analysis was conducted on the dynamic response and damage of composite protective structures consisting of three types of shield layers—normal strength concrete (NSC), ultra-high performance concrete (UHPC), and corundum rubble concrete (CRC), and two types of distribution layers—C3 foam concrete and sand. The results indicated that: (1) The NSC shield layer is perforated by projectile and the peak reflected stress at the top of structure layer in “UHPC shield layer + sand distribution layer + NSC structure layer” composite protective structure is larger than local dynamic bearing capacity, both fail to meet protective requirements; “UHPC/CRC shield layer + C3 foam concrete distribution layer + NSC structure layer” exhibit localized yielding at the bottom of distribution layer, with peak reflected stresses at the top of structure layer is less than local dynamic capacity, both meet protective requirements. (2) The compression ratios of the distribution layers in both “UHPC shield layer + C3 foam concrete/sand distribution layer + NSC structure layer” are similar (approximately 30%), but the peak stresses at both the top and bottom of C3 foam concrete distribution layer are only 16% and 13% of those in the sand distribution layer. The impedance mismatch effect of composite structure with C3 foam concrete distribution layer is more pronounced than sand distribution layer `and exhibits better wave attenuation performance. (3) The “CRC shield layer + C3 foam concrete distribution layer + NSC structure layer” exhibits the best resistance against combined penetration and explosion, with penetration depth in shield layer, as well as compression ratio, peak stress and strain at the top, and peak strain at the bottom of distribution layer are 87%, 29%, 55%, 47%, and 21% respectively of those in the corresponding UHPC shield layer configuration.
, Available online ,
doi: 10.11883/bzycj-2026-0021
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Abstract:
N-butane is an extremely versatile low-molecular-weight alkane. It serves not only as a clean, efficient energy carrier but also as a key starting material in modern petrochemical industries. Its inherent high flammability and explosive properties pose significant safety challenges during production, storage, transportation, and use. To effectively mitigate explosion risks, a multi-viewport gas/dust/liquid mist explosion suppression integrated test apparatus was employed to investigate the explosion process of n-butane-air mixtures and the suppression effects of pure N2 and N2/CO2 mixtures on this process. By varying n-butane concentrations, the optimal explosive concentration was determined. Subsequently, different concentrations of nitrogen and varying mixtures of nitrogen/carbon dioxide were introduced. As the proportion of carbon dioxide increased, the maximum explosion pressure, maximum pressure rise rate, and explosion index of the n-butane-air mixture all decreased progressively. The time to reach peak pressure and the time to reach maximum pressure rise rate were progressively delayed. Adjusting the inert gas ratio revealed that the physicochemical synergistic suppression effect of N2/CO2 outperformed the physical suppression effect of N2 alone. High-speed camera analysis of changes in flame velocity and structure further validated the superiority of this synergistic suppression effect. It was concluded that the physicochemical synergistic suppression effect of N2/CO2 outperforms the physical suppression effect of pure N2. Furthermore, the chemical reaction kinetics of n-butane-air premixed gas under varying conditions was investigated via Chemkin numerical simulation software. The results demonstrate that as the proportion of CO2 in the inert gas mixture increases, the sensitivity of explosion pressure gradually diminishes, and the explosion reaction rate decreases substantially. In comparison to pure N2, CO2 exhibits a stronger synergistic physicochemical inhibitory effect on H radicals and OH radicals during the reaction process. Moreover, it modulates the maximum reaction rate (ROP) of elementary reactions, thereby effectively suppressing the explosion reaction of n-butane premixed gas. This provides experimental evidence and theoretical support for inhibiting n-butane explosion technology.
N-butane is an extremely versatile low-molecular-weight alkane. It serves not only as a clean, efficient energy carrier but also as a key starting material in modern petrochemical industries. Its inherent high flammability and explosive properties pose significant safety challenges during production, storage, transportation, and use. To effectively mitigate explosion risks, a multi-viewport gas/dust/liquid mist explosion suppression integrated test apparatus was employed to investigate the explosion process of n-butane-air mixtures and the suppression effects of pure N2 and N2/CO2 mixtures on this process. By varying n-butane concentrations, the optimal explosive concentration was determined. Subsequently, different concentrations of nitrogen and varying mixtures of nitrogen/carbon dioxide were introduced. As the proportion of carbon dioxide increased, the maximum explosion pressure, maximum pressure rise rate, and explosion index of the n-butane-air mixture all decreased progressively. The time to reach peak pressure and the time to reach maximum pressure rise rate were progressively delayed. Adjusting the inert gas ratio revealed that the physicochemical synergistic suppression effect of N2/CO2 outperformed the physical suppression effect of N2 alone. High-speed camera analysis of changes in flame velocity and structure further validated the superiority of this synergistic suppression effect. It was concluded that the physicochemical synergistic suppression effect of N2/CO2 outperforms the physical suppression effect of pure N2. Furthermore, the chemical reaction kinetics of n-butane-air premixed gas under varying conditions was investigated via Chemkin numerical simulation software. The results demonstrate that as the proportion of CO2 in the inert gas mixture increases, the sensitivity of explosion pressure gradually diminishes, and the explosion reaction rate decreases substantially. In comparison to pure N2, CO2 exhibits a stronger synergistic physicochemical inhibitory effect on H radicals and OH radicals during the reaction process. Moreover, it modulates the maximum reaction rate (ROP) of elementary reactions, thereby effectively suppressing the explosion reaction of n-butane premixed gas. This provides experimental evidence and theoretical support for inhibiting n-butane explosion technology.
, Available online ,
doi: 10.11883/bzycj-2025-0412
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Abstract:
In western mining construction, the freezing shaft method is employed to penetrate water-bearing fractured rock masses, forming ice-rock composite structures. However, the blast shock waves during construction can affect frozen surrounding rock, posing safety risks. Using the Hopkinson bar test apparatus, we systematically analyzed the propagation and attenuation patterns of post-blast stress waves in frozen rock fracture surfaces. Key findings include: (1) When impact pressure reaches the specimen failure threshold, specimens 0 and 15 exhibit decreasing reflection coefficients (R) followed by increasing transmission coefficients (T) as pressure rises, while specimens 30 and 45 show decreasing R and T values. (2) When incident stress wave intensity is below rock's dynamic compressive strength but above ice's dynamic compressive strength, the ice-rock composite demonstrates three failure modes: compressive, shear, and combined compressive-shear failure, depending on structural surface angle and loading strain rate. (3) The overall weakening effect at structural surfaces significantly outweighs strain rate-induced reinforcement. Notably, specimens with 45° inclination show gradually reduced R value decline but maintain substantial T value decrease, indicating lower sensitivity to stress wave reflection at steep angles compared to transmission effects. This study provides theoretical insights for mitigating disturbance effects in fractured rock masses during freezing shaft construction in cold regions.
In western mining construction, the freezing shaft method is employed to penetrate water-bearing fractured rock masses, forming ice-rock composite structures. However, the blast shock waves during construction can affect frozen surrounding rock, posing safety risks. Using the Hopkinson bar test apparatus, we systematically analyzed the propagation and attenuation patterns of post-blast stress waves in frozen rock fracture surfaces. Key findings include: (1) When impact pressure reaches the specimen failure threshold, specimens 0 and 15 exhibit decreasing reflection coefficients (R) followed by increasing transmission coefficients (T) as pressure rises, while specimens 30 and 45 show decreasing R and T values. (2) When incident stress wave intensity is below rock's dynamic compressive strength but above ice's dynamic compressive strength, the ice-rock composite demonstrates three failure modes: compressive, shear, and combined compressive-shear failure, depending on structural surface angle and loading strain rate. (3) The overall weakening effect at structural surfaces significantly outweighs strain rate-induced reinforcement. Notably, specimens with 45° inclination show gradually reduced R value decline but maintain substantial T value decrease, indicating lower sensitivity to stress wave reflection at steep angles compared to transmission effects. This study provides theoretical insights for mitigating disturbance effects in fractured rock masses during freezing shaft construction in cold regions.
, Available online ,
doi: 10.11883/bzycj-2026-0015
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Abstract:
To elucidate the mechanism by which shock and obstacle interactions induce local detonation initiation, an experimental investigation was conducted on flame acceleration of premixed hydrogen–air mixtures in an obstacle-laden tube. Experiments were performed over a range of equivalence ratios from 0.8 to 1.3, spanning both fuel-lean and fuel-rich conditions relative to stoichiometry. Particular emphasis was placed on the interaction between the Mach stem of the leading shock and a single obstacle, and on how this interaction governs the formation of localized hot spots and the subsequent onset of local detonation. At an equivalence ratio of 0.8, initiation was not observed. Under this condition, the reflected shock interacted with the flame front and induced Richtmyer–Meshkov instability, generating pronounced wrinkling of the flame surface. This interaction further densified the pre-existing flame folds and increased the flame surface area, thereby accelerating the flame; however, no local detonation was initiated. In contrast, if the equivalence ratio was within the range from 0.9 to 1.3, successful initiation was observed. Shock reflection in the obstacle vicinity generated localized regions of elevated temperature that acted as hot spots, providing favorable conditions for rapid energy release and the onset of a locally detonative event. However, the locally initiated detonation did not develop into a self-sustained stable detonation. During subsequent diffraction, expansion waves imposed pronounced cooling and attenuation, causing progressive decoupling between the leading shock and the reaction zone, and thereby suppressing further development into a stable detonation wave. Through analysis of the critical initiation characteristics, it is found that increasing either the shock strength or the equivalence ratio increases the critical initiation parameter, and the critical initiation parameter is more sensitive to shock strength than to equivalence ratio. Furthermore, considering the discrepancy between the Thomas critical initiation model and the incident shock wave in the present experiments, the shock reflection zone was divided into sections for calculation. The analysis reveals that, at an equivalence ratio of 1.2, the lower sonic velocity following reflection of the leading shock wave prolongs the time taken for the expansion wave to reach the base of the obstacle, thereby favoring initiation. Conversely, at an equivalence ratio of 0.8, the lower equivalence ratio reduces the reactivity of the mixture, leading to a longer ignition delay time and consequently reducing the likelihood of initiation.
To elucidate the mechanism by which shock and obstacle interactions induce local detonation initiation, an experimental investigation was conducted on flame acceleration of premixed hydrogen–air mixtures in an obstacle-laden tube. Experiments were performed over a range of equivalence ratios from 0.8 to 1.3, spanning both fuel-lean and fuel-rich conditions relative to stoichiometry. Particular emphasis was placed on the interaction between the Mach stem of the leading shock and a single obstacle, and on how this interaction governs the formation of localized hot spots and the subsequent onset of local detonation. At an equivalence ratio of 0.8, initiation was not observed. Under this condition, the reflected shock interacted with the flame front and induced Richtmyer–Meshkov instability, generating pronounced wrinkling of the flame surface. This interaction further densified the pre-existing flame folds and increased the flame surface area, thereby accelerating the flame; however, no local detonation was initiated. In contrast, if the equivalence ratio was within the range from 0.9 to 1.3, successful initiation was observed. Shock reflection in the obstacle vicinity generated localized regions of elevated temperature that acted as hot spots, providing favorable conditions for rapid energy release and the onset of a locally detonative event. However, the locally initiated detonation did not develop into a self-sustained stable detonation. During subsequent diffraction, expansion waves imposed pronounced cooling and attenuation, causing progressive decoupling between the leading shock and the reaction zone, and thereby suppressing further development into a stable detonation wave. Through analysis of the critical initiation characteristics, it is found that increasing either the shock strength or the equivalence ratio increases the critical initiation parameter, and the critical initiation parameter is more sensitive to shock strength than to equivalence ratio. Furthermore, considering the discrepancy between the Thomas critical initiation model and the incident shock wave in the present experiments, the shock reflection zone was divided into sections for calculation. The analysis reveals that, at an equivalence ratio of 1.2, the lower sonic velocity following reflection of the leading shock wave prolongs the time taken for the expansion wave to reach the base of the obstacle, thereby favoring initiation. Conversely, at an equivalence ratio of 0.8, the lower equivalence ratio reduces the reactivity of the mixture, leading to a longer ignition delay time and consequently reducing the likelihood of initiation.
, Available online ,
doi: 10.11883/bzycj-2026-0048
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Abstract:
With the continuous deepening of China 's deep strategy, a new situation has been opened for the expansion of resource development to the deep. At the same time, it also needs to face more complex engineering problems, such as high ground stress, high strength rock mass and other geological conditions. In order to solve the problems of low efficiency and high energy consumption of traditional blasting in deep rock mass, a new method of microwave-assisted blasting rock breaking is proposed. In this paper, the coupling test of microwave radiation and single-hole blasting in simulated deep environment is carried out with magnetite as the research object. Based on the analysis of the test results, combined with X-ray high-precision micro-CT scanning and three-dimensional reconstruction technology, the changes of pore volume, surface area, fractal dimension, pore structure and crack propagation under different loading conditions are analyzed, and the influence of different loading conditions on the evolution of pore and fracture structure of iron ore is discussed. The research shows that : (1) Microwave radiation promotes the development and initiation of pores and fissures. With the increase of microwave damage, the volume, surface area and fractal dimension of pore fracture distribution complexity of iron ore after blasting show a gradual upward trend. Compared with prolonging the irradiation time, increasing the microwave power has a more significant effect on the development of pore fracture of iron ore. When high power microwave radiation is used, the increase of pore volume and surface area of the sample reaches the maximum of 30.48 % and 31.37 %, respectively. (2) Microwave radiation can effectively improve the blasting effect, which can be attributed to the connection and penetration of pores and microcracks, providing more channels for blasting stress wave propagation. The peak of the distribution curve of pore radius and throat length of the sample gradually shifts to the direction of larger radius and longer length with the increase of microwave damage, and the distribution range of pore coordination number increases.(3) The confining pressure inhibits the synergistic effect of microwave-blasting. With the increase of confining pressure, the crack propagation is obviously limited, the volume and maximum length of the through-hole cracks are significantly reduced, and the volume ratio of the isolated hole cracks is increased. The confining pressure changes the propagation direction of the main crack, and the propagation direction of the main crack is changed from the radial shape without confining pressure to the direction of the maximum principal stress. This study provides a reference for the engineering application of microwave-assisted blasting technology in deep high stress environment.
, Available online ,
doi: 10.11883/bzycj-2025-0396
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Abstract:
Traditional Lagrangian and Eulerian algorithms exhibited certain limitations when addressing problems involving large mesh deformations and complex fluid–structure interaction (FSI) in explosions. To investigate the load characteristics of acetylene explosions and their impact effects on adjacent structures, a finite element model was established based on the structured arbitrary Lagrangian–Eulerian (S-ALE) FSI method. Numerical simulations were conducted to model the explosion of a 20 L spherical acetylene–air mixture and its subsequent impact on a target plate. The simulations were performed using ANSYS/LS-DYNA, with the geometric model consisting of the explosive domain, the air domain, and the target plate. To reduce computational cost while maintaining accuracy, a one-eighth symmetry model was adopted. Key parameters under different acetylene volume fractions and equivalent trinitrotoluene (TNT) masses, as well as the dynamic response of the target plate, were systematically examined, with results compared against those obtained using the multi-material arbitrary Lagrangian–Eulerian (MMALE) coupling method. The results indicate the following: (1) Compared with traditional methods, both the S-ALE and MMALE methods demonstrate superior accuracy and effectiveness in simulating acetylene explosion coupling problems. However, the S-ALE method offers greater advantages in model setup, meshing, computational efficiency, and stability, with these benefits becoming more pronounced as the model size increases. (2) Under identical conditions, the peak overpressure and peak velocity of the shock wave generated by a 7.75% volume fraction acetylene explosion in the air domain are lower than those of an equivalent TNT explosion, whereas the positive pressure duration is relatively longer. The differences in pressure and von Mises stress responses on the target plate between the two cases are minimal, indicating that, based on the principle of equivalent explosion energy, acetylene can induce damage effects comparable in magnitude to those of chemical explosives in terms of specific structural response indicators. (3) Through systematic comparisons involving target plates of different materials and various acetylene volume fractions, the load characteristics of acetylene explosions and the corresponding structural response patterns are elucidated. The validity and superiority of the S-ALE method in simulating acetylene explosion impact problems are confirmed, providing a numerical basis for assessing the feasibility of acetylene as an explosion source in specific scenarios and offering important references for the design of blast-resistant structures and the optimization of safety protection measures.
Traditional Lagrangian and Eulerian algorithms exhibited certain limitations when addressing problems involving large mesh deformations and complex fluid–structure interaction (FSI) in explosions. To investigate the load characteristics of acetylene explosions and their impact effects on adjacent structures, a finite element model was established based on the structured arbitrary Lagrangian–Eulerian (S-ALE) FSI method. Numerical simulations were conducted to model the explosion of a 20 L spherical acetylene–air mixture and its subsequent impact on a target plate. The simulations were performed using ANSYS/LS-DYNA, with the geometric model consisting of the explosive domain, the air domain, and the target plate. To reduce computational cost while maintaining accuracy, a one-eighth symmetry model was adopted. Key parameters under different acetylene volume fractions and equivalent trinitrotoluene (TNT) masses, as well as the dynamic response of the target plate, were systematically examined, with results compared against those obtained using the multi-material arbitrary Lagrangian–Eulerian (MMALE) coupling method. The results indicate the following: (1) Compared with traditional methods, both the S-ALE and MMALE methods demonstrate superior accuracy and effectiveness in simulating acetylene explosion coupling problems. However, the S-ALE method offers greater advantages in model setup, meshing, computational efficiency, and stability, with these benefits becoming more pronounced as the model size increases. (2) Under identical conditions, the peak overpressure and peak velocity of the shock wave generated by a 7.75% volume fraction acetylene explosion in the air domain are lower than those of an equivalent TNT explosion, whereas the positive pressure duration is relatively longer. The differences in pressure and von Mises stress responses on the target plate between the two cases are minimal, indicating that, based on the principle of equivalent explosion energy, acetylene can induce damage effects comparable in magnitude to those of chemical explosives in terms of specific structural response indicators. (3) Through systematic comparisons involving target plates of different materials and various acetylene volume fractions, the load characteristics of acetylene explosions and the corresponding structural response patterns are elucidated. The validity and superiority of the S-ALE method in simulating acetylene explosion impact problems are confirmed, providing a numerical basis for assessing the feasibility of acetylene as an explosion source in specific scenarios and offering important references for the design of blast-resistant structures and the optimization of safety protection measures.
, Available online ,
doi: 10.11883/bzycj-2025-0415
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Abstract:
To investigate the dynamic characteristics of structures breaking through ice sheets and entering water, a series of vertical ice-breaking water-entry experiments were conducted using a water-entry experimental platform combined with high-speed photography. The experiments considered an ice-free condition and three ice sheet thicknesses equal to 1.5, 2.5, and 3.5 times the structure diameter (D0). The effects of ice sheet thickness on cavity evolution, ice failure modes, and motion characteristics of the structure were systematically analyzed. The results show that the presence of the ice sheet significantly alters the cavity evolution during water entry. The ice sheet accelerates cavity surface closure, suppresses radial cavity expansion, and promotes a rapid collapse of the cavity at later stages. When the ice thickness is 1.5D0, the cavity is able to fully envelop the structure, whereas for thicker ice sheets (2.5D0 and 3.5D0), the cavity fails to completely wrap around the structure. After the structure penetrates the ice sheet, conical craters are formed on both the upper and lower ice surfaces. For thinner ice sheets, the craters are symmetrically distributed around the penetration hole. In contrast, when the ice thickness reaches 3.5D0, an obvious asymmetry in crater geometry is observed due to the structure’s deflection during the ice-breaking process. Compared with the ice-free condition, the presence of the ice sheet leads to pronounced velocity attenuation and trajectory deviation during water entry. However, thicker ice sheets result in a reduction of the hydrodynamic resistance experienced by the structure in the subsequent underwater stage, indicating that the ice-breaking process plays a crucial role in modifying the downstream flow field and the overall water-entry dynamics.
To investigate the dynamic characteristics of structures breaking through ice sheets and entering water, a series of vertical ice-breaking water-entry experiments were conducted using a water-entry experimental platform combined with high-speed photography. The experiments considered an ice-free condition and three ice sheet thicknesses equal to 1.5, 2.5, and 3.5 times the structure diameter (D0). The effects of ice sheet thickness on cavity evolution, ice failure modes, and motion characteristics of the structure were systematically analyzed. The results show that the presence of the ice sheet significantly alters the cavity evolution during water entry. The ice sheet accelerates cavity surface closure, suppresses radial cavity expansion, and promotes a rapid collapse of the cavity at later stages. When the ice thickness is 1.5D0, the cavity is able to fully envelop the structure, whereas for thicker ice sheets (2.5D0 and 3.5D0), the cavity fails to completely wrap around the structure. After the structure penetrates the ice sheet, conical craters are formed on both the upper and lower ice surfaces. For thinner ice sheets, the craters are symmetrically distributed around the penetration hole. In contrast, when the ice thickness reaches 3.5D0, an obvious asymmetry in crater geometry is observed due to the structure’s deflection during the ice-breaking process. Compared with the ice-free condition, the presence of the ice sheet leads to pronounced velocity attenuation and trajectory deviation during water entry. However, thicker ice sheets result in a reduction of the hydrodynamic resistance experienced by the structure in the subsequent underwater stage, indicating that the ice-breaking process plays a crucial role in modifying the downstream flow field and the overall water-entry dynamics.
