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, Available online ,
doi: 10.11883/bzycj-2026-0010
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Steel truss bridges are typically composed of a large number of slender members and represent one of the primary structural forms of railway bridges, facing the threat of overall collapse caused by explosions from unmanned aerial vehicles. Numerical simulation analysis was conducted on the failure mode and residual bearing capacity degradation law of railway steel truss bridges subjected to contact explosions at the present work. Firstly, the reliability of the numerical simulation method was verified by existing explosion tests on stiffened steel plates and steel box arches, as well as the residual bearing capacity of I-shaped steel column after explosion. Subsequently, mesh sensitivity analyses were performed for the damage and failure of upper chord member under contact explosions and for the residual bearing capacity of the entire bridge. Then, the most unfavorable member of the typical steel truss bridge was identified, and the influence of explosion yield on the residual bearing capacity was explored. Finally, the evolution mechanism of damage and failure of the entire bridge under multi-point explosions was discussed. The results show that, (i) under contact explosions, steel truss girder bridges are mainly characterized by localized member damage. For an explosive charge of 100 kg, the overall bridge bearing capacity decreases by 29.8% and 18.0% when the explosion occurs on the side and top surfaces of the upper chord member. The side explosion on the upper chord is the most unfavorable scenario. (ii) As the charge weight for side explosion on upper chord increases from 25 kg to 150 kg, the reduction in residual bearing capacity of the entire bridge increases from 8.8% to 33.4%. Taking the ratio of bearing capacity loss to the ultimate bearing capacity of intact bridge as the damage index, a quantitative relationship between the entire bridge damage index and the explosive charge weight is established. (iii) Under multi-point explosion scenarios, the damage factor increases to 0.452, indicating the structural redundancy and residual bearing capacity are significantly reduced compared with those under single-point explosion conditions.
Steel truss bridges are typically composed of a large number of slender members and represent one of the primary structural forms of railway bridges, facing the threat of overall collapse caused by explosions from unmanned aerial vehicles. Numerical simulation analysis was conducted on the failure mode and residual bearing capacity degradation law of railway steel truss bridges subjected to contact explosions at the present work. Firstly, the reliability of the numerical simulation method was verified by existing explosion tests on stiffened steel plates and steel box arches, as well as the residual bearing capacity of I-shaped steel column after explosion. Subsequently, mesh sensitivity analyses were performed for the damage and failure of upper chord member under contact explosions and for the residual bearing capacity of the entire bridge. Then, the most unfavorable member of the typical steel truss bridge was identified, and the influence of explosion yield on the residual bearing capacity was explored. Finally, the evolution mechanism of damage and failure of the entire bridge under multi-point explosions was discussed. The results show that, (i) under contact explosions, steel truss girder bridges are mainly characterized by localized member damage. For an explosive charge of 100 kg, the overall bridge bearing capacity decreases by 29.8% and 18.0% when the explosion occurs on the side and top surfaces of the upper chord member. The side explosion on the upper chord is the most unfavorable scenario. (ii) As the charge weight for side explosion on upper chord increases from 25 kg to 150 kg, the reduction in residual bearing capacity of the entire bridge increases from 8.8% to 33.4%. Taking the ratio of bearing capacity loss to the ultimate bearing capacity of intact bridge as the damage index, a quantitative relationship between the entire bridge damage index and the explosive charge weight is established. (iii) Under multi-point explosion scenarios, the damage factor increases to 0.452, indicating the structural redundancy and residual bearing capacity are significantly reduced compared with those under single-point explosion conditions.
, Available online ,
doi: 10.11883/bzycj-2025-0412
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In western mining construction, the freezing shaft method is employed to penetrate water-bearing fractured rock masses, forming ice-rock composite structures. However, the blast shock waves during construction can affect frozen surrounding rock, posing safety risks. Using the Hopkinson bar test apparatus, we systematically analyzed the propagation and attenuation patterns of post-blast stress waves in frozen rock fracture surfaces. Key findings include: (1) When impact pressure reaches the specimen failure threshold, specimens 0 and 15 exhibit decreasing reflection coefficients (R) followed by increasing transmission coefficients (T) as pressure rises, while specimens 30 and 45 show decreasing R and T values. (2) When incident stress wave intensity is below rock's dynamic compressive strength but above ice's dynamic compressive strength, the ice-rock composite demonstrates three failure modes: compressive, shear, and combined compressive-shear failure, depending on structural surface angle and loading strain rate. (3) The overall weakening effect at structural surfaces significantly outweighs strain rate-induced reinforcement. Notably, specimens with 45° inclination show gradually reduced R value decline but maintain substantial T value decrease, indicating lower sensitivity to stress wave reflection at steep angles compared to transmission effects. This study provides theoretical insights for mitigating disturbance effects in fractured rock masses during freezing shaft construction in cold regions.
In western mining construction, the freezing shaft method is employed to penetrate water-bearing fractured rock masses, forming ice-rock composite structures. However, the blast shock waves during construction can affect frozen surrounding rock, posing safety risks. Using the Hopkinson bar test apparatus, we systematically analyzed the propagation and attenuation patterns of post-blast stress waves in frozen rock fracture surfaces. Key findings include: (1) When impact pressure reaches the specimen failure threshold, specimens 0 and 15 exhibit decreasing reflection coefficients (R) followed by increasing transmission coefficients (T) as pressure rises, while specimens 30 and 45 show decreasing R and T values. (2) When incident stress wave intensity is below rock's dynamic compressive strength but above ice's dynamic compressive strength, the ice-rock composite demonstrates three failure modes: compressive, shear, and combined compressive-shear failure, depending on structural surface angle and loading strain rate. (3) The overall weakening effect at structural surfaces significantly outweighs strain rate-induced reinforcement. Notably, specimens with 45° inclination show gradually reduced R value decline but maintain substantial T value decrease, indicating lower sensitivity to stress wave reflection at steep angles compared to transmission effects. This study provides theoretical insights for mitigating disturbance effects in fractured rock masses during freezing shaft construction in cold regions.
, Available online ,
doi: 10.11883/bzycj-2026-0018
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Scaled models of shallow-buried RC oil depots were designed by changing depots structure, the type and volume of oil, and explosion source locations to investigate the damage modes and mechanisms of shallow-buried RC oil depots subjected to the coupling of shock waves and oil-gas explosions. The research indicates that the shock wave loading on the oil depot cover causes punching-perforation failure on the blast-facing side and spalling failure on the blast-opposite side. The damage degree of the oil depot cover is greater when the depot contains 50% diesel. Two peaks appear in the overpressure rise stage of the shock wave when the oil depot contains 100% diesel while due to multiple interface reflection in the internal cavity, three peaks appear with the increase of the positive pressure duration of the shock wave when the depot contains 50% diesel. The explosion source located at the bottom of the oil depot causes severe damage to both the cover and the main depot structure. The reflection and superposition of shock waves at the corners lead to significant shear cracking at the edges of the main depot structure. Compared to the explosion of 50% diesel, the explosion of 50% gasoline produces a larger fireball with a longer burning duration, which does not cause damage to the main structure of the oil depot.
Scaled models of shallow-buried RC oil depots were designed by changing depots structure, the type and volume of oil, and explosion source locations to investigate the damage modes and mechanisms of shallow-buried RC oil depots subjected to the coupling of shock waves and oil-gas explosions. The research indicates that the shock wave loading on the oil depot cover causes punching-perforation failure on the blast-facing side and spalling failure on the blast-opposite side. The damage degree of the oil depot cover is greater when the depot contains 50% diesel. Two peaks appear in the overpressure rise stage of the shock wave when the oil depot contains 100% diesel while due to multiple interface reflection in the internal cavity, three peaks appear with the increase of the positive pressure duration of the shock wave when the depot contains 50% diesel. The explosion source located at the bottom of the oil depot causes severe damage to both the cover and the main depot structure. The reflection and superposition of shock waves at the corners lead to significant shear cracking at the edges of the main depot structure. Compared to the explosion of 50% diesel, the explosion of 50% gasoline produces a larger fireball with a longer burning duration, which does not cause damage to the main structure of the oil depot.
