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, Available online , doi: 10.11883/bzycj-2024-0520
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Significant structural and layout disparities exist between the blended wing body (BWB) civil aircraft and conventional cylindrical fuselage metal aircraft. These differences render the impact resistance characteristics of the non-circular fuselage structure and the injury mechanisms for occupants unclear. To address this, a 460-seat BWB aircraft model was developed based on the pultruded rod stitched efficient unitized structure (PRSEUS) proposed by the National Aeronautics and Space Administration (NASA). The aircraft features a wingspan of 80 meters, a range of approximately 16,000 km, a cruising Mach number of 0.85, and a cruising altitude of 11 000 m. Three typical loading conditions were employed to evaluate the strength and stiffness of the BWB structure: critical maneuvering loads (2.5g positive overload and −1.0g negative overload) and cabin pressurization loads (double the cabin pressurization load). Through iterative structural design optimization, the model was confirmed to meet these typical loading requirements while demonstrating sufficient safety margins. The model incorporated all major structural components of the BWB configuration, including skin, frames, stringers, cargo floor, cabin floor, support columns, and fuselage ribs. In the finite element modeling process, elements with minimal influence on the crash response were reasonably simplified to reduce computational complexity. For instance, the outer wings and engines were simplified as concentrated mass points, and the cabin seats and passengers were modeled as concentrated masses fixed to the seat rails. The primary structural components, such as the skin, stringers, floor, and floor beams, were constructed from AS4 carbon fiber composite laminates and modeled using shell elements. The pultruded rods were made of AS4 carbon fiber composite and modeled using beam elements. The foam core of the frames and fuselage ribs were made of Rohacell-110-WF foam material and modeled using solid elements. The remaining structures were made of7075 aluminum alloy and modeled using shell elements. The final model had a total mass of 162.87 tons and consisted of 2 679 991 elements. Five vertical impact velocities ranging from 7.92 to 9.14 m/s were selected to analyze the cabin space integrity, acceleration response of the cabin floor, and the impact characteristics of the primary load-bearing structures. The results indicate that the cabin area of the lift-body fuselage remains largely intact under the different impact velocities. The primary damage occurs below the cabin floor, with compressive damage concentrated in the lower structures of the middle and aft fuselage. The survivable space is preserved. Compared to a round-section fuselage, the deformation of the BWB frames is relatively small, and upward bulging is not significant, making it challenging to form effective plastic hinges. During the crash, the acceleration load distribution of the blended wing body-integrated aircraft exhibits a decreasing trend from the central aisle to the sides of the fuselage, with peak acceleration loads being higher at the central aisle. Under all five crash conditions, passenger injury levels at various cabin positions fall within the serious but acceptable and safe regions. Regarding structural energy absorption, the frames are identified as the primary energy-absorbing structures, followed by the fuselage ribs. However, the cargo pillars do not effectively crush and absorb energy. For future crashworthiness design of BWB civil aircraft, the cargo structure should be a key consideration.
Significant structural and layout disparities exist between the blended wing body (BWB) civil aircraft and conventional cylindrical fuselage metal aircraft. These differences render the impact resistance characteristics of the non-circular fuselage structure and the injury mechanisms for occupants unclear. To address this, a 460-seat BWB aircraft model was developed based on the pultruded rod stitched efficient unitized structure (PRSEUS) proposed by the National Aeronautics and Space Administration (NASA). The aircraft features a wingspan of 80 meters, a range of approximately 16,000 km, a cruising Mach number of 0.85, and a cruising altitude of 11 000 m. Three typical loading conditions were employed to evaluate the strength and stiffness of the BWB structure: critical maneuvering loads (2.5g positive overload and −1.0g negative overload) and cabin pressurization loads (double the cabin pressurization load). Through iterative structural design optimization, the model was confirmed to meet these typical loading requirements while demonstrating sufficient safety margins. The model incorporated all major structural components of the BWB configuration, including skin, frames, stringers, cargo floor, cabin floor, support columns, and fuselage ribs. In the finite element modeling process, elements with minimal influence on the crash response were reasonably simplified to reduce computational complexity. For instance, the outer wings and engines were simplified as concentrated mass points, and the cabin seats and passengers were modeled as concentrated masses fixed to the seat rails. The primary structural components, such as the skin, stringers, floor, and floor beams, were constructed from AS4 carbon fiber composite laminates and modeled using shell elements. The pultruded rods were made of AS4 carbon fiber composite and modeled using beam elements. The foam core of the frames and fuselage ribs were made of Rohacell-110-WF foam material and modeled using solid elements. The remaining structures were made of
, Available online , doi: 10.11883/bzycj-2025-0465
Abstract:
The evolution of a planar heavy/light gas interface (SF6/N2) subjected to a perturbed shock wave produced by diffracting a planar incident shock over a rigid cylinder is investigated by numerical and theoretical analysis, particularly focusing on the incident impact stage of Mach reflection wave configuration. While the Mach number of incident planar shock wave is 1.8, numerical schlieren images of the Mach reflection wave over a rigid cylinder are provided, and the wave evolution during the incident impact on the heavy/light interface is quantitatively analyzed. Utilizing the three-shock theory, an analytical solution describing the refraction process is derived, which accurately predicts the post-refraction shock wave shape, as well as the velocity perturbation and circulation deposition on the interface. Additionally, by drawing shock polar curves and rarefaction wave characteristic lines, the pressure changes and flow deflection across the wave configuration during the incident impact process are straightly described. Both the results of theoretical analysis and numerical simulation indicate that the differences in shock intensity and incident angles within the Mach reflection wave configuration lead to the velocity perturbation on the interface. And the tangential velocity caused by the shock impact results in circulation deposition on the interface. Velocity perturbation and circulation deposition dominate the early evolution of the heavy/light interface.
The evolution of a planar heavy/light gas interface (SF6/N2) subjected to a perturbed shock wave produced by diffracting a planar incident shock over a rigid cylinder is investigated by numerical and theoretical analysis, particularly focusing on the incident impact stage of Mach reflection wave configuration. While the Mach number of incident planar shock wave is 1.8, numerical schlieren images of the Mach reflection wave over a rigid cylinder are provided, and the wave evolution during the incident impact on the heavy/light interface is quantitatively analyzed. Utilizing the three-shock theory, an analytical solution describing the refraction process is derived, which accurately predicts the post-refraction shock wave shape, as well as the velocity perturbation and circulation deposition on the interface. Additionally, by drawing shock polar curves and rarefaction wave characteristic lines, the pressure changes and flow deflection across the wave configuration during the incident impact process are straightly described. Both the results of theoretical analysis and numerical simulation indicate that the differences in shock intensity and incident angles within the Mach reflection wave configuration lead to the velocity perturbation on the interface. And the tangential velocity caused by the shock impact results in circulation deposition on the interface. Velocity perturbation and circulation deposition dominate the early evolution of the heavy/light interface.
, Available online , doi: 10.11883/bzycj-2024-0332
Abstract:
To investigate the damage mechanism and load characteristics of caisson wharf under underwater contact and near-field explosion, a high-fidelity numerical model was conducted based on the scaled model tests of caisson wharf and verified by comparing the simulation results with the experimental data. The propagation and attenuation characteristics of shock waves inside the caisson, partition walls, and internal backfill soil were analyzed. The destruction process and typical damage mechanisms of the caisson wharf were analyzed by comparing Holmquist‒Johnson‒Cook constitutive model damage contour maps with experimental results. The results shows that the damage areas and characteristics of the caisson wharf are largely consistent under both underwater contact and near-field explosion. The primary damage areas are blast-facing wall and deck slab. The blast-facing wall exhibits cratering and breaching phenomena, while of the deck slab shows transverse full-length cracks at trench-slab connections, longitudinal cracks, and blow-off. The side walls and internal partitions of the caisson wharf sustain relatively minor damage. Shock wave within the caisson subjected to underwater contact and near-field explosions undergo reflection and transmission at the interfaces between the partitions and fillings within the compartments. The blast-facing wall and side walls of the wharf are subjected to shock loads. The transmitted compressive waves across the transverse bulkheads and blast-resistant back walls exhibited amplification compared to the incident waves, whereas attenuation was observed as the waves traversed the sand-filled compartments. Numerical simulation results revealed that the shock wave load within the caisson undergoes a decay rate that transitions from rapid to gradual. Damage characteristics of caisson wharf is primarily shaped during the underwater explosion shockwave phase. Neglecting large-scale macroscopic movements such as uplift and scattering post panel failure, the damage formation time slightly exceeds twice the shockwave propagation duration through the structure.
To investigate the damage mechanism and load characteristics of caisson wharf under underwater contact and near-field explosion, a high-fidelity numerical model was conducted based on the scaled model tests of caisson wharf and verified by comparing the simulation results with the experimental data. The propagation and attenuation characteristics of shock waves inside the caisson, partition walls, and internal backfill soil were analyzed. The destruction process and typical damage mechanisms of the caisson wharf were analyzed by comparing Holmquist‒Johnson‒Cook constitutive model damage contour maps with experimental results. The results shows that the damage areas and characteristics of the caisson wharf are largely consistent under both underwater contact and near-field explosion. The primary damage areas are blast-facing wall and deck slab. The blast-facing wall exhibits cratering and breaching phenomena, while of the deck slab shows transverse full-length cracks at trench-slab connections, longitudinal cracks, and blow-off. The side walls and internal partitions of the caisson wharf sustain relatively minor damage. Shock wave within the caisson subjected to underwater contact and near-field explosions undergo reflection and transmission at the interfaces between the partitions and fillings within the compartments. The blast-facing wall and side walls of the wharf are subjected to shock loads. The transmitted compressive waves across the transverse bulkheads and blast-resistant back walls exhibited amplification compared to the incident waves, whereas attenuation was observed as the waves traversed the sand-filled compartments. Numerical simulation results revealed that the shock wave load within the caisson undergoes a decay rate that transitions from rapid to gradual. Damage characteristics of caisson wharf is primarily shaped during the underwater explosion shockwave phase. Neglecting large-scale macroscopic movements such as uplift and scattering post panel failure, the damage formation time slightly exceeds twice the shockwave propagation duration through the structure.
, Available online , doi: 10.11883/bzycj-2024-0471
Abstract:
To accurately predict the explosion power fields in buildings, solving the failure of traditional empirical formulas often failing to account for complex environmental factor due to their inability to account for complex environmental factors, and that of numerical simulations inefficient for large-scale urban scenarios and do not meet the needs of rapid damage assessment. Addressing this challenge, an innovative prediction model for explosion power fields based on Graph Neural Networks (GNN) was constructed using an end-to-end strategy. This model enabled rapid and precise forecasting of three-dimensional physical fields, including peak overpressure, peak impulse, and shock-wave arrival times on building surfaces. Compared to numerical simulations, the proposed GNN model demonstrated excellent predictive performance: it achieved a mean square error of 0.97% for predicting surface overpressure parameters of single buildings with varying geometries, and an average prediction error of 3.17% for complex geometric buildings and building communities. When applied to real-world urban settings, the model maintains an average prediction error of 1.29%, completing individual physical field predictions in under 0.6 seconds—three to four orders of magnitude faster than numerical simulations. Furthermore, the model's high-precision predictions allow for the reconstruction of overpressure time history curves at any building surface location and the accurate assessment of structural damage. The proposed GNN model offers a novel approach for rapidly and accurately predicting explosion power fields in urban buildings during blast events. This advancement significantly enhances the capabilities for explosion damage assessment and anti-explosion design in ultra-large-scale complex engineering scenarios, providing substantial engineering value.