, Available online ,
doi: 10.11883/bzycj-2025-0307
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Abstract:
To explore the ice-breaking effect of underwater explosion in polar low-temperature environments, the LS-DYNA software was used to conduct numerical analysis on the underwater explosion ice-breaking process. Considering the temperature gradient of ice layers in polar low-temperature environments, the dynamic response process and failure mechanism of ice layers during the shock wave stage and bubble pulsation stage were analyzed. The influencing factors of underwater explosion ice-breaking effect and their changes in the failure mode were discussed. The influence laws and reasons of each factor were analyzed from the perspectives of stress wave propagation and energy release. The research results show that under complete typical working conditions, the dynamic response process of ice layers under underwater explosion loads can be roughly divided into five stages: the stress wave action stage, the initial crack initiation stage, the local bending deformation stage, the overall rebound stage, and the jet penetration stage. Increasing the charge mass brings limited improvement to the ice-breaking effect. The blast distance can directly affect the energy transfer efficiency, and there exists an optimal blast distance that makes the fragmentation zone effect the best, while the optimal blast distance for the crack zone is larger. The influence of ice layer thickness is nonlinear. As the thickness increases, the range of the fragmentation zone gradually decreases and tends to be stable, while the range of the crack zone dominated by bubble movement may increase under certain conditions. Through numerical simulation methods, it was found that the failure modes of temperature gradient ice layers and equivalent temperature ice layers are similar, but the fragmentation effects under the same explosion loads are slightly different.
To explore the ice-breaking effect of underwater explosion in polar low-temperature environments, the LS-DYNA software was used to conduct numerical analysis on the underwater explosion ice-breaking process. Considering the temperature gradient of ice layers in polar low-temperature environments, the dynamic response process and failure mechanism of ice layers during the shock wave stage and bubble pulsation stage were analyzed. The influencing factors of underwater explosion ice-breaking effect and their changes in the failure mode were discussed. The influence laws and reasons of each factor were analyzed from the perspectives of stress wave propagation and energy release. The research results show that under complete typical working conditions, the dynamic response process of ice layers under underwater explosion loads can be roughly divided into five stages: the stress wave action stage, the initial crack initiation stage, the local bending deformation stage, the overall rebound stage, and the jet penetration stage. Increasing the charge mass brings limited improvement to the ice-breaking effect. The blast distance can directly affect the energy transfer efficiency, and there exists an optimal blast distance that makes the fragmentation zone effect the best, while the optimal blast distance for the crack zone is larger. The influence of ice layer thickness is nonlinear. As the thickness increases, the range of the fragmentation zone gradually decreases and tends to be stable, while the range of the crack zone dominated by bubble movement may increase under certain conditions. Through numerical simulation methods, it was found that the failure modes of temperature gradient ice layers and equivalent temperature ice layers are similar, but the fragmentation effects under the same explosion loads are slightly different.
, Available online ,
doi: 10.11883/bzycj-2025-0406
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Abstract:
To comprehensively investigate the impact of length-to-diameter ratio on hydrogen explosion within confined slender pipelines, an integrated methodology combining experimental approaches with three-dimensional numerical simulations was implemented. The influence of the equivalence ratio and length-to-diameter ratio on hydrogen explosion overpressure, flame propagation velocity, and flame structure was systematically examined. Based on the findings, an interval prediction theoretical model for the maximum explosion pressure rise rate of hydrogen in narrow pipelines was developed. The results indicate that the number of flame acceleration events is proportional to the length-to-diameter ratio of pipeline, and the flame propagation velocity is highly dependent on the evolution of flame morphology. Specifically, the flame propagation velocity increases when the flame front protrudes outward and decreases when it concaves inward. During the process of hydrogen explosion, pressure waves propagate faster than the flame front. These waves continuously reflect within the pipeline and interact with the flame front, altering the flame structure and resulting in high-frequency oscillations in the pressure curve. Under high length-to-diameter ratios, the explosion overpressure peak generated at both ends of the pipeline is greater than that generated in the middle. Both the explosion overpressure peak and pressure oscillation amplitude of the explosion exhibit a decreasing trend as the length-to-diameter ratio of the pipeline increases. The theoretical value of the explosion overpressure peak is not influenced by the pipeline length-to-diameter ratio and reaches its maximum under stoichiometric conditions. However, there are heat losses during the experiments, and these losses are more significant at higher length-to-diameter ratios, leading to a reduction in the explosion overpressure peak. Furthermore, the experimentally measured maximum pressure rise rate falls within the range predicted by the interval prediction theoretical model. This demonstrates that hydrogen explosion in narrow pipelines are not purely laminar or turbulent processes but rather complex phenomena intermediate between the two.
To comprehensively investigate the impact of length-to-diameter ratio on hydrogen explosion within confined slender pipelines, an integrated methodology combining experimental approaches with three-dimensional numerical simulations was implemented. The influence of the equivalence ratio and length-to-diameter ratio on hydrogen explosion overpressure, flame propagation velocity, and flame structure was systematically examined. Based on the findings, an interval prediction theoretical model for the maximum explosion pressure rise rate of hydrogen in narrow pipelines was developed. The results indicate that the number of flame acceleration events is proportional to the length-to-diameter ratio of pipeline, and the flame propagation velocity is highly dependent on the evolution of flame morphology. Specifically, the flame propagation velocity increases when the flame front protrudes outward and decreases when it concaves inward. During the process of hydrogen explosion, pressure waves propagate faster than the flame front. These waves continuously reflect within the pipeline and interact with the flame front, altering the flame structure and resulting in high-frequency oscillations in the pressure curve. Under high length-to-diameter ratios, the explosion overpressure peak generated at both ends of the pipeline is greater than that generated in the middle. Both the explosion overpressure peak and pressure oscillation amplitude of the explosion exhibit a decreasing trend as the length-to-diameter ratio of the pipeline increases. The theoretical value of the explosion overpressure peak is not influenced by the pipeline length-to-diameter ratio and reaches its maximum under stoichiometric conditions. However, there are heat losses during the experiments, and these losses are more significant at higher length-to-diameter ratios, leading to a reduction in the explosion overpressure peak. Furthermore, the experimentally measured maximum pressure rise rate falls within the range predicted by the interval prediction theoretical model. This demonstrates that hydrogen explosion in narrow pipelines are not purely laminar or turbulent processes but rather complex phenomena intermediate between the two.
, Available online ,
doi: 10.11883/bzycj-2025-0390
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Abstract:
The study of local instability of metals under ultra-low temperature and high strain rate is of crucial importance for the safety assessment of aerospace structures. To achieve the ultra-low temperature environment, a refrigeration system based on liquid helium circulation was developed. The specimen to be tested was cooled by a contact-conduction method to achieve the temperature in the liquid helium temperature range. Combined with the Hopkinson pressure bar experiment, impact compression experiments were conducted on titanium alloy specimens to study the dynamic properties of titanium alloys as low as the liquid helium temperature range (30K). The titanium alloy specimens adopted a circular ring structure, with the hollow structure having sufficient deformation space, which is conducive to the generation of shear bands. The experimental results show that: low temperature enhances the dynamic strength of titanium alloys; the material as a whole exhibits brittle deformation characteristics, and low temperature makes shear bands more likely to occur in titanium alloys; the width of shear bands gradually narrows with the decrease in temperature; Conjugate shear bands are more likely to occur under ultra-low temperature and high strain rate. Based on the generalized variational principle and constitutive relation incorporating microstructural evolution, a governing equation for localized dynamic instability was established. From this governing equation, an angular criterion for shear band formation was derived, which effectively characterizes the formation of shear bands. And the three development stages of localized shear bands were studied (i.e., shear deformation, shear band, and shear fracture). The results show that: low temperature changes the plastic stiffness of the material, promoting the generation of shear bands at lower strains; shear bands form before the peak point of the stress-strain curve. This work provides experimental and theoretical references for ultra-low temperature experimental techniques and the plastic instability of titanium alloys under ultra-low temperature and high strain rate.
The study of local instability of metals under ultra-low temperature and high strain rate is of crucial importance for the safety assessment of aerospace structures. To achieve the ultra-low temperature environment, a refrigeration system based on liquid helium circulation was developed. The specimen to be tested was cooled by a contact-conduction method to achieve the temperature in the liquid helium temperature range. Combined with the Hopkinson pressure bar experiment, impact compression experiments were conducted on titanium alloy specimens to study the dynamic properties of titanium alloys as low as the liquid helium temperature range (30K). The titanium alloy specimens adopted a circular ring structure, with the hollow structure having sufficient deformation space, which is conducive to the generation of shear bands. The experimental results show that: low temperature enhances the dynamic strength of titanium alloys; the material as a whole exhibits brittle deformation characteristics, and low temperature makes shear bands more likely to occur in titanium alloys; the width of shear bands gradually narrows with the decrease in temperature; Conjugate shear bands are more likely to occur under ultra-low temperature and high strain rate. Based on the generalized variational principle and constitutive relation incorporating microstructural evolution, a governing equation for localized dynamic instability was established. From this governing equation, an angular criterion for shear band formation was derived, which effectively characterizes the formation of shear bands. And the three development stages of localized shear bands were studied (i.e., shear deformation, shear band, and shear fracture). The results show that: low temperature changes the plastic stiffness of the material, promoting the generation of shear bands at lower strains; shear bands form before the peak point of the stress-strain curve. This work provides experimental and theoretical references for ultra-low temperature experimental techniques and the plastic instability of titanium alloys under ultra-low temperature and high strain rate.
, Available online ,
doi: 10.11883/bzycj-2025-0365
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Abstract:
All-terrain vehicles (ATVs) are widely used in border patrol, disaster relief transportation, forest fire protection and other fields due to their excellent environmental adaptability and off-road capabilities. Major emergencies often lead to a significant decline in regional accessibility, putting forward clear requirements for the repeated airdrop operation capability of ATVs. However, the airdrop landing process exerts intense impact on the vehicle, and repeated airdrops are more likely to cause cumulative damage to the vehicle, thereby affecting its operational reliability. To address this issue, this paper establishes a numerical simulation model for the airdrop system of a certain type of ATV. First, the low-cycle fatigue analysis method is adopted to evaluate the airdrop lifespan, and then combined with the J-C damage model, the evolution law of airdrop impact damage and life characteristics of the vehicle under multiple landing scenarios are systematically studied. The results show that the initial maximum damage of the ATV is concentrated on the chassis crossbeams; as the number of airdrops increases, the location of maximum damage shifts to structures such as upright columns. Under ideal airdrop conditions, the airdrop life of the vehicle is 10 times, and the life decreases with the increase of landing speed, among which the impact of oblique landing speed is the most significant. When the longitudinal, oblique, transverse and vertical landing speeds reach 1m/s, 1.5m/s, 3m/s and15 m/s respectively, airdrop operations are not recommended. The relevant research results provide important technical support for ensuring the repeated airdrop operation capability of ATVs under multiple landing scenarios.
All-terrain vehicles (ATVs) are widely used in border patrol, disaster relief transportation, forest fire protection and other fields due to their excellent environmental adaptability and off-road capabilities. Major emergencies often lead to a significant decline in regional accessibility, putting forward clear requirements for the repeated airdrop operation capability of ATVs. However, the airdrop landing process exerts intense impact on the vehicle, and repeated airdrops are more likely to cause cumulative damage to the vehicle, thereby affecting its operational reliability. To address this issue, this paper establishes a numerical simulation model for the airdrop system of a certain type of ATV. First, the low-cycle fatigue analysis method is adopted to evaluate the airdrop lifespan, and then combined with the J-C damage model, the evolution law of airdrop impact damage and life characteristics of the vehicle under multiple landing scenarios are systematically studied. The results show that the initial maximum damage of the ATV is concentrated on the chassis crossbeams; as the number of airdrops increases, the location of maximum damage shifts to structures such as upright columns. Under ideal airdrop conditions, the airdrop life of the vehicle is 10 times, and the life decreases with the increase of landing speed, among which the impact of oblique landing speed is the most significant. When the longitudinal, oblique, transverse and vertical landing speeds reach 1m/s, 1.5m/s, 3m/s and15 m/s respectively, airdrop operations are not recommended. The relevant research results provide important technical support for ensuring the repeated airdrop operation capability of ATVs under multiple landing scenarios.
, Available online ,
doi: 10.11883/bzycj-2025-0373
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Abstract:
The gradient structure has superior strength-ductility synergy due to its unique design strategy. This synergistic effect is mainly attributed to the heterogeneous deformation induced (HDI) strengthening caused by plastic strain gradient. The quasi-static mechanical behavior of gradient structures has been extensively revealed, but research on their mechanical property under dynamic conditions is almost blank, and the mechanical behavior of gradient structures under dynamic impact is not clear, which limits the application scope of gradient structures. Therefore, this study used the cyclic torsion method to prepare deep gradient structures on low carbon steel and the compression tests were conducted under a wide strain rate range (10-4-103 /s). The results indicate that the gradient structure significantly improves the yield strength of low carbon steel. At a strain rate of 0.001 /s, the yield strengths of GS1 and GS2 samples were 407.5 and 483.6 MPa, respectively. Compared to the initial state (203.2 MPa), the yield strengths increased by 100.5% and 137.9%, respectively. Moreover, as the strain rate increases, the yield strength also gradually increases, exhibiting significant sensitivity to positive strain rate. Under dynamic conditions, the strain rate sensitivity of GS1 and GS2 samples increases sharply, reaching 0.129 and 0.1097, respectively, which is almost an order of magnitude higher than quasi-static conditions. In addition, the degree of gradient will have an impact on the deformation mechanism: samples with a higher degree of gradient mainly consume the work hardening ability of the central soft domain during the deformation process, while the hardening effect of the edge region is weakened. Under dynamic conditions, due to the adiabatic temperature rise effect, the dislocation density of the edge hard domain is actually reduced. This study deeply reveals the mechanical response and deformation mechanism related to strain rate in heterogeneous regions of gradient structures. On the one hand, it provides reference for the design of gradient structures, and on the other hand, it provides theoretical value for the future application of gradient structures in extreme service environments such as dynamic impact.
The gradient structure has superior strength-ductility synergy due to its unique design strategy. This synergistic effect is mainly attributed to the heterogeneous deformation induced (HDI) strengthening caused by plastic strain gradient. The quasi-static mechanical behavior of gradient structures has been extensively revealed, but research on their mechanical property under dynamic conditions is almost blank, and the mechanical behavior of gradient structures under dynamic impact is not clear, which limits the application scope of gradient structures. Therefore, this study used the cyclic torsion method to prepare deep gradient structures on low carbon steel and the compression tests were conducted under a wide strain rate range (10-4-103 /s). The results indicate that the gradient structure significantly improves the yield strength of low carbon steel. At a strain rate of 0.001 /s, the yield strengths of GS1 and GS2 samples were 407.5 and 483.6 MPa, respectively. Compared to the initial state (203.2 MPa), the yield strengths increased by 100.5% and 137.9%, respectively. Moreover, as the strain rate increases, the yield strength also gradually increases, exhibiting significant sensitivity to positive strain rate. Under dynamic conditions, the strain rate sensitivity of GS1 and GS2 samples increases sharply, reaching 0.129 and 0.1097, respectively, which is almost an order of magnitude higher than quasi-static conditions. In addition, the degree of gradient will have an impact on the deformation mechanism: samples with a higher degree of gradient mainly consume the work hardening ability of the central soft domain during the deformation process, while the hardening effect of the edge region is weakened. Under dynamic conditions, due to the adiabatic temperature rise effect, the dislocation density of the edge hard domain is actually reduced. This study deeply reveals the mechanical response and deformation mechanism related to strain rate in heterogeneous regions of gradient structures. On the one hand, it provides reference for the design of gradient structures, and on the other hand, it provides theoretical value for the future application of gradient structures in extreme service environments such as dynamic impact.
, Available online ,
doi: 10.11883/bzycj-2025-0394
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Abstract:
The speed of underground blasting driving is primarily determined by the effectiveness of cutting blasting. To address the low cavity forming efficiency of parallel cutting in deep hole blasting driving, a solution involving delayed detonation of the bottom charge in the empty hole was proposed. Firstly, theoretical analysis, model experiments, and numerical simulations were conducted to investigate the influences of delayed detonation of empty hole bottom charge on the cavity forming efficiency. Subsequently, combined with high speed photography and numerical simulations of rock throwing process, the cavity forming mechanism under the synergistic effect of charge blasting in two types of blasting holes was revealed. Finally, field tests were performed to verify its actual application effects. The results indicate that delayed detonation of the empty hole bottom charge could significantly eliminate residual stumps at the bottom of the cutting cavity, increasing the cavity forming efficiency from less than 80 % to over 95 %. During the blasting stage of cutting holes, the strong clamping effect of surrounding rock leads to residual stumps in the cavity, but the newly formed free face could facilitate the throw of stumps subsequently. During the blasting stage of empty hole bottom charge, the weakened clamping effect of surrounding rock enables the residual stumps to be thrown out at the relatively high velocity, thereby achieving an excellent cavity forming effect. The rock throwing velocity during the empty hole blasting is about 2.0 m·s⁻1 higher than that during cutting hole blasting. Compared with the traditional parallel cutting technique, the proposed method increases the cycle footage by 0.35 m and reduces the specific charge by 0.43 kg·m⁻³. This confirms that the improved parallel cutting technique is conducive to enhancing driving efficiency and reducing driving costs. The research findings could provide theoretical supports and practical references for the optimization of deep hole cutting blasting in underground engineering.
The speed of underground blasting driving is primarily determined by the effectiveness of cutting blasting. To address the low cavity forming efficiency of parallel cutting in deep hole blasting driving, a solution involving delayed detonation of the bottom charge in the empty hole was proposed. Firstly, theoretical analysis, model experiments, and numerical simulations were conducted to investigate the influences of delayed detonation of empty hole bottom charge on the cavity forming efficiency. Subsequently, combined with high speed photography and numerical simulations of rock throwing process, the cavity forming mechanism under the synergistic effect of charge blasting in two types of blasting holes was revealed. Finally, field tests were performed to verify its actual application effects. The results indicate that delayed detonation of the empty hole bottom charge could significantly eliminate residual stumps at the bottom of the cutting cavity, increasing the cavity forming efficiency from less than 80 % to over 95 %. During the blasting stage of cutting holes, the strong clamping effect of surrounding rock leads to residual stumps in the cavity, but the newly formed free face could facilitate the throw of stumps subsequently. During the blasting stage of empty hole bottom charge, the weakened clamping effect of surrounding rock enables the residual stumps to be thrown out at the relatively high velocity, thereby achieving an excellent cavity forming effect. The rock throwing velocity during the empty hole blasting is about 2.0 m·s⁻1 higher than that during cutting hole blasting. Compared with the traditional parallel cutting technique, the proposed method increases the cycle footage by 0.35 m and reduces the specific charge by 0.43 kg·m⁻³. This confirms that the improved parallel cutting technique is conducive to enhancing driving efficiency and reducing driving costs. The research findings could provide theoretical supports and practical references for the optimization of deep hole cutting blasting in underground engineering.
, Available online ,
doi: 10.11883/bzycj-2025-0312
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Abstract:
During the high-speed water entry of a projectile, cavitation occurs, forming a cavity bubble that alters the flow field and subsequently affects the projectile’s motion stability. Our study investigates the characteristics of flow field changes after double-cone projectiles with different head cone angles traverse the free surface. High-speed water entry experiments were conducted by using an electromagnetic launch device, and a numerical simulation model of high-speed water entry was established basing on the overset mesh technique and the VOF multiphase flow model. The validity of the simulation model was verified through experiments, and the flow field characteristics after the vertical water entry of projectiles with different head shapes were obtained. The research findings are as follows: After the vertical water entry of a double-cone projectile, the cavity bubble develops symmetrically. Following surface closure of the cavity bubble, its total length increases while its maximum width gradually decreases. As the head cone angle of the projectile's cavitator increases: during the initial entry phase, the closure point and wetted surface position move closer to the tail; the cavity contour becomes wider; the resistance experienced at the moment of entry and during underwater motion increases, leading to faster velocity decay; the time of surface closure for the cavity bubble is delayed. At the same moment during underwater motion, the length of the tail cavity bubble is longer, while the length of the vortex structures within the water domain is shorter.
During the high-speed water entry of a projectile, cavitation occurs, forming a cavity bubble that alters the flow field and subsequently affects the projectile’s motion stability. Our study investigates the characteristics of flow field changes after double-cone projectiles with different head cone angles traverse the free surface. High-speed water entry experiments were conducted by using an electromagnetic launch device, and a numerical simulation model of high-speed water entry was established basing on the overset mesh technique and the VOF multiphase flow model. The validity of the simulation model was verified through experiments, and the flow field characteristics after the vertical water entry of projectiles with different head shapes were obtained. The research findings are as follows: After the vertical water entry of a double-cone projectile, the cavity bubble develops symmetrically. Following surface closure of the cavity bubble, its total length increases while its maximum width gradually decreases. As the head cone angle of the projectile's cavitator increases: during the initial entry phase, the closure point and wetted surface position move closer to the tail; the cavity contour becomes wider; the resistance experienced at the moment of entry and during underwater motion increases, leading to faster velocity decay; the time of surface closure for the cavity bubble is delayed. At the same moment during underwater motion, the length of the tail cavity bubble is longer, while the length of the vortex structures within the water domain is shorter.