, Available online ,
doi: 10.11883/bzycj-2025-0327
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Through spatial arrangement of different microstructures, well-designed hybrid lattice structures exhibit enhanced mechanical properties compared with uniform lattice structures composed of a single unit cell, thereby serving as a promising strategy for lightweight lattice structure design. However, current microstructure design approaches for hybrid lattices primarily focus on improving quasi-static compressive mechanical performance. In reality, engineering protection often involves complex dynamic impact environments rather than simple quasi-static loads. However, research on the microstructural design of hybrid lattices under high strain rate impact loading remains limited. This is due to the significant influence of inertial effects on dynamic structural mechanical response, which complicates multi-objective optimization. In this study, a fourth-order hybrid orthogonal isotropic lattice structure is constructed using two types of rhombic dodecahedron unit cells with different relative densities. A Bidirectional Long Short-Term Memory (Bi-LSTM) network is employed to develop a predictive model that expands the dataset of stress-strain curves obtained from finite element simulations. The reliability of the model’s predictions is validated through multi-dimensional evaluation metrics. Specific energy absorption is adopted as an indicator for evaluating energy absorption capacity based on the accurately predicted stress-strain curves. The structural effects on the energy absorption behavior of the hybrid lattice are analyzed under quasi-static planar compression. By increasing the compression speed to 100 m/s to simulate high strain rate conditions, the role of inertial effects on the dynamic mechanical response is investigated through comparative analysis. Furthermore, the competition and synergy between inertial effects and structural effects are systematically analyzed by categorizing the hybrid lattices according to the degree of unit cell mixing. By using machine learning to efficiently expand the data scale of finite element simulations, this study demonstrates the internal relationships among inertial effects, unit cell proportion, and spatial arrangement under high strain rate conditions. The findings provide valuable insights for the application of hybrid lattice structures in impact protection and related engineering fields.
Through spatial arrangement of different microstructures, well-designed hybrid lattice structures exhibit enhanced mechanical properties compared with uniform lattice structures composed of a single unit cell, thereby serving as a promising strategy for lightweight lattice structure design. However, current microstructure design approaches for hybrid lattices primarily focus on improving quasi-static compressive mechanical performance. In reality, engineering protection often involves complex dynamic impact environments rather than simple quasi-static loads. However, research on the microstructural design of hybrid lattices under high strain rate impact loading remains limited. This is due to the significant influence of inertial effects on dynamic structural mechanical response, which complicates multi-objective optimization. In this study, a fourth-order hybrid orthogonal isotropic lattice structure is constructed using two types of rhombic dodecahedron unit cells with different relative densities. A Bidirectional Long Short-Term Memory (Bi-LSTM) network is employed to develop a predictive model that expands the dataset of stress-strain curves obtained from finite element simulations. The reliability of the model’s predictions is validated through multi-dimensional evaluation metrics. Specific energy absorption is adopted as an indicator for evaluating energy absorption capacity based on the accurately predicted stress-strain curves. The structural effects on the energy absorption behavior of the hybrid lattice are analyzed under quasi-static planar compression. By increasing the compression speed to 100 m/s to simulate high strain rate conditions, the role of inertial effects on the dynamic mechanical response is investigated through comparative analysis. Furthermore, the competition and synergy between inertial effects and structural effects are systematically analyzed by categorizing the hybrid lattices according to the degree of unit cell mixing. By using machine learning to efficiently expand the data scale of finite element simulations, this study demonstrates the internal relationships among inertial effects, unit cell proportion, and spatial arrangement under high strain rate conditions. The findings provide valuable insights for the application of hybrid lattice structures in impact protection and related engineering fields.
, Available online ,
doi: 10.11883/bzycj-2026-0035
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When fuel-rich explosives are detonated in a confined space, their load characteristics are verified to exhibit remarkable differences from those generated in an open space. Specifically, the reflected shock waves are significantly intensified, the afterburning effect is prominently manifested, and the effective duration during which the expansion of detonation products performs work is obviously prolonged. Meanwhile, the calculation of structural deformation under the action of confined blast loading is confronted with multiple challenges, including a large number of involved variables, complex expression forms and high research costs. To tackle these problems, based on a validated numerical calculation method for explosion loads in confined spaces where the afterburning effect is taken into consideration, a systematic analysis is carried out on the spatiotemporal distribution law of explosion loads in confined spaces, and an equivalent load simplification method that simultaneously accounts for the saturation response time and quasi-static pressure is proposed in this paper. Through an in-depth investigation into the spatial distribution form of the equivalent load and the influence exerted by quasi-static pressure on structural response, the results demonstrate that within the scope of the current research, the impact of the spatial distribution of the equivalent load on structural response is relatively minor, whereas the contribution of quasi-static pressure cannot be neglected. On the basis of the above research findings, a two-stage load simplification model represented by the load characteristics at the central point of the target plate is further developed. A comparative analysis is conducted between the residual deformation values derived from 10 groups of simplified models and those obtained from actual experiments, which verifies the effectiveness of the established simplified model. The research results indicate that the proposed model possesses excellent applicability under different working conditions, can not only guarantee calculation precision but also remarkably enhance computational efficiency, and thus provides a reliable technical approach for the simplified analysis of engineering problems related to confined space explosions.
When fuel-rich explosives are detonated in a confined space, their load characteristics are verified to exhibit remarkable differences from those generated in an open space. Specifically, the reflected shock waves are significantly intensified, the afterburning effect is prominently manifested, and the effective duration during which the expansion of detonation products performs work is obviously prolonged. Meanwhile, the calculation of structural deformation under the action of confined blast loading is confronted with multiple challenges, including a large number of involved variables, complex expression forms and high research costs. To tackle these problems, based on a validated numerical calculation method for explosion loads in confined spaces where the afterburning effect is taken into consideration, a systematic analysis is carried out on the spatiotemporal distribution law of explosion loads in confined spaces, and an equivalent load simplification method that simultaneously accounts for the saturation response time and quasi-static pressure is proposed in this paper. Through an in-depth investigation into the spatial distribution form of the equivalent load and the influence exerted by quasi-static pressure on structural response, the results demonstrate that within the scope of the current research, the impact of the spatial distribution of the equivalent load on structural response is relatively minor, whereas the contribution of quasi-static pressure cannot be neglected. On the basis of the above research findings, a two-stage load simplification model represented by the load characteristics at the central point of the target plate is further developed. A comparative analysis is conducted between the residual deformation values derived from 10 groups of simplified models and those obtained from actual experiments, which verifies the effectiveness of the established simplified model. The research results indicate that the proposed model possesses excellent applicability under different working conditions, can not only guarantee calculation precision but also remarkably enhance computational efficiency, and thus provides a reliable technical approach for the simplified analysis of engineering problems related to confined space explosions.
, Available online ,
doi: 10.11883/bzycj-2026-0002
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To further analyze the damage effects of projectile penetration into concrete targets and their influence on the penetration process, this study established a spalling effect model for normal projectile penetration based on the observed spalling damage phenomena. Subsequently, by integrating the target resistance function, a theoretical penetration model was developed. The cratering effect and the spalling effect were considered in the presented model. The reliability of the theoretical penetration model was verified using experimental data on crater depth, spalling depth, and residual velocity. Finally, based on this presented model, the influence of the concrete target thickness and initial impact velocity on the penetration process and the damage parameters of concrete targets were discussed. As the thickness increases, the influence of spalling damage on penetration resistance and the residual velocity becomes more pronounced, while the proportion of the splashing zone decreases during the spalling stage. When the thickness is less than 3d, the spalling zone is a splash zone. When the concrete thickness exceeds 4.5d, the influence of the spalling effect on the residual velocity exceeds 10%, rendering the spalling effect non-negligible. With increasing impact velocity, the influence of the spalling effect on penetration resistance and residual velocity decreases. Concurrently, the proportion of the splashing zone within the spalling stage gradually expands, causing the splashing effect to become the dominant factor governing resistance variations during spalling. With increasing concrete target thickness, the crater depth first increases linearly (thickness≤4d) and then stabilizes, while the spalling depth initially exhibits a linear increase (thickness≤6.9d) followed by a linear decrease. During the linear growth phase, both the crater depth and the spalling depth approximate half of the concrete target thickness. Compared to thin concrete targets, variations in impact velocity exhibit a more pronounced influence on the crater depth and spalling depth during the penetration of thick concrete targets.