To accurately predict the explosion power fields in buildings, solving the failure of traditional empirical formulas often failing to account for complex environmental factor due to their inability to account for complex environmental factors, and that of numerical simulations inefficient for large-scale urban scenarios and do not meet the needs of rapid damage assessment. Addressing this challenge, an innovative prediction model for explosion power fields based on Graph Neural Networks (GNN) was constructed using an end-to-end strategy. This model enabled rapid and precise forecasting of three-dimensional physical fields, including peak overpressure, peak impulse, and shock-wave arrival times on building surfaces. Compared to numerical simulations, the proposed GNN model demonstrated excellent predictive performance: it achieved a mean square error of 0.97% for predicting surface overpressure parameters of single buildings with varying geometries, and an average prediction error of 3.17% for complex geometric buildings and building communities. When applied to real-world urban settings, the model maintains an average prediction error of 1.29%, completing individual physical field predictions in under 0.6 seconds—three to four orders of magnitude faster than numerical simulations. Furthermore, the model's high-precision predictions allow for the reconstruction of overpressure time history curves at any building surface location and the accurate assessment of structural damage. The proposed GNN model offers a novel approach for rapidly and accurately predicting explosion power fields in urban buildings during blast events. This advancement significantly enhances the capabilities for explosion damage assessment and anti-explosion design in ultra-large-scale complex engineering scenarios, providing substantial engineering value.
, Available online , doi: 10.11883/bzycj-2024-0213
Abstract:
Two kinds of structural projectiles made of two different materials were designed in this paper. An experimental study of 11kg projectiles penetrating the reinforced concrete target at 1400m/s was carried out using a 203mm Davis gun. Based on the experimental results, the structural response, penetration capability and related engineering issues of the projectile are discussed. The results show that when the reinforced concrete target is penetrated at a velocity of1400 m/s, the heads of projectiles made of two different materials experienced erosion and were mushroomed. This was caused by high temperatures resulting from friction between the projectile and the concrete during penetration, which significantly softened the surface of the projectile. Furthermore, the contact pressure between the projectile and the target exceeded the yield strength of the projectile material near the surface, causing the material to enter a state of plastic flow and ultimately leading to the erosion and mushrooming of the projectile head. Additionally, the surface material of the projectile was stripped due to the cutting action of the hard aggregates in the concrete, resulting in severe abrasion of the projectile body. When comparing the structural responses of projectiles made of different materials, it was evident that material properties influenced their behavior. Compared to 30CrMnSiNi2MoVE, DT1900, known for its higher strength, hardness and better resistance to impact compression, showed less erosion at the projectile head. However, the inferior shear resistance and wear resistance of DT1900 led to severe abrasion on the projectile body. The mass loss pattern of a conical projectile is different from that of a solid long-rod projectile, with the latter concentrated mainly in the projectile body. The conical flared tail design, while suppressing ballistic deflection, increased the contact area between the projectile body and the target, enhancing the abrasive and cutting actions of aggregates and steel. Moreover, under high-speed penetration conditions, the erosion and mushrooming of the projectile head could reduce the penetration depth; the less erosion at the head, the greater the penetration depth. In experiments, the maximum penetration depth of DT1900 projectiles could reach up to nine times the length of the projectile.
Two kinds of structural projectiles made of two different materials were designed in this paper. An experimental study of 11kg projectiles penetrating the reinforced concrete target at 1400m/s was carried out using a 203mm Davis gun. Based on the experimental results, the structural response, penetration capability and related engineering issues of the projectile are discussed. The results show that when the reinforced concrete target is penetrated at a velocity of
, Available online , doi: 10.11883/bzycj-2024-0446
Abstract:
Experimental investigation of internal explosion effects on ship structures still faces fundamental challenges. The prohibitively high costs of specialized naval steel plates impose disproportionate financial burdens on experimental budgets. Additionally, the restricted availability of standardized thickness variants has dimensional scaling conflicts during reduced-scale internal explosion experiments. This research proposes an equivalent substitution method for scaled model testing. The methodology enables a strategic replacement of naval steel with conventional steel while maintaining response similitude during the internal explosion of ship structures. The primary research objective focuses on validating the equivalent substitution method for conventional steel as a replacement for specialized naval steel without degrading the accuracy of the recorded data. According to the principle of central deformation similarity, the equivalence relationship among target plates of different grades was established under the assumption of structural integrity during the explosion. Based on the theory of large deflection of thin plates, the relationship between plate thickness and deformation was clarified thoroughly. An equivalence substitution method for different plate grades was explained, and an equivalence substitution method for different plates was proposed. It provides a theoretical foundation for substituting specialized naval steel with conventional steel. Comprehensive numerical simulations were conducted using the finite element analysis software AUTODYN to validate the proposed method. The simulations modeled the dynamic response of four different grades of steel target plates (921A steel, 907A steel, Q235 steel, and Q355 steel) under internal blast loading. The maximum deviation between the simulation results and experimental data is only 5.6%, thereby fully confirming the accuracy and reliability of the numerical model. The equivalence relationships among grades under internal blast loading with different charge volume ratios (0.1, 0.2, 0.4, 0.8, and 1.0) were further explored through extensive numerical simulations involving four plates grades (Q235, Q355, 907A, and 921A) with various thicknesses. A fitting analysis of equivalent plate thickness was conducted. By integrating empirical formulas correlating equivalent plate thickness with dynamic yield strength, the substituted target plate showed less than 10% deviation in central deformation compared to the original plate. The proposed equivalence method for steel target plates of different grades under internal explosion loads has been demonstrated to be both rational and practically applicable. This provides a theoretical foundation and empirical reference for substituting specialized naval steel with ordinary steel in internal explosion experiments.
Experimental investigation of internal explosion effects on ship structures still faces fundamental challenges. The prohibitively high costs of specialized naval steel plates impose disproportionate financial burdens on experimental budgets. Additionally, the restricted availability of standardized thickness variants has dimensional scaling conflicts during reduced-scale internal explosion experiments. This research proposes an equivalent substitution method for scaled model testing. The methodology enables a strategic replacement of naval steel with conventional steel while maintaining response similitude during the internal explosion of ship structures. The primary research objective focuses on validating the equivalent substitution method for conventional steel as a replacement for specialized naval steel without degrading the accuracy of the recorded data. According to the principle of central deformation similarity, the equivalence relationship among target plates of different grades was established under the assumption of structural integrity during the explosion. Based on the theory of large deflection of thin plates, the relationship between plate thickness and deformation was clarified thoroughly. An equivalence substitution method for different plate grades was explained, and an equivalence substitution method for different plates was proposed. It provides a theoretical foundation for substituting specialized naval steel with conventional steel. Comprehensive numerical simulations were conducted using the finite element analysis software AUTODYN to validate the proposed method. The simulations modeled the dynamic response of four different grades of steel target plates (921A steel, 907A steel, Q235 steel, and Q355 steel) under internal blast loading. The maximum deviation between the simulation results and experimental data is only 5.6%, thereby fully confirming the accuracy and reliability of the numerical model. The equivalence relationships among grades under internal blast loading with different charge volume ratios (0.1, 0.2, 0.4, 0.8, and 1.0) were further explored through extensive numerical simulations involving four plates grades (Q235, Q355, 907A, and 921A) with various thicknesses. A fitting analysis of equivalent plate thickness was conducted. By integrating empirical formulas correlating equivalent plate thickness with dynamic yield strength, the substituted target plate showed less than 10% deviation in central deformation compared to the original plate. The proposed equivalence method for steel target plates of different grades under internal explosion loads has been demonstrated to be both rational and practically applicable. This provides a theoretical foundation and empirical reference for substituting specialized naval steel with ordinary steel in internal explosion experiments.
, Available online , doi: 10.11883/bzycj-2025-0027
Abstract:
The quasi-static pressure thermodynamic model for confined explosions provides an effective characterization of pressure evolution with mass-to-volume ratio m/V, and derivation of physical quantities such as gas adiabatic index from products and temperature. However, the thermodynamic model based on detonation and combustion equations that neglects reaction equilibrium demonstrates growing deviations from the quasi-static pressure curve in UFC 3-340-02 blast-resistant design standard after carbon precipitates in detonation products, and existing research inadequately addresses the necessity of incorporating reaction equilibrium for various physical quantities in TNT confined explosion thermodynamic models. In order to investigate the influence of reaction equilibrium on thermodynamic calculation results, the model neglecting reaction equilibrium was modified based on the energy conservation equation of isochoric processes and the solid carbon precipitation phenomenon. The modified model has a consistency with the UFC curve for m/V≥0.371 kg/m3. Then, a comparative analysis was conducted on the results of thermodynamic models considering and not considering the reaction equilibrium based on the unified solution framework. The results indicate that incorporating chemical equilibrium into quasi-static pressure calculation introduces a maximum relative deviation below 20%, and critical thresholds alters, i.e., the m/V for carbon precipitation shifts from 0.371 to 3.850 kg/m3, and peak temperature transitions from 0.371 to 0.680 kg/m3. Significant divergence in mole numbers of product composition emerges progressively when m/V exceeds 0.1 kg/m3. Therefore, the reaction equilibrium-based thermodynamic model is a more rational choice for calculating quantities related to components and temperature in TNT confined explosions with m/V>0.1 kg/m3. Finally, a simplified calculation method for products, temperature, and pressure during the quasi-static phase of TNT confined explosions considering reaction equilibrium is proposed based on symbolic regression algorithm. The research contributes to a theoretical understanding of equilibrium effects on thermodynamic model results and the practical implementation of rapid parameter estimation in TNT confined explosion scenarios.
The quasi-static pressure thermodynamic model for confined explosions provides an effective characterization of pressure evolution with mass-to-volume ratio m/V, and derivation of physical quantities such as gas adiabatic index from products and temperature. However, the thermodynamic model based on detonation and combustion equations that neglects reaction equilibrium demonstrates growing deviations from the quasi-static pressure curve in UFC 3-340-02 blast-resistant design standard after carbon precipitates in detonation products, and existing research inadequately addresses the necessity of incorporating reaction equilibrium for various physical quantities in TNT confined explosion thermodynamic models. In order to investigate the influence of reaction equilibrium on thermodynamic calculation results, the model neglecting reaction equilibrium was modified based on the energy conservation equation of isochoric processes and the solid carbon precipitation phenomenon. The modified model has a consistency with the UFC curve for m/V≥0.371 kg/m3. Then, a comparative analysis was conducted on the results of thermodynamic models considering and not considering the reaction equilibrium based on the unified solution framework. The results indicate that incorporating chemical equilibrium into quasi-static pressure calculation introduces a maximum relative deviation below 20%, and critical thresholds alters, i.e., the m/V for carbon precipitation shifts from 0.371 to 3.850 kg/m3, and peak temperature transitions from 0.371 to 0.680 kg/m3. Significant divergence in mole numbers of product composition emerges progressively when m/V exceeds 0.1 kg/m3. Therefore, the reaction equilibrium-based thermodynamic model is a more rational choice for calculating quantities related to components and temperature in TNT confined explosions with m/V>0.1 kg/m3. Finally, a simplified calculation method for products, temperature, and pressure during the quasi-static phase of TNT confined explosions considering reaction equilibrium is proposed based on symbolic regression algorithm. The research contributes to a theoretical understanding of equilibrium effects on thermodynamic model results and the practical implementation of rapid parameter estimation in TNT confined explosion scenarios.