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, Available online ,
doi: 10.11883/bzycj-2026-0060
Abstract:
The bubble coupling and morphological evolution characteristics in underwater multipoint explosions have long been a focus of research. Among various research approaches, the centrifuge-based hypergravity underwater explosion experiments have emerged as one of the most effective methods for conducting prototype experiments on large-yield underwater explosions, owing to its simultaneous satisfaction of both the Mach number and the Froude number. This study presents both experimental and numerical investigation into the coupling dynamics of underwater multipoint explosion bubbles under hypergravity conditions. First, two-point underwater explosion experiments were conducted under a hypergravity environment with a acceleration of 100g, and the morphological evolution of dual bubbles was captured with high precision using a high-speed camera. Second, a hypergravity underwater multi-point explosion numerical model, validated against the experimental data, was employed to further investigate the effects of gravitational field on the coupled morphological evolution and characteristic parameters of dual bubbles. The results indicate that under higher gravitational acceleration, the morphological evolution, pulsation, and migration characteristics of underwater explosion bubbles differ significantly from those under normal gravity. This hypergravity environment, as an extreme physical condition, intensifies the pressure gradient and buoyancy effects, leading to unique jetting behaviors. The hypergravity environment increases the vertical pressure gradient in the flow field, enhances the instability on the bubble surfaces, and induces more intense fluid acceleration, thereby leading to higher bubble migration velocities. In addition, the hypergravity field introduces a "spatiotemporal compression effect" on bubble pulsation and alters the buoyancy-inertia force balance of the bubble system, which significantly affects the jetting direction and the interaction intensity between the bubbles, consequently modifying the energy distribution within the dual-bubble system.
The bubble coupling and morphological evolution characteristics in underwater multipoint explosions have long been a focus of research. Among various research approaches, the centrifuge-based hypergravity underwater explosion experiments have emerged as one of the most effective methods for conducting prototype experiments on large-yield underwater explosions, owing to its simultaneous satisfaction of both the Mach number and the Froude number. This study presents both experimental and numerical investigation into the coupling dynamics of underwater multipoint explosion bubbles under hypergravity conditions. First, two-point underwater explosion experiments were conducted under a hypergravity environment with a acceleration of 100g, and the morphological evolution of dual bubbles was captured with high precision using a high-speed camera. Second, a hypergravity underwater multi-point explosion numerical model, validated against the experimental data, was employed to further investigate the effects of gravitational field on the coupled morphological evolution and characteristic parameters of dual bubbles. The results indicate that under higher gravitational acceleration, the morphological evolution, pulsation, and migration characteristics of underwater explosion bubbles differ significantly from those under normal gravity. This hypergravity environment, as an extreme physical condition, intensifies the pressure gradient and buoyancy effects, leading to unique jetting behaviors. The hypergravity environment increases the vertical pressure gradient in the flow field, enhances the instability on the bubble surfaces, and induces more intense fluid acceleration, thereby leading to higher bubble migration velocities. In addition, the hypergravity field introduces a "spatiotemporal compression effect" on bubble pulsation and alters the buoyancy-inertia force balance of the bubble system, which significantly affects the jetting direction and the interaction intensity between the bubbles, consequently modifying the energy distribution within the dual-bubble system.
, Available online ,
doi: 10.11883/bzycj-2026-0012
Abstract:
Vented deflagrations in ducts with a high length-to-diameter ratio are frequently encountered in hydrogen–ammonia energy systems, yet the pressure evolution and the applicability of engineering venting standards remain insufficiently validated for “large length-to-diameter ratio plus small end vent” configurations. An experimental study was therefore conducted to quantify how end-vent diameter affected the internal and external pressure characteristics of ammonia–hydrogen premixed gas in a long tube, and to improve the prediction accuracy of the NFPA (national fire protection association) standard 68, which standard on explosion protection by deflagration venting. Experiments were carried out in a stainless-steel duct system with a total length of 2 m, one end closed and the other end equipped with an end vent sealed by a thin vent membrane. Three circular vent diameters (120, 80, and 40 mm) were tested, corresponding to venting ratios of 100%, 44.4%, and 11.1%, respectively. Tests were performed under near-ambient initial conditions at a fixed equivalence ratio of 0.8, while the ammonia fraction in the fuel (ammonia plus hydrogen) was varied from 30% to 70%. Gas mixtures were prepared by partial-pressure charging after evacuating the mixing vessel, followed by sufficient standing time to promote homogeneity. A pressure transducer installed near the downstream region recorded the pressure–time history. For each condition, 3–4 repeated runs were conducted; representative traces were selected based on proximity to the mean of characteristic parameters. From each pressure trace, the membrane burst pressure, the internal venting peak pressure, the peak pressure associated with an external secondary explosion, and the duration of the pressure plateau or quasi-plateau were extracted. The maximum reduced explosion pressure was also calculated using NFPA 68 and compared against measurements; a correction correlation was then developed by incorporating the geometric venting ratio and the static activation pressure of the venting device. Under full venting, pressure histories exhibited a typical three-peak structure corresponding to membrane rupture, internal venting peak, and external secondary explosion peak. Increasing the ammonia fraction caused only minor changes in burst pressure but markedly reduced both the internal venting peak and the external secondary-explosion peak, while extending the plateau or quasi-plateau duration; at high ammonia fractions, the external secondary explosion was strongly suppressed. Decreasing the vent diameter intensified pressure oscillations, prolonged the time to membrane rupture, and generally increased both burst pressure and internal venting peak pressure; the external peak showed a vent-size-dependent trend that differed between low- and high- ammonia regimes. NFPA 68 predictions were close to measurements for the largest vent but showed systematic overestimation for medium and small vents; the deviation was governed mainly by vent geometry rather than mixture composition. For the investigated duct (length-to-diameter ratio about 16.7) with end venting, the overestimation reached approximately 4–8 times for the medium vent and about 30–80 times for the small vent. A correction model incorporating geometric venting ratio and static activation pressure reduced the discrepancy substantially, with the corrected-to-measured maximum reduced explosion pressure ratio mostly constrained within about 1–4.3. These findings provide experimentally grounded guidance and a practical correlation for vent design and safety evaluation of end-vented long-duct systems using ammonia–hydrogen premixed fuels.
Vented deflagrations in ducts with a high length-to-diameter ratio are frequently encountered in hydrogen–ammonia energy systems, yet the pressure evolution and the applicability of engineering venting standards remain insufficiently validated for “large length-to-diameter ratio plus small end vent” configurations. An experimental study was therefore conducted to quantify how end-vent diameter affected the internal and external pressure characteristics of ammonia–hydrogen premixed gas in a long tube, and to improve the prediction accuracy of the NFPA (national fire protection association) standard 68, which standard on explosion protection by deflagration venting. Experiments were carried out in a stainless-steel duct system with a total length of 2 m, one end closed and the other end equipped with an end vent sealed by a thin vent membrane. Three circular vent diameters (120, 80, and 40 mm) were tested, corresponding to venting ratios of 100%, 44.4%, and 11.1%, respectively. Tests were performed under near-ambient initial conditions at a fixed equivalence ratio of 0.8, while the ammonia fraction in the fuel (ammonia plus hydrogen) was varied from 30% to 70%. Gas mixtures were prepared by partial-pressure charging after evacuating the mixing vessel, followed by sufficient standing time to promote homogeneity. A pressure transducer installed near the downstream region recorded the pressure–time history. For each condition, 3–4 repeated runs were conducted; representative traces were selected based on proximity to the mean of characteristic parameters. From each pressure trace, the membrane burst pressure, the internal venting peak pressure, the peak pressure associated with an external secondary explosion, and the duration of the pressure plateau or quasi-plateau were extracted. The maximum reduced explosion pressure was also calculated using NFPA 68 and compared against measurements; a correction correlation was then developed by incorporating the geometric venting ratio and the static activation pressure of the venting device. Under full venting, pressure histories exhibited a typical three-peak structure corresponding to membrane rupture, internal venting peak, and external secondary explosion peak. Increasing the ammonia fraction caused only minor changes in burst pressure but markedly reduced both the internal venting peak and the external secondary-explosion peak, while extending the plateau or quasi-plateau duration; at high ammonia fractions, the external secondary explosion was strongly suppressed. Decreasing the vent diameter intensified pressure oscillations, prolonged the time to membrane rupture, and generally increased both burst pressure and internal venting peak pressure; the external peak showed a vent-size-dependent trend that differed between low- and high- ammonia regimes. NFPA 68 predictions were close to measurements for the largest vent but showed systematic overestimation for medium and small vents; the deviation was governed mainly by vent geometry rather than mixture composition. For the investigated duct (length-to-diameter ratio about 16.7) with end venting, the overestimation reached approximately 4–8 times for the medium vent and about 30–80 times for the small vent. A correction model incorporating geometric venting ratio and static activation pressure reduced the discrepancy substantially, with the corrected-to-measured maximum reduced explosion pressure ratio mostly constrained within about 1–4.3. These findings provide experimentally grounded guidance and a practical correlation for vent design and safety evaluation of end-vented long-duct systems using ammonia–hydrogen premixed fuels.
, Available online ,
doi: 10.11883/bzycj-2025-0309
Abstract:
An uniaxial compression tests were conducted on chicken femoral cortical bone under quasi-static (0.001 s−1) and dynamic (350 and 700 s−1) conditions by using a universal testing machine and a split Hopkinson pressure bar (SHPB). Chicken femoral cortical bone specimens were obtained via cutting and grinding, with high-contrast speckle patterns prepared on them. Images of cortical bone were recorded during the experiment using two cameras, with an acquisition frequency of 5 Hz for the quasi-static test and 150 kHz for the dynamic test. Full-field strain distributions were obtained using digital image correlation (DIC), and fracture micro-morphology was observed via scanning electron microscopy (SEM) to analyze the effect of strain rate on fracture behavior. The experimental results show that the failure stress of cortical bone exhibits a non-monotonic trend with increasing strain rate, with average values of 99.6, 195.5 and 171.3 MPa at 0.001, 350, and 700 s−1, respectively, demonstrating an “increase-then-decrease” tendency. A similar trend was observed for fracture strain. Under quasi-static loading, the macroscopic crack propagation path aligns with the maximum shear strain region, and the fracture surface exhibits typical shear failure characteristics (layered delamination and abundant debris), indicating shear strain as the primary fracture driver. In contrast, under dynamic loading, the macroscopic crack correlates more closely with the maximum tensile strain region, and the fracture surface appears smooth, characteristic of tensile fracture morphology, confirming tensile strain as the dominant mechanism. Strain rate exerts a significant influence on the fracture mechanism by regulating the fracture-inducing factor, which may account for one of the key reasons for the variation in fracture stress of cortical bone under dynamic conditions. This study reveals, from a macro-micro correlated perspective, the shift in fracture mechanisms of cortical bone from shear dominance to tensile dominance with increasing strain rate, which provides experimental evidence for understanding the fracture mechanism of bone under impact loading and a reference for the design of bone biomimetic materials and the development of orthopedic protective equipment.
An uniaxial compression tests were conducted on chicken femoral cortical bone under quasi-static (0.001 s−1) and dynamic (350 and 700 s−1) conditions by using a universal testing machine and a split Hopkinson pressure bar (SHPB). Chicken femoral cortical bone specimens were obtained via cutting and grinding, with high-contrast speckle patterns prepared on them. Images of cortical bone were recorded during the experiment using two cameras, with an acquisition frequency of 5 Hz for the quasi-static test and 150 kHz for the dynamic test. Full-field strain distributions were obtained using digital image correlation (DIC), and fracture micro-morphology was observed via scanning electron microscopy (SEM) to analyze the effect of strain rate on fracture behavior. The experimental results show that the failure stress of cortical bone exhibits a non-monotonic trend with increasing strain rate, with average values of 99.6, 195.5 and 171.3 MPa at 0.001, 350, and 700 s−1, respectively, demonstrating an “increase-then-decrease” tendency. A similar trend was observed for fracture strain. Under quasi-static loading, the macroscopic crack propagation path aligns with the maximum shear strain region, and the fracture surface exhibits typical shear failure characteristics (layered delamination and abundant debris), indicating shear strain as the primary fracture driver. In contrast, under dynamic loading, the macroscopic crack correlates more closely with the maximum tensile strain region, and the fracture surface appears smooth, characteristic of tensile fracture morphology, confirming tensile strain as the dominant mechanism. Strain rate exerts a significant influence on the fracture mechanism by regulating the fracture-inducing factor, which may account for one of the key reasons for the variation in fracture stress of cortical bone under dynamic conditions. This study reveals, from a macro-micro correlated perspective, the shift in fracture mechanisms of cortical bone from shear dominance to tensile dominance with increasing strain rate, which provides experimental evidence for understanding the fracture mechanism of bone under impact loading and a reference for the design of bone biomimetic materials and the development of orthopedic protective equipment.
, Available online ,
doi: 10.11883/bzycj-2025-0330
Abstract:
To rapidly obtain the explosion power of incident, a non-contact inversion methodology that leverages fused audio-video data to estimate explosion power is presented by analyzing the temporal lag between the optical flash and the arrival of the blast wave. Based on the Hopkinson-Cranz proportionality law, the Rankine-Hugoniot equation, and the free-field and near-ground overpressure models, the critical proportion distance parameter during the attenuation of the shock wave to the sound wave stage is introduced, and a theoretical model for yield inversion based on the travel time of the two waves is constructed. Through near-ground and air explosion experiments, the validity and applicability of the established model are verified, and the influences of explosion height, frame rate, and frame extraction method on the model’s prediction accuracy are analyzed. The results show that in the near-ground explosion condition, the ground reflection effect significantly increases the propagation speed of the explosion wave. Compared with the empirical formula based on the travel time of the shock wave and the improved formula combining the travel time of the sound wave, the dual-wave theoretical model proposed in this paper significantly considers the differences in the propagation characteristics of the shock wave and the sound wave and the ground reflection effect in near-ground explosions. Under the influence of multiple factors such as explosion height, frame rate, and frame extraction method, it shows better stability and superior prediction accuracy.
To rapidly obtain the explosion power of incident, a non-contact inversion methodology that leverages fused audio-video data to estimate explosion power is presented by analyzing the temporal lag between the optical flash and the arrival of the blast wave. Based on the Hopkinson-Cranz proportionality law, the Rankine-Hugoniot equation, and the free-field and near-ground overpressure models, the critical proportion distance parameter during the attenuation of the shock wave to the sound wave stage is introduced, and a theoretical model for yield inversion based on the travel time of the two waves is constructed. Through near-ground and air explosion experiments, the validity and applicability of the established model are verified, and the influences of explosion height, frame rate, and frame extraction method on the model’s prediction accuracy are analyzed. The results show that in the near-ground explosion condition, the ground reflection effect significantly increases the propagation speed of the explosion wave. Compared with the empirical formula based on the travel time of the shock wave and the improved formula combining the travel time of the sound wave, the dual-wave theoretical model proposed in this paper significantly considers the differences in the propagation characteristics of the shock wave and the sound wave and the ground reflection effect in near-ground explosions. Under the influence of multiple factors such as explosion height, frame rate, and frame extraction method, it shows better stability and superior prediction accuracy.
, Available online ,
doi: 10.11883/bzycj-2026-0072
Abstract:
Independent embedded steel sheet piles, characterized by convenient construction and strong damage resistance, are widely used in nearshore coastal protection engineering. The damage characteristics of steel sheet piles subjected to shallow-water explosions play a critical role in determining the reliability of blast-resistant design. However, existing studies remain insufficient to fully elucidate the damage mechanisms of steel sheet piles under shallow-water blast loading. Based on the attenuation law of underwater explosion loads, an engineering calculation model was established to evaluate the blast-induced damage of steel sheet piles in shallow water. Meanwhile, a coupled numerical simulation model accounting for the interaction among multiple materials was developed. Model tests were further conducted to validate the reliability of both the engineering calculation model and the numerical simulations. The effects of explosive charge equivalent, standoff distance, and water depth on the structural damage response were systematically analyzed. The results indicate that the weak zone of steel sheet piles is mainly concentrated near the water-soil interface, with punching shear fracture and bending deformation identified as the dominant failure modes. The scaled distance was found to be the key parameter governing the damage behavior. When the scaled distance is less than 0.086m/kg1/3, punching shear fracture occurs; when it exceeds 1.026 m/kg1/3, no significant damage is observed; and within the intermediate range, plastic bending deformation develops. Increasing water depth has a limited effect on fracture failure but can significantly extend the bending deformation zone, with an increase of up to 35%. Good agreement was achieved among the theoretical calculations, numerical simulations, and experimental results, with relative errors within 10%, satisfying the accuracy requirements for engineering prediction. These findings provide a reliable theoretical basis and practical guidance for the blast-resistant design, damage assessment, and protective reinforcement of independent embedded steel sheet pile structures.
Independent embedded steel sheet piles, characterized by convenient construction and strong damage resistance, are widely used in nearshore coastal protection engineering. The damage characteristics of steel sheet piles subjected to shallow-water explosions play a critical role in determining the reliability of blast-resistant design. However, existing studies remain insufficient to fully elucidate the damage mechanisms of steel sheet piles under shallow-water blast loading. Based on the attenuation law of underwater explosion loads, an engineering calculation model was established to evaluate the blast-induced damage of steel sheet piles in shallow water. Meanwhile, a coupled numerical simulation model accounting for the interaction among multiple materials was developed. Model tests were further conducted to validate the reliability of both the engineering calculation model and the numerical simulations. The effects of explosive charge equivalent, standoff distance, and water depth on the structural damage response were systematically analyzed. The results indicate that the weak zone of steel sheet piles is mainly concentrated near the water-soil interface, with punching shear fracture and bending deformation identified as the dominant failure modes. The scaled distance was found to be the key parameter governing the damage behavior. When the scaled distance is less than 0.086m/kg1/3, punching shear fracture occurs; when it exceeds 1.026 m/kg1/3, no significant damage is observed; and within the intermediate range, plastic bending deformation develops. Increasing water depth has a limited effect on fracture failure but can significantly extend the bending deformation zone, with an increase of up to 35%. Good agreement was achieved among the theoretical calculations, numerical simulations, and experimental results, with relative errors within 10%, satisfying the accuracy requirements for engineering prediction. These findings provide a reliable theoretical basis and practical guidance for the blast-resistant design, damage assessment, and protective reinforcement of independent embedded steel sheet pile structures.
, Available online ,
doi: 10.11883/bzycj-2025-0148
Abstract:
To address the challenges of rapid deployment for heavy-duty unmanned platforms and impact protection during drop-landing, a buffer airbag system was designed to ensure the safe landing of the unmanned platform. First, theoretical modeling was used to preliminarily determine the geometric parameters of the buffer airbag and the size of the vent holes. A finite element simulation model that included the buffer airbag, the unmanned platform and the ground was established using the control volume method (CVM) to simulate the cushioning process of the airbag. The impact dynamics response during the landing attenuation process was analyzed, and the specific energy absorption (SEA) of the buffer airbag system was introduced to evaluate its cushioning performance. The analysis results indicate that during the landing buffer process, the unmanned platform reached a maximum overload value of 16.8g at 0.06s, and the platform velocity reached a post-rebound maximum of 0.79 m/s at 0.1 s. At 0.18 s, the platform shifted laterally due to the center of gravity, and one side of the platform first contacted the ground. This led to fluctuations in overload value and velocity, but the overall landing process remained stable. The calculated SEA of the buffer airbag system was1527 J/kg. Using the control variable method, the influence of key parameters on the buffer performance of the airbag was analyzed, revealing the effects of vent hole size, critical exhaust pressure, airbag base area and airbag height on the performance of the buffer. The study found that the influence of airbag height on the two key indicators (maximum overload and SEA) was consistent, presenting no optimization conflict. However, after the height exceeded 0.37 m, a diminishing returns effect appeared. When the other three variables were changed individually, they caused a conflict between the goals of minimizing maximum overload and maximizing SEA, making it impossible to improve both simultaneously through independent optimization. To resolve this issue, an optimal latin hypercube design was used for sampling, and a three-layer neural network was employed to construct proxy models for the objective functions. The root mean square error (RMSE) and coefficient of determination (R2) of these two types of proxy models were calculated to evaluate their regression performance. The NSGA-II genetic algorithm was integrated for multi-objective optimization. The results showed that for the proxy models predicting maximum overload and SEA, the RMSEs were 0.4895 and 0.7262 , and the R2 values were 0.9833 and 0.9364 , respectively. All R2 values were greater than the industry benchmark of 0.9, indicating high reliability of the proxy models. When the vent hole area was 3952 mm2, the critical exhaust pressure, the airbag base area were 158 kPa and 1.08 m2, respectively. Meanwhile, the maximum overload was reduced from 16.8g to 14.5g, and the SEA remained stable at 1529 J/kg. Based on the characteristics of the airbag's buffer process, a gantry crane-based simulation test method for unmanned platform airdrop and lifting was designed. A piezoelectric IEPE acceleration sensor was used to measure the overload value of the unmanned platform. Experimental verification showed that the measured maximum overload value was 15.2g, with a mere 4.8% error compared to the simulation result, confirming the correctness of the optimization scheme. This research provides efficient and low-cost design technical support for the soft landing systems of unmanned platforms, enhancing the safety and efficiency of operational deployment.