To further analyze the damage effects of projectile penetration into concrete targets and their influence on the penetration process, this study established a spalling effect model for normal projectile penetration based on the observed spalling damage phenomena. Subsequently, by integrating the target resistance function, a theoretical penetration model was developed. The cratering effect and the spalling effect were considered in the presented model. The reliability of the theoretical penetration model was verified using experimental data on crater depth, spalling depth, and residual velocity. Finally, based on this presented model, the influence of the concrete target thickness and initial impact velocity on the penetration process and the damage parameters of concrete targets were discussed. As the thickness increases, the influence of spalling damage on penetration resistance and the residual velocity becomes more pronounced, while the proportion of the splashing zone decreases during the spalling stage. When the thickness is less than 3d, the spalling zone is a splash zone. When the concrete thickness exceeds 4.5d, the influence of the spalling effect on the residual velocity exceeds 10%, rendering the spalling effect non-negligible. With increasing impact velocity, the influence of the spalling effect on penetration resistance and residual velocity decreases. Concurrently, the proportion of the splashing zone within the spalling stage gradually expands, causing the splashing effect to become the dominant factor governing resistance variations during spalling. With increasing concrete target thickness, the crater depth first increases linearly (thickness≤4d) and then stabilizes, while the spalling depth initially exhibits a linear increase (thickness≤6.9d) followed by a linear decrease. During the linear growth phase, both the crater depth and the spalling depth approximate half of the concrete target thickness. Compared to thin concrete targets, variations in impact velocity exhibit a more pronounced influence on the crater depth and spalling depth during the penetration of thick concrete targets.
, Available online ,
doi: 10.11883/bzycj-2025-0235
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Projectile’s structural vibration during high-speed penetration of hard targets is an important factor causing mixed overload signals and charge’s localized-deformation magnification issues, which restricts the destructive capability of projectiles. To accurately characterize the elastic vibration characteristics of the penetrating projectile, a refined theoretical modal modeling method for the projectile was derived based on the theories of variable cross-section rods. Furthermore, two 30-kg class projectiles with the same mass and outline but different internal cavity structures were manufactured, together with an even hollow cylindrical tube with the same mass and outer diameter as the two projectiles. Using these three structures as examples, theoretical, experimental, and simulation modal analysis were conducted to explore the modal features of the projectile from the perspectives of characteristic frequencies and their corresponding low-order tensile-compressive modes. The structural similarities and differences between projectile and even bar were compared, and the influence of charges on projectile modes was explored. Eventually, the vibration characteristics of the projectile penetrating semi-infinite and multi-layer concrete targets were deduced with the introduction of projectile’s modal characteristics conducted before. Research has shown that the Mindlin-Herrmann rod models have derived similar modal characteristic compared with simulation and experimental results, while the even bar model shows larger discrepancies. In weak load environments, the charge increases the structural damping, and the higher the modal order of the projectile, the weaker the coupling relationship between the projectile and the charge. However, the applicability of this conclusion in harsh load environments still needs to be explored. The low-order tensile-compressive modes dominate the vibration characteristics of the penetrating projectile, and the deformation and overload distribution are mostly affected by the first-order tensile-compressive mode, while the high-order modes supplement the vibration of the projectile. Benefiting from the variable cross-section effect, projectiles with short and concentrated inner cavities have better anti-vibration characteristics during ideal penetration. Projectile’s vibration characteristics obtained through modal analysis provides more reliable guidance for the design of the projectile-fuse-charge system.
Projectile’s structural vibration during high-speed penetration of hard targets is an important factor causing mixed overload signals and charge’s localized-deformation magnification issues, which restricts the destructive capability of projectiles. To accurately characterize the elastic vibration characteristics of the penetrating projectile, a refined theoretical modal modeling method for the projectile was derived based on the theories of variable cross-section rods. Furthermore, two 30-kg class projectiles with the same mass and outline but different internal cavity structures were manufactured, together with an even hollow cylindrical tube with the same mass and outer diameter as the two projectiles. Using these three structures as examples, theoretical, experimental, and simulation modal analysis were conducted to explore the modal features of the projectile from the perspectives of characteristic frequencies and their corresponding low-order tensile-compressive modes. The structural similarities and differences between projectile and even bar were compared, and the influence of charges on projectile modes was explored. Eventually, the vibration characteristics of the projectile penetrating semi-infinite and multi-layer concrete targets were deduced with the introduction of projectile’s modal characteristics conducted before. Research has shown that the Mindlin-Herrmann rod models have derived similar modal characteristic compared with simulation and experimental results, while the even bar model shows larger discrepancies. In weak load environments, the charge increases the structural damping, and the higher the modal order of the projectile, the weaker the coupling relationship between the projectile and the charge. However, the applicability of this conclusion in harsh load environments still needs to be explored. The low-order tensile-compressive modes dominate the vibration characteristics of the penetrating projectile, and the deformation and overload distribution are mostly affected by the first-order tensile-compressive mode, while the high-order modes supplement the vibration of the projectile. Benefiting from the variable cross-section effect, projectiles with short and concentrated inner cavities have better anti-vibration characteristics during ideal penetration. Projectile’s vibration characteristics obtained through modal analysis provides more reliable guidance for the design of the projectile-fuse-charge system.
, Available online ,
doi: 10.11883/bzycj-2025-0383
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To address the high cost and low sample efficiency of deep learning-based blast loading prediction in urban environments, a Bayesian deep active learning (BDAL) method is proposed. The objective is to significantly reduce the dependency on large-scale, high-fidelity numerical simulation data while maintaining prediction accuracy and providing reliable uncertainty quantification. A three-dimensional typical urban building cluster consisting of a 3×3 regular array of cuboid buildings was constructed. A seven-dimensional parameter space was defined, including explosive charge equivalence (1000, 2000, 3000 kT), detonation distance (1000, 2000, 3000 m), building length (10, 20, 30 m), building width (20, 40 m), building height (75, 100 m), street length (50, 75, 100 m), and street width (50, 75 m). A full factorial experimental design was employed, generating 648 parameter combinations. For each combination, the open-source computational fluid dynamics (CFD) software blastFoam was used to perform three-dimensional numerical simulations of blast wave propagation. The background mesh size was set to 30 m based on grid sensitivity analysis, and adaptive mesh refinement (AMR) with local refinement level 2 and dynamic refinement level 1 was applied to capture shock wave details. Peak overpressure values were recorded at 12 points of interest (POIs) in the building cluster, resulting in a dataset of 7776 samples. A Bayesian deep active learning framework was then developed. Bayesian inference was integrated into a deep neural network to enable probabilistic modeling of parameters. Monte Carlo dropout (MC-Dropout) was adopted as an approximate variational inference method to estimate predictive uncertainty. An uncertainty-driven active sampling strategy was designed: the predictive variance of each unlabeled sample was computed via 30 stochastic forward passes with dropout enabled. Samples with variance exceeding 85% of the maximum variance were selected as candidates, and the top 28 cases (336 samples) with the highest variance were chosen in each active learning cycle. These selected samples were labeled by the blastFoam simulator and added to the training set. The model was retrained iteratively until the relative improvement in mean absolute percentage error (MAPE) fell below 1% or the labeled set reached the full training size. On a test set of 780 unseen samples (65 cases), the proposed BDAL method achieved a MAPE of 13.1% and an R² of 0.972 for peak overpressure prediction. The 95% prediction interval covered the true values in 85.9% of the cases, with a normalized mean prediction interval width (NMPIW) of 0.026. Single-point prediction response time was below 20 ms, representing a speedup of more than 10⁵ compared to high-fidelity numerical simulations. Compared to passive deep learning models trained on the full dataset, the BDAL method required only about 50% of labeled data to reach comparable prediction accuracy. In a comparative experiment with 50% training data, BDAL achieved a MAPE of 17.2%, while a conventional fully connected neural network (FCNN) and a three-dimensional direction-encoded Bayesian neural network (3D-DeBNN) gave MAPEs of 52.9% and 22.6%, respectively. The proposed Bayesian deep active learning method enables efficient and low-cost blast loading prediction in typical regularized urban environments. It effectively reduces the dependency on large-scale numerical simulation data, maintains high prediction accuracy and reliable uncertainty quantification, and achieves millisecond-level inference speed. The method shows strong potential for disaster prevention and mitigation applications, such as pre-disaster anti-blast design and post-disaster emergency response.