, Available online , doi: 10.11883/bzycj-2024-0435
Abstract:
During the underwater launch of multiple projectiles, each projectile operates within a highly complex and dynamic flow field, where its trajectory deflection is influenced by a combination of factors. These factors include initial conditions such as the projectile’s velocity and the presence of crossflow, as well as the mutual interference effects among the projectiles. To gain a deeper understanding of the cavitation evolution and trajectory interference characteristics during the underwater launch of multiple projectiles, this study develops a comprehensive numerical simulation model. The model integrates the overlapping grid technique and the finite volume method and is coupled with a six-degree-of-freedom(6-DOF) motion model. Through this model, the influence mechanisms of spatial arrangement, launch velocity, and crossflow on trajectory deflection are systematically analyzed. The results of this study reveal several important findings. First, the spatial arrangement of the projectiles has a relatively minor impact on trajectory deflection. An equilateral triangular configuration is found to be an optimal choice for practical applications, as it maximizes the efficient utilization of the launch space. Second, as the launch velocity increases, the wake interference between projectiles becomes more pronounced. This intensified interference leads to significant disturbances in the flow field and stronger mutual trajectory interference among the projectiles. Third, higher crossflow velocities exacerbate the asymmetric development of cavitation near the projectile shoulders. When the crossflow velocity exceeds 0.75 m/s, it becomes the dominant factor influencing trajectory deflection. These research findings provide a robust theoretical foundation for trajectory prediction and layout optimization in the underwater launch of multiple projectiles.
During the underwater launch of multiple projectiles, each projectile operates within a highly complex and dynamic flow field, where its trajectory deflection is influenced by a combination of factors. These factors include initial conditions such as the projectile’s velocity and the presence of crossflow, as well as the mutual interference effects among the projectiles. To gain a deeper understanding of the cavitation evolution and trajectory interference characteristics during the underwater launch of multiple projectiles, this study develops a comprehensive numerical simulation model. The model integrates the overlapping grid technique and the finite volume method and is coupled with a six-degree-of-freedom(6-DOF) motion model. Through this model, the influence mechanisms of spatial arrangement, launch velocity, and crossflow on trajectory deflection are systematically analyzed. The results of this study reveal several important findings. First, the spatial arrangement of the projectiles has a relatively minor impact on trajectory deflection. An equilateral triangular configuration is found to be an optimal choice for practical applications, as it maximizes the efficient utilization of the launch space. Second, as the launch velocity increases, the wake interference between projectiles becomes more pronounced. This intensified interference leads to significant disturbances in the flow field and stronger mutual trajectory interference among the projectiles. Third, higher crossflow velocities exacerbate the asymmetric development of cavitation near the projectile shoulders. When the crossflow velocity exceeds 0.75 m/s, it becomes the dominant factor influencing trajectory deflection. These research findings provide a robust theoretical foundation for trajectory prediction and layout optimization in the underwater launch of multiple projectiles.
, Available online , doi: 10.11883/bzycj-2024-0443
Abstract:
Supercritical CO2 phase transition rock-breaking is a dynamic destruction process under the combined action of shock waves and high-pressure gas. To deeply investigate the rock-breaking mechanisms of supercritical CO2 phase transition under multi-hole synchronous initiation and in-situ stress coupling conditions, targeting the actual working conditions of CO2 field rock-breaking, the initial rock-breaking pressure of a single hole was analyzed based on the thin-walled cylinder theory. A predictive model for the joint rock-breaking radius of multi-hole shock waves and high-pressure gas under in-situ stress was developed by integrating the one-dimensional detonation gas expansion theory. Field experiments on multi-hole CO2 phase transition rock-breaking were subsequently conducted for comparative validation. The results show that when the fracturing pipe is buried shallowly, the influence of in-situ stress on the stress distribution of the rock mass is relatively weak. When the pressure of a single hole is consistent, the more fracturing holes there are, the greater the superposed peak stress of each hole. In the direction perpendicular to the layout of the test hole, the peak stress of each hole shows a U-shaped parabolic distribution. The superposed stress of the fracturing holes at both ends is the largest. In the direction parallel to the layout of the test hole, the peak stress of each hole shows an inverted U-shaped parabolic distribution, and the superposed stress of the middle fracturing hole is the largest. In addition, the rock mass damage and fracture range under multi-pore impact obtained by acoustic wave testing in the field is in the shape of a three-dimensional funnel. The vertical damage and fracture range is between 5.05 and 5.73 m, and the planar damage and fracture range is between 4.3 and 5.6 m. The error between the measured value of the planar damage and fracture range and the theoretically calculated value is between 5.0% and 18.7%. The calculation error mainly comes from the uneven superposition stress of each fracturing hole. Further analysis shows that the radius of supercritical CO2 phase transition rock-breaking increases semi-parabolically with the superposed stress of the fracturing hole and increases logarithmically with the depth of the fracturing hole. As the compressive strength of the rock mass increases, the rock fracture toughness increases nearly linearly, and the corresponding rock-breaking radius decreases nearly linearly. The research results can provide a quantitative design basis for optimizing engineering parameters in the multi-pore supercritical CO2 phase transition for rock-breaking.
Supercritical CO2 phase transition rock-breaking is a dynamic destruction process under the combined action of shock waves and high-pressure gas. To deeply investigate the rock-breaking mechanisms of supercritical CO2 phase transition under multi-hole synchronous initiation and in-situ stress coupling conditions, targeting the actual working conditions of CO2 field rock-breaking, the initial rock-breaking pressure of a single hole was analyzed based on the thin-walled cylinder theory. A predictive model for the joint rock-breaking radius of multi-hole shock waves and high-pressure gas under in-situ stress was developed by integrating the one-dimensional detonation gas expansion theory. Field experiments on multi-hole CO2 phase transition rock-breaking were subsequently conducted for comparative validation. The results show that when the fracturing pipe is buried shallowly, the influence of in-situ stress on the stress distribution of the rock mass is relatively weak. When the pressure of a single hole is consistent, the more fracturing holes there are, the greater the superposed peak stress of each hole. In the direction perpendicular to the layout of the test hole, the peak stress of each hole shows a U-shaped parabolic distribution. The superposed stress of the fracturing holes at both ends is the largest. In the direction parallel to the layout of the test hole, the peak stress of each hole shows an inverted U-shaped parabolic distribution, and the superposed stress of the middle fracturing hole is the largest. In addition, the rock mass damage and fracture range under multi-pore impact obtained by acoustic wave testing in the field is in the shape of a three-dimensional funnel. The vertical damage and fracture range is between 5.05 and 5.73 m, and the planar damage and fracture range is between 4.3 and 5.6 m. The error between the measured value of the planar damage and fracture range and the theoretically calculated value is between 5.0% and 18.7%. The calculation error mainly comes from the uneven superposition stress of each fracturing hole. Further analysis shows that the radius of supercritical CO2 phase transition rock-breaking increases semi-parabolically with the superposed stress of the fracturing hole and increases logarithmically with the depth of the fracturing hole. As the compressive strength of the rock mass increases, the rock fracture toughness increases nearly linearly, and the corresponding rock-breaking radius decreases nearly linearly. The research results can provide a quantitative design basis for optimizing engineering parameters in the multi-pore supercritical CO2 phase transition for rock-breaking.
, Available online , doi: 10.11883/bzycj-2024-0252
Abstract:
To investigate the explosive energy release of Zr-based reactive material (Zr-RM) casings and the ignition effect of fragments driven by the explosion on fuel, casings composed primarily of zirconium (Zr), copper (Cu), nickel (Ni), aluminum (Al), and ytterbium (Y) were fabricated using alloy melting and casting techniques. The casings mentioned above had an outer diameter of 40 mm, a height of 80 mm, and a wall thickness of 5 mm. For comparison of subsequent damage effects, steel casings made of 45 steel with the same dimensions and mass were also prepared. Both types of casings were filled with JH-2 explosive charges. The charged structures were placed on a polyvinyl chloride pipe stand 1.5 m above the ground, and a fuel box containing 2.5 L of gasoline was positioned 2.0 m away from the explosion center. During the explosion-driven tests, a high-speed camera was utilized to capture the formation and propagation of the explosion fireball, the shockwave, and the impact process of casing fragments on the fuel tank. The fireball duration, shockwave velocity, and fragment impact effects were measured and analyzed. Additionally, the ignition and destruction effects of the fragments on the fuel were observed and recorded. The experimental results demonstrate that, when compared to steel casings of equal mass, Zr-RM casings under explosion-driven conditions exhibit a longer duration of firelight and faster shockwave velocities. Specifically, the fireball duration of Zr-RM casings is approximately 25.84 times that of steel casings, and the shockwave velocity is roughly 1.17 times faster. Zr-RM casings exhibit an enhancement effect on air shockwaves under explosion-driven conditions. Fragments of different materials cause structural damage to fuel tanks, including perforation and plastic deformation. After piercing the fuel tank, the reactive material ignites the fuel inside, demonstrating the ability to ignite gasoline. On the contrary, steel casings of equal mass do not ignite the fuel within the tank. This research provides a reference for the application of Zr-RM casing warheads.
To investigate the explosive energy release of Zr-based reactive material (Zr-RM) casings and the ignition effect of fragments driven by the explosion on fuel, casings composed primarily of zirconium (Zr), copper (Cu), nickel (Ni), aluminum (Al), and ytterbium (Y) were fabricated using alloy melting and casting techniques. The casings mentioned above had an outer diameter of 40 mm, a height of 80 mm, and a wall thickness of 5 mm. For comparison of subsequent damage effects, steel casings made of 45 steel with the same dimensions and mass were also prepared. Both types of casings were filled with JH-2 explosive charges. The charged structures were placed on a polyvinyl chloride pipe stand 1.5 m above the ground, and a fuel box containing 2.5 L of gasoline was positioned 2.0 m away from the explosion center. During the explosion-driven tests, a high-speed camera was utilized to capture the formation and propagation of the explosion fireball, the shockwave, and the impact process of casing fragments on the fuel tank. The fireball duration, shockwave velocity, and fragment impact effects were measured and analyzed. Additionally, the ignition and destruction effects of the fragments on the fuel were observed and recorded. The experimental results demonstrate that, when compared to steel casings of equal mass, Zr-RM casings under explosion-driven conditions exhibit a longer duration of firelight and faster shockwave velocities. Specifically, the fireball duration of Zr-RM casings is approximately 25.84 times that of steel casings, and the shockwave velocity is roughly 1.17 times faster. Zr-RM casings exhibit an enhancement effect on air shockwaves under explosion-driven conditions. Fragments of different materials cause structural damage to fuel tanks, including perforation and plastic deformation. After piercing the fuel tank, the reactive material ignites the fuel inside, demonstrating the ability to ignite gasoline. On the contrary, steel casings of equal mass do not ignite the fuel within the tank. This research provides a reference for the application of Zr-RM casing warheads.