To address the challenges of rapid deployment for heavy-duty unmanned platforms and impact protection during drop-landing, a buffer airbag system was designed to ensure the safe landing of the unmanned platform. First, theoretical modeling was used to preliminarily determine the geometric parameters of the buffer airbag and the size of the vent holes. A finite element simulation model that included the buffer airbag, the unmanned platform and the ground was established using the control volume method (CVM) to simulate the cushioning process of the airbag. The impact dynamics response during the landing attenuation process was analyzed, and the specific energy absorption (SEA) of the buffer airbag system was introduced to evaluate its cushioning performance. The analysis results indicate that during the landing buffer process, the unmanned platform reached a maximum overload value of 16.8g at 0.06s, and the platform velocity reached a post-rebound maximum of 0.79 m/s at 0.1 s. At 0.18 s, the platform shifted laterally due to the center of gravity, and one side of the platform first contacted the ground. This led to fluctuations in overload value and velocity, but the overall landing process remained stable. The calculated SEA of the buffer airbag system was
, Available online ,
doi: 10.11883/bzycj-2025-0383
Abstract:
To address the high cost and low sample efficiency of deep learning-based blast loading prediction in urban environments, a Bayesian deep active learning (BDAL) method is proposed. The objective is to significantly reduce the dependency on large-scale, high-fidelity numerical simulation data while maintaining prediction accuracy and providing reliable uncertainty quantification. A three-dimensional typical urban building cluster consisting of a 3×3 regular array of cuboid buildings was constructed. A seven-dimensional parameter space was defined, including explosive charge equivalence (1000 , 2000 , 3000 kT), detonation distance (1000 , 2000, 3000 m), building length (10, 20, 30 m), building width (20, 40 m), building height (75, 100 m), street length (50, 75, 100 m), and street width (50, 75 m). A full factorial experimental design was employed, generating 648 parameter combinations. For each combination, the open-source computational fluid dynamics (CFD) software blastFoam was used to perform three-dimensional numerical simulations of blast wave propagation. The background mesh size was set to 30 m based on grid sensitivity analysis, and adaptive mesh refinement (AMR) with local refinement level 2 and dynamic refinement level 1 was applied to capture shock wave details. Peak overpressure values were recorded at 12 points of interest (POIs) in the building cluster, resulting in a dataset of 7776 samples. A BDAL framework was then developed. Bayesian inference was integrated into a deep neural network to enable probabilistic modeling of parameters. Monte Carlo (MC) dropout was adopted as an approximate variational inference method to estimate predictive uncertainty. An uncertainty-driven active sampling strategy was designed: the predictive variance of each unlabeled sample was computed via 30 stochastic forward passes with dropout enabled. Samples with variance exceeding 85% of the maximum variance were selected as candidates, and the top 28 cases (336 samples) with the highest variance were chosen in each active learning cycle. These selected samples were labeled by the blastFoam simulator and added to the training set. The model was retrained iteratively until the relative improvement in mean absolute percentage error (MAPE) fell below 1% or the labeled set reached the full training size. On a test set of 780 unseen samples (65 cases), the proposed BDAL method achieved an MAPE of 13.1% and an R2 of 0.972 for peak overpressure prediction. The 95% prediction interval covered the true values in 85.9% of the cases, with a normalized mean prediction interval width (NMPIW) of 0.026. Single-point prediction response time was below 20 ms, representing a speedup of more than 105 compared to high-fidelity numerical simulations. Compared to passive deep learning models trained on the full dataset, the BDAL method required only about 50% of labeled data to reach comparable prediction accuracy. In a comparative experiment with 50% training data, BDAL achieved a MAPE of 17.2%, while a conventional fully connected neural network (FCNN) and a three-dimensional direction-encoded Bayesian neural network (3D-DeBNN) gave MAPEs of 52.9% and 22.6%, respectively. The proposed Bayesian deep active learning method enables efficient and low-cost blast loading prediction in typical regularized urban environments. It effectively reduces the dependency on large-scale numerical simulation data, maintains high prediction accuracy and reliable uncertainty quantification, and meanwhile achieves millisecond-level inference speed. The method shows strong potential for disaster prevention and mitigation applications, such as pre-disaster anti-blast design and post-disaster emergency response.
To address the high cost and low sample efficiency of deep learning-based blast loading prediction in urban environments, a Bayesian deep active learning (BDAL) method is proposed. The objective is to significantly reduce the dependency on large-scale, high-fidelity numerical simulation data while maintaining prediction accuracy and providing reliable uncertainty quantification. A three-dimensional typical urban building cluster consisting of a 3×3 regular array of cuboid buildings was constructed. A seven-dimensional parameter space was defined, including explosive charge equivalence (
, Available online ,
doi: 10.11883/bzycj-2026-0027
Abstract:
In complex and sensitive environments, minimizing the disturbance of blasting vibration to surrounding residents is the primary concern during blasting construction. To explore a quantitative evaluation method for human dynamic response to blasting vibration, this study conducted single-subject in-situ blasting tests under strictly controlled safety conditions. By integrating digital image correlation (DIC) with a synchronous electrocardiogram (ECG) measurement system, the dynamic response characteristics of the human body surface under varying blasting vibration intensities were preliminarily analyzed. A height-dependent fitting relationship for peak particle velocity (PPV) was established under the present test conditions, with the body divided into two regions: below the waist and above the waist. Given the safety constraints of in-situ blasting tests, laboratory shake-table tests were also conducted. A comparative analysis using heart rate variability (HRV) evaluation indices was performed to preliminarily demonstrate the feasibility of using a shake table to simulate blasting vibration for human perception studies. The preliminary results indicate that under the present test conditions, the vertical vibration velocity of the human body is significantly higher than the horizontal velocity, with the vertical direction identified as the dominant vibration direction. The vertical vibration velocity exhibits a characteristic pattern of “attenuation below the waist and amplification above the waist”. Compared with the ground surface velocity, the attenuation rate in the lower body region ranges from 55.7% to 65.9%. The vibration velocity in the upper body region is amplified by a factor of 1.25 to 1.74. The horizontal vibration velocity decreases from the feet to the head, with an attenuation rate of 52.6% to 60%. The error in HRV indices obtained from the in-situ and shake-table tests is less than 10%, preliminarily confirming the feasibility of employing a shake table to simulate blasting vibration for human perception research. These exploratory in-situ tests provide a methodological reference for quantifying human vibration response and studying perceived ECG changes due to blasting vibrations.
In complex and sensitive environments, minimizing the disturbance of blasting vibration to surrounding residents is the primary concern during blasting construction. To explore a quantitative evaluation method for human dynamic response to blasting vibration, this study conducted single-subject in-situ blasting tests under strictly controlled safety conditions. By integrating digital image correlation (DIC) with a synchronous electrocardiogram (ECG) measurement system, the dynamic response characteristics of the human body surface under varying blasting vibration intensities were preliminarily analyzed. A height-dependent fitting relationship for peak particle velocity (PPV) was established under the present test conditions, with the body divided into two regions: below the waist and above the waist. Given the safety constraints of in-situ blasting tests, laboratory shake-table tests were also conducted. A comparative analysis using heart rate variability (HRV) evaluation indices was performed to preliminarily demonstrate the feasibility of using a shake table to simulate blasting vibration for human perception studies. The preliminary results indicate that under the present test conditions, the vertical vibration velocity of the human body is significantly higher than the horizontal velocity, with the vertical direction identified as the dominant vibration direction. The vertical vibration velocity exhibits a characteristic pattern of “attenuation below the waist and amplification above the waist”. Compared with the ground surface velocity, the attenuation rate in the lower body region ranges from 55.7% to 65.9%. The vibration velocity in the upper body region is amplified by a factor of 1.25 to 1.74. The horizontal vibration velocity decreases from the feet to the head, with an attenuation rate of 52.6% to 60%. The error in HRV indices obtained from the in-situ and shake-table tests is less than 10%, preliminarily confirming the feasibility of employing a shake table to simulate blasting vibration for human perception research. These exploratory in-situ tests provide a methodological reference for quantifying human vibration response and studying perceived ECG changes due to blasting vibrations.
, Available online ,
doi: 10.11883/bzycj-2025-0409
Abstract:
Reinforced concrete (RC) columns are critical load-bearing members in engineering structures. Under explosive loading, they may sustain severe damage and potentially trigger the collapse of the entire structure. Therefore, rapid and accurate assessment of the damage state of RC columns subjected to explosive loading is essential for ensuring structural safety and implementing effective protective measures. Accordingly, a data-driven machine learning (ML) model is proposed to predict the damage indices of RC columns under explosive loading. To train the model, a comprehensive database comprising3133 samples was established by integrating 259 samples collected from the literature and 2874 supplementary samples generated through numerical simulations. The database includes both RC columns with uniformly spaced stirrups and those with densified stirrups satisfying seismic design requirements. Eleven key parameters were selected as input features, with the RC column damage index taken as the output. Six ML models were employed to predict the damage indices under explosive loading, and their predictive performance was comparatively evaluated using four regression metrics. The results indicate that the tabular prior-data fitted network (TabPFN) achieved the best predictive accuracy and generalization performance, with a coefficient of determination of 0.989 on the test set and a mean absolute error and a root mean square error of 0.018 and 0.030, respectively. The interpretability of the TabPFN model was further analyzed using SHAP (Shapley additive explanations). The results show that charge mass, standoff distance, and column cross-sectional depth are the key features governing the damage severity of RC columns. Notably, the volumetric stirrup reinforcement ratio contributes more significantly to improving the blast resistance of RC columns than the longitudinal reinforcement ratio. Finally, comparison with independent finite element simulation results confirmed that the TabPFN model exhibits good predictive stability as a surrogate model under unseen loading conditions. In terms of computational efficiency, the proposed model achieves a single-prediction inference time of approximately 0.5 s, representing an efficiency improvement of nearly four orders of magnitude compared with conventional numerical simulation methods. The established model enables rapid surrogate prediction of RC column damage under explosive loading and provides guidance for preliminary parameter analysis in blast-resistant structural optimization design.
Reinforced concrete (RC) columns are critical load-bearing members in engineering structures. Under explosive loading, they may sustain severe damage and potentially trigger the collapse of the entire structure. Therefore, rapid and accurate assessment of the damage state of RC columns subjected to explosive loading is essential for ensuring structural safety and implementing effective protective measures. Accordingly, a data-driven machine learning (ML) model is proposed to predict the damage indices of RC columns under explosive loading. To train the model, a comprehensive database comprising
, Available online ,
doi: 10.11883/bzycj-2026-0030
Abstract:
In recent years, with the widespread application of various explosive weapons, the number of explosion-induced traumatic brain injury (TBI) cases has surged. Current research on explosive blast injuries predominantly focuses on plain environments, while studies on the injury mechanisms, trauma characteristics, and treatment strategies under the special physical and chemical environment of the plateau remain relatively scarce. To investigate the kinematic response of the human head–neck system subjected to blast loading under low-ambient-pressure conditions, this study employed a high-fidelity physical anthropomorphic surrogate instrumented with overpressure transducers, accelerometers, angular-rate sensors, and a six-axis load cell. Experiments were conducted using a shock-tube test system at four ambient-pressure levels, with three blast overpressure magnitudes applied sequentially for each pressure condition. The results show that, under ambient pressures ranging from 54 kPa to 101 kPa, the free-field peak overpressure decreases with decreasing ambient pressure (relative to 101 kPa, the peak overpressure at 54 kPa is reduced by approximately 16.03%). The peak overpressure measured at various locations on the head surface also shows a decreasing trend in the low-pressure range. Meanwhile, translational metrics—such as the peak head center-of-gravity accelerations in the x and z directions and the peak neck forces in the x and z directions—decrease overall with decreasing ambient pressure, whereas rotational metrics such as the peak head center-of-gravity angular velocity in the y direction and the peak neck torque in the y direction—increase overall with decreasing ambient pressure. These findings indicate that, under the present test conditions, low ambient pressure exerts opposite effects on the translational and rotational responses of the head-neck system. The study reveals that the injury quantification assessment method established under normothermic and normobaric conditions exhibits applicability bias in high-altitude (hypobaric) environments. This bias arises because high-altitude (hypobaric) conditions can alter human physiological functions (e.g., hypoxia and hypothermia reduce tissue tolerance). Under identical blast loading conditions, injuries tend to be more severe than those at plain levels. Therefore, the method requires calibration and validation under hypobaric conditions. In summary, this study provides a mechanics-based reference for blast-induced injury research and for evaluating the applicability of injury criteria in plateau (low-ambient-pressure) environments.
In recent years, with the widespread application of various explosive weapons, the number of explosion-induced traumatic brain injury (TBI) cases has surged. Current research on explosive blast injuries predominantly focuses on plain environments, while studies on the injury mechanisms, trauma characteristics, and treatment strategies under the special physical and chemical environment of the plateau remain relatively scarce. To investigate the kinematic response of the human head–neck system subjected to blast loading under low-ambient-pressure conditions, this study employed a high-fidelity physical anthropomorphic surrogate instrumented with overpressure transducers, accelerometers, angular-rate sensors, and a six-axis load cell. Experiments were conducted using a shock-tube test system at four ambient-pressure levels, with three blast overpressure magnitudes applied sequentially for each pressure condition. The results show that, under ambient pressures ranging from 54 kPa to 101 kPa, the free-field peak overpressure decreases with decreasing ambient pressure (relative to 101 kPa, the peak overpressure at 54 kPa is reduced by approximately 16.03%). The peak overpressure measured at various locations on the head surface also shows a decreasing trend in the low-pressure range. Meanwhile, translational metrics—such as the peak head center-of-gravity accelerations in the x and z directions and the peak neck forces in the x and z directions—decrease overall with decreasing ambient pressure, whereas rotational metrics such as the peak head center-of-gravity angular velocity in the y direction and the peak neck torque in the y direction—increase overall with decreasing ambient pressure. These findings indicate that, under the present test conditions, low ambient pressure exerts opposite effects on the translational and rotational responses of the head-neck system. The study reveals that the injury quantification assessment method established under normothermic and normobaric conditions exhibits applicability bias in high-altitude (hypobaric) environments. This bias arises because high-altitude (hypobaric) conditions can alter human physiological functions (e.g., hypoxia and hypothermia reduce tissue tolerance). Under identical blast loading conditions, injuries tend to be more severe than those at plain levels. Therefore, the method requires calibration and validation under hypobaric conditions. In summary, this study provides a mechanics-based reference for blast-induced injury research and for evaluating the applicability of injury criteria in plateau (low-ambient-pressure) environments.
, Available online ,
doi: 10.11883/bzycj-2026-0057
Abstract:
To address the issues of insufficient cycle advance and low blast-hole utilization resulting from inappropriate cut blasting layouts during roadway excavation, the empty-hole effect was employed to establish a three-dimensional cut blasting model using FEM-SPH（finite element method-smooth particle hydrodynamics）coupled numerical simulation. In the numerical modeling, the rock mass was described by the RHT constitutive model, which accounts for strain-rate sensitivity and confinement effects under high-strain-rate loading. The explosive was modeled using the Jones-Wilkins-Lee equation of state. A central charged hole was surrounded by four, five, or six empty holes with a spacing of 210 mm determined theoretically. SPH particles were applied to the central zone to capture large deformation, fragmentation, and rock ejection, while the FEM was used for the outer region to reduce computational cost. Non-reflecting boundaries were set to avoid stress wave reflection. The model was then used to simulate and analyze the influence of different cut blasting arrangements on rock mass damage, rock throw efficiency, and fragmentation patterns. Furthermore, field engineering tests were conducted in a copper mine roadway to validate the simulation results by examining the residual hole depth after blasting and the achieved cycle advance. The research findings indicate that a cut blasting layout with one central charged hole and five empty holes provides a moderate number of free surfaces, allowing for more sufficient superposition of stress waves and resulting in better blasting performance. Compared to layouts with four or six empty holes, the five-empty-hole configuration demonstrates optimal rock throw effects, with the slot cavity opening size increasing by 42.5% and 20.3%, respectively, and the slot cavity cross-sectional size improving by 52.4% and 34.7%, respectively. Field test results show that the cycle advance achieved with the five-empty-hole layout is 10.2% and 3.2% higher than that of the four-empty-hole and six-empty-hole layouts, respectively. The research reveals a nonlinear relationship between the number of empty holes and blasting effects, demonstrating that the optimal balance between stress wave superposition and energy concentration can be achieved using a moderate number of empty holes, providing a basis for the design and optimization of cut blasting schemes in roadway excavation.
To address the issues of insufficient cycle advance and low blast-hole utilization resulting from inappropriate cut blasting layouts during roadway excavation, the empty-hole effect was employed to establish a three-dimensional cut blasting model using FEM-SPH（finite element method-smooth particle hydrodynamics）coupled numerical simulation. In the numerical modeling, the rock mass was described by the RHT constitutive model, which accounts for strain-rate sensitivity and confinement effects under high-strain-rate loading. The explosive was modeled using the Jones-Wilkins-Lee equation of state. A central charged hole was surrounded by four, five, or six empty holes with a spacing of 210 mm determined theoretically. SPH particles were applied to the central zone to capture large deformation, fragmentation, and rock ejection, while the FEM was used for the outer region to reduce computational cost. Non-reflecting boundaries were set to avoid stress wave reflection. The model was then used to simulate and analyze the influence of different cut blasting arrangements on rock mass damage, rock throw efficiency, and fragmentation patterns. Furthermore, field engineering tests were conducted in a copper mine roadway to validate the simulation results by examining the residual hole depth after blasting and the achieved cycle advance. The research findings indicate that a cut blasting layout with one central charged hole and five empty holes provides a moderate number of free surfaces, allowing for more sufficient superposition of stress waves and resulting in better blasting performance. Compared to layouts with four or six empty holes, the five-empty-hole configuration demonstrates optimal rock throw effects, with the slot cavity opening size increasing by 42.5% and 20.3%, respectively, and the slot cavity cross-sectional size improving by 52.4% and 34.7%, respectively. Field test results show that the cycle advance achieved with the five-empty-hole layout is 10.2% and 3.2% higher than that of the four-empty-hole and six-empty-hole layouts, respectively. The research reveals a nonlinear relationship between the number of empty holes and blasting effects, demonstrating that the optimal balance between stress wave superposition and energy concentration can be achieved using a moderate number of empty holes, providing a basis for the design and optimization of cut blasting schemes in roadway excavation.
, Available online ,
doi: 10.11883/bzycj-2026-0002
Abstract:
To further analyze the damage effects of projectile penetration into concrete targets and their influence on the penetration process, a systematic theoretical investigation was carried out. A spalling effect model was established based on the spalling phenomenon observed during normal perforation of concrete targets by projectiles. By integrating this model with the cratering effect model and the target resistance function, a theoretical model for penetration that comprehensively accounts for both cratering and spalling effects was developed. By means of the presented model, the influence of target thickness and impact velocity on the penetration process and target damage parameters were analyzed. The results show that as the concrete target thickness decreases or the impact velocity increases, the influence of the spalling effect on penetration resistance and residual velocity diminishes, while the proportion of the splash zone during the spalling stage increases, making the splash effect the dominant factor affecting resistance in the spalling stage. When the target thickness exceeds 4.5 times the projectile diameter, the influence of the spalling effect on the residual velocity exceeds 10%, rendering the spalling effect non-negligible. Cratering depth increases linearly with thickness when the thickness is not more than 4 times the projectile diameter, and then tends to stabilize. Spalling depth increases linearly with thickness when the thickness is not more than 6.9 times the projectile diameter, and then decreases linearly. During the linear increase stage, both cratering depth and spalling depth are approximately half of the concrete target thickness. Compared with perforation of thin concrete targets, variations in impact velocity exhibit a more pronounced influence on the crater depth and spalling depth during the penetration of thick concrete targets. The proposed model effectively characterizes the damage effects of concrete targets and can provide a theoretical basis for penetration analysis and protective design of concrete targets.
To further analyze the damage effects of projectile penetration into concrete targets and their influence on the penetration process, a systematic theoretical investigation was carried out. A spalling effect model was established based on the spalling phenomenon observed during normal perforation of concrete targets by projectiles. By integrating this model with the cratering effect model and the target resistance function, a theoretical model for penetration that comprehensively accounts for both cratering and spalling effects was developed. By means of the presented model, the influence of target thickness and impact velocity on the penetration process and target damage parameters were analyzed. The results show that as the concrete target thickness decreases or the impact velocity increases, the influence of the spalling effect on penetration resistance and residual velocity diminishes, while the proportion of the splash zone during the spalling stage increases, making the splash effect the dominant factor affecting resistance in the spalling stage. When the target thickness exceeds 4.5 times the projectile diameter, the influence of the spalling effect on the residual velocity exceeds 10%, rendering the spalling effect non-negligible. Cratering depth increases linearly with thickness when the thickness is not more than 4 times the projectile diameter, and then tends to stabilize. Spalling depth increases linearly with thickness when the thickness is not more than 6.9 times the projectile diameter, and then decreases linearly. During the linear increase stage, both cratering depth and spalling depth are approximately half of the concrete target thickness. Compared with perforation of thin concrete targets, variations in impact velocity exhibit a more pronounced influence on the crater depth and spalling depth during the penetration of thick concrete targets. The proposed model effectively characterizes the damage effects of concrete targets and can provide a theoretical basis for penetration analysis and protective design of concrete targets.