To address the high cost and low sample efficiency of deep learning-based blast loading prediction in urban environments, a Bayesian deep active learning (BDAL) method is proposed. The objective is to significantly reduce the dependency on large-scale, high-fidelity numerical simulation data while maintaining prediction accuracy and providing reliable uncertainty quantification. A three-dimensional typical urban building cluster consisting of a 3×3 regular array of cuboid buildings was constructed. A seven-dimensional parameter space was defined, including explosive charge equivalence (1000, 2000, 3000 kT), detonation distance (1000, 2000, 3000 m), building length (10, 20, 30 m), building width (20, 40 m), building height (75, 100 m), street length (50, 75, 100 m), and street width (50, 75 m). A full factorial experimental design was employed, generating 648 parameter combinations. For each combination, the open-source computational fluid dynamics (CFD) software blastFoam was used to perform three-dimensional numerical simulations of blast wave propagation. The background mesh size was set to 30 m based on grid sensitivity analysis, and adaptive mesh refinement (AMR) with local refinement level 2 and dynamic refinement level 1 was applied to capture shock wave details. Peak overpressure values were recorded at 12 points of interest (POIs) in the building cluster, resulting in a dataset of 7776 samples. A Bayesian deep active learning framework was then developed. Bayesian inference was integrated into a deep neural network to enable probabilistic modeling of parameters. Monte Carlo dropout (MC-Dropout) was adopted as an approximate variational inference method to estimate predictive uncertainty. An uncertainty-driven active sampling strategy was designed: the predictive variance of each unlabeled sample was computed via 30 stochastic forward passes with dropout enabled. Samples with variance exceeding 85% of the maximum variance were selected as candidates, and the top 28 cases (336 samples) with the highest variance were chosen in each active learning cycle. These selected samples were labeled by the blastFoam simulator and added to the training set. The model was retrained iteratively until the relative improvement in mean absolute percentage error (MAPE) fell below 1% or the labeled set reached the full training size. On a test set of 780 unseen samples (65 cases), the proposed BDAL method achieved a MAPE of 13.1% and an R² of 0.972 for peak overpressure prediction. The 95% prediction interval covered the true values in 85.9% of the cases, with a normalized mean prediction interval width (NMPIW) of 0.026. Single-point prediction response time was below 20 ms, representing a speedup of more than 10⁵ compared to high-fidelity numerical simulations. Compared to passive deep learning models trained on the full dataset, the BDAL method required only about 50% of labeled data to reach comparable prediction accuracy. In a comparative experiment with 50% training data, BDAL achieved a MAPE of 17.2%, while a conventional fully connected neural network (FCNN) and a three-dimensional direction-encoded Bayesian neural network (3D-DeBNN) gave MAPEs of 52.9% and 22.6%, respectively. The proposed Bayesian deep active learning method enables efficient and low-cost blast loading prediction in typical regularized urban environments. It effectively reduces the dependency on large-scale numerical simulation data, maintains high prediction accuracy and reliable uncertainty quantification, and achieves millisecond-level inference speed. The method shows strong potential for disaster prevention and mitigation applications, such as pre-disaster anti-blast design and post-disaster emergency response.
Experimental Study on Damage Effects of RC Frame Structures with Masonry Walls under Explosion Loads
, Available online ,
doi: 10.11883/bzycj-2025-0378
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Abstract:
Reinforced Concrete (RC) frame structures play a key role in numerous political and economic activities. However, the increasing frequency of explosion attacks and public safety incidents, coupled with the complex international situation, has rendered RC frame structures as crucial targets for both attack and protection. To investigate the damage effects of multiple explosions on RC frame structures, a full-scale two-story RC frame structure with masonry walls was designed and constructed. Based on this building, external and internal explosion tests were conducted under different TNT equivalents (11.573kg and 20kg). The load characteristics of shock waves, dynamic response and failure modes of structural components were examined. The results show that under close-range external explosion, the floor slabs and masonry walls can attenuate the shock wave loads propagated into the adjacent room, with a peak overpressure reduction of 84.75%. The floor slabs and masonry walls exhibit local shear failure, while the damage to the internal components and the global structure is minor. In contrast, under internal explosion, the floor slabs and masonry walls show global shear failure, with higher damage compared to the RC columns and beams. In addition to the shock wave loads, the explosive ejection of wall/slab fragments from the explosion source room is the primary reason for damage to the masonry walls and slabs along the direction of shock wave propagation. Finally, based on damage assessment criteria, the damage levels of components, rooms, and the RC structure for each test were determined. The damage level and range of RC structure under internal explosion is significantly higher than that under external explosion loads.
Reinforced Concrete (RC) frame structures play a key role in numerous political and economic activities. However, the increasing frequency of explosion attacks and public safety incidents, coupled with the complex international situation, has rendered RC frame structures as crucial targets for both attack and protection. To investigate the damage effects of multiple explosions on RC frame structures, a full-scale two-story RC frame structure with masonry walls was designed and constructed. Based on this building, external and internal explosion tests were conducted under different TNT equivalents (11.573kg and 20kg). The load characteristics of shock waves, dynamic response and failure modes of structural components were examined. The results show that under close-range external explosion, the floor slabs and masonry walls can attenuate the shock wave loads propagated into the adjacent room, with a peak overpressure reduction of 84.75%. The floor slabs and masonry walls exhibit local shear failure, while the damage to the internal components and the global structure is minor. In contrast, under internal explosion, the floor slabs and masonry walls show global shear failure, with higher damage compared to the RC columns and beams. In addition to the shock wave loads, the explosive ejection of wall/slab fragments from the explosion source room is the primary reason for damage to the masonry walls and slabs along the direction of shock wave propagation. Finally, based on damage assessment criteria, the damage levels of components, rooms, and the RC structure for each test were determined. The damage level and range of RC structure under internal explosion is significantly higher than that under external explosion loads.