, Available online , doi: 10.11883/bzycj-2025-0154
Abstract:
Gas leakage and explosion accidents pose a serious threat to public safety. A critical prerequisite for accurately predicting the explosive effects of combustible gas leakage lies in determining the concentration distribution following the leakage. To develop a real-time, full-field spatiotemporal prediction model for combustible gas leakage and diffusion, and to achieve efficient prediction of the equivalent gas cloud volume, a novel graph neural network model based on a dual-neural-network architecture and a multi-stage training strategy, named multi-stage dual graph neural network (MSDGNN), was proposed. The MSDGNN model consists of two synergistic sub-networks: (1) a concentration network (Ncon), which establishes the mapping relationship between the concentration fields of two consecutive timesteps, and (2) a volume network (Nvol), which generates the equivalent gas cloud volume at each timestep to provide a quantitative metric for explosion risk assessment. To further enhance model performance, a multi-stage progressive training strategy was developed to jointly optimize the dual networks. Experimental results demonstrate that compared with mesh-based graph network (MGN), the dual-network architecture effectively decouples the tasks of concentration field prediction and equivalent gas cloud volume prediction. This approach significantly mitigates the interference of weight factors in single-objective loss functions during the training process. The multi-stage training strategy, through stepwise parameter optimization, addresses the issue of insufficient data fitting encountered in traditional methods, significantly reducing the mean absolute percentage error\begin{document}$ {{ \varepsilon }}_{\rm{MAPE}} $\end{document} ![]()
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Gas leakage and explosion accidents pose a serious threat to public safety. A critical prerequisite for accurately predicting the explosive effects of combustible gas leakage lies in determining the concentration distribution following the leakage. To develop a real-time, full-field spatiotemporal prediction model for combustible gas leakage and diffusion, and to achieve efficient prediction of the equivalent gas cloud volume, a novel graph neural network model based on a dual-neural-network architecture and a multi-stage training strategy, named multi-stage dual graph neural network (MSDGNN), was proposed. The MSDGNN model consists of two synergistic sub-networks: (1) a concentration network (Ncon), which establishes the mapping relationship between the concentration fields of two consecutive timesteps, and (2) a volume network (Nvol), which generates the equivalent gas cloud volume at each timestep to provide a quantitative metric for explosion risk assessment. To further enhance model performance, a multi-stage progressive training strategy was developed to jointly optimize the dual networks. Experimental results demonstrate that compared with mesh-based graph network (MGN), the dual-network architecture effectively decouples the tasks of concentration field prediction and equivalent gas cloud volume prediction. This approach significantly mitigates the interference of weight factors in single-objective loss functions during the training process. The multi-stage training strategy, through stepwise parameter optimization, addresses the issue of insufficient data fitting encountered in traditional methods, significantly reducing the mean absolute percentage error
, Available online , doi: 10.11883/bzycj-2024-0273
Abstract:
Prestressed reinforced concrete (RC) T-beam bridges are commonly employed in highway bridges construction. After explosive attacks, the deck damage mostly exists in the form of breaches and affects its traffic capacity. While significant attention has been devoted to evaluating post-blast residual capacity of RC beam bridge piers and girders in existing blast damage assessment studies, there remains a critical gap in methodologies enabling intuitive and rapid damage assessment method for bridge serviceability. Therefore, the rapid assessment of bridge deck damage is investigated in this study by combining numerical simulation with multivariate nonlinear regression analysis, in which the breach size of the prestressed RC T-beam bridge deck subjected to explosive loading is taken as the damage index. Through comparative analysis of the transverse size of the deck breach under blast loading, it was revealed that concrete strength exhibits relatively minor influence, whereas parameters including explosion location, deck thickness, diaphragm spacing, TNT equivalent, and scaled distance demonstrate more pronounced effects. Owing to the pronounced reinforcing and constraining effects of webs and diaphragms on the bridge deck, comparative analyses under identical conditions demonstrate that transverse size of the breach caused by explosion above deck areas between webs and diaphragms is significantly smaller than that by explosion directly above the web, while on-bridge explosion exhibit lower damage compared to under-bridge explosion. Based upon the aforementioned parameters with significant influence, utilizing transverse size of the breach as the damage index, a rapid blast damage assessment formula is proposed for predicting the post-blast traffic capacity of bridges.
Prestressed reinforced concrete (RC) T-beam bridges are commonly employed in highway bridges construction. After explosive attacks, the deck damage mostly exists in the form of breaches and affects its traffic capacity. While significant attention has been devoted to evaluating post-blast residual capacity of RC beam bridge piers and girders in existing blast damage assessment studies, there remains a critical gap in methodologies enabling intuitive and rapid damage assessment method for bridge serviceability. Therefore, the rapid assessment of bridge deck damage is investigated in this study by combining numerical simulation with multivariate nonlinear regression analysis, in which the breach size of the prestressed RC T-beam bridge deck subjected to explosive loading is taken as the damage index. Through comparative analysis of the transverse size of the deck breach under blast loading, it was revealed that concrete strength exhibits relatively minor influence, whereas parameters including explosion location, deck thickness, diaphragm spacing, TNT equivalent, and scaled distance demonstrate more pronounced effects. Owing to the pronounced reinforcing and constraining effects of webs and diaphragms on the bridge deck, comparative analyses under identical conditions demonstrate that transverse size of the breach caused by explosion above deck areas between webs and diaphragms is significantly smaller than that by explosion directly above the web, while on-bridge explosion exhibit lower damage compared to under-bridge explosion. Based upon the aforementioned parameters with significant influence, utilizing transverse size of the breach as the damage index, a rapid blast damage assessment formula is proposed for predicting the post-blast traffic capacity of bridges.
, Available online , doi: 10.11883/bzycj-2024-0388
Abstract:
In a reinforced concrete (RC) box structure, the dissipation of blast waves is restricted, and damage to the structure can be intensified due to multiple reflections. To thoroughly investigate the load characteristics and dynamic behavior of internal explosions in an RC box structure, the applicability of the finite element method was verified by replicating internal explosion tests on fully enclosed and semi-enclosed (with venting openings) RC box structures. Based on this, numerical simulations of internal explosions were conducted for the prototypical RC box structure and the type of terrorist bombing attacks specified by the Federal Emergency Management Agency (FEMA) under three explosion scenarios and four venting areas. The influence of venting area on the load characteristics at the inner surfaces and corners, the load distribution on the inner surfaces, and the time histories of displacement and velocity at the centers of the inner surfaces under internal explosion loads were explored. Additionally, a formula for calculating the total impulse of the structure’s inner surface was proposed, considering both the venting area and the spatial distribution of the impulse. The results show that the venting area has a negligible effect on the overpressure, while the impulse decreases exponentially with increasing venting area. The load distribution characteristics on the structure’s inner surface are significantly influenced by the structural dimensions, exhibiting an “indented” or “W” pattern. The maximum displacement at the centers of walls and slabs is reduced by about 50% as the venting coefficient changes from 0.457 to 1.220. Finally, based on the total impulse and maximum displacement response of each component under free-field explosion loads, a calculation method for the impulse and damage enhancement coefficient was proposed based on the venting area, effectively predicting the internal explosion load and the structure’s dynamic behavior at various venting coefficients.
In a reinforced concrete (RC) box structure, the dissipation of blast waves is restricted, and damage to the structure can be intensified due to multiple reflections. To thoroughly investigate the load characteristics and dynamic behavior of internal explosions in an RC box structure, the applicability of the finite element method was verified by replicating internal explosion tests on fully enclosed and semi-enclosed (with venting openings) RC box structures. Based on this, numerical simulations of internal explosions were conducted for the prototypical RC box structure and the type of terrorist bombing attacks specified by the Federal Emergency Management Agency (FEMA) under three explosion scenarios and four venting areas. The influence of venting area on the load characteristics at the inner surfaces and corners, the load distribution on the inner surfaces, and the time histories of displacement and velocity at the centers of the inner surfaces under internal explosion loads were explored. Additionally, a formula for calculating the total impulse of the structure’s inner surface was proposed, considering both the venting area and the spatial distribution of the impulse. The results show that the venting area has a negligible effect on the overpressure, while the impulse decreases exponentially with increasing venting area. The load distribution characteristics on the structure’s inner surface are significantly influenced by the structural dimensions, exhibiting an “indented” or “W” pattern. The maximum displacement at the centers of walls and slabs is reduced by about 50% as the venting coefficient changes from 0.457 to 1.220. Finally, based on the total impulse and maximum displacement response of each component under free-field explosion loads, a calculation method for the impulse and damage enhancement coefficient was proposed based on the venting area, effectively predicting the internal explosion load and the structure’s dynamic behavior at various venting coefficients.
, Available online , doi: 10.11883/bzycj-2024-0411
Abstract:
In order to address the needs of modern combat vehicles for both personnel protection and lightweight design, optimizing their blast-resistant structures is necessary. Due to the high cost of physical experiments, finite element simulation has been commonly used instead. However, simulations of explosion and vehicle responses require extensive computational resources and incur high computational costs, leading to limited data availability for the optimization of explosion-proof structures. Since structural optimization demands sufficient data support, larger amount of valid data can improve the accuracy of the surrogate model and the precision of the optimal solution, yielding better optimization results. To overcome these challenges, a data-driven optimization method for vehicle’s explosion-proof structures was proposed, integrating data augmentation and semi-supervised regression. To address the limitations of generative adversarial networks (GANs) in handling numerical data, an improved model, a Gaussian density estimation-Wasserstein generative adversarial network (GDE-WGAN), was developed by modifying both the generator and discriminator of the WGAN model, a variant of the GANs. The feasibility of the proposed method was demonstrated based on the principle of information gain. The data generated by the GDE-WGAN were incorporated into a self-training framework, where an adaptive confidence assessment mechanism dynamically adjusted the way that the semi-supervised support vector regression model utilizes the generated data. The feasibility and superiority of the method were validated by comparing the enhanced performance of the semi-supervised regression model using different numerical data expansion techniques. Finally, multi-objective optimization was performed to obtain the optimal solutions of the data-augmented semi-supervised regression model and the initial model, followed by verification and comparison with finite element simulation results. It shows that the GDE-WGAN significantly enhances the performance of the semi-supervised regression model, and the generated data exhibit greater randomness and diversity through the network structure of the GANs, which benefits semi-supervised learning. When handling semi-supervised regression for high-dimensional nonlinear numerical data, both global and local data distribution similarities play a crucial role. Furthermore, finite element simulations indicate that the improved model predicts results more accurately than the initial model and achieves superior optimization outcomes.