, Available online ,
doi: 10.11883/bzycj-2026-0022
Abstract:
Current transformers are core components of power systems used for current measurement and relay protection. During long-term service under coupled multiphysical-field conditions, the internal insulation structure is susceptible to breakdown under locally intensified electric fields, triggering arc discharge in the insulating oil. The resulting oil cracking and rapid gas expansion produce a sharp rise in internal pressure. If this pressure is not relieved promptly, the resulting pressure surge may lead to combustion and explosion accidents. Therefore, the rapid-response capability of pressure relief devices under explosive loading is critical to the operational safety of current transformers. This study focuses on the expander–rupture disc pressure relief assembly of an LVB-220 current transformer and systematically investigates its dynamic mechanical behavior and failure mechanism under explosive impact loading. An equivalent hydrogen–air premixed-gas explosion test platform was constructed. The test system consisted of two stainless-steel flame-acceleration tubes with an inner diameter of 168.3 mm and a total length of4250 mm, a gas-filling and mixing unit, an ignition device, and a high-speed data-acquisition system. A hydrogen-air mixture with a volume ratio of 27:75 was used as the combustible gas to reproduce the most severe explosion conditions caused by arc-generated cracking gas in transformer oil. Pressure and flame signals were recorded synchronously using a high-temperature pressure transducer and two flame detectors installed along the tube. The tested assembly consisted of a positive-arch, cross-scored rupture disc made of 316L stainless steel, with a static burst pressure of 0.2 MPa, and a nine-convolution expander. In addition, an explicit dynamic finite element model was developed using ANSYS/LS-DYNA. The Johnson-Cook constitutive model was adopted to describe the strain-rate-dependent behavior of 316L stainless steel. The cross-scored region of the rupture disc was finely meshed with a minimum element size of approximately 0.02 mm to accurately capture crack initiation and propagation. The measured pressure–time history was applied as the loading boundary condition. The model was validated by comparing the simulated opening pressure and expander deformation with the experimental results. The results show that, during the early stage of the explosion, the pressure wave reaches the relief port ahead of the flame front and triggers the opening of the rupture disc. The measured peak pressure before disc opening is 0.72 MPa, which is significantly higher than the static calibration value of 0.2 MPa because of strain-rate hardening, structural inertia, and the spatial nonuniformity of the pressure field under rapid loading. The expander exhibits limited plastic deformation, with the axial deformation of the nine convolutions ranging from 0.60 to 2.30 mm. The deformation distribution is characterized by larger values at both ends and smaller values in the middle, reflecting an energy-absorption mechanism dominated by low-order bending modes. The asymmetric curling of the rupture-disc petals is closely associated with stress-wave reflections and fluid–structure interaction induced by high-speed venting. The numerical simulation reproduces the crack-growth sequence, opening morphology, and stress distribution in good agreement with the experimental observations. The proposed integrated experimental-numerical approach provides a reliable mechanical basis and engineering guidance for optimizing the blast-resistant design of pressure relief devices for current transformers.
Current transformers are core components of power systems used for current measurement and relay protection. During long-term service under coupled multiphysical-field conditions, the internal insulation structure is susceptible to breakdown under locally intensified electric fields, triggering arc discharge in the insulating oil. The resulting oil cracking and rapid gas expansion produce a sharp rise in internal pressure. If this pressure is not relieved promptly, the resulting pressure surge may lead to combustion and explosion accidents. Therefore, the rapid-response capability of pressure relief devices under explosive loading is critical to the operational safety of current transformers. This study focuses on the expander–rupture disc pressure relief assembly of an LVB-220 current transformer and systematically investigates its dynamic mechanical behavior and failure mechanism under explosive impact loading. An equivalent hydrogen–air premixed-gas explosion test platform was constructed. The test system consisted of two stainless-steel flame-acceleration tubes with an inner diameter of 168.3 mm and a total length of
, Available online ,
doi: 10.11883/bzycj-2026-0132
Abstract:
Accurate sound velocity measurement under high pressure requires high-impedance window materials. However, no ideal candidates have been reported to date. In this study, the Hugoniot data and sound velocity of single-crystal lead fluoride (PbF2) in the pressure range from 64 GPa to 198 GPa were investigated by applying shock compression techniques and quantum molecular dynamics simulations. The theoretical simulation results of Hugoniot data and sound velocities are in excellent agreement with the experimental data. Along the Hugoniot curve, the sound velocities of liquid FbF2 increase linear with particle velocity. The signal from a displacement interferometer system for any reflector (DISAR) and simulation results confirm that PbF2 transforms into a liquid metal at 89.6 GPa, which enables efficient laser reflection at the shock front. Using a DISAR, both the shock wave velocity and the catch-up time of rarefaction waves can be accurately measured, providing critical technical support for the precise determination of sound velocity in materials under extremely high pressure. These superior properties, including high impedance, structural stability under high pressure, and pressure-induced metallization, enable PbF2 fully meet the core requirements for high-impedance standard windows.
Accurate sound velocity measurement under high pressure requires high-impedance window materials. However, no ideal candidates have been reported to date. In this study, the Hugoniot data and sound velocity of single-crystal lead fluoride (PbF2) in the pressure range from 64 GPa to 198 GPa were investigated by applying shock compression techniques and quantum molecular dynamics simulations. The theoretical simulation results of Hugoniot data and sound velocities are in excellent agreement with the experimental data. Along the Hugoniot curve, the sound velocities of liquid FbF2 increase linear with particle velocity. The signal from a displacement interferometer system for any reflector (DISAR) and simulation results confirm that PbF2 transforms into a liquid metal at 89.6 GPa, which enables efficient laser reflection at the shock front. Using a DISAR, both the shock wave velocity and the catch-up time of rarefaction waves can be accurately measured, providing critical technical support for the precise determination of sound velocity in materials under extremely high pressure. These superior properties, including high impedance, structural stability under high pressure, and pressure-induced metallization, enable PbF2 fully meet the core requirements for high-impedance standard windows.
, Available online ,
doi: 10.11883/bzycj-2025-0342
Abstract:
Efficiently achieving plane wave loading on the test specimen is a key technical issue in the design of blast wave simulators. Based on the existing device, testing data of large-scale shock tubes, and LS-DYNA software, numerical models of blast wave propagation in simulators were established. Numerical simulations were conducted to develop a safe, economical, and reusable blast wave simulator. A quantitative method for assessing the uniformity of overpressure load on the loading area was proposed. Numerical analyses were performed to investigate the influence of the shape and length of the expansion section and the length of the conditioning section on the uniformity of overpressure load on the loading area. Key structural parameters, including the wall thickness of the expansion and conditioning sections, as well as the spacing and height of the stiffeners, were numerically optimized. Validation tests were conducted on the blast wave simulator. It is found that the established numerical model can accurately reproduce the blast wave propagation, and the prediction results show good agreement with the testing data. Taking the errors of overpressure peak value and arrival time as indicators, the quantitative evaluation of overpressure load uniformity on the loading area is achieved. Considering the balance between technical and economic factors, the developed blast wave simulator is designed with a symmetrically configured expansion section 3 m in length. The length of the conditioning section can be extended as much as the actual investment allows. Based on the numerical results, the wall thickness of both the expansion and conditioning sections is determined to be 30 mm. The height and spacing of the stiffeners are both recommended to be 150 mm. The results of validation tests confirm that the geometric and structural design meets the requirements of blast loads and structural resistance, and the developed simulator is suitable for component-level tests.
Efficiently achieving plane wave loading on the test specimen is a key technical issue in the design of blast wave simulators. Based on the existing device, testing data of large-scale shock tubes, and LS-DYNA software, numerical models of blast wave propagation in simulators were established. Numerical simulations were conducted to develop a safe, economical, and reusable blast wave simulator. A quantitative method for assessing the uniformity of overpressure load on the loading area was proposed. Numerical analyses were performed to investigate the influence of the shape and length of the expansion section and the length of the conditioning section on the uniformity of overpressure load on the loading area. Key structural parameters, including the wall thickness of the expansion and conditioning sections, as well as the spacing and height of the stiffeners, were numerically optimized. Validation tests were conducted on the blast wave simulator. It is found that the established numerical model can accurately reproduce the blast wave propagation, and the prediction results show good agreement with the testing data. Taking the errors of overpressure peak value and arrival time as indicators, the quantitative evaluation of overpressure load uniformity on the loading area is achieved. Considering the balance between technical and economic factors, the developed blast wave simulator is designed with a symmetrically configured expansion section 3 m in length. The length of the conditioning section can be extended as much as the actual investment allows. Based on the numerical results, the wall thickness of both the expansion and conditioning sections is determined to be 30 mm. The height and spacing of the stiffeners are both recommended to be 150 mm. The results of validation tests confirm that the geometric and structural design meets the requirements of blast loads and structural resistance, and the developed simulator is suitable for component-level tests.
, Available online ,
doi: 10.11883/bzycj-2025-0355
Abstract:
The design of blast wave simulators for prototype or large-scale engineering structures and components must carefully balance safety, cost, and performance. To address this challenge, a blast wave simulator driven by methane–air deflagration was developed in this study. Numerical models of methane–air deflagration in large-scale tubes were established using the CFD software OpenFOAM and validated against experimental data. On the basis of the validated model, numerical simulations were performed to investigate the effects of gas cloud length, venting conditions, and obstacle configurations on overpressure loads, thereby revealing the mechanisms of blast wave and flame propagation in the methane–air deflagration-driven simulator. A testing scheme was subsequently proposed to generate different levels of blast loading. The results show that the developed numerical model can reasonably predict the overpressure time histories and spatial distributions of gas explosions in large-scale tubes. In the simulator, increasing the gas cloud volume and placing obstacles near the ignition zone of the driven section can significantly intensify the deflagration of methane–air mixtures. Moreover, side venting effectively separates the pressure wave from the flame, thereby preventing high-temperature effects in the loading area. An optimized loading configuration was proposed, in which four obstacles (1×50% blockage ratio and 3×25% blockage ratio, spaced at 3 m intervals) were arranged, and different blast load levels were achieved by varying the gas cloud length from 1.5 m to 6 m in the driven section. Trial tests of the developed simulator showed that the measured peak overpressures agree well with the numerical predictions, with deviations less than 12%, and the results exhibit good uniformity and high repeatability. These findings demonstrate that the proposed methane-air deflagration-driven blast wave simulator is suitable for blast testing of structural components such as reinforced concrete slabs.
The design of blast wave simulators for prototype or large-scale engineering structures and components must carefully balance safety, cost, and performance. To address this challenge, a blast wave simulator driven by methane–air deflagration was developed in this study. Numerical models of methane–air deflagration in large-scale tubes were established using the CFD software OpenFOAM and validated against experimental data. On the basis of the validated model, numerical simulations were performed to investigate the effects of gas cloud length, venting conditions, and obstacle configurations on overpressure loads, thereby revealing the mechanisms of blast wave and flame propagation in the methane–air deflagration-driven simulator. A testing scheme was subsequently proposed to generate different levels of blast loading. The results show that the developed numerical model can reasonably predict the overpressure time histories and spatial distributions of gas explosions in large-scale tubes. In the simulator, increasing the gas cloud volume and placing obstacles near the ignition zone of the driven section can significantly intensify the deflagration of methane–air mixtures. Moreover, side venting effectively separates the pressure wave from the flame, thereby preventing high-temperature effects in the loading area. An optimized loading configuration was proposed, in which four obstacles (1×50% blockage ratio and 3×25% blockage ratio, spaced at 3 m intervals) were arranged, and different blast load levels were achieved by varying the gas cloud length from 1.5 m to 6 m in the driven section. Trial tests of the developed simulator showed that the measured peak overpressures agree well with the numerical predictions, with deviations less than 12%, and the results exhibit good uniformity and high repeatability. These findings demonstrate that the proposed methane-air deflagration-driven blast wave simulator is suitable for blast testing of structural components such as reinforced concrete slabs.
, Available online ,
doi: 10.11883/bzycj-2025-0419
Abstract:
Addressing the high probability of injury and fatality associated with traditionalanti-riot kinetic energy projectiles represented by rubber bullets, a novel low-kinetic-energy frangible projectile with the characteristics of reliable shell fragmentation and the energy release of powder dispersion was designed based on the existing launch platforms of non-lethal weapons, aimed to improve the application safety of anti-riot kinetic energy projectiles. Through shooting tests on anthropomorphic dummy targets and ballistic gelatin targets, the dynamic impact responses of the two targets under the blunt impacts of frangible projectiles were obtained. In the dummy target tests, the frangible projectile achieved reliable fragmentation and exhibited a significant kinetic energy slow-release effect; the calculated injury assessment indicators for different parts of the dummy were all within the safety threshold. Comparative analyses with the blunt impact test results of rubber bullets show that this type of frangible projectile has significantly higher safety than rubber bullets while maintaining effective pain-inducing performance. In the ballistic gelatin target shooting tests, under the same projectile mass and impact velocity, the peak pressure generated in the gelatin measured by the internal sensor differed by approximately one order of magnitude between the frangible projectile and the rubber bullet. The test results show that the novel low-kinetic-energy frangible projectile can effectively attenuate the peak impact pressure of the projectile and greatly reduce its injury potential through the fragmentation of the projectile shell and the dispersion of the powder filled inside the projectile, which provides technical support for improving the application safety of anti-riot kinetic energy ammunition.
Addressing the high probability of injury and fatality associated with traditionalanti-riot kinetic energy projectiles represented by rubber bullets, a novel low-kinetic-energy frangible projectile with the characteristics of reliable shell fragmentation and the energy release of powder dispersion was designed based on the existing launch platforms of non-lethal weapons, aimed to improve the application safety of anti-riot kinetic energy projectiles. Through shooting tests on anthropomorphic dummy targets and ballistic gelatin targets, the dynamic impact responses of the two targets under the blunt impacts of frangible projectiles were obtained. In the dummy target tests, the frangible projectile achieved reliable fragmentation and exhibited a significant kinetic energy slow-release effect; the calculated injury assessment indicators for different parts of the dummy were all within the safety threshold. Comparative analyses with the blunt impact test results of rubber bullets show that this type of frangible projectile has significantly higher safety than rubber bullets while maintaining effective pain-inducing performance. In the ballistic gelatin target shooting tests, under the same projectile mass and impact velocity, the peak pressure generated in the gelatin measured by the internal sensor differed by approximately one order of magnitude between the frangible projectile and the rubber bullet. The test results show that the novel low-kinetic-energy frangible projectile can effectively attenuate the peak impact pressure of the projectile and greatly reduce its injury potential through the fragmentation of the projectile shell and the dispersion of the powder filled inside the projectile, which provides technical support for improving the application safety of anti-riot kinetic energy ammunition.
, Available online ,
doi: 10.11883/bzycj-2026-0035
Abstract:
Aiming at the problems of complex characteristics of blast load induced by fuel-rich explosives in confined spaces, as well as the high cost of high-precision solution and engineering application, a numerical calculation method for confined blast loading considering the afterburning effect was established. The method was verified for its reliability by comparing the calculated quasi-static pressure, impulse within the saturation response time and residual deformation of the target with the experimental results, with all relative errors controlled within 10%. The spatiotemporal distribution law of confined blast loading in confined spaces was systematically analyzed, and a simplified equivalent loading method considering both the saturation response time and quasi-static pressure was proposed. The reliability of the simplification method was validated by comparing the calculated first peak deformation and residual deformation at the central point with the results from fully coupled calculation, with all errors within 10%. Through an investigation into the spatial distribution form of the equivalent load and the influence of quasi-static pressure on structural response, the results show that within the scope of the current research, the spatial distribution of the equivalent load has a relatively minor effect on structural response, while the contribution of quasi-static pressure cannot be neglected. On the basis of the above findings, a two-stage load simplification model based on the load characteristics at the central point of the target plate was proposed. The reliability of the simplified model was confirmed by comparing the residual deformation values obtained from 10 groups of simplified model calculations with the experimental data, with all errors within 15%. The research results indicate that the proposed model exhibits good applicability under different working conditions; it can significantly improve the calculation efficiency while ensuring the calculation accuracy, and thus provides a technical approach for the simplified analysis of engineering problems related to confined space explosions.
Aiming at the problems of complex characteristics of blast load induced by fuel-rich explosives in confined spaces, as well as the high cost of high-precision solution and engineering application, a numerical calculation method for confined blast loading considering the afterburning effect was established. The method was verified for its reliability by comparing the calculated quasi-static pressure, impulse within the saturation response time and residual deformation of the target with the experimental results, with all relative errors controlled within 10%. The spatiotemporal distribution law of confined blast loading in confined spaces was systematically analyzed, and a simplified equivalent loading method considering both the saturation response time and quasi-static pressure was proposed. The reliability of the simplification method was validated by comparing the calculated first peak deformation and residual deformation at the central point with the results from fully coupled calculation, with all errors within 10%. Through an investigation into the spatial distribution form of the equivalent load and the influence of quasi-static pressure on structural response, the results show that within the scope of the current research, the spatial distribution of the equivalent load has a relatively minor effect on structural response, while the contribution of quasi-static pressure cannot be neglected. On the basis of the above findings, a two-stage load simplification model based on the load characteristics at the central point of the target plate was proposed. The reliability of the simplified model was confirmed by comparing the residual deformation values obtained from 10 groups of simplified model calculations with the experimental data, with all errors within 15%. The research results indicate that the proposed model exhibits good applicability under different working conditions; it can significantly improve the calculation efficiency while ensuring the calculation accuracy, and thus provides a technical approach for the simplified analysis of engineering problems related to confined space explosions.
, Available online ,
doi: 10.11883/bzycj-2026-0056
Abstract:
To clarify the ultimate load-bearing capacity characteristics of prestressed concrete T-girder bridges under typical blast loads and address the technical difficulties in the residual load-bearing capacity evaluation of blast-damaged bridge structures, a two-stage test method combining blast damage test and post-blast static loading test is adopted in this study. A full-scale (1:1) prestressed concrete T-girder bridge specimen consistent with practical engineering structural parameters is taken as the test object to carry out large-equivalent field blast tests. Multi-stage graded static loading tests are further implemented on the blast-damaged specimen to obtain structural damage evolution features and deflection response data under post-blast service conditions. Based on the measured damage morphologies, deformation data and mechanical response laws acquired from physical tests, a refined three-dimensional finite element (FE) numerical simulation model for prestressed concrete T-girder bridges is established. Key structural characteristics including concrete and reinforcement strain-rate effects, material nonlinearity, prestress loss and structural contact interaction are fully considered in model establishment. The accuracy and reliability of the numerical model are validated through comparative calibration with experimental results. The validated model is subsequently employed to quantitatively investigate the ultimate load-bearing performance of bridges under three typical blast working conditions, including deck central contact blast, combined blast of deck central explosion and inter-girder internal explosion, and bilateral inter-girder internal explosion. The research results demonstrate distinct structural damage and bearing degradation characteristics under different blast scenarios. Contact blast acting on the bridge deck mainly induces local slab perforation failure and concentrated plastic deformation of deck concrete. For internal explosion occurring between main girders, structural damage presents a more severe and extensive pattern. In addition to concrete spalling and fragmentation on the bottom surface of the bridge deck, obvious outward bulging deformation, concrete crushing and local collapse failure occur on the webs and transverse diaphragms of T-girders. Among the three typical blast damage states, the combined blast condition with deck central explosion followed by secondary inter-girder explosion causes the most significant degradation of structural ultimate load-bearing capacity due to the superimposed synergistic damage effect. Reasonable optimization of live load layout effectively avoids severe damage areas of blast-affected bridges, eliminates the adverse influence of blast-induced structural defects, and achieves a remarkable improvement in the ultimate load-bearing capacity of damaged bridges. An integrated evaluation system covering the whole process from blast damage characterization to ultimate load-bearing capacity quantification is established in this research. The proposed evaluation method provides a systematic theoretical basis and feasible technical support for residual load-bearing capacity assessment, damage prediction and blast-resistant reinforcement design of prestressed concrete T-girder bridges suffering blast loads.
To clarify the ultimate load-bearing capacity characteristics of prestressed concrete T-girder bridges under typical blast loads and address the technical difficulties in the residual load-bearing capacity evaluation of blast-damaged bridge structures, a two-stage test method combining blast damage test and post-blast static loading test is adopted in this study. A full-scale (1:1) prestressed concrete T-girder bridge specimen consistent with practical engineering structural parameters is taken as the test object to carry out large-equivalent field blast tests. Multi-stage graded static loading tests are further implemented on the blast-damaged specimen to obtain structural damage evolution features and deflection response data under post-blast service conditions. Based on the measured damage morphologies, deformation data and mechanical response laws acquired from physical tests, a refined three-dimensional finite element (FE) numerical simulation model for prestressed concrete T-girder bridges is established. Key structural characteristics including concrete and reinforcement strain-rate effects, material nonlinearity, prestress loss and structural contact interaction are fully considered in model establishment. The accuracy and reliability of the numerical model are validated through comparative calibration with experimental results. The validated model is subsequently employed to quantitatively investigate the ultimate load-bearing performance of bridges under three typical blast working conditions, including deck central contact blast, combined blast of deck central explosion and inter-girder internal explosion, and bilateral inter-girder internal explosion. The research results demonstrate distinct structural damage and bearing degradation characteristics under different blast scenarios. Contact blast acting on the bridge deck mainly induces local slab perforation failure and concentrated plastic deformation of deck concrete. For internal explosion occurring between main girders, structural damage presents a more severe and extensive pattern. In addition to concrete spalling and fragmentation on the bottom surface of the bridge deck, obvious outward bulging deformation, concrete crushing and local collapse failure occur on the webs and transverse diaphragms of T-girders. Among the three typical blast damage states, the combined blast condition with deck central explosion followed by secondary inter-girder explosion causes the most significant degradation of structural ultimate load-bearing capacity due to the superimposed synergistic damage effect. Reasonable optimization of live load layout effectively avoids severe damage areas of blast-affected bridges, eliminates the adverse influence of blast-induced structural defects, and achieves a remarkable improvement in the ultimate load-bearing capacity of damaged bridges. An integrated evaluation system covering the whole process from blast damage characterization to ultimate load-bearing capacity quantification is established in this research. The proposed evaluation method provides a systematic theoretical basis and feasible technical support for residual load-bearing capacity assessment, damage prediction and blast-resistant reinforcement design of prestressed concrete T-girder bridges suffering blast loads.