, Available online ,
doi: 10.11883/bzycj-2026-0054
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Abstract:
Impact fatigue refers to the phenomenon in which materials or structures, subjected to repeated impact loading, experience localized stress concentrations and rapid strain accumulation, leading to the initiation of internal micro-damage and ultimately culminating in fracture failure. Impact fatigue loads are characterized by their brief duration, rapid loading rates, and significantly elevated strain rates, which has greater perniciousness than conventional fatigue. The dynamic contact forces between the wheel and rail of high-speed trains exhibit classic characteristics of impact fatigue loading, which induces the accumulation of impact fatigue damage, accelerates the deterioration of material mechanical properties; and consequently, compromises the operational safety of high-speed trains. In light of this, the present study integrates a material-based impact fatigue damage-coupled constitutive model to develop a comprehensive three-dimensional half-wheel-rail rolling contact finite element model. The stress-strain states and stick-slip characteristics of wheel-rail rolling/sliding contact are clarified, and the distribution features and accumulation evolution law of wheel-rail impact fatigue damage are analyzed. Meanwhile, the effects of train speed, friction coefficient, and traction coefficient on impact fatigue damage are explored, and the influence of material constitutive model on typical wheel-rail contact mechanical behavior is examined. The results clearly indicate that the proposed impact fatigue model is able to well represent the wheel-rail contact responses, stick-slip distribution characteristics and damage accumulation law. Under repeated rolling contact, the impact fatigue damage of the rail exhibits a nonlinear cumulative increasing trend with the rise of rolling cycles; however, the growth rate gradually decreases and eventually tends to stabilize approximately. Compared with the elastoplastic constitutive model, the wheel-rail contact mechanical responses predicted by the impact fatigue constitutive model are more severe and dangerous. Moreover, such coupling effect gradually intensifies with the increase of rolling cycles. These findings provide valuable theoretical insights and technical support for fatigue damage assessment and life prediction of high-speed wheel-rail systems.
Impact fatigue refers to the phenomenon in which materials or structures, subjected to repeated impact loading, experience localized stress concentrations and rapid strain accumulation, leading to the initiation of internal micro-damage and ultimately culminating in fracture failure. Impact fatigue loads are characterized by their brief duration, rapid loading rates, and significantly elevated strain rates, which has greater perniciousness than conventional fatigue. The dynamic contact forces between the wheel and rail of high-speed trains exhibit classic characteristics of impact fatigue loading, which induces the accumulation of impact fatigue damage, accelerates the deterioration of material mechanical properties; and consequently, compromises the operational safety of high-speed trains. In light of this, the present study integrates a material-based impact fatigue damage-coupled constitutive model to develop a comprehensive three-dimensional half-wheel-rail rolling contact finite element model. The stress-strain states and stick-slip characteristics of wheel-rail rolling/sliding contact are clarified, and the distribution features and accumulation evolution law of wheel-rail impact fatigue damage are analyzed. Meanwhile, the effects of train speed, friction coefficient, and traction coefficient on impact fatigue damage are explored, and the influence of material constitutive model on typical wheel-rail contact mechanical behavior is examined. The results clearly indicate that the proposed impact fatigue model is able to well represent the wheel-rail contact responses, stick-slip distribution characteristics and damage accumulation law. Under repeated rolling contact, the impact fatigue damage of the rail exhibits a nonlinear cumulative increasing trend with the rise of rolling cycles; however, the growth rate gradually decreases and eventually tends to stabilize approximately. Compared with the elastoplastic constitutive model, the wheel-rail contact mechanical responses predicted by the impact fatigue constitutive model are more severe and dangerous. Moreover, such coupling effect gradually intensifies with the increase of rolling cycles. These findings provide valuable theoretical insights and technical support for fatigue damage assessment and life prediction of high-speed wheel-rail systems.
, Available online ,
doi: 10.11883/bzycj-2026-0015
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Abstract:
To elucidate the mechanism by which shock and obstacle interactions induce local detonation initiation, an experimental investigation was conducted on flame acceleration of premixed hydrogen–air mixtures in an obstacle-laden tube. Experiments were performed over a range of equivalence ratios from 0.8 to 1.3, spanning both fuel-lean and fuel-rich conditions relative to stoichiometry. Particular emphasis was placed on the interaction between the Mach stem of the leading shock and a single obstacle, and on how this interaction governs the formation of localized hot spots and the subsequent onset of local detonation. At an equivalence ratio of 0.8, initiation was not observed. Under this condition, the reflected shock interacted with the flame front and induced Richtmyer–Meshkov instability, generating pronounced wrinkling of the flame surface. This interaction further densified the pre-existing flame folds and increased the flame surface area, thereby accelerating the flame; however, no local detonation was initiated. In contrast, if the equivalence ratio was within the range from 0.9 to 1.3, successful initiation was observed. Shock reflection in the obstacle vicinity generated localized regions of elevated temperature that acted as hot spots, providing favorable conditions for rapid energy release and the onset of a locally detonative event. However, the locally initiated detonation did not develop into a self-sustained stable detonation. During subsequent diffraction, expansion waves imposed pronounced cooling and attenuation, causing progressive decoupling between the leading shock and the reaction zone, and thereby suppressing further development into a stable detonation wave. Through analysis of the critical initiation characteristics, it is found that increasing either the shock strength or the equivalence ratio increases the critical initiation parameter, and the critical initiation parameter is more sensitive to shock strength than to equivalence ratio. Furthermore, considering the discrepancy between the Thomas critical initiation model and the incident shock wave in the present experiments, the shock reflection zone was divided into sections for calculation. The analysis reveals that, at an equivalence ratio of 1.2, the lower sonic velocity following reflection of the leading shock wave prolongs the time taken for the expansion wave to reach the base of the obstacle, thereby favoring initiation. Conversely, at an equivalence ratio of 0.8, the lower equivalence ratio reduces the reactivity of the mixture, leading to a longer ignition delay time and consequently reducing the likelihood of initiation.
To elucidate the mechanism by which shock and obstacle interactions induce local detonation initiation, an experimental investigation was conducted on flame acceleration of premixed hydrogen–air mixtures in an obstacle-laden tube. Experiments were performed over a range of equivalence ratios from 0.8 to 1.3, spanning both fuel-lean and fuel-rich conditions relative to stoichiometry. Particular emphasis was placed on the interaction between the Mach stem of the leading shock and a single obstacle, and on how this interaction governs the formation of localized hot spots and the subsequent onset of local detonation. At an equivalence ratio of 0.8, initiation was not observed. Under this condition, the reflected shock interacted with the flame front and induced Richtmyer–Meshkov instability, generating pronounced wrinkling of the flame surface. This interaction further densified the pre-existing flame folds and increased the flame surface area, thereby accelerating the flame; however, no local detonation was initiated. In contrast, if the equivalence ratio was within the range from 0.9 to 1.3, successful initiation was observed. Shock reflection in the obstacle vicinity generated localized regions of elevated temperature that acted as hot spots, providing favorable conditions for rapid energy release and the onset of a locally detonative event. However, the locally initiated detonation did not develop into a self-sustained stable detonation. During subsequent diffraction, expansion waves imposed pronounced cooling and attenuation, causing progressive decoupling between the leading shock and the reaction zone, and thereby suppressing further development into a stable detonation wave. Through analysis of the critical initiation characteristics, it is found that increasing either the shock strength or the equivalence ratio increases the critical initiation parameter, and the critical initiation parameter is more sensitive to shock strength than to equivalence ratio. Furthermore, considering the discrepancy between the Thomas critical initiation model and the incident shock wave in the present experiments, the shock reflection zone was divided into sections for calculation. The analysis reveals that, at an equivalence ratio of 1.2, the lower sonic velocity following reflection of the leading shock wave prolongs the time taken for the expansion wave to reach the base of the obstacle, thereby favoring initiation. Conversely, at an equivalence ratio of 0.8, the lower equivalence ratio reduces the reactivity of the mixture, leading to a longer ignition delay time and consequently reducing the likelihood of initiation.