In order to address the needs of modern combat vehicles for both personnel protection and lightweight design, optimizing their blast-resistant structures is necessary. Due to the high cost of physical experiments, finite element simulation has been commonly used instead. However, simulations of explosion and vehicle responses require extensive computational resources and incur high computational costs, leading to limited data availability for the optimization of explosion-proof structures. Since structural optimization demands sufficient data support, larger amount of valid data can improve the accuracy of the surrogate model and the precision of the optimal solution, yielding better optimization results. To overcome these challenges, a data-driven optimization method for vehicle’s explosion-proof structures was proposed, integrating data augmentation and semi-supervised regression. To address the limitations of generative adversarial networks (GANs) in handling numerical data, an improved model, a Gaussian density estimation-Wasserstein generative adversarial network (GDE-WGAN), was developed by modifying both the generator and discriminator of the WGAN model, a variant of the GANs. The feasibility of the proposed method was demonstrated based on the principle of information gain. The data generated by the GDE-WGAN were incorporated into a self-training framework, where an adaptive confidence assessment mechanism dynamically adjusted the way that the semi-supervised support vector regression model utilizes the generated data. The feasibility and superiority of the method were validated by comparing the enhanced performance of the semi-supervised regression model using different numerical data expansion techniques. Finally, multi-objective optimization was performed to obtain the optimal solutions of the data-augmented semi-supervised regression model and the initial model, followed by verification and comparison with finite element simulation results. It shows that the GDE-WGAN significantly enhances the performance of the semi-supervised regression model, and the generated data exhibit greater randomness and diversity through the network structure of the GANs, which benefits semi-supervised learning. When handling semi-supervised regression for high-dimensional nonlinear numerical data, both global and local data distribution similarities play a crucial role. Furthermore, finite element simulations indicate that the improved model predicts results more accurately than the initial model and achieves superior optimization outcomes.
, Available online , doi: 10.11883/bzycj-2025-0134
Abstract:
To explore the anti-penetration abilities of irregular structures made of high-strength alloy steel, a target enhanced with ultra-high-strength spherical structures (UHS-SS) was manufactured in this work. The UHS-SS is fabricated from ultra-high-strength steel (UHSS) and mechanically anchored to the target via threaded high-tensile rods, ensuring structural integrity under projectile penetration loading. A series of penetration tests at an impact velocity of 400 m/s was performed using a 125 mm diameter cannon. The yaw-induced projectile deflection was recorded at5000 s−1, and the failure mode and penetration depth of the projectile were obtained. Through a comparative analysis of anti-penetration experimental results between semi-infinite concrete targets and UHS-SS-reinforced targets, the influences of ultra-high mechanical performances and the spherical yaw-inducing structure on the deflection and fragmentation of the projectile were disclosed. The test results reveal that at a penetration velocity of 400 m/s, the dimensionless penetration depth of the UHS-SS target is 0.11, and the penetration resistance of the UHS-SS target is about 9 times that of C40 concrete. The anti-penetration performance of UHS-SS is significantly enhanced in comparison to that of the ordinary concrete target. Furthermore, as the projectile penetrates the UHS-SS target, the resultant force on the projectile is in a different direction from that of the projectile velocity, which can deflect and shatter the projectile. The behavior of ricocheting off the surface, deflection-induced secondary impact, and fragmentation of the projectile occurred during the anti-penetration test of the UHS-SS target, and the maximal deflection angle was 83º during the experiment, preventing the projectile from penetrating the interior of the protective structure. The UHS-SS target has a severe erosion effect on the projectile at a lower speed of 400m/s, which resulted in a mass loss rate of 23.66% in the experiment. Therefore, the risk of a ground-penetrating weapon penetrating the protective works and detonating is significantly reduced．
To explore the anti-penetration abilities of irregular structures made of high-strength alloy steel, a target enhanced with ultra-high-strength spherical structures (UHS-SS) was manufactured in this work. The UHS-SS is fabricated from ultra-high-strength steel (UHSS) and mechanically anchored to the target via threaded high-tensile rods, ensuring structural integrity under projectile penetration loading. A series of penetration tests at an impact velocity of 400 m/s was performed using a 125 mm diameter cannon. The yaw-induced projectile deflection was recorded at
, Available online , doi: 10.11883/bzycj-2025-0050
Abstract:
Iridium alloys have been extensively utilized as structural materials in specific high-temperature applications, attributed to their superior strength and ductility at elevated temperatures. To enhance the understanding of high-speed impacts at elevated temperatures, it is imperative to characterize the mechanical properties of iridium alloys, including their failure response under high strain rates and elevated temperatures. In this study, the conventional split Hopkinson tension bar technique was modified to evaluate the tensile behavior of an iridium alloy at high strain rates and elevated temperatures. A dynamic high-temperature tensile testing technique for thin and flat specimens was established based on the high current heating method. A fixture with a slot was employed, enabling the specimen shoulder to bear the load and transmit it to the gauge section of the specimen. An integrated high current heater equipped with a self-controlled system was utilized to heat the iridium alloy specimen and maintain the desired high-temperature conditions. To prevent unintended heating of the bars, a pair of hollow water-cooled pillow blocks were installed. Moreover, to mitigate rapid cooling of the specimen, the cold contact time was meticulously controlled to be less than 1 ms. To elucidate the dynamic high-temperature properties of the iridium alloy, tensile tests were conducted using this technique at a strain rate of 103 s−1 and at temperatures of room temperature, 600, 900, and1100 ℃. Experimental results revealed that as the temperature increased from room temperature to 900 ℃, the tensile strength of the iridium alloy decreased by 12%, while its ductility doubled. However, when the temperature was further elevated to 1100 ℃, the tensile strength decreased by 43%, and the ductility increased by a factor of 7.3. Macroscopic and microscopic analyses of the fracture morphologies were conducted to reveal the deformation mechanisms of the iridium alloy. It was found that with increasing temperature, the failure mode of the iridium alloy transitioned from predominantly intergranular fracture to plastic deformation and granular fracture. The dynamic fracture behavior of iridium alloy at high temperatures is governed by the competition between grain-boundary failure and granular softening.
Iridium alloys have been extensively utilized as structural materials in specific high-temperature applications, attributed to their superior strength and ductility at elevated temperatures. To enhance the understanding of high-speed impacts at elevated temperatures, it is imperative to characterize the mechanical properties of iridium alloys, including their failure response under high strain rates and elevated temperatures. In this study, the conventional split Hopkinson tension bar technique was modified to evaluate the tensile behavior of an iridium alloy at high strain rates and elevated temperatures. A dynamic high-temperature tensile testing technique for thin and flat specimens was established based on the high current heating method. A fixture with a slot was employed, enabling the specimen shoulder to bear the load and transmit it to the gauge section of the specimen. An integrated high current heater equipped with a self-controlled system was utilized to heat the iridium alloy specimen and maintain the desired high-temperature conditions. To prevent unintended heating of the bars, a pair of hollow water-cooled pillow blocks were installed. Moreover, to mitigate rapid cooling of the specimen, the cold contact time was meticulously controlled to be less than 1 ms. To elucidate the dynamic high-temperature properties of the iridium alloy, tensile tests were conducted using this technique at a strain rate of 103 s−1 and at temperatures of room temperature, 600, 900, and
, Available online , doi: 10.11883/bzycj-2024-0274
Abstract:
The pressure characteristics and structural deformation mechanism of aluminum honeycomb sandwich plates (AHSPs) under water-entry impact were investigated through experimental methods. A self-designed drop experimental platform in the water tank was established, and the water-entry impact experiments of AHSPs at different drop heights were carried out. Meanwhile, the deformation of the face sheets was measured by a 3D scanner, and the time history of water impact pressure at different measuring points was monitored. Furthermore, the repeatability of the experiment was verified. On this basis, the water impact load characteristics of AHSPs during the process of water entry were studied and compared with those of other structures in published papers. In addition, the deformation modes and permanent deflection characteristics of AHSPs were analyzed, and the fitting formulas of the permanent deflection of the face sheets and the compression of the core were proposed. Results show that the distribution of the water impact pressure on the front sheet of AHSPs is uneven. However, within the range of drop heights studied, the peak value of the water impact pressure is approximately linear with the drop height. Additionally, compared to the water entry of rigid plates, the peak value of the water impact pressure of AHSPs is smaller. Compared with the mass equivalent aluminum plates, the peak value of the water impact pressure of AHSPs is much smaller, while the pressure duration of AHSPs is longer. The deformation modes of the face sheets of AHSPs at different drop heights are almost the same. Besides, with the increase of the drop height, the permanent deflections of the front and back faces of AHSPs increase approximately in the form of a quadratic parabola with decreasing slope. Suffering from water entry impact loadings, the permanent deflections of the back sheet of AHSPs are smaller than those of the equivalent aluminum plates, indicating that the AHSPs have better impact resistance compared with the equivalent aluminum plates.
The pressure characteristics and structural deformation mechanism of aluminum honeycomb sandwich plates (AHSPs) under water-entry impact were investigated through experimental methods. A self-designed drop experimental platform in the water tank was established, and the water-entry impact experiments of AHSPs at different drop heights were carried out. Meanwhile, the deformation of the face sheets was measured by a 3D scanner, and the time history of water impact pressure at different measuring points was monitored. Furthermore, the repeatability of the experiment was verified. On this basis, the water impact load characteristics of AHSPs during the process of water entry were studied and compared with those of other structures in published papers. In addition, the deformation modes and permanent deflection characteristics of AHSPs were analyzed, and the fitting formulas of the permanent deflection of the face sheets and the compression of the core were proposed. Results show that the distribution of the water impact pressure on the front sheet of AHSPs is uneven. However, within the range of drop heights studied, the peak value of the water impact pressure is approximately linear with the drop height. Additionally, compared to the water entry of rigid plates, the peak value of the water impact pressure of AHSPs is smaller. Compared with the mass equivalent aluminum plates, the peak value of the water impact pressure of AHSPs is much smaller, while the pressure duration of AHSPs is longer. The deformation modes of the face sheets of AHSPs at different drop heights are almost the same. Besides, with the increase of the drop height, the permanent deflections of the front and back faces of AHSPs increase approximately in the form of a quadratic parabola with decreasing slope. Suffering from water entry impact loadings, the permanent deflections of the back sheet of AHSPs are smaller than those of the equivalent aluminum plates, indicating that the AHSPs have better impact resistance compared with the equivalent aluminum plates.