, Available online ,
doi: 10.11883/bzycj-2026-0054
Abstract:
Impact fatigue refers to the phenomenon in which materials or structures, subjected to repeated impact loading, experience localized stress concentrations and rapid strain accumulation, leading to the initiation of internal micro-damage and ultimately the fracture failure. Impact fatigue loads are characterized by their short duration, rapid loading rates and significantly elevated strain-rates, which has greater threat than conventional fatigue. The wheel-rail dynamic contact forces of high-speed trains exhibit typical characteristics of impact fatigue loading, which induces the accumulation of impact fatigue damage, accelerates the deterioration of material’s mechanical properties; and consequently, compromises the operational safety of high-speed trains. The present study integrates a material-based impact fatigue damage-coupled constitutive model to develop a comprehensive three-dimensional wheel-rail rolling contact finite element model. The stress-strain states and adhesion-slip characteristics of wheel-rail rolling/sliding contact are clarified, and the distribution features and accumulation evolution of wheel-rail impact fatigue damage are analyzed. Meanwhile, the effects of train speed, friction coefficient, and traction coefficient on impact fatigue damage are studied, and the influence of material constitutive model on typical wheel-rail contact mechanical behavior is examined. The results clearly indicate that the proposed impact fatigue model is able to well represent the wheel-rail contact responses, adhesion-slip distribution characteristics and damage accumulation. Under repeated rolling contact, the impact fatigue damage of the rail exhibits a nonlinear cumulative increasing trend with the increase of rolling cycles; however, the growth rate gradually decreases and eventually tends to stabilize approximately. Compared with the elastoplastic constitutive model, the wheel-rail contact mechanical responses predicted by the impact fatigue constitutive model are more severe and dangerous. Moreover, the coupling effect of impact fatigue damage gradually intensifies with the increase of wheel passages. These findings provide valuable theoretical insights and technical support for fatigue damage assessment and life prediction of high-speed wheel-rail systems.
Impact fatigue refers to the phenomenon in which materials or structures, subjected to repeated impact loading, experience localized stress concentrations and rapid strain accumulation, leading to the initiation of internal micro-damage and ultimately the fracture failure. Impact fatigue loads are characterized by their short duration, rapid loading rates and significantly elevated strain-rates, which has greater threat than conventional fatigue. The wheel-rail dynamic contact forces of high-speed trains exhibit typical characteristics of impact fatigue loading, which induces the accumulation of impact fatigue damage, accelerates the deterioration of material’s mechanical properties; and consequently, compromises the operational safety of high-speed trains. The present study integrates a material-based impact fatigue damage-coupled constitutive model to develop a comprehensive three-dimensional wheel-rail rolling contact finite element model. The stress-strain states and adhesion-slip characteristics of wheel-rail rolling/sliding contact are clarified, and the distribution features and accumulation evolution of wheel-rail impact fatigue damage are analyzed. Meanwhile, the effects of train speed, friction coefficient, and traction coefficient on impact fatigue damage are studied, and the influence of material constitutive model on typical wheel-rail contact mechanical behavior is examined. The results clearly indicate that the proposed impact fatigue model is able to well represent the wheel-rail contact responses, adhesion-slip distribution characteristics and damage accumulation. Under repeated rolling contact, the impact fatigue damage of the rail exhibits a nonlinear cumulative increasing trend with the increase of rolling cycles; however, the growth rate gradually decreases and eventually tends to stabilize approximately. Compared with the elastoplastic constitutive model, the wheel-rail contact mechanical responses predicted by the impact fatigue constitutive model are more severe and dangerous. Moreover, the coupling effect of impact fatigue damage gradually intensifies with the increase of wheel passages. These findings provide valuable theoretical insights and technical support for fatigue damage assessment and life prediction of high-speed wheel-rail systems.
, Available online ,
doi: 10.11883/bzycj-2025-0348
Abstract:
The present investigation examines the effectiveness of a composite cushion charging structure, placed at the bottom of underwater boreholes, to mitigate bedrock damage induced by blasting excavation during cross-sea engineering. With reference to the embedded open caisson blasting project for a major cross-sea bridge, this research adopted a combined methodology of field sampling and controlled underwater explosion model tests. A piezoelectric ceramic detection system was employed to quantitatively analyze how the composite cushion, composed of iron-sand concrete layers with varying wave impedances, affects rock sample damage. Piezoelectric signals were processed via wavelet packet analysis to calculate the axial damage factor (DI) of the blast hole. Furthermore, by integrating fractal dimension theory with damage mechanics, a quantitative assessment was performed on the propagation behavior of cracks formed on the top surfaces of rock specimens under different test conditions. Results demonstrate that the implemented composite bottom cushion effectively mitigates blast-induced damage by significantly inhibiting macroscopic crack propagation, reducing surface crack density, and decreasing the axial penetration depth of cracks into the rock mass. Detailed analysis of axial damage reveals a clear trend, showing that the reduction in DI becomes more pronounced as the wave impedance of the cushion material increases. Specifically, within the borehole-affected zone (0–12 cm), the maximum achievable reduction in DI reaches 10.70%. In the adjacent bedrock zone, damage mitigation is even more evident, with DI decreasing by 95.7% to 95.8%, depending on the specific wave impedance. In conclusion, this work confirms that employing a composite cushion charging structure in underwater drilling and blasting operations can significantly alleviate blast-induced damage to foundational bedrock. The findings also establish that axial damage to the rock mass can be effectively controlled by adjusting the wave impedance of the iron-sand concrete in the cushion layer. These outcomes offer valuable insights for optimizing blasting design and enhancing damage control in marine engineering projects.
The present investigation examines the effectiveness of a composite cushion charging structure, placed at the bottom of underwater boreholes, to mitigate bedrock damage induced by blasting excavation during cross-sea engineering. With reference to the embedded open caisson blasting project for a major cross-sea bridge, this research adopted a combined methodology of field sampling and controlled underwater explosion model tests. A piezoelectric ceramic detection system was employed to quantitatively analyze how the composite cushion, composed of iron-sand concrete layers with varying wave impedances, affects rock sample damage. Piezoelectric signals were processed via wavelet packet analysis to calculate the axial damage factor (DI) of the blast hole. Furthermore, by integrating fractal dimension theory with damage mechanics, a quantitative assessment was performed on the propagation behavior of cracks formed on the top surfaces of rock specimens under different test conditions. Results demonstrate that the implemented composite bottom cushion effectively mitigates blast-induced damage by significantly inhibiting macroscopic crack propagation, reducing surface crack density, and decreasing the axial penetration depth of cracks into the rock mass. Detailed analysis of axial damage reveals a clear trend, showing that the reduction in DI becomes more pronounced as the wave impedance of the cushion material increases. Specifically, within the borehole-affected zone (0–12 cm), the maximum achievable reduction in DI reaches 10.70%. In the adjacent bedrock zone, damage mitigation is even more evident, with DI decreasing by 95.7% to 95.8%, depending on the specific wave impedance. In conclusion, this work confirms that employing a composite cushion charging structure in underwater drilling and blasting operations can significantly alleviate blast-induced damage to foundational bedrock. The findings also establish that axial damage to the rock mass can be effectively controlled by adjusting the wave impedance of the iron-sand concrete in the cushion layer. These outcomes offer valuable insights for optimizing blasting design and enhancing damage control in marine engineering projects.
, Available online ,
doi: 10.11883/bzycj-2025-0401
Abstract:
Coupling coefficients and stemming coefficients are essential for predicting ground shock magnitude and damage zones from underground explosions, yet their variation with burial depth and dependence on media and explosion types remain insufficiently compared. Experimental and theoretical methods for determining these coefficients in concrete, rock, and soil under both chemical and nuclear explosions were systematically reviewed. Based on collected data from published tests, definitions of different coupling coefficients (energy coupling, ground shock parameter coupling, equivalent yield, and stemming coefficients) were clarified, and conversion relationships among them were derived using energy conservation and wave attenuation principles. The critical burial depth for full coupling was analyzed separately for peak quantities (e.g., peak stress, particle velocity) and integral quantities (e.g., impulse, surface vibration). Experimental results show that peak quantities reach full coupling at a depth approximately equal to the contained explosion cavity radius, which is much shallower than the critical depth for contained explosions. In contrast, impulse and ground motion require depths close to the contained explosion threshold. The coupling energy is proportional to the volume of the damaged zone, and the evolution of coupling coefficients with scaled depth of burial follows a Boltzmann function, requiring only two parameters to define the entire curve. For chemical explosions, the fully coupled equivalent yield coefficient (relative to contained explosions) in concrete, limestone, and soils was quantified, with stemming coefficients ranging from 1.4~1.8 in rocks and 2.4~2.6 in soils. It is concluded that different ground shock parameters exhibit distinct coupling behaviors, challenging the assumption of a universal coupling coefficient. Proposed empirical formulas provide conservative estimates for engineering design, while the underlying mechanisms of free-surface unloading require further quantitative investigation.
Coupling coefficients and stemming coefficients are essential for predicting ground shock magnitude and damage zones from underground explosions, yet their variation with burial depth and dependence on media and explosion types remain insufficiently compared. Experimental and theoretical methods for determining these coefficients in concrete, rock, and soil under both chemical and nuclear explosions were systematically reviewed. Based on collected data from published tests, definitions of different coupling coefficients (energy coupling, ground shock parameter coupling, equivalent yield, and stemming coefficients) were clarified, and conversion relationships among them were derived using energy conservation and wave attenuation principles. The critical burial depth for full coupling was analyzed separately for peak quantities (e.g., peak stress, particle velocity) and integral quantities (e.g., impulse, surface vibration). Experimental results show that peak quantities reach full coupling at a depth approximately equal to the contained explosion cavity radius, which is much shallower than the critical depth for contained explosions. In contrast, impulse and ground motion require depths close to the contained explosion threshold. The coupling energy is proportional to the volume of the damaged zone, and the evolution of coupling coefficients with scaled depth of burial follows a Boltzmann function, requiring only two parameters to define the entire curve. For chemical explosions, the fully coupled equivalent yield coefficient (relative to contained explosions) in concrete, limestone, and soils was quantified, with stemming coefficients ranging from 1.4~1.8 in rocks and 2.4~2.6 in soils. It is concluded that different ground shock parameters exhibit distinct coupling behaviors, challenging the assumption of a universal coupling coefficient. Proposed empirical formulas provide conservative estimates for engineering design, while the underlying mechanisms of free-surface unloading require further quantitative investigation.
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2026, 46(10): 101001.
doi: 10.11883/bzycj-2025-0133
Abstract:
In order to quantitatively evaluate the overload stability of charge with defects, by adjusting the material and thickness of the waveform modulator, the waveform, amplitude, and pulse width of the loading signal were precisely controlled, based on the overload environmental force experimental device, the eigenvalues of charge load with different defects were measured, which can take into account the high overload pressure and wide pulse at the same time. The response degree of the charges under investigation was quantitatively characterized based on the burn marks, damage level, and mechanical fitting performance of the witness plates, grayscale numerical processing was applied to the surface images of the recovered witness plates after testing, the influence of the experimental system on the eigenvalues of charge load was quantified, and the correlation mechanism between charge response behavior and image grayscale was established. Based on clustering analysis, the primary stimulating factors affecting the stability of the charges, including defect diameter, flyer thickness, and the material and thickness of the waveform modulator, were classified, the corresponding conversion factors of the test device were introduced, the evaluation model of overload stability of defective charge was constructed, and the response critical pressure thresholds of different defective charges were predicted. The results indicate that the overload peak value greater than 1 GPa and high-impact pulse width greater than 100 μs can be achieved. With the increase of defect diameter, the response level of loading response increases significantly. The critical pressure of combustion reaction decreases from 0.71 GPa to 0.26 GPa with the increase of charge defect diameter from 0 mm to 12 mm. When the defect diameter of the charge reaches 10 mm, the critical pressure of deflagration reaction is 1.56 GPa. With the increase of defect diameter, the critical pressure of deflagration reaction decreases to 1.25 GPa when the defect is\begin{document}$\varnothing $\end{document}
In order to quantitatively evaluate the overload stability of charge with defects, by adjusting the material and thickness of the waveform modulator, the waveform, amplitude, and pulse width of the loading signal were precisely controlled, based on the overload environmental force experimental device, the eigenvalues of charge load with different defects were measured, which can take into account the high overload pressure and wide pulse at the same time. The response degree of the charges under investigation was quantitatively characterized based on the burn marks, damage level, and mechanical fitting performance of the witness plates, grayscale numerical processing was applied to the surface images of the recovered witness plates after testing, the influence of the experimental system on the eigenvalues of charge load was quantified, and the correlation mechanism between charge response behavior and image grayscale was established. Based on clustering analysis, the primary stimulating factors affecting the stability of the charges, including defect diameter, flyer thickness, and the material and thickness of the waveform modulator, were classified, the corresponding conversion factors of the test device were introduced, the evaluation model of overload stability of defective charge was constructed, and the response critical pressure thresholds of different defective charges were predicted. The results indicate that the overload peak value greater than 1 GPa and high-impact pulse width greater than 100 μs can be achieved. With the increase of defect diameter, the response level of loading response increases significantly. The critical pressure of combustion reaction decreases from 0.71 GPa to 0.26 GPa with the increase of charge defect diameter from 0 mm to 12 mm. When the defect diameter of the charge reaches 10 mm, the critical pressure of deflagration reaction is 1.56 GPa. With the increase of defect diameter, the critical pressure of deflagration reaction decreases to 1.25 GPa when the defect is
2026, 46(10): 101101.
doi: 10.11883/bzycj-2025-0352
Abstract:
During service, numerous structural metals in nuclear reactors are subjected to high-energy particle irradiation under prestressed conditions and may also experience unpredictable impact loads. These conditions can lead to significant degradation of the mechanical properties of structural metals, including irradiation hardening, irradiation embrittlement, irradiation swelling, and irradiation creep, thereby reducing reactor safety and reliability. However, existing studies have predominantly focused on the effects of either irradiation or impact loading on the mechanical properties and deformation mechanisms of metals. A limited number of studies have investigated the degradation behavior of irradiated metals under dynamic loading, whereas the coupled effect of prestress, which is a typical reactor service condition, has been considered even less frequently. The current status of experimental research on the hardening and embrittlement behavior and underlying micromechanisms of metals subjected to the coupled effects of irradiation, prestress, and impact loading is reviewed and summarized. Shortcomings and major challenges in current research are identified, and perspectives and recommendations are proposed regarding the key scientific issues requiring further attention and the critical technological bottlenecks that must be overcome in future studies. Specifically, the following issues should be addressed: (1) the necessity and sufficiency of the causal relationship between dislocation channels and irradiation-induced hardening and embrittlement mechanisms require thorough investigation; (2) equivalent dose-rate assessment methods for metal hardening and embrittlement induced by different irradiation particle sources need to be strengthened; (3) the hardening and embrittlement mechanisms of structural metals in nuclear reactors under prestress and neutron irradiation conditions require further investigation; and (4) research on the impact behavior of prestressed and neutron-irradiated metals urgently needs to be initiated, while safe and efficient experimental techniques for characterizing the dynamic properties of neutron-irradiated metals must be developed immediately. This review is expected to provide a scientific basis and research methodology for future investigations into the hardening and embrittlement behavior and mechanisms of metals under irradiation-prestress conditions, as required in major national projects such as nuclear reactor life extension and the development of advanced reactors.
During service, numerous structural metals in nuclear reactors are subjected to high-energy particle irradiation under prestressed conditions and may also experience unpredictable impact loads. These conditions can lead to significant degradation of the mechanical properties of structural metals, including irradiation hardening, irradiation embrittlement, irradiation swelling, and irradiation creep, thereby reducing reactor safety and reliability. However, existing studies have predominantly focused on the effects of either irradiation or impact loading on the mechanical properties and deformation mechanisms of metals. A limited number of studies have investigated the degradation behavior of irradiated metals under dynamic loading, whereas the coupled effect of prestress, which is a typical reactor service condition, has been considered even less frequently. The current status of experimental research on the hardening and embrittlement behavior and underlying micromechanisms of metals subjected to the coupled effects of irradiation, prestress, and impact loading is reviewed and summarized. Shortcomings and major challenges in current research are identified, and perspectives and recommendations are proposed regarding the key scientific issues requiring further attention and the critical technological bottlenecks that must be overcome in future studies. Specifically, the following issues should be addressed: (1) the necessity and sufficiency of the causal relationship between dislocation channels and irradiation-induced hardening and embrittlement mechanisms require thorough investigation; (2) equivalent dose-rate assessment methods for metal hardening and embrittlement induced by different irradiation particle sources need to be strengthened; (3) the hardening and embrittlement mechanisms of structural metals in nuclear reactors under prestress and neutron irradiation conditions require further investigation; and (4) research on the impact behavior of prestressed and neutron-irradiated metals urgently needs to be initiated, while safe and efficient experimental techniques for characterizing the dynamic properties of neutron-irradiated metals must be developed immediately. This review is expected to provide a scientific basis and research methodology for future investigations into the hardening and embrittlement behavior and mechanisms of metals under irradiation-prestress conditions, as required in major national projects such as nuclear reactor life extension and the development of advanced reactors.
2026, 46(10): 101501.
doi: 10.11883/bzycj-2025-0327
Abstract:
Through spatial arrangement of different microstructures, well-designed hybrid lattice structures exhibit enhanced mechanical properties compared with uniform lattice structures composed of a single unit cell, thereby serving as a promising strategy for lightweight lattice structure design. However, current microstructure design approaches for hybrid lattices primarily focus on improving quasi-static compressive mechanical performance. In reality, engineering protection often involves complex dynamic impact environments rather than simple quasi-static loads. However, research on the microstructural design of hybrid lattices under high strain rate impact loading remains limited. This is due to the significant influence of inertial effects on dynamic structural mechanical response, which complicates multi-objective optimization. A fourth-order hybrid orthogonal isotropic lattice structure was constructed using two types of rhombic dodecahedron (RD) unit cells with different relative densities. A bidirectional long short-term memory (Bi-LSTM) network was employed to develop a predictive model that expanded the dataset of stress-strain curves obtained from finite element simulations. The reliability of the model’s predictions was validated through multi-dimensional evaluation metrics based on the predicted stress points along the stress–strain curves. The coefficient of determination (R2) of the predicted results reached 0.971 and 0.990 under dynamic and quasi-static compression, respectively. Specific energy absorption (SEA) was adopted as an indicator for evaluating energy absorption capacity based on the accurately predicted stress-strain curves. The structural effects on the energy absorption behavior of the hybrid lattice were analyzed under quasi-static planar compression. By increasing the compression speed to 100 m/s to simulate high strain rate conditions, the role of inertial effects on the dynamic mechanical response was investigated through comparative analysis. Furthermore, the competition and synergy between inertial effects and structural effects were systematically analyzed by categorizing the hybrid lattices according to the degree of unit cell mixing. The results indicate that inertial effects become dominant under high strain rate loading, while structural effects govern the response under quasi-static conditions. By using machine learning to efficiently expand the data scale of finite element simulations, the internal relationships among inertial effects, unit cell proportion, and spatial arrangement under high strain rate conditions were revealed. The findings provide valuable insights for the application of hybrid lattice structures in impact protection and related engineering fields.
Through spatial arrangement of different microstructures, well-designed hybrid lattice structures exhibit enhanced mechanical properties compared with uniform lattice structures composed of a single unit cell, thereby serving as a promising strategy for lightweight lattice structure design. However, current microstructure design approaches for hybrid lattices primarily focus on improving quasi-static compressive mechanical performance. In reality, engineering protection often involves complex dynamic impact environments rather than simple quasi-static loads. However, research on the microstructural design of hybrid lattices under high strain rate impact loading remains limited. This is due to the significant influence of inertial effects on dynamic structural mechanical response, which complicates multi-objective optimization. A fourth-order hybrid orthogonal isotropic lattice structure was constructed using two types of rhombic dodecahedron (RD) unit cells with different relative densities. A bidirectional long short-term memory (Bi-LSTM) network was employed to develop a predictive model that expanded the dataset of stress-strain curves obtained from finite element simulations. The reliability of the model’s predictions was validated through multi-dimensional evaluation metrics based on the predicted stress points along the stress–strain curves. The coefficient of determination (R2) of the predicted results reached 0.971 and 0.990 under dynamic and quasi-static compression, respectively. Specific energy absorption (SEA) was adopted as an indicator for evaluating energy absorption capacity based on the accurately predicted stress-strain curves. The structural effects on the energy absorption behavior of the hybrid lattice were analyzed under quasi-static planar compression. By increasing the compression speed to 100 m/s to simulate high strain rate conditions, the role of inertial effects on the dynamic mechanical response was investigated through comparative analysis. Furthermore, the competition and synergy between inertial effects and structural effects were systematically analyzed by categorizing the hybrid lattices according to the degree of unit cell mixing. The results indicate that inertial effects become dominant under high strain rate loading, while structural effects govern the response under quasi-static conditions. By using machine learning to efficiently expand the data scale of finite element simulations, the internal relationships among inertial effects, unit cell proportion, and spatial arrangement under high strain rate conditions were revealed. The findings provide valuable insights for the application of hybrid lattice structures in impact protection and related engineering fields.