, Available online ,
doi: 10.11883/bzycj-2025-0177
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Abstract:
The Doppler pins system (Doppler pins system) array and high-speed photography are used to study the expansion and fracture behavior of single and double-layer metal cylindrical shells under detonation loading of hollow explosives(the total thickness of the two layers is equal to the thickness of the single layer). The velocity curves and high-speed photography images of the outer surface of the single and double-layer cylindrical shells are obtained. The results of velocity curves show that spallation occurs at about 2/5 of the outer surface of the single-layer cylindrical shell, and the remaining fragments of the single-layer cylindrical shell quickly catch up with the spallation cylindrical shell with incomplete separation after about 1.89μs and generate secondary impact loading. The inner and outer cylindrical shells of the double-layer cylindrical shell are separated rapidly because they cannot withstand the tensile stress. The outer cylindrical shell expands freely radially, and the inner cylindrical shell continues to catch up with the outer cylindrical shell after 26.13μs for a long time under detonation loading and undergoes secondary loading. The difference in secondary loading time is significant in the single-layer and double-layer expansion experiments. The premature separation of the double-layered cylindrical shell hinders the crack penetration from the inside to the outside, and delays the crack penetration until the complete fracture behavior of the whole cylindrical shell. Different from the traditional single-layer cylindrical shell fracture, the detonation product leakage time is late when the outer layer of the double-layer cylindrical shell expands, the fragment size of double-layer shell is obviously smaller than that of single-layer cylindrical shell, the overflowing detonation product distribution is relatively scattered and rare, and the overall crack of the outer cylindrical shell is clearly visible. The results of numerical simulation by SPH method show that the higher the spallation strength of single-layer cylindrical shells, the earlier the remaining fragments catch up with the spallation shell under secondary loading, and the more easily the penetrating fracture occurs. The gap blocking crack at the interface of double-layer cylindrical shells has a remarkable effect on the penetrating development of the cracks at the interface of double-layer cylindrical shells..
The Doppler pins system (Doppler pins system) array and high-speed photography are used to study the expansion and fracture behavior of single and double-layer metal cylindrical shells under detonation loading of hollow explosives(the total thickness of the two layers is equal to the thickness of the single layer). The velocity curves and high-speed photography images of the outer surface of the single and double-layer cylindrical shells are obtained. The results of velocity curves show that spallation occurs at about 2/5 of the outer surface of the single-layer cylindrical shell, and the remaining fragments of the single-layer cylindrical shell quickly catch up with the spallation cylindrical shell with incomplete separation after about 1.89μs and generate secondary impact loading. The inner and outer cylindrical shells of the double-layer cylindrical shell are separated rapidly because they cannot withstand the tensile stress. The outer cylindrical shell expands freely radially, and the inner cylindrical shell continues to catch up with the outer cylindrical shell after 26.13μs for a long time under detonation loading and undergoes secondary loading. The difference in secondary loading time is significant in the single-layer and double-layer expansion experiments. The premature separation of the double-layered cylindrical shell hinders the crack penetration from the inside to the outside, and delays the crack penetration until the complete fracture behavior of the whole cylindrical shell. Different from the traditional single-layer cylindrical shell fracture, the detonation product leakage time is late when the outer layer of the double-layer cylindrical shell expands, the fragment size of double-layer shell is obviously smaller than that of single-layer cylindrical shell, the overflowing detonation product distribution is relatively scattered and rare, and the overall crack of the outer cylindrical shell is clearly visible. The results of numerical simulation by SPH method show that the higher the spallation strength of single-layer cylindrical shells, the earlier the remaining fragments catch up with the spallation shell under secondary loading, and the more easily the penetrating fracture occurs. The gap blocking crack at the interface of double-layer cylindrical shells has a remarkable effect on the penetrating development of the cracks at the interface of double-layer cylindrical shells..
, Available online ,
doi: 10.11883/bzycj-2025-0399
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Abstract:
Crack propagation in rock blasting exhibits strong randomness, making directional fracture control difficult and leading to low energy utilization efficiency, which remains a key issue in controlled blasting. To improve the energy utilization efficiency in directional fracturing, a composite shaped charge liner with a “slotting + shaped-charge” structure was designed. A combination of dynamic caustics experiments and numerical simulations was employed to investigate the effects of liner opening angle on crack propagation and energy release. In the experimental study, dynamic caustics techniques were used to capture the initiation and evolution of cracks under blasting loading, and key dynamic parameters such as crack propagation velocity and stress intensity factor were obtained from caustic patterns. Meanwhile, fractal dimension analysis was introduced to quantitatively characterize the complexity and directional distribution of blast-induced cracks. In the numerical study, a fluid–structure coupled model was established to simulate the blasting process, enabling further analysis of stress wave propagation, energy release behavior, and the formation and penetration characteristics of the shaped charge jet under different opening angles. The results show that the composite shaped charge liner significantly enhances crack propagation in the energy-focused direction while suppressing damage in non-focused directions. The shaped-charge effect first increases and then decreases with increasing opening angle. When the opening angle is 60°, the crack propagation length, propagation velocity, the ratio of fractal dimensions between focused and non-focused directions, and the dynamic stress intensity factor all reach their peak values, indicating the optimal directional fracturing performance. The energy release rate increases with the opening angle and reaches 746.05 N/m at 75°. Numerical simulations indicate that, at an opening angle of 60°, the formed metal jet exhibits the most coherent morphology and the highest jet-tip velocity, with the penetration depth and inlet aperture reaching 21.5 mm and 14.1 mm, respectively. The study reveals the coupling mechanism between the quasi-static action of detonation gases and metal jet penetration in the composite liner, providing a reference for the optimization of shaped charge structures and the design of directional controlled blasting in rock engineering.
Crack propagation in rock blasting exhibits strong randomness, making directional fracture control difficult and leading to low energy utilization efficiency, which remains a key issue in controlled blasting. To improve the energy utilization efficiency in directional fracturing, a composite shaped charge liner with a “slotting + shaped-charge” structure was designed. A combination of dynamic caustics experiments and numerical simulations was employed to investigate the effects of liner opening angle on crack propagation and energy release. In the experimental study, dynamic caustics techniques were used to capture the initiation and evolution of cracks under blasting loading, and key dynamic parameters such as crack propagation velocity and stress intensity factor were obtained from caustic patterns. Meanwhile, fractal dimension analysis was introduced to quantitatively characterize the complexity and directional distribution of blast-induced cracks. In the numerical study, a fluid–structure coupled model was established to simulate the blasting process, enabling further analysis of stress wave propagation, energy release behavior, and the formation and penetration characteristics of the shaped charge jet under different opening angles. The results show that the composite shaped charge liner significantly enhances crack propagation in the energy-focused direction while suppressing damage in non-focused directions. The shaped-charge effect first increases and then decreases with increasing opening angle. When the opening angle is 60°, the crack propagation length, propagation velocity, the ratio of fractal dimensions between focused and non-focused directions, and the dynamic stress intensity factor all reach their peak values, indicating the optimal directional fracturing performance. The energy release rate increases with the opening angle and reaches 746.05 N/m at 75°. Numerical simulations indicate that, at an opening angle of 60°, the formed metal jet exhibits the most coherent morphology and the highest jet-tip velocity, with the penetration depth and inlet aperture reaching 21.5 mm and 14.1 mm, respectively. The study reveals the coupling mechanism between the quasi-static action of detonation gases and metal jet penetration in the composite liner, providing a reference for the optimization of shaped charge structures and the design of directional controlled blasting in rock engineering.
, Available online ,
doi: 10.11883/bzycj-2026-0048
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Abstract:
With the continuous deepening of China 's deep strategy, a new situation has been opened for the expansion of resource development to the deep. At the same time, it also needs to face more complex engineering problems, such as high ground stress, high strength rock mass and other geological conditions. In order to solve the problems of low efficiency and high energy consumption of traditional blasting in deep rock mass, a new method of microwave-assisted blasting rock breaking is proposed. In this paper, the coupling test of microwave radiation and single-hole blasting in simulated deep environment is carried out with magnetite as the research object. Based on the analysis of the test results, combined with X-ray high-precision micro-CT scanning and three-dimensional reconstruction technology, the changes of pore volume, surface area, fractal dimension, pore structure and crack propagation under different loading conditions are analyzed, and the influence of different loading conditions on the evolution of pore and fracture structure of iron ore is discussed. The research shows that : (1) Microwave radiation promotes the development and initiation of pores and fissures. With the increase of microwave damage, the volume, surface area and fractal dimension of pore fracture distribution complexity of iron ore after blasting show a gradual upward trend. Compared with prolonging the irradiation time, increasing the microwave power has a more significant effect on the development of pore fracture of iron ore. When high power microwave radiation is used, the increase of pore volume and surface area of the sample reaches the maximum of 30.48 % and 31.37 %, respectively. (2) Microwave radiation can effectively improve the blasting effect, which can be attributed to the connection and penetration of pores and microcracks, providing more channels for blasting stress wave propagation. The peak of the distribution curve of pore radius and throat length of the sample gradually shifts to the direction of larger radius and longer length with the increase of microwave damage, and the distribution range of pore coordination number increases.(3) The confining pressure inhibits the synergistic effect of microwave-blasting. With the increase of confining pressure, the crack propagation is obviously limited, the volume and maximum length of the through-hole cracks are significantly reduced, and the volume ratio of the isolated hole cracks is increased. The confining pressure changes the propagation direction of the main crack, and the propagation direction of the main crack is changed from the radial shape without confining pressure to the direction of the maximum principal stress. This study provides a reference for the engineering application of microwave-assisted blasting technology in deep high stress environment.