, Available online , doi: 10.11883/bzycj-2025-0037
Abstract:
Shock initiation and ignition techniques driven by electrically exploded metallic bridge foils with insulating flyers have been widely implemented in initiation and ignition system of weapon. To address the deficiency in existing research regarding the description of the flow field evolution during the motion of flyer and promote the development of this technology towards efficient energy utilization and miniaturization, a double-pulse laser schlieren transient observation system was constructed. This system enables the acquisition of density distributions of the flow field and the motion distance of the flyer at different time. Additionally, a two-dimensional axisymmetric fluid dynamics calculation model and calculation method for the motion process of flyer driven by the electric explosion of metal foil were established, and corresponding numerical simulation calculations were performed in consideration of the evolution laws of the flow field inside and outside the acceleration chamber under the effects of the motion of flyer, the compression of shock wave, and the expansion of high-temperature and high-pressure plasma. The phase transition of bridge foil from solid phase to plasma phase was described by phase transition fraction, the state of plasma with high temperature and pressure was described by the state equation of plasma which consider the changes in particle number and coulomb interaction between particles, and the motion of flyer was described by dynamic grid model. The calculated flow field density distribution closely matches the experimental results, and the maximum errors in flyer motion distance and velocity are 6.1% and 8.1%, respectively, validating the accuracy of the calculation model and calculation method. The research results indicate that when the capacitance is 0.33 μF and the initiation voltage is2800 V, within the research range, the maximum pressure in the flow field remains approximately at 1×107 Pa; the temperature in the flow field gradually decreases from 9950 K at 516 ns to 3100 K at 2310 ns; and the plasma phase distribution in the flow field gradually evolves from a flat shape to a long strip shape, with the maximum diffusion distance of plasma in the direction perpendicular to the motion of the flyer being 0.8 mm. At 1360 ns, upon flyer breakthrough the shock wave front, a distinct bulge-shaped profile emerges in the leading edge of both pressure and temperature distributions within the flow field.
Shock initiation and ignition techniques driven by electrically exploded metallic bridge foils with insulating flyers have been widely implemented in initiation and ignition system of weapon. To address the deficiency in existing research regarding the description of the flow field evolution during the motion of flyer and promote the development of this technology towards efficient energy utilization and miniaturization, a double-pulse laser schlieren transient observation system was constructed. This system enables the acquisition of density distributions of the flow field and the motion distance of the flyer at different time. Additionally, a two-dimensional axisymmetric fluid dynamics calculation model and calculation method for the motion process of flyer driven by the electric explosion of metal foil were established, and corresponding numerical simulation calculations were performed in consideration of the evolution laws of the flow field inside and outside the acceleration chamber under the effects of the motion of flyer, the compression of shock wave, and the expansion of high-temperature and high-pressure plasma. The phase transition of bridge foil from solid phase to plasma phase was described by phase transition fraction, the state of plasma with high temperature and pressure was described by the state equation of plasma which consider the changes in particle number and coulomb interaction between particles, and the motion of flyer was described by dynamic grid model. The calculated flow field density distribution closely matches the experimental results, and the maximum errors in flyer motion distance and velocity are 6.1% and 8.1%, respectively, validating the accuracy of the calculation model and calculation method. The research results indicate that when the capacitance is 0.33 μF and the initiation voltage is
, Available online , doi: 10.11883/bzycj-2024-0483
Abstract:
To enhance the damage efficiency of fluoropolymer-based reactive fragments and broaden their application range, a novel core-shell composite structure active fragment has been proposed. To improve the strength of the matrix material, carbon fiber was introduced via a wet mixing method. Under specific sintering conditions, two types of samples were prepared: PTFE/Al/CF tungsten powder and PTFE/Al/CF tungsten ball. The basic mechanical properties of these samples were tested. The addition of tungsten powder was found to increase the dynamic compressive strength of the composite. Penetration tests were conducted on 3 mm+3 mm+2 mm+2 mm multi-layer interval aluminum targets using both types of fragments. The experimental data were automatically processed using a Python-based program, yielding the perforation area, deformation volume, and reaction light intensity for each layer of the target plate. The damage characteristics of the multi-interval target under different velocity and constraint conditions were compared and analyzed. The results show that the core-shell type fragment exhibits superior penetration ability. It can penetrate all four layers of the target plates at low speeds, although the perforation area is relatively small, with a perforation diameter approximately 0.95 times the fragment diameter. In contrast, the homogeneous fragment has a larger perforation area but weaker penetration ability. Its perforation diameter is about 1.21 times the fragment diameter, and it can only penetrate three layers of target plates at high speeds. The steel shell constraint significantly enhances the punching and penetration capabilities of the fragments. The primary active reaction of the fragment occurs during impact with the second layer of the target. The energy release reaction has a limited effect on improving the punching effect. The differences in damage characteristics are mainly attributed to the mechanical properties of the fragments. These findings provide valuable insights for the structural design and damage effect evaluation of reactive fragments.
To enhance the damage efficiency of fluoropolymer-based reactive fragments and broaden their application range, a novel core-shell composite structure active fragment has been proposed. To improve the strength of the matrix material, carbon fiber was introduced via a wet mixing method. Under specific sintering conditions, two types of samples were prepared: PTFE/Al/CF tungsten powder and PTFE/Al/CF tungsten ball. The basic mechanical properties of these samples were tested. The addition of tungsten powder was found to increase the dynamic compressive strength of the composite. Penetration tests were conducted on 3 mm+3 mm+2 mm+2 mm multi-layer interval aluminum targets using both types of fragments. The experimental data were automatically processed using a Python-based program, yielding the perforation area, deformation volume, and reaction light intensity for each layer of the target plate. The damage characteristics of the multi-interval target under different velocity and constraint conditions were compared and analyzed. The results show that the core-shell type fragment exhibits superior penetration ability. It can penetrate all four layers of the target plates at low speeds, although the perforation area is relatively small, with a perforation diameter approximately 0.95 times the fragment diameter. In contrast, the homogeneous fragment has a larger perforation area but weaker penetration ability. Its perforation diameter is about 1.21 times the fragment diameter, and it can only penetrate three layers of target plates at high speeds. The steel shell constraint significantly enhances the punching and penetration capabilities of the fragments. The primary active reaction of the fragment occurs during impact with the second layer of the target. The energy release reaction has a limited effect on improving the punching effect. The differences in damage characteristics are mainly attributed to the mechanical properties of the fragments. These findings provide valuable insights for the structural design and damage effect evaluation of reactive fragments.
, Available online , doi: 10.11883/bzycj-2025-0101
Abstract:
Lattice mechanical metamaterials have been widely used in various fields due to the lightweight, flexible designability and excellent impact resistance. In this paper, an enhanced X-shaped lattice mechanical metamaterial was designed and fabricated by selective laser melting. The dynamic crushing behavior and energy absorption mechanism of this metamaterials subjected to low-velocity impact were explored experimentally and numerically. The influence of impact velocity on the deformation mode and energy absorption capability of the enhanced X-shaped lattice mechanical metamaterials was analyzed. It is shown that the impact velocity has significant effects on the deformation modes of the mechanical metamaterials. At the lower impact velocities, the deformation mode of lattice mechanical metamaterials resembles that observed under quasi-static compression, characterized by the layer-by-layer crushing mode of the cells around the shear band. At the higher impact velocities, the deformation mode of lattice mechanical metamaterials transitions from X-shaped shear band to V-shaped shear band, and finally evolves into an arc-shaped shear band. The further study suggests that enhanced X-shaped lattice mechanical metamaterial exhibits a certain degree of velocity sensitivity. With the increase of the impact velocity, the initial peak stress, plateau stress, and specific energy absorption all increase correspondingly.
Lattice mechanical metamaterials have been widely used in various fields due to the lightweight, flexible designability and excellent impact resistance. In this paper, an enhanced X-shaped lattice mechanical metamaterial was designed and fabricated by selective laser melting. The dynamic crushing behavior and energy absorption mechanism of this metamaterials subjected to low-velocity impact were explored experimentally and numerically. The influence of impact velocity on the deformation mode and energy absorption capability of the enhanced X-shaped lattice mechanical metamaterials was analyzed. It is shown that the impact velocity has significant effects on the deformation modes of the mechanical metamaterials. At the lower impact velocities, the deformation mode of lattice mechanical metamaterials resembles that observed under quasi-static compression, characterized by the layer-by-layer crushing mode of the cells around the shear band. At the higher impact velocities, the deformation mode of lattice mechanical metamaterials transitions from X-shaped shear band to V-shaped shear band, and finally evolves into an arc-shaped shear band. The further study suggests that enhanced X-shaped lattice mechanical metamaterial exhibits a certain degree of velocity sensitivity. With the increase of the impact velocity, the initial peak stress, plateau stress, and specific energy absorption all increase correspondingly.
, Available online , doi: 10.11883/bzycj-2024-0153
Abstract:
Impact ejecting is a critical part of the impact process and plays a pivotal role in engineering applications and scientific analyses in deep space exploration. Its importance extends to space missions such as asteroid surface anchoring for mission stability, impact sampling for scientific analysis of extraterrestrial materials, kinetic impact deflection for planetary defense strategies, and the detailed analysis of ejecta deposition patterns on planetary surfaces to understand surface evolution and regolith dynamics. With small asteroids whose surfaces are commonly covered with regolith, granular targets are employed in laboratory settings to simulate the impact ejecting process. This paper presents a review of the research progress concerning the behavior of impact ejecting on granular targets. The formation process of impact ejecting and methods for describing ejecta curtains are evaluated. An analysis of the dimensional similarity laws governing impact ejecta, along with their applicability and limitations, is conducted. Additionally, the influence of factors, such as target material parameters, impact conditions, target surface morphology, and impactor shape and structure, on impact ejecting behavior is summarized. Finally, existing research challenges are objectively identified, and potential directions for further scientific research about the behavior of impact ejecta on granular targets are proposed.
Impact ejecting is a critical part of the impact process and plays a pivotal role in engineering applications and scientific analyses in deep space exploration. Its importance extends to space missions such as asteroid surface anchoring for mission stability, impact sampling for scientific analysis of extraterrestrial materials, kinetic impact deflection for planetary defense strategies, and the detailed analysis of ejecta deposition patterns on planetary surfaces to understand surface evolution and regolith dynamics. With small asteroids whose surfaces are commonly covered with regolith, granular targets are employed in laboratory settings to simulate the impact ejecting process. This paper presents a review of the research progress concerning the behavior of impact ejecting on granular targets. The formation process of impact ejecting and methods for describing ejecta curtains are evaluated. An analysis of the dimensional similarity laws governing impact ejecta, along with their applicability and limitations, is conducted. Additionally, the influence of factors, such as target material parameters, impact conditions, target surface morphology, and impactor shape and structure, on impact ejecting behavior is summarized. Finally, existing research challenges are objectively identified, and potential directions for further scientific research about the behavior of impact ejecta on granular targets are proposed.