2026, 46(10): 102201.
doi: 10.11883/bzycj-2025-0358
Abstract:
Pathological detonation is a non-ideal detonation that cannot effectively support the propagation of detonation waves due to other physical or chemical factors offsetting part of the chemical heat release. It is common in the practical processes, and the study on propagation stability of the detonation is of great significance. A single-step global reaction model was adopted to analyze the propagation stability of pathological detonation waves. Reduction of the reactant molar quantity decreased the overall system volume, introducing a negative-work effect that enables the pathological detonation regime. The process was numerically simulated using the one-dimensional reactive Euler equations, which couples chemical energy release with flow-field dynamics. A high-order finite difference method combined with a high-resolution flux-splitting scheme ensured accurate resolution of shock fronts and detailed reaction-zone structures. Parametric variations in piston-driven speed and activation energy were introduced to represent the effects of external mechanical forcing and intrinsic chemical reactivity, respectively. Comparative analyses of temporal evolution across parameter sets revealed the coupling mechanism between piston-driven flow dynamics and chemical kinetics. Further examination of the spatiotemporal distributions of temperature, pressure, and reactant mass fraction elucidated the link between detonation stability and the internal structural evolution of the reaction zone. The effects of piston-driven speed and activation energy on the stability of pathological detonation wave are systematically investigated, and the relationship between the stability of detonation wave and the reaction zone structure is analyzed. The results show that the pathological detonation is more unstable than the ideal detonation wave under the same reaction exothermic conditions. The increase of piston-driven speed is beneficial to the stability of the pathological detonation wave, while the increase of activation energy can lead to the instability of the pathological detonation wave. The high-frequency and low-amplitude oscillation of overdriven pathological detonation has little change in the structure of the reaction zone; the low-frequency and low-amplitude oscillation of detonation wave under the condition of strong solution is caused by the alternation of two configurations of strong solution in the reaction zone. The low-frequency and high-amplitude oscillation characteristics of overdriven pathological detonation are characterized by the alternating occurrence of reaction zone structures such as weak solution, strong solution and overdriven solution.
Pathological detonation is a non-ideal detonation that cannot effectively support the propagation of detonation waves due to other physical or chemical factors offsetting part of the chemical heat release. It is common in the practical processes, and the study on propagation stability of the detonation is of great significance. A single-step global reaction model was adopted to analyze the propagation stability of pathological detonation waves. Reduction of the reactant molar quantity decreased the overall system volume, introducing a negative-work effect that enables the pathological detonation regime. The process was numerically simulated using the one-dimensional reactive Euler equations, which couples chemical energy release with flow-field dynamics. A high-order finite difference method combined with a high-resolution flux-splitting scheme ensured accurate resolution of shock fronts and detailed reaction-zone structures. Parametric variations in piston-driven speed and activation energy were introduced to represent the effects of external mechanical forcing and intrinsic chemical reactivity, respectively. Comparative analyses of temporal evolution across parameter sets revealed the coupling mechanism between piston-driven flow dynamics and chemical kinetics. Further examination of the spatiotemporal distributions of temperature, pressure, and reactant mass fraction elucidated the link between detonation stability and the internal structural evolution of the reaction zone. The effects of piston-driven speed and activation energy on the stability of pathological detonation wave are systematically investigated, and the relationship between the stability of detonation wave and the reaction zone structure is analyzed. The results show that the pathological detonation is more unstable than the ideal detonation wave under the same reaction exothermic conditions. The increase of piston-driven speed is beneficial to the stability of the pathological detonation wave, while the increase of activation energy can lead to the instability of the pathological detonation wave. The high-frequency and low-amplitude oscillation of overdriven pathological detonation has little change in the structure of the reaction zone; the low-frequency and low-amplitude oscillation of detonation wave under the condition of strong solution is caused by the alternation of two configurations of strong solution in the reaction zone. The low-frequency and high-amplitude oscillation characteristics of overdriven pathological detonation are characterized by the alternating occurrence of reaction zone structures such as weak solution, strong solution and overdriven solution.
2026, 46(10): 102301.
doi: 10.11883/bzycj-2025-0336
Abstract:
To explore the feasibility of nano aluminum thermite as a detonator substitute for achieving stable detonation in mixed biomass blasting agent systems, and to clarify the differences in detonation effects relative to detonators, digital electronic detonators (S0), Al/CuO thermite (S1), and Al/Bi2O3 thermite (S2) were selected to detonate a mixed biomass blasting agent composed of wood powder and peanut shell powder (mass ratio 1∶1). Based on theoretical analysis, qualitative analysis and quantitative calculation were conducted for the total energy release and energy release power of different detonation methods to estimate detonation performance. Industrial explosive performance testing methods-including aluminum thermite detonation test, orthogonal tests of detonation velocity and intensity, underwater explosion tests, and blasting funnel tests-were used to systematically test and compare the detonation response characteristics of the mixed biomass blasting agent under different detonation conditions. The evolutionary laws of the explosive performance were explored from perspectives of impact effect, energy release intensity, and spatial damage effect. Results indicate that detonators and thermites belong to two distinct energy release power level systems: detonators enable instantaneous power output in the MW range, while thermites only reach the kW range. Aluminum thermite detonation is a typical high-temperature explosive energy release process with high energy density, which can achieve effective energy coupling under limited constraints and possesses reliable detonation capability. Oxygen pressure is the dominant factor affecting detonation velocity and intensity, followed by steel pipe wall thickness. The impact of detonation methods is relatively weak, and detonation methods are substitutable. Synergistic enhancement of detonation velocity and intensity can be achieved by increasing oxygen pressure and optimizing constraint conditions. The excitation efficiency of the three detonation methods follows a consistent ranking: S0 is the strongest, S2 ranks second, and S1 is slightly weaker. This ranking has been verified by shock wave parameters and crater volumes (0.33, 0.24, 0.21 m3). This research provides experimental support for the optimization and application of biomass blasting technology.
To explore the feasibility of nano aluminum thermite as a detonator substitute for achieving stable detonation in mixed biomass blasting agent systems, and to clarify the differences in detonation effects relative to detonators, digital electronic detonators (S0), Al/CuO thermite (S1), and Al/Bi2O3 thermite (S2) were selected to detonate a mixed biomass blasting agent composed of wood powder and peanut shell powder (mass ratio 1∶1). Based on theoretical analysis, qualitative analysis and quantitative calculation were conducted for the total energy release and energy release power of different detonation methods to estimate detonation performance. Industrial explosive performance testing methods-including aluminum thermite detonation test, orthogonal tests of detonation velocity and intensity, underwater explosion tests, and blasting funnel tests-were used to systematically test and compare the detonation response characteristics of the mixed biomass blasting agent under different detonation conditions. The evolutionary laws of the explosive performance were explored from perspectives of impact effect, energy release intensity, and spatial damage effect. Results indicate that detonators and thermites belong to two distinct energy release power level systems: detonators enable instantaneous power output in the MW range, while thermites only reach the kW range. Aluminum thermite detonation is a typical high-temperature explosive energy release process with high energy density, which can achieve effective energy coupling under limited constraints and possesses reliable detonation capability. Oxygen pressure is the dominant factor affecting detonation velocity and intensity, followed by steel pipe wall thickness. The impact of detonation methods is relatively weak, and detonation methods are substitutable. Synergistic enhancement of detonation velocity and intensity can be achieved by increasing oxygen pressure and optimizing constraint conditions. The excitation efficiency of the three detonation methods follows a consistent ranking: S0 is the strongest, S2 ranks second, and S1 is slightly weaker. This ranking has been verified by shock wave parameters and crater volumes (0.33, 0.24, 0.21 m3). This research provides experimental support for the optimization and application of biomass blasting technology.
2026, 46(10): 103101.
doi: 10.11883/bzycj-2025-0351
Abstract:
Ti/steel clad plates are considered as ideal candidate materials for applications such as marine engineering and low-temperature pressure vessels operating at −70 ℃. However, their large-scale production and application are severely restricted by the manufacturing process and the quality of interfacial bonding. To investigate the influence mechanism of vacuum pressure on interfacial morphology and mechanical properties, TC4/09MnNiDR (Ti/steel) clad plates were fabricated using explosive welding under ambient pressures of 20, 60, and 100 kPa, and the fabricated clad plates were named as CP-20, CP-60 and CP-100, respectively. A specially designed vacuum chamber was employed to precisely control the environmental pressure during the explosive process. After welding, all specimens were subjected to a uniform stress-relief annealing treatment at 550 ℃ for 2 h under a vacuum atmosphere to eliminate residual stresses and improve the reliability of subsequent characterization. The interfacial microstructure and chemical characteristics were systematically analyzed using multiple characterization techniques. Scanning electron microscopy (SEM) was used to observe interfacial morphology, including wave formation and defect distribution. Energy dispersive spectroscopy (EDS) was applied to examine elemental distribution across the bonding interface. Electron backscatter diffraction (EBSD) was employed to evaluate grain structure, grain boundary characteristics, recrystallization fraction, and texture evolution near the interface. Electron probe microanalysis (EPMA) was conducted to quantitatively determine the chemical composition of the interfacial melting zone and vortex regions, with both mapping and point analyses performed to identify the constituent phases. Mechanical properties at −70 ℃ were evaluated through tensile tests, Charpy impact tests, and three-point bending tests, all carried out in accordance with relevant national standards, with the results reported as mean values ± standard deviations. Results show that the vacuum environment significantly improves interfacial quality. With increasing vacuum degree, the interfacial wave becomes finer, more continuous, and more uniform, while the thickness of the molten layer decreases, and the presence of defects and brittle intermetallic compounds is reduced. EBSD analysis reveals grain refinement and an increased recrystallization fraction at the interface under vacuum conditions, demonstrating that the interfacial microstructure can be effectively controlled by adjusting the ambient pressure. EPMA further reveals that the vortex regions are mainly composed of Fe and Ti elements, while the weld seam region exhibits a stable chemical composition with Ti-to-Fe atom number ratios close to 1∶1 or 2∶1, indicating that the dominant intermetallic phases formed at the interface are TiFe and TiFe2. Benefiting from the optimized interfacial structure, the clad plates exhibit excellent mechanical properties at −70 ℃. The tensile strengths of the CP-20, CP-60 and CP-100 are 880, 911, and 867 MPa, respectively. The impact absorbed energies are 17.5, 10.2, and 6.4 J, respectively. And the flexural strengths are1469 , 1350 , and 1167 MPa, respectively. This study demonstrates that vacuum explosive welding is a reliable technique for producing high-performance low-temperature metal composites, with 60 kPa identified as the optimal processing window.
Ti/steel clad plates are considered as ideal candidate materials for applications such as marine engineering and low-temperature pressure vessels operating at −70 ℃. However, their large-scale production and application are severely restricted by the manufacturing process and the quality of interfacial bonding. To investigate the influence mechanism of vacuum pressure on interfacial morphology and mechanical properties, TC4/09MnNiDR (Ti/steel) clad plates were fabricated using explosive welding under ambient pressures of 20, 60, and 100 kPa, and the fabricated clad plates were named as CP-20, CP-60 and CP-100, respectively. A specially designed vacuum chamber was employed to precisely control the environmental pressure during the explosive process. After welding, all specimens were subjected to a uniform stress-relief annealing treatment at 550 ℃ for 2 h under a vacuum atmosphere to eliminate residual stresses and improve the reliability of subsequent characterization. The interfacial microstructure and chemical characteristics were systematically analyzed using multiple characterization techniques. Scanning electron microscopy (SEM) was used to observe interfacial morphology, including wave formation and defect distribution. Energy dispersive spectroscopy (EDS) was applied to examine elemental distribution across the bonding interface. Electron backscatter diffraction (EBSD) was employed to evaluate grain structure, grain boundary characteristics, recrystallization fraction, and texture evolution near the interface. Electron probe microanalysis (EPMA) was conducted to quantitatively determine the chemical composition of the interfacial melting zone and vortex regions, with both mapping and point analyses performed to identify the constituent phases. Mechanical properties at −70 ℃ were evaluated through tensile tests, Charpy impact tests, and three-point bending tests, all carried out in accordance with relevant national standards, with the results reported as mean values ± standard deviations. Results show that the vacuum environment significantly improves interfacial quality. With increasing vacuum degree, the interfacial wave becomes finer, more continuous, and more uniform, while the thickness of the molten layer decreases, and the presence of defects and brittle intermetallic compounds is reduced. EBSD analysis reveals grain refinement and an increased recrystallization fraction at the interface under vacuum conditions, demonstrating that the interfacial microstructure can be effectively controlled by adjusting the ambient pressure. EPMA further reveals that the vortex regions are mainly composed of Fe and Ti elements, while the weld seam region exhibits a stable chemical composition with Ti-to-Fe atom number ratios close to 1∶1 or 2∶1, indicating that the dominant intermetallic phases formed at the interface are TiFe and TiFe2. Benefiting from the optimized interfacial structure, the clad plates exhibit excellent mechanical properties at −70 ℃. The tensile strengths of the CP-20, CP-60 and CP-100 are 880, 911, and 867 MPa, respectively. The impact absorbed energies are 17.5, 10.2, and 6.4 J, respectively. And the flexural strengths are
2026, 46(10): 103201.
doi: 10.11883/bzycj-2025-0146
Abstract:
In order to investigate the propagation characteristics of P-wave in nonlinear oblique joints rock mass, a comprehensive approach integrating theoretical analysis, comparative validation and numerical calculation was employed. Initially, the hyperbolic joint constitutive model featuring normal nonlinear deformation and tangential linear deformation was presented. Based on the interaction relationship between stress waves and a linear single joint, the propagation equation for P-wave incident on oblique joints was derived according to superposition principle. Then, by using the parameters of the incident P-wave and the conditions of jointed rock mass reported in literature, the transmission and reflection coefficients were calculated and found to be in close agreement, verifying the accuracy and feasibility of the theoretical model. Furthermore, the auxiliary function of δ function was selected as the incident P-wave to analyze the influence rule of waveform, duration and joint stiffness on the propagation characteristics of P-wave in oblique joints rock mass through parameter study. The results demonstrate that the phenomenon of amplitude reduction, amplitude-time delay and duration extension is pronounced when the auxiliary function of δ function incident on oblique joints, which can better reflect the abrupt change characteristics and nonlinear attenuation behavior of P-wave in a short time. The duration of the incident P-wave in oblique joints rock mass can significantly enhance the transmission performance of P-wave and slightly reduce the reflection characteristics of P-wave and S-wave. As the initial normal stiffness and the shear stiffness of joint increase, the reflection coefficient of S-wave decays in a concave surface shape, while the transmission coefficient of P-wave increases in a convex shape. The transmission performance of P-wave is closely related to the normal stiffness of joints, whereas the reflection characteristics of S-waves are significantly influenced by the second joint in the oblique joints. These research findings offer valuable insights into the mechanical properties and dynamic response of natural jointed rock mass.
In order to investigate the propagation characteristics of P-wave in nonlinear oblique joints rock mass, a comprehensive approach integrating theoretical analysis, comparative validation and numerical calculation was employed. Initially, the hyperbolic joint constitutive model featuring normal nonlinear deformation and tangential linear deformation was presented. Based on the interaction relationship between stress waves and a linear single joint, the propagation equation for P-wave incident on oblique joints was derived according to superposition principle. Then, by using the parameters of the incident P-wave and the conditions of jointed rock mass reported in literature, the transmission and reflection coefficients were calculated and found to be in close agreement, verifying the accuracy and feasibility of the theoretical model. Furthermore, the auxiliary function of δ function was selected as the incident P-wave to analyze the influence rule of waveform, duration and joint stiffness on the propagation characteristics of P-wave in oblique joints rock mass through parameter study. The results demonstrate that the phenomenon of amplitude reduction, amplitude-time delay and duration extension is pronounced when the auxiliary function of δ function incident on oblique joints, which can better reflect the abrupt change characteristics and nonlinear attenuation behavior of P-wave in a short time. The duration of the incident P-wave in oblique joints rock mass can significantly enhance the transmission performance of P-wave and slightly reduce the reflection characteristics of P-wave and S-wave. As the initial normal stiffness and the shear stiffness of joint increase, the reflection coefficient of S-wave decays in a concave surface shape, while the transmission coefficient of P-wave increases in a convex shape. The transmission performance of P-wave is closely related to the normal stiffness of joints, whereas the reflection characteristics of S-waves are significantly influenced by the second joint in the oblique joints. These research findings offer valuable insights into the mechanical properties and dynamic response of natural jointed rock mass.
2026, 46(10): 103301.
doi: 10.11883/bzycj-2025-0357
Abstract:
Because of the difficulty in obtaining granite materials and the high cost of conducting penetration tests on granite targets, an equivalence study between reinforced concrete and granite targets was carried out. To establish the equivalence relationship between the two target types, dimensional analysis and a modified compensation method were adopted, with the projectile residual velocity taken as the equivalence criterion, and a computational method for determining equivalent thickness was derived. Based on existing experimental data, numerical models for medium-velocity projectile penetration into reinforced concrete and granite targets were developed and validated using the LS-DYNA software. By varying the projectile impact velocity and target thickness in the numerical simulations, the similarities in damage characteristics between reinforced concrete and granite targets were systematically investigated, and the corresponding failure regions were classified. On the basis of the simulation results, specific equivalent design formulas for granite and reinforced concrete targets were obtained through data fitting. The results show that the established numerical models can accurately predict the projectile residual velocity and reproduce the failure characteristics of both target types during penetration. Compared with reinforced concrete, granite exhibits a smaller compaction zone and tunnel diameter, finer and longer cracks with higher propagation velocities, larger surface crack areas, and a greater tendency to form large spallation craters. Under identical penetration conditions, granite targets and reinforced concrete targets of equivalent thickness display similar failure characteristics, and both can be divided into five distinct failure regions. Through dimensional analysis and compensation correction, a dimensionless residual-velocity function for projectile penetration into reinforced concrete and granite targets was derived, together with an equivalent thickness formula relating the two materials. The fitted equivalent thickness coefficient between granite and reinforced concrete was determined to be 1.699 66. Validation of the proposed equivalence formula indicates that the residual-velocity error between the prototype and equivalent model targets is less than 5%. These results provide a useful reference for the equivalent design of rock targets subjected to medium-velocity projectile penetration and offer a systematic methodology for substituting reinforced concrete for granite in related experimental and engineering applications.
Because of the difficulty in obtaining granite materials and the high cost of conducting penetration tests on granite targets, an equivalence study between reinforced concrete and granite targets was carried out. To establish the equivalence relationship between the two target types, dimensional analysis and a modified compensation method were adopted, with the projectile residual velocity taken as the equivalence criterion, and a computational method for determining equivalent thickness was derived. Based on existing experimental data, numerical models for medium-velocity projectile penetration into reinforced concrete and granite targets were developed and validated using the LS-DYNA software. By varying the projectile impact velocity and target thickness in the numerical simulations, the similarities in damage characteristics between reinforced concrete and granite targets were systematically investigated, and the corresponding failure regions were classified. On the basis of the simulation results, specific equivalent design formulas for granite and reinforced concrete targets were obtained through data fitting. The results show that the established numerical models can accurately predict the projectile residual velocity and reproduce the failure characteristics of both target types during penetration. Compared with reinforced concrete, granite exhibits a smaller compaction zone and tunnel diameter, finer and longer cracks with higher propagation velocities, larger surface crack areas, and a greater tendency to form large spallation craters. Under identical penetration conditions, granite targets and reinforced concrete targets of equivalent thickness display similar failure characteristics, and both can be divided into five distinct failure regions. Through dimensional analysis and compensation correction, a dimensionless residual-velocity function for projectile penetration into reinforced concrete and granite targets was derived, together with an equivalent thickness formula relating the two materials. The fitted equivalent thickness coefficient between granite and reinforced concrete was determined to be 1.699 66. Validation of the proposed equivalence formula indicates that the residual-velocity error between the prototype and equivalent model targets is less than 5%. These results provide a useful reference for the equivalent design of rock targets subjected to medium-velocity projectile penetration and offer a systematic methodology for substituting reinforced concrete for granite in related experimental and engineering applications.