, Available online ,
doi: 10.11883/bzycj-2025-0396
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Abstract:
Traditional Lagrangian and Eulerian algorithms exhibited certain limitations when addressing problems involving large mesh deformations and complex fluid–structure interaction (FSI) in explosions. To investigate the load characteristics of acetylene explosions and their impact effects on adjacent structures, a finite element model was established based on the structured arbitrary Lagrangian–Eulerian (S-ALE) FSI method. Numerical simulations were conducted to model the explosion of a 20 L spherical acetylene–air mixture and its subsequent impact on a target plate. The simulations were performed using ANSYS/LS-DYNA, with the geometric model consisting of the explosive domain, the air domain, and the target plate. To reduce computational cost while maintaining accuracy, a one-eighth symmetry model was adopted. Key parameters under different acetylene volume fractions and equivalent trinitrotoluene (TNT) masses, as well as the dynamic response of the target plate, were systematically examined, with results compared against those obtained using the multi-material arbitrary Lagrangian–Eulerian (MMALE) coupling method. The results indicate the following: (1) Compared with traditional methods, both the S-ALE and MMALE methods demonstrate superior accuracy and effectiveness in simulating acetylene explosion coupling problems. However, the S-ALE method offers greater advantages in model setup, meshing, computational efficiency, and stability, with these benefits becoming more pronounced as the model size increases. (2) Under identical conditions, the peak overpressure and peak velocity of the shock wave generated by a 7.75% volume fraction acetylene explosion in the air domain are lower than those of an equivalent TNT explosion, whereas the positive pressure duration is relatively longer. The differences in pressure and von Mises stress responses on the target plate between the two cases are minimal, indicating that, based on the principle of equivalent explosion energy, acetylene can induce damage effects comparable in magnitude to those of chemical explosives in terms of specific structural response indicators. (3) Through systematic comparisons involving target plates of different materials and various acetylene volume fractions, the load characteristics of acetylene explosions and the corresponding structural response patterns are elucidated. The validity and superiority of the S-ALE method in simulating acetylene explosion impact problems are confirmed, providing a numerical basis for assessing the feasibility of acetylene as an explosion source in specific scenarios and offering important references for the design of blast-resistant structures and the optimization of safety protection measures.
Traditional Lagrangian and Eulerian algorithms exhibited certain limitations when addressing problems involving large mesh deformations and complex fluid–structure interaction (FSI) in explosions. To investigate the load characteristics of acetylene explosions and their impact effects on adjacent structures, a finite element model was established based on the structured arbitrary Lagrangian–Eulerian (S-ALE) FSI method. Numerical simulations were conducted to model the explosion of a 20 L spherical acetylene–air mixture and its subsequent impact on a target plate. The simulations were performed using ANSYS/LS-DYNA, with the geometric model consisting of the explosive domain, the air domain, and the target plate. To reduce computational cost while maintaining accuracy, a one-eighth symmetry model was adopted. Key parameters under different acetylene volume fractions and equivalent trinitrotoluene (TNT) masses, as well as the dynamic response of the target plate, were systematically examined, with results compared against those obtained using the multi-material arbitrary Lagrangian–Eulerian (MMALE) coupling method. The results indicate the following: (1) Compared with traditional methods, both the S-ALE and MMALE methods demonstrate superior accuracy and effectiveness in simulating acetylene explosion coupling problems. However, the S-ALE method offers greater advantages in model setup, meshing, computational efficiency, and stability, with these benefits becoming more pronounced as the model size increases. (2) Under identical conditions, the peak overpressure and peak velocity of the shock wave generated by a 7.75% volume fraction acetylene explosion in the air domain are lower than those of an equivalent TNT explosion, whereas the positive pressure duration is relatively longer. The differences in pressure and von Mises stress responses on the target plate between the two cases are minimal, indicating that, based on the principle of equivalent explosion energy, acetylene can induce damage effects comparable in magnitude to those of chemical explosives in terms of specific structural response indicators. (3) Through systematic comparisons involving target plates of different materials and various acetylene volume fractions, the load characteristics of acetylene explosions and the corresponding structural response patterns are elucidated. The validity and superiority of the S-ALE method in simulating acetylene explosion impact problems are confirmed, providing a numerical basis for assessing the feasibility of acetylene as an explosion source in specific scenarios and offering important references for the design of blast-resistant structures and the optimization of safety protection measures.
, Available online ,
doi: 10.11883/bzycj-2025-0351
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Abstract:
Ti/steel clad plates are considered ideal candidate materials for applications such as marine engineering and low-temperature pressure vessels operating at −70 °C. However, their large-scale production and application are severely restricted by the manufacturing process and the quality of interfacial bonding. To investigate the influence mechanism of vacuum pressure on interfacial morphology and mechanical properties, TC4/09MnNiDR Ti/steel clad plates were fabricated using explosive welding under ambient pressures of 20 kPa, 60 kPa, and 100 kPa. A specially designed vacuum chamber was employed to precisely control the environmental pressure during the explosive process. After welding, all specimens were subjected to a uniform stress-relief annealing treatment at 550 °C for 2 h under a vacuum atmosphere to eliminate residual stresses and improve the reliability of subsequent characterization. The interfacial microstructure and chemical characteristics were systematically analyzed using multiple characterization techniques. Scanning electron microscopy (SEM) was used to observe interfacial morphology, including wave formation and defect distribution. Energy dispersive spectroscopy (EDS) was applied to examine elemental distribution across the bonding interface. Electron backscatter diffraction (EBSD) was employed to evaluate grain structure, grain boundary characteristics, recrystallization fraction, and texture evolution near the interface. Electron probe microanalysis (EPMA) was conducted to quantitatively determine the chemical composition of the interfacial melting zone and vortex regions, with both mapping and point analyses performed to identify the constituent phases. Mechanical properties at −70 °C were evaluated through tensile tests, Charpy impact tests, and three-point bending tests, all carried out in accordance with relevant national standards, with the results reported as mean values ± standard deviations. Results show that the vacuum environment significantly improves interfacial quality. With increasing vacuum degree, the interfacial wave becomes finer, more continuous, and more uniform, while the thickness of the molten layer decreases, and the presence of defects and brittle intermetallic compounds is reduced. Electron backscatter diffraction (EBSD) analysis reveals grain refinement and an increased recrystallization fraction at the interface under vacuum conditions, demonstrating that the interfacial microstructure can be effectively controlled by adjusting the ambient pressure. Electron probe microanalysis (EPMA) further reveals that the vortex regions are mainly composed of Fe and Ti elements, while the weld seam region exhibits a stable chemical composition with Ti:Fe atomic ratios close to 1:1 or 2:1, indicating that the dominant intermetallic phases formed at the interface are TiFe and TiFe₂. Benefiting from the optimized interfacial structure, the clad plates exhibit excellent mechanical properties at −70 °C. The tensile strengths under 20 kPa, 60 kPa, and 100 kPa are 880 MPa, 911 MPa, and 867 MPa, respectively. The impact absorbed energies are 17.5 J, 10.2 J, and 6.4 J, and the flexural strengths are 1469 MPa, 1350 MPa, and 1167 MPa, respectively. This study demonstrates that vacuum explosive welding is a reliable technique for producing high-performance low-temperature metal composites, with 60 kPa identified as the optimal processing window.