, Available online , doi: 10.11883/bzycj-2024-0485
Abstract:
To accurately predict the dynamic tensile fracture in concrete materials subjected to impact and blast loadings, this study first establishes a modified Monaghan artificial bulk viscosity computation method within the framework of a non-ordinary state-based peridynamics (NOSB-PD) theory to eliminate numerical oscillations. Subsequently, the corrected strain-rate computation method, previously developed, is integrated into the Kong-Fang concrete material model, which was proposed earlier by the research group to calculate accurately the strain-rate effect during sudden changes. Based on the two methods above, numerical simulations of elastic wave propagation in a one-dimensional rod are conducted, and the results demonstrate that the additional inclusion of the modified Monaghan artificial bulk viscosity force vector state into the original force vector state can effectively suppress the non-physical numerical oscillations caused by the deformation gradient approximation. The superiority of the modified Monaghan artificial bulk viscosity is validated through comparative analysis with the original Monaghan artificial bulk viscosity. Furthermore, the influence of the modified Monaghan artificial bulk viscosity parameters is investigated, and recommended values for these parameters are provided. Finally, the aforementioned model is used to numerically simulate the spall test in concrete specimens, where the effects of including or excluding the modified Monaghan artificial bulk viscosity and different strain-rate computation methods on the prediction results of dynamic tensile fracture are compared and analyzed. The numerical simulation results demonstrate that accurately predicting the dynamic tensile fracture in concrete materials requires simultaneous consideration of the modified Monaghan artificial bulk viscosity and corrected strain-rate computation. The established non-ordinary state-based peridynamics model that accounts for both the modified Monaghan artificial bulk viscosity and corrected strain-rate computation demonstrates strong capabilities in predicting crack locations and quantities based on both qualitative and quantitative analysis metrics. This work provides new insights into the numerical simulation of dynamic tensile fracture in concrete materials under impact and blast loadings.
To accurately predict the dynamic tensile fracture in concrete materials subjected to impact and blast loadings, this study first establishes a modified Monaghan artificial bulk viscosity computation method within the framework of a non-ordinary state-based peridynamics (NOSB-PD) theory to eliminate numerical oscillations. Subsequently, the corrected strain-rate computation method, previously developed, is integrated into the Kong-Fang concrete material model, which was proposed earlier by the research group to calculate accurately the strain-rate effect during sudden changes. Based on the two methods above, numerical simulations of elastic wave propagation in a one-dimensional rod are conducted, and the results demonstrate that the additional inclusion of the modified Monaghan artificial bulk viscosity force vector state into the original force vector state can effectively suppress the non-physical numerical oscillations caused by the deformation gradient approximation. The superiority of the modified Monaghan artificial bulk viscosity is validated through comparative analysis with the original Monaghan artificial bulk viscosity. Furthermore, the influence of the modified Monaghan artificial bulk viscosity parameters is investigated, and recommended values for these parameters are provided. Finally, the aforementioned model is used to numerically simulate the spall test in concrete specimens, where the effects of including or excluding the modified Monaghan artificial bulk viscosity and different strain-rate computation methods on the prediction results of dynamic tensile fracture are compared and analyzed. The numerical simulation results demonstrate that accurately predicting the dynamic tensile fracture in concrete materials requires simultaneous consideration of the modified Monaghan artificial bulk viscosity and corrected strain-rate computation. The established non-ordinary state-based peridynamics model that accounts for both the modified Monaghan artificial bulk viscosity and corrected strain-rate computation demonstrates strong capabilities in predicting crack locations and quantities based on both qualitative and quantitative analysis metrics. This work provides new insights into the numerical simulation of dynamic tensile fracture in concrete materials under impact and blast loadings.
, Available online , doi: 10.11883/bzycj-2025-0047
Abstract:
With the increasing speed of trains, the impacts of mechanical shock, arc heat, and Joule heat on the high-speed railway catenary system have become increasingly significant. The coupling effect of high temperature and impact load has emerged as a key limiting factor for the safe operation of the pantograph-catenary system. This study focuses on copper-magnesium alloy materials used in the catenary system to address the challenges of dynamic impact and friction-induced heat generation in high-speed railways. To investigate the mechanical properties of the high-speed railway pantograph-catenary system under service conditions such as dynamic impact and frictional temperature rise, a DF14.205D electronic universal testing machine and a split Hopkinson pressure bar were employed. The uniaxial compression mechanical properties of the copper-magnesium alloy in the catenary were tested over a strain rate range of 0.001 s−1 to3000 s−1 and a temperature range of 293 K to 873 K. The strain-rate effect and temperature sensitivity of the stress-strain response were carefully analyzed. The study also revealed the compression deformation mechanism and the evolution law of the alloy’s microstructure under the combined influence of strain rate and temperature. Furthermore, a dynamic constitutive model was established to accurately describe the plastic flow behavior of the material. The findings indicate that during compression, the copper-magnesium alloy materials exhibit significant strain-rate strengthening and temperature softening effects. These effects result from the combined action of work hardening, strain rate, and temperature softening. When the temperature exceeds 473 K, temperature softening becomes the dominant factor in material deformation, and the elevated temperature can stimulate dynamic recovery and dynamic recrystallization processes. The modified Johnson-Cook model was found to be capable of accurately predicting the plastic flow stress-strain response. These research outcomes provide valuable guidance and references for the safety design and evaluation of the high-speed train pantograph-catenary system during its service.
With the increasing speed of trains, the impacts of mechanical shock, arc heat, and Joule heat on the high-speed railway catenary system have become increasingly significant. The coupling effect of high temperature and impact load has emerged as a key limiting factor for the safe operation of the pantograph-catenary system. This study focuses on copper-magnesium alloy materials used in the catenary system to address the challenges of dynamic impact and friction-induced heat generation in high-speed railways. To investigate the mechanical properties of the high-speed railway pantograph-catenary system under service conditions such as dynamic impact and frictional temperature rise, a DF14.205D electronic universal testing machine and a split Hopkinson pressure bar were employed. The uniaxial compression mechanical properties of the copper-magnesium alloy in the catenary were tested over a strain rate range of 0.001 s−1 to
, Available online , doi: 10.11883/bzycj-2025-0054
Abstract:
In recent years, polyurea-coated reinforced concrete (RC) slabs have been extensively studied both experimentally and numerically for structural strengthening against contact explosions. However, theoretical investigations remain limited, particularly concerning the impact of polyurea on the local damages of the RC substrates. In this paper, an analytical model based on stress wave propagation theory was proposed to investigate the reflection of compression waves at the backside of the RC substrate slab and predict the spalling depth. Utilizing this analytical model, a quantitative and detailed discussion was presented regarding the effect of the polyurea on the critical spalling and breach of the RC substrate slab. Furthermore, the applicability of the empirical breach prediction, originally developed for uncoated RC slabs, was validated through existing experiments to predict the breach of polyurea-coated RC substrate slabs. The results indicate that polyurea affects the spalling process of the RC substrate slabs. Specifically, the net stress wave adjacent to the concrete-polyurea interface is a compression wave, while it transitions to a tensile wave in the deeper concrete. Polyurea primarily impacts the first spall of the RC substrate slab; subsequent spalling processes after the first spall align with those observed in uncoated RC slabs. Upon the occurrence of critical spalling, polyurea enhances the critical spalling resistance of RC slabs, although it significantly increases the spalling depth. Conversely, when a breach occurs, polyurea reduces the number of spalls but minimally affects on the total spalling depth. Based on these findings, the empirical method for predicting breaches of uncoated RC slabs can effectively be applied to predict the breach of RC substrate slabs coated with polyurea. The test results from more than twenty contact explosion experiments are consistent with the predicted outcomes, thereby validating the effectiveness of the analytical model and providing a method for estimating the breach of polyurea-coated RC substrate slabs.
In recent years, polyurea-coated reinforced concrete (RC) slabs have been extensively studied both experimentally and numerically for structural strengthening against contact explosions. However, theoretical investigations remain limited, particularly concerning the impact of polyurea on the local damages of the RC substrates. In this paper, an analytical model based on stress wave propagation theory was proposed to investigate the reflection of compression waves at the backside of the RC substrate slab and predict the spalling depth. Utilizing this analytical model, a quantitative and detailed discussion was presented regarding the effect of the polyurea on the critical spalling and breach of the RC substrate slab. Furthermore, the applicability of the empirical breach prediction, originally developed for uncoated RC slabs, was validated through existing experiments to predict the breach of polyurea-coated RC substrate slabs. The results indicate that polyurea affects the spalling process of the RC substrate slabs. Specifically, the net stress wave adjacent to the concrete-polyurea interface is a compression wave, while it transitions to a tensile wave in the deeper concrete. Polyurea primarily impacts the first spall of the RC substrate slab; subsequent spalling processes after the first spall align with those observed in uncoated RC slabs. Upon the occurrence of critical spalling, polyurea enhances the critical spalling resistance of RC slabs, although it significantly increases the spalling depth. Conversely, when a breach occurs, polyurea reduces the number of spalls but minimally affects on the total spalling depth. Based on these findings, the empirical method for predicting breaches of uncoated RC slabs can effectively be applied to predict the breach of RC substrate slabs coated with polyurea. The test results from more than twenty contact explosion experiments are consistent with the predicted outcomes, thereby validating the effectiveness of the analytical model and providing a method for estimating the breach of polyurea-coated RC substrate slabs.
, Available online , doi: 10.11883/bzycj-2025-0024
Abstract:
To investigate the penetration resistance of metal honeycomb tube-constrained concrete structures under hypervelocity impact, penetration experiments were conducted using a two-stage light gas gun with projectile velocities near 1 500 m/s. The material point method (MPM) was employed to simulate the penetration process and validate the reasonableness of target and projectile parameters. This method was further used to analyze the effects of honeycomb tube parameters, including wall thickness, height, diameter, and material, on the penetration resistance of the target structure. Numerical simulations showed that MPM can accurately simulate high-velocity penetration processes, with simulation results deviating from experimental data by less than 10%. Through orthogonal analysis, the factors influencing penetration depth were ranked in descending order as follows: characteristic tube depth, characteristic inner diameter, characteristic wall thickness, and material. For the cratering effect, the primary influencing factors were identified as characteristic wall thickness, characteristic tube depth, material, and characteristic inner diameter. For the projectiles tested in this study, optimization results indicated the following: A combination of 4 mm wall thickness, 150 mm height, 30 mm incircle diameter, and tungsten alloy demonstrated the best penetration resistance, reducing penetration depth by 25.1% compared to plain concrete. A combination of 4 mm wall thickness, 150 mm height, 90 mm incircle diameter, and aluminum exhibited superior resistance to the cratering effect, decreasing crater radius by 28.7% compared to plain concrete. Multi-objective optimization analysis determined the optimal overall configuration to be: 4 mm wall thickness, 150 mm height, 30 mm incircle diameter, and aluminum.