2026, 46(10): 103302.
doi: 10.11883/bzycj-2025-0129
Abstract:
To investigate the influence of trajectory angle and pitch angle on the deflection characteristics of a projectile penetrating into concrete thin targets, numerical simulation methods were validated by comparing parameters such as projectile velocity, attitude, and trajectory deflection with experimental data from multi-layered concrete thin-target penetration tests. This verification methodology ensured the accuracy and reliability of the numerical model for subsequent parametric studies.Based on this validation, the projectile was divided into six axial segments (the nose section comprising two segments and the body section divided into four segments) to systematically analyze the force distribution characteristics and overall motion behavior under both individual and combined effects of different trajectory angles (ranging from 5° to 30°) and pitch angles (ranging from −6° to 6°). The results show that the direction of the resultant force acting on the projectile body maintains stability across all tested impact conditions, demonstrating consistent patterns regardless of angle variations.While the reversal of the force direction on the projectile nose and the change in the deflection moment caused by the forward motion of the projectile body jointly contribute to the projectile's deflection. Under a positive trajectory angle, the trajectory exhibits an upward deflection. When a pitch angle is introduced, the deflection direction is dominated by the trajectory angle if the negative pitch angle is less than 2° and the trajectory angle exceeds 20°; otherwise, the pitch angle determines the deflection direction. When the trajectory angle and pitch angle are in the same direction, the projectile's attitude angle first decreases after exiting the target and then reverses to increase. When they are in opposite directions, a small pitch angle causes the attitude angle to continuously increase after exiting the target, while a larger trajectory angle induces three deflection reversals during penetration. If the pitch angle exceeds 2°, the attitude angle initially decreases after exiting the target before reversing to increase.
To investigate the influence of trajectory angle and pitch angle on the deflection characteristics of a projectile penetrating into concrete thin targets, numerical simulation methods were validated by comparing parameters such as projectile velocity, attitude, and trajectory deflection with experimental data from multi-layered concrete thin-target penetration tests. This verification methodology ensured the accuracy and reliability of the numerical model for subsequent parametric studies.Based on this validation, the projectile was divided into six axial segments (the nose section comprising two segments and the body section divided into four segments) to systematically analyze the force distribution characteristics and overall motion behavior under both individual and combined effects of different trajectory angles (ranging from 5° to 30°) and pitch angles (ranging from −6° to 6°). The results show that the direction of the resultant force acting on the projectile body maintains stability across all tested impact conditions, demonstrating consistent patterns regardless of angle variations.While the reversal of the force direction on the projectile nose and the change in the deflection moment caused by the forward motion of the projectile body jointly contribute to the projectile's deflection. Under a positive trajectory angle, the trajectory exhibits an upward deflection. When a pitch angle is introduced, the deflection direction is dominated by the trajectory angle if the negative pitch angle is less than 2° and the trajectory angle exceeds 20°; otherwise, the pitch angle determines the deflection direction. When the trajectory angle and pitch angle are in the same direction, the projectile's attitude angle first decreases after exiting the target and then reverses to increase. When they are in opposite directions, a small pitch angle causes the attitude angle to continuously increase after exiting the target, while a larger trajectory angle induces three deflection reversals during penetration. If the pitch angle exceeds 2°, the attitude angle initially decreases after exiting the target before reversing to increase.
2026, 46(10): 103401.
doi: 10.11883/bzycj-2025-0386
Abstract:
To investigate the damage characteristics of concrete arch slabs subjected to underwater contact explosions, a series of underwater contact explosion tests was conducted on three concrete arch slabs. During the experiments, the spalled fragments generated by detonation were carefully collected and quantitatively analyzed using a mass-based partitioning statistical method, thereby enabling systematic characterization of the slabs’ fragmentation and spalling behavior. On this basis, a three-dimensional fluid-structure interaction numerical model was developed using the coupled Eulerian-Lagrangian method, which incorporates water, a concrete arch slab, and TNT. The reliability and effectiveness of the numerical model were validated by comparing the simulated macroscopic failure patterns and crack propagation paths with the experimental observations. Further analyses were conducted using the validated model to investigate the damage evolution process and the characteristics of stress wave propagation within the arch slabs under explosive loading, thereby systematically elucidating the damage mechanisms of concrete arch slabs subjected to underwater contact explosions. In addition, parametric studies were performed to examine the effects of explosive charge and span length on the damage characteristics of the arch slabs. The results indicate that, under underwater contact explosion, an annular damage zone composed of radial and circumferential cracks forms on the blast-facing surface of the arch slab. With increasing explosive charge, the number of spalled fragments increases, and their size becomes progressively finer. As the span length increases, the structure tends to generate larger fragments. When the TNT charge increases from 0.4 g to 1.6 g, the annular damage zone on the blast-facing surface expands from a localized region to the full width of the slab, and the failure mode transitions from localized damage to global failure. With increasing span length, the degree of damage at the arch ends decreases, while the damaged region near the mid-span expands. Compared with the slab with a span of 400 mm, the total energy dissipation of the slab with a span of 600 mm increases by 4.5%.
To investigate the damage characteristics of concrete arch slabs subjected to underwater contact explosions, a series of underwater contact explosion tests was conducted on three concrete arch slabs. During the experiments, the spalled fragments generated by detonation were carefully collected and quantitatively analyzed using a mass-based partitioning statistical method, thereby enabling systematic characterization of the slabs’ fragmentation and spalling behavior. On this basis, a three-dimensional fluid-structure interaction numerical model was developed using the coupled Eulerian-Lagrangian method, which incorporates water, a concrete arch slab, and TNT. The reliability and effectiveness of the numerical model were validated by comparing the simulated macroscopic failure patterns and crack propagation paths with the experimental observations. Further analyses were conducted using the validated model to investigate the damage evolution process and the characteristics of stress wave propagation within the arch slabs under explosive loading, thereby systematically elucidating the damage mechanisms of concrete arch slabs subjected to underwater contact explosions. In addition, parametric studies were performed to examine the effects of explosive charge and span length on the damage characteristics of the arch slabs. The results indicate that, under underwater contact explosion, an annular damage zone composed of radial and circumferential cracks forms on the blast-facing surface of the arch slab. With increasing explosive charge, the number of spalled fragments increases, and their size becomes progressively finer. As the span length increases, the structure tends to generate larger fragments. When the TNT charge increases from 0.4 g to 1.6 g, the annular damage zone on the blast-facing surface expands from a localized region to the full width of the slab, and the failure mode transitions from localized damage to global failure. With increasing span length, the degree of damage at the arch ends decreases, while the damaged region near the mid-span expands. Compared with the slab with a span of 400 mm, the total energy dissipation of the slab with a span of 600 mm increases by 4.5%.
2026, 46(10): 104101.
doi: 10.11883/bzycj-2025-0095
Abstract:
The multi-point focused explosions of new low-yield earth-penetrating nuclear weapons pose a serious threat to deep underground engineering projects. Addressing the challenge that traditional single-point simulations struggle to replicate the cratering effects of such multi-point synergistic damage, and considering that current explosive testing, while efficient, faces significant limitations hindering normal operations, research innovatively designs and develops a vacuum chamber-based simulation test system for large-yield multi-point focused explosion cratering effects. The core innovation lies in applying similarity theory to convert prototype tests into simulated tests. The vacuum chamber simulation technology enables efficient and rapid simulation of large-yield multi-point explosion cratering effects, with low experimental costs and repeatable results. Based on vacuum chamber explosion simulation theory, the similarity laws governing large-yield multi-point focused explosion cratering were established, defining key parameters such as vacuum chamber pressure and multi-point simulated blast cavity pressure. Synchronization tests verified the simultaneity of multiple explosive sources. Referencing the underground nuclear test, we conducted vacuum chamber simulations for three-point sources under deep burial (4.3 kt, 85 m depth) and shallow burial (5 kt, 20 m depth) scenarios, comparing results with single-point explosion prototype data and empirical formulas. Through synchronization tests and three-point explosive source cratering tests, differences in cratering parameters under varying burial depths and yields were quantitatively analyzed. This revealed a significant advantage in damage range for multi-point sources compared to single-point sources when the total yield is identical. Key results indicate: A vacuum chamber simulation system is successfully developed, relying on a miniature explosive device based on the two-stage gas gun principle and the vacuum chamber. Synchronization tests confirmed good simultaneity among explosive sources using a common detonation control switch; Compared to single-point explosions, multi-point explosions significantly increased crater radius, volume, and free surface projection area, greatly expanding the damage zone; Explosive source burial depth significantly impacts the damage effect.
The multi-point focused explosions of new low-yield earth-penetrating nuclear weapons pose a serious threat to deep underground engineering projects. Addressing the challenge that traditional single-point simulations struggle to replicate the cratering effects of such multi-point synergistic damage, and considering that current explosive testing, while efficient, faces significant limitations hindering normal operations, research innovatively designs and develops a vacuum chamber-based simulation test system for large-yield multi-point focused explosion cratering effects. The core innovation lies in applying similarity theory to convert prototype tests into simulated tests. The vacuum chamber simulation technology enables efficient and rapid simulation of large-yield multi-point explosion cratering effects, with low experimental costs and repeatable results. Based on vacuum chamber explosion simulation theory, the similarity laws governing large-yield multi-point focused explosion cratering were established, defining key parameters such as vacuum chamber pressure and multi-point simulated blast cavity pressure. Synchronization tests verified the simultaneity of multiple explosive sources. Referencing the underground nuclear test, we conducted vacuum chamber simulations for three-point sources under deep burial (4.3 kt, 85 m depth) and shallow burial (5 kt, 20 m depth) scenarios, comparing results with single-point explosion prototype data and empirical formulas. Through synchronization tests and three-point explosive source cratering tests, differences in cratering parameters under varying burial depths and yields were quantitatively analyzed. This revealed a significant advantage in damage range for multi-point sources compared to single-point sources when the total yield is identical. Key results indicate: A vacuum chamber simulation system is successfully developed, relying on a miniature explosive device based on the two-stage gas gun principle and the vacuum chamber. Synchronization tests confirmed good simultaneity among explosive sources using a common detonation control switch; Compared to single-point explosions, multi-point explosions significantly increased crater radius, volume, and free surface projection area, greatly expanding the damage zone; Explosive source burial depth significantly impacts the damage effect.
2026, 46(10): 104102.
doi: 10.11883/bzycj-2025-0138
Abstract:
To address the accidental explosion risks caused by sensitive primary explosives in industrial electronic detonators, as well as the safety and environmental issues associated with traditional no-primary detonators, a new intelligent flyer-type electronic detonator design was proposed to enhance the safety and environmental performance through flyer initiation technology. To achieve reliable initiation without sensitive primary explosives, a multi-dimensional approach combining experimental and numerical simulation methods is employed for the design and performance optimization of the new intelligent flyer-type electronic detonator. First, critical parameters for slapper initiation were determined through theoretical modeling of shock wave propagation and energy transfer. A finite element model of the flyer acceleration process was established to simulate the effects of different charge structures (e.g., confinement diameter, thickness) on flyer velocity, comprehensively considering material deformation, detonation wave interactions, and flyer fragmentation effects. Second, a high-speed camera (500 kHz) was used to synchronously record the detonation process, capturing the actual velocity, flight attitude, and deformation behavior of the flyer upon target impact. This data was used to validate the numerical model and optimize the structural design of the flyer generator. Third, the axial initiation capability was evaluated through standardized lead plate (5 mm thickness) penetration tests. The penetration depth and crater morphology were comparatively analyzed to quantify performance differences with traditional no-primary detonators. Fourth, an underwater explosion test system was utilized, with an array of pressure sensors measuring shock wave overpressure and bubble pulse energy to assess detonation stability and energy output efficiency. Fifth, donor/acceptor detonator arrays were set up at 10–50 mm intervals, and high-speed cameras were used to monitor sympathetic detonation phenomena, verifying compliance with the industrial safety standard of 40 mm minimum separation distance. Sixth, charge parameters were optimized through iterative testing: primary charge (400 mg, compaction density 1.56 g/cm3), secondary charge (200 mg, compaction density 1.41 g/cm3), tertiary charge (320 mg, loosely packed),the fourth charge layer was eliminated to simplify the production process while maintaining performance. This multi-scale methodology system provides systematic validation support for the reliability, safety, and environmental friendliness of the flyer initiation technology. The results were acquired as follows. Optimized main charge configuration (primary charge: 400 mg-1.56 g/cm3, secondary charge: 200 mg-1.41 g/cm3, tertiary charge: 320 mg-loosely packed) achieved stable detonation, achieve synergistic improvement of detonation performance and safety. When the slapper generator's necking diameter was 5.6−5.7 mm, the flyer velocity reached the reliable initiation threshold. Lead plate tests demonstrated superior axial initiation capability compared to traditional no-primary detonators. Underwater explosion tests confirmed stable detonation performance, with an air-gap sympathetic detonation distance larger than 30 mm, meeting the 40 mm safety requirement for production processes. The innovative elimination of the fourth charge simplified the production process while maintaining high safety and environmental friendliness. The technical bottlenecks of traditional no-primary detonators has been broken. The results show that the new intelligent flyer-type electronic detonator completely avoids the use of sensitive primary explosives through flyer initiation technology. It significantly outperforms traditional designs in initiation reliability, safety distance, and environmental performance, aligning with the industry's trend toward safer and greener detonators. This study provides an innovative solution for the field.
To address the accidental explosion risks caused by sensitive primary explosives in industrial electronic detonators, as well as the safety and environmental issues associated with traditional no-primary detonators, a new intelligent flyer-type electronic detonator design was proposed to enhance the safety and environmental performance through flyer initiation technology. To achieve reliable initiation without sensitive primary explosives, a multi-dimensional approach combining experimental and numerical simulation methods is employed for the design and performance optimization of the new intelligent flyer-type electronic detonator. First, critical parameters for slapper initiation were determined through theoretical modeling of shock wave propagation and energy transfer. A finite element model of the flyer acceleration process was established to simulate the effects of different charge structures (e.g., confinement diameter, thickness) on flyer velocity, comprehensively considering material deformation, detonation wave interactions, and flyer fragmentation effects. Second, a high-speed camera (500 kHz) was used to synchronously record the detonation process, capturing the actual velocity, flight attitude, and deformation behavior of the flyer upon target impact. This data was used to validate the numerical model and optimize the structural design of the flyer generator. Third, the axial initiation capability was evaluated through standardized lead plate (5 mm thickness) penetration tests. The penetration depth and crater morphology were comparatively analyzed to quantify performance differences with traditional no-primary detonators. Fourth, an underwater explosion test system was utilized, with an array of pressure sensors measuring shock wave overpressure and bubble pulse energy to assess detonation stability and energy output efficiency. Fifth, donor/acceptor detonator arrays were set up at 10–50 mm intervals, and high-speed cameras were used to monitor sympathetic detonation phenomena, verifying compliance with the industrial safety standard of 40 mm minimum separation distance. Sixth, charge parameters were optimized through iterative testing: primary charge (400 mg, compaction density 1.56 g/cm3), secondary charge (200 mg, compaction density 1.41 g/cm3), tertiary charge (320 mg, loosely packed),the fourth charge layer was eliminated to simplify the production process while maintaining performance. This multi-scale methodology system provides systematic validation support for the reliability, safety, and environmental friendliness of the flyer initiation technology. The results were acquired as follows. Optimized main charge configuration (primary charge: 400 mg-1.56 g/cm3, secondary charge: 200 mg-1.41 g/cm3, tertiary charge: 320 mg-loosely packed) achieved stable detonation, achieve synergistic improvement of detonation performance and safety. When the slapper generator's necking diameter was 5.6−5.7 mm, the flyer velocity reached the reliable initiation threshold. Lead plate tests demonstrated superior axial initiation capability compared to traditional no-primary detonators. Underwater explosion tests confirmed stable detonation performance, with an air-gap sympathetic detonation distance larger than 30 mm, meeting the 40 mm safety requirement for production processes. The innovative elimination of the fourth charge simplified the production process while maintaining high safety and environmental friendliness. The technical bottlenecks of traditional no-primary detonators has been broken. The results show that the new intelligent flyer-type electronic detonator completely avoids the use of sensitive primary explosives through flyer initiation technology. It significantly outperforms traditional designs in initiation reliability, safety distance, and environmental performance, aligning with the industry's trend toward safer and greener detonators. This study provides an innovative solution for the field.
2026, 46(10): 105101.
doi: 10.11883/bzycj-2025-0071
Abstract:
In order to study the anti-explosion performance of a single-room reinforced concrete building under internal explosion loads, a full-scale reinforced concrete single-room building, whose dimensions were 4m×4m×3m, was designed and constructed. For the internal explosion test, 3 kg TNT was placed in the geometric center of the room. Sensors were installed at the center of the shear wall and roof to record data and analyze the damage characteristics of the single-room structure. In addition, an anti-explosion numerical model of the reinforced concrete single-room structure was established and verified using the LS-DYNA software. The weight of the explosives in the numerical model was changed to study the damage process and shock wave propagation law of the single-room building. Based on the experimental and simulation results, the damage modes of the single room structure were categorized by the dimensionless weighted parameter Dr, and relevant empirical formulas were obtained through data fitting. The results show that when 3 kg TNT explodes in the geometric center of the room structure, the single-room structure exhibits roof bulging, with long cracks appearing along the roof edges. However, the whole structure does not collapse; Under the internal explosion condition, the local damage characteristics of reinforced concrete buildings are not only closely related to the explosive yield, but also significantly affected by the design of structural connection nodes and structural details; Due to the delayed dynamic response of reinforced concrete, the next shock wave has acted on the building before the last shock wave has reacted obviously, which subjects it to multiple impacts within a very short time; By varying the charge weight, five damage-aggravating modes (Model Ⅰ to Model Ⅴ) were identified. The five damage modes were quantitatively defined using the weighted parameter Dr, and a function curve relating it to the explosive equivalent was fitted.
In order to study the anti-explosion performance of a single-room reinforced concrete building under internal explosion loads, a full-scale reinforced concrete single-room building, whose dimensions were 4m×4m×3m, was designed and constructed. For the internal explosion test, 3 kg TNT was placed in the geometric center of the room. Sensors were installed at the center of the shear wall and roof to record data and analyze the damage characteristics of the single-room structure. In addition, an anti-explosion numerical model of the reinforced concrete single-room structure was established and verified using the LS-DYNA software. The weight of the explosives in the numerical model was changed to study the damage process and shock wave propagation law of the single-room building. Based on the experimental and simulation results, the damage modes of the single room structure were categorized by the dimensionless weighted parameter Dr, and relevant empirical formulas were obtained through data fitting. The results show that when 3 kg TNT explodes in the geometric center of the room structure, the single-room structure exhibits roof bulging, with long cracks appearing along the roof edges. However, the whole structure does not collapse; Under the internal explosion condition, the local damage characteristics of reinforced concrete buildings are not only closely related to the explosive yield, but also significantly affected by the design of structural connection nodes and structural details; Due to the delayed dynamic response of reinforced concrete, the next shock wave has acted on the building before the last shock wave has reacted obviously, which subjects it to multiple impacts within a very short time; By varying the charge weight, five damage-aggravating modes (Model Ⅰ to Model Ⅴ) were identified. The five damage modes were quantitatively defined using the weighted parameter Dr, and a function curve relating it to the explosive equivalent was fitted.
2026, 46(10): 105901.
doi: 10.11883/bzycj-2025-0384
Abstract:
Following an explosion accident, a public safety explosion accident analysis method based on open-source information fusion was proposed to quickly and accurately assess the scope and severity of the accident's impact and to formulate a scientific and reasonable emergency response strategy. Furthermore, regarding the May 27 chemical plant explosion accident in Gaomi, Shandong, a logical chain for accident analysis was rapidly constructed. Specifically, open-source information was used to obtain critical details such as the explosion generation, the shock waves propagation, and structural damage to buildings in both the plant area and far field. Based on criteria for structural damage and the laws of shockwave propagation, the explosion source location and TNT equivalent were reverse-calculated, and the cause of the accident was analyzed. Numerical simulations provided key evidence for improving safety protection in industrial plants. The results indicate that the explosion source was located at the No.1 nitration device, with a TNT equivalent of approximately12000 kg TNT, consistent with the conclusion based on field investigation, thereby verifying the effectiveness and accuracy of this method. The main causes of the accident were identified as the company's actual production load exceeding design standards, prolonged operation of equipment under full load conditions, and long-term neglect of the safety interlock system. The production plant should strengthen the blast-resistant protection measures for buildings from four aspects: control the stockpile of explosive hazardous materials, general layout zoning and isolation, safety control against sympathetic detonation, and peripheral protection for key explosion-prone installations, so as to improve the structural blast resistance, reduce casualties and equipment damage, and narrow the damage scope. The proposal of this method provides a novel approach to the existing accident investigation system, effectively enriches investigation techniques, overcomes the limitations of traditional analytical methods, and demonstrates the necessity for continued research and practical value.
Following an explosion accident, a public safety explosion accident analysis method based on open-source information fusion was proposed to quickly and accurately assess the scope and severity of the accident's impact and to formulate a scientific and reasonable emergency response strategy. Furthermore, regarding the May 27 chemical plant explosion accident in Gaomi, Shandong, a logical chain for accident analysis was rapidly constructed. Specifically, open-source information was used to obtain critical details such as the explosion generation, the shock waves propagation, and structural damage to buildings in both the plant area and far field. Based on criteria for structural damage and the laws of shockwave propagation, the explosion source location and TNT equivalent were reverse-calculated, and the cause of the accident was analyzed. Numerical simulations provided key evidence for improving safety protection in industrial plants. The results indicate that the explosion source was located at the No.1 nitration device, with a TNT equivalent of approximately
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