To investigate the penetration resistance of metal honeycomb tube-constrained concrete structures under hypervelocity impact, penetration experiments were conducted using a two-stage light gas gun with projectile velocities near 1 500 m/s. The material point method (MPM) was employed to simulate the penetration process and validate the reasonableness of target and projectile parameters. This method was further used to analyze the effects of honeycomb tube parameters, including wall thickness, height, diameter, and material, on the penetration resistance of the target structure. Numerical simulations showed that MPM can accurately simulate high-velocity penetration processes, with simulation results deviating from experimental data by less than 10%. Through orthogonal analysis, the factors influencing penetration depth were ranked in descending order as follows: characteristic tube depth, characteristic inner diameter, characteristic wall thickness, and material. For the cratering effect, the primary influencing factors were identified as characteristic wall thickness, characteristic tube depth, material, and characteristic inner diameter. For the projectiles tested in this study, optimization results indicated the following: A combination of 4 mm wall thickness, 150 mm height, 30 mm incircle diameter, and tungsten alloy demonstrated the best penetration resistance, reducing penetration depth by 25.1% compared to plain concrete. A combination of 4 mm wall thickness, 150 mm height, 90 mm incircle diameter, and aluminum exhibited superior resistance to the cratering effect, decreasing crater radius by 28.7% compared to plain concrete. Multi-objective optimization analysis determined the optimal overall configuration to be: 4 mm wall thickness, 150 mm height, 30 mm incircle diameter, and aluminum.
, Available online , doi: 10.11883/bzycj-2025-0058
Abstract:
To address the fracture problem of dynamic submarine cables and their protective sheaths caused by friction and collision with wind turbine platforms under harsh sea conditions, a multi-impact resistant composite protective layer was designed using EVA foam and rubber as the main materials, which possess high elasticity and excellent cushioning properties.Mechanical property tests were conducted on EVA foam materials with various relative densities under different loading conditions using a universal testing machine and drop hammer. Energy absorption efficiency, densification strain, plateau stress and maximum specific energy absorption were introduced to characterize the mechanical properties of EVA foam. The effects of relative density, strain rate and repeated loading on the energy absorption characteristics of EVA foam were revealed.Based on the matching relationship between the energy absorption per unit volume of EVA foam and the kinetic energy of dynamic submarine cables to be absorbed, the optimal thickness of the protective layer was determined, and composite protective layer specimens were fabricated. Subsequently, drop hammer impact tests were performed to compare the cushioning and energy absorption characteristics of the composite protective layer with other materials, preliminarily verifying its high energy absorption efficiency. Further drop hammer impact tests were conducted to investigate the effects of impact energy and loading cycles on the cushioning and energy absorption characteristics of the composite protective layer. The experimental results showed that: (1) Under single impact, the peak force and maximum displacement of the composite protective layer showed a linear positive correlation with the drop hammer mass and impact velocity, with energy absorption efficiency reaching 85 %; (2) Under multiple impacts, the mechanical properties of the composite protective layer exhibited remarkable stability - the maximum displacement in the fourth impact increased by only 5.5 % compared to the first impact, with fluctuations in energy absorption value and instantaneous rebound rate remaining below 5 %. The composite protective layer demonstrates unique mechanical properties that provide effective long-term protection for dynamic submarine cables under harsh marine conditions.
To address the fracture problem of dynamic submarine cables and their protective sheaths caused by friction and collision with wind turbine platforms under harsh sea conditions, a multi-impact resistant composite protective layer was designed using EVA foam and rubber as the main materials, which possess high elasticity and excellent cushioning properties.Mechanical property tests were conducted on EVA foam materials with various relative densities under different loading conditions using a universal testing machine and drop hammer. Energy absorption efficiency, densification strain, plateau stress and maximum specific energy absorption were introduced to characterize the mechanical properties of EVA foam. The effects of relative density, strain rate and repeated loading on the energy absorption characteristics of EVA foam were revealed.Based on the matching relationship between the energy absorption per unit volume of EVA foam and the kinetic energy of dynamic submarine cables to be absorbed, the optimal thickness of the protective layer was determined, and composite protective layer specimens were fabricated. Subsequently, drop hammer impact tests were performed to compare the cushioning and energy absorption characteristics of the composite protective layer with other materials, preliminarily verifying its high energy absorption efficiency. Further drop hammer impact tests were conducted to investigate the effects of impact energy and loading cycles on the cushioning and energy absorption characteristics of the composite protective layer. The experimental results showed that: (1) Under single impact, the peak force and maximum displacement of the composite protective layer showed a linear positive correlation with the drop hammer mass and impact velocity, with energy absorption efficiency reaching 85 %; (2) Under multiple impacts, the mechanical properties of the composite protective layer exhibited remarkable stability - the maximum displacement in the fourth impact increased by only 5.5 % compared to the first impact, with fluctuations in energy absorption value and instantaneous rebound rate remaining below 5 %. The composite protective layer demonstrates unique mechanical properties that provide effective long-term protection for dynamic submarine cables under harsh marine conditions.
, Available online , doi: 10.11883/bzycj-2024-0502
Abstract:
Porous materials are accompanied by pore collapse behavior during impact compression. Based on the shock wave structure observed in experiments carried out by predecessors, the theoretically analysis of the relationship between the shock wave formation process and pore collapse behavior of porous materials is made. Firstly, considering the compression curve characteristics of porous materials and the overtaking of shock wave, it is proposed that the shock wave structure of porous materials has three modes: low pressure single wave mode, double shock wave mode and high pressure single wave mode. These different shock wave modes are mainly caused by the influence of elastic-plastic mechanical behavior in pore collapse on the compression curve of porous materials. Furthermore, combined with the Wu-Jing equation of state, the calculation method of shock compression characteristics compatible with different shock wave modes is developed. The relationship between the Hugoniot Curve of porous material and dense material is established, and the calculation equation of impact specific volume compatible with single shock wave mode is obtained, which can directly calculate the critical specific volume without approximate conditions. In addition, the equation of pore collapse established by Carroll is modified by taking the linear approximation of the variation of porosity with pressure in the elastic stage and the elastic-plastic stage, and considering the relationship between the stress of the matrix material and the macroscopic stress in the porous material. Based on the calculation model of shock compression characteristics considering pore collapse behavior, the Hugoniot data of the material are calculated, and the influence of pore collapse behavior on the shock compression characteristics of porous materials is discussed. The results show that the shock compression characteristics of the material are significantly affected by the pore collapse behavior at lower pressures, and the model in this paper can predict the shock wave parameters of porous materials more accurately.
Porous materials are accompanied by pore collapse behavior during impact compression. Based on the shock wave structure observed in experiments carried out by predecessors, the theoretically analysis of the relationship between the shock wave formation process and pore collapse behavior of porous materials is made. Firstly, considering the compression curve characteristics of porous materials and the overtaking of shock wave, it is proposed that the shock wave structure of porous materials has three modes: low pressure single wave mode, double shock wave mode and high pressure single wave mode. These different shock wave modes are mainly caused by the influence of elastic-plastic mechanical behavior in pore collapse on the compression curve of porous materials. Furthermore, combined with the Wu-Jing equation of state, the calculation method of shock compression characteristics compatible with different shock wave modes is developed. The relationship between the Hugoniot Curve of porous material and dense material is established, and the calculation equation of impact specific volume compatible with single shock wave mode is obtained, which can directly calculate the critical specific volume without approximate conditions. In addition, the equation of pore collapse established by Carroll is modified by taking the linear approximation of the variation of porosity with pressure in the elastic stage and the elastic-plastic stage, and considering the relationship between the stress of the matrix material and the macroscopic stress in the porous material. Based on the calculation model of shock compression characteristics considering pore collapse behavior, the Hugoniot data of the material are calculated, and the influence of pore collapse behavior on the shock compression characteristics of porous materials is discussed. The results show that the shock compression characteristics of the material are significantly affected by the pore collapse behavior at lower pressures, and the model in this paper can predict the shock wave parameters of porous materials more accurately.
, Available online , doi: 10.11883/bzycj-2025-0106
Abstract:
To investigate the evolution of phase structure, dislocation distribution, energy absorption capacity, and impact accumulation effect of high-entropy alloys (HEA) under shock loading, molecular dynamics simulations were employed to systematically analyze the dynamic response behavior of Al0.3CoCrFeNi HEA plate subjected to single and secondary impact load. The results show that under the first impact, the phase structure evolution and energy absorption mode of the plastic region of Al0.3CoCrFeNi HEA plate exhibits significant velocity dependence. As the speed increases, the proportion of face-centered cubic structure shows a three-stage downward trend, while the disorder structure increases accordingly. Under low velocity impact (0.5-1.0 km/s), energy is mainly absorbed by dislocation network; at medium velocity impact (1.0-2.0 km/s), both dislocations and disordered atoms contribute; under high velocity impact (2.0-3.0 km/s), disordered atoms dominate energy absorption. Within the velocity range of 0.5-0.8 km/s of the rigid sphere, the dislocation line length increases linearly with the impact velocity. However, at higher impact velocities, the dislocation line length decreases due to the limitation of the plate thickness. The stress analysis shows that when the impact velocity increases, both the maximum stress and the boundary stress of the plastic zone exhibit nonlinear variations characterized by a quadratic relationship. Under the secondary impact, the Al0.3CoCrFeNi HEA plate forms a damage zone resembling a trapezoidal shape after impact. The radius of the pit within this damage zone exhibits a quadratic relationship with the impact velocity. Additionally, the minimum affected area resulting from the secondary impact also demonstrates a quadratic relationship with the impact velocity. Regarding impact resistance, as the initial impact velocity increases, the residual velocity following the secondary impact also rises, indicating a reduction in the resistance capability of HEA. At a distance of 10 nm from the impact center, the ballistic limit velocity decreases nonlinearly with increasing initial impact velocity. However, an increase in the secondary impact velocity mitigates the effects induced by the initial impact.
To investigate the evolution of phase structure, dislocation distribution, energy absorption capacity, and impact accumulation effect of high-entropy alloys (HEA) under shock loading, molecular dynamics simulations were employed to systematically analyze the dynamic response behavior of Al0.3CoCrFeNi HEA plate subjected to single and secondary impact load. The results show that under the first impact, the phase structure evolution and energy absorption mode of the plastic region of Al0.3CoCrFeNi HEA plate exhibits significant velocity dependence. As the speed increases, the proportion of face-centered cubic structure shows a three-stage downward trend, while the disorder structure increases accordingly. Under low velocity impact (0.5-1.0 km/s), energy is mainly absorbed by dislocation network; at medium velocity impact (1.0-2.0 km/s), both dislocations and disordered atoms contribute; under high velocity impact (2.0-3.0 km/s), disordered atoms dominate energy absorption. Within the velocity range of 0.5-0.8 km/s of the rigid sphere, the dislocation line length increases linearly with the impact velocity. However, at higher impact velocities, the dislocation line length decreases due to the limitation of the plate thickness. The stress analysis shows that when the impact velocity increases, both the maximum stress and the boundary stress of the plastic zone exhibit nonlinear variations characterized by a quadratic relationship. Under the secondary impact, the Al0.3CoCrFeNi HEA plate forms a damage zone resembling a trapezoidal shape after impact. The radius of the pit within this damage zone exhibits a quadratic relationship with the impact velocity. Additionally, the minimum affected area resulting from the secondary impact also demonstrates a quadratic relationship with the impact velocity. Regarding impact resistance, as the initial impact velocity increases, the residual velocity following the secondary impact also rises, indicating a reduction in the resistance capability of HEA. At a distance of 10 nm from the impact center, the ballistic limit velocity decreases nonlinearly with increasing initial impact velocity. However, an increase in the secondary impact velocity mitigates the effects induced by the initial impact.