Ti/steel clad plates are considered ideal candidate materials for applications such as marine engineering and low-temperature pressure vessels operating at −70 °C. However, their large-scale production and application are severely restricted by the manufacturing process and the quality of interfacial bonding. To investigate the influence mechanism of vacuum pressure on interfacial morphology and mechanical properties, TC4/09MnNiDR Ti/steel clad plates were fabricated using explosive welding under ambient pressures of 20 kPa, 60 kPa, and 100 kPa. A specially designed vacuum chamber was employed to precisely control the environmental pressure during the explosive process. After welding, all specimens were subjected to a uniform stress-relief annealing treatment at 550 °C for 2 h under a vacuum atmosphere to eliminate residual stresses and improve the reliability of subsequent characterization. The interfacial microstructure and chemical characteristics were systematically analyzed using multiple characterization techniques. Scanning electron microscopy (SEM) was used to observe interfacial morphology, including wave formation and defect distribution. Energy dispersive spectroscopy (EDS) was applied to examine elemental distribution across the bonding interface. Electron backscatter diffraction (EBSD) was employed to evaluate grain structure, grain boundary characteristics, recrystallization fraction, and texture evolution near the interface. Electron probe microanalysis (EPMA) was conducted to quantitatively determine the chemical composition of the interfacial melting zone and vortex regions, with both mapping and point analyses performed to identify the constituent phases. Mechanical properties at −70 °C were evaluated through tensile tests, Charpy impact tests, and three-point bending tests, all carried out in accordance with relevant national standards, with the results reported as mean values ± standard deviations. Results show that the vacuum environment significantly improves interfacial quality. With increasing vacuum degree, the interfacial wave becomes finer, more continuous, and more uniform, while the thickness of the molten layer decreases, and the presence of defects and brittle intermetallic compounds is reduced. Electron backscatter diffraction (EBSD) analysis reveals grain refinement and an increased recrystallization fraction at the interface under vacuum conditions, demonstrating that the interfacial microstructure can be effectively controlled by adjusting the ambient pressure. Electron probe microanalysis (EPMA) further reveals that the vortex regions are mainly composed of Fe and Ti elements, while the weld seam region exhibits a stable chemical composition with Ti:Fe atomic ratios close to 1:1 or 2:1, indicating that the dominant intermetallic phases formed at the interface are TiFe and TiFe₂. Benefiting from the optimized interfacial structure, the clad plates exhibit excellent mechanical properties at −70 °C. The tensile strengths under 20 kPa, 60 kPa, and 100 kPa are 880 MPa, 911 MPa, and 867 MPa, respectively. The impact absorbed energies are 17.5 J, 10.2 J, and 6.4 J, and the flexural strengths are 1469 MPa, 1350 MPa, and 1167 MPa, respectively. This study demonstrates that vacuum explosive welding is a reliable technique for producing high-performance low-temperature metal composites, with 60 kPa identified as the optimal processing window.
, Available online ,
doi: 10.11883/bzycj-2025-0218
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Abstract:
The research addresses the safety imperative of preventing flammable gas explosions in enclosed pipelines by establishing a predictive model for the critical quenching diameter within porous media flame arresters. A novel predictive framework was developed based on a comprehensive nine-dimensional feature space incorporating gas composition parameters (e.g., hydrogen equivalence ratio), pipeline geometry dimensions (length-to-diameter ratio), initial thermodynamic conditions (pressure), and porous medium structural characteristics (thickness, material thermal conductivity). A systematic investigation was conducted to identify the optimal hyperparameter configurations for both Convolutional Neural Network (CNN) and Transformer architectures. Rigorous validation demonstrated the Transformer model's statistically significant superiority over the CNN model across all key performance metrics. Specifically, the model achieved a Mean Absolute Error (MAE) of 0.068, a Mean Squared Error (MSE) of 0.008, and an R2 coefficient of determination of 0.928. The performance notably surpassed the CNN results (MAE = 0.079, MSE = 0.012, R2 = 0.906). Beyond evaluation indicators, detailed error distribution analysis confirmed the Transformer's enhanced predictive accuracy and reduced susceptibility to outliers. The superior performance is attributed to the Transformer’s intrinsic self-attention mechanism, which excels at dynamically identifying and weighting critical interdependencies among the diverse input features governing the complex quenching process. The capability enables more precise capture of the nonlinear phenomena defining the quenching limit. Furthermore, robustness testing involving diverse data normalization schemes revealed the Transformer model exhibits greater stability. This resilience stems from its inherent layer normalization mechanism, which effectively decouples feature dependencies and mitigates sensitivity to input scaling variations. Consequently, the Transformer architecture is established as the definitive optimal model for this critical safety prediction task. Its significant advantage of requiring minimal data preprocessing prior to deployment offers substantial practical utility. The model provides robust quantitative decision-making support essential for formulating effective gas explosion mitigation strategies and optimizing the safety design parameters of pipeline flame arresters. By enabling accurate prediction of the critical quenching diameter under varied scenarios, this work delivers a valuable tool for enhancing inherent safety in industries handling combustible gases within confined pipeline systems.
The research addresses the safety imperative of preventing flammable gas explosions in enclosed pipelines by establishing a predictive model for the critical quenching diameter within porous media flame arresters. A novel predictive framework was developed based on a comprehensive nine-dimensional feature space incorporating gas composition parameters (e.g., hydrogen equivalence ratio), pipeline geometry dimensions (length-to-diameter ratio), initial thermodynamic conditions (pressure), and porous medium structural characteristics (thickness, material thermal conductivity). A systematic investigation was conducted to identify the optimal hyperparameter configurations for both Convolutional Neural Network (CNN) and Transformer architectures. Rigorous validation demonstrated the Transformer model's statistically significant superiority over the CNN model across all key performance metrics. Specifically, the model achieved a Mean Absolute Error (MAE) of 0.068, a Mean Squared Error (MSE) of 0.008, and an R2 coefficient of determination of 0.928. The performance notably surpassed the CNN results (MAE = 0.079, MSE = 0.012, R2 = 0.906). Beyond evaluation indicators, detailed error distribution analysis confirmed the Transformer's enhanced predictive accuracy and reduced susceptibility to outliers. The superior performance is attributed to the Transformer’s intrinsic self-attention mechanism, which excels at dynamically identifying and weighting critical interdependencies among the diverse input features governing the complex quenching process. The capability enables more precise capture of the nonlinear phenomena defining the quenching limit. Furthermore, robustness testing involving diverse data normalization schemes revealed the Transformer model exhibits greater stability. This resilience stems from its inherent layer normalization mechanism, which effectively decouples feature dependencies and mitigates sensitivity to input scaling variations. Consequently, the Transformer architecture is established as the definitive optimal model for this critical safety prediction task. Its significant advantage of requiring minimal data preprocessing prior to deployment offers substantial practical utility. The model provides robust quantitative decision-making support essential for formulating effective gas explosion mitigation strategies and optimizing the safety design parameters of pipeline flame arresters. By enabling accurate prediction of the critical quenching diameter under varied scenarios, this work delivers a valuable tool for enhancing inherent safety in industries handling combustible gases within confined pipeline systems.
, Available online ,
doi: 10.11883/bzycj-2025-0308
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Abstract:
To investigate the complex wake field characteristics of multi-motor parallel rocket sleds, this study focuses on analyzing the mechanisms by which horizontal nozzle center distance and impact height influence flow structures and ground effects. By comparing four operating conditions including large spacing (l=7d), small spacing (l=1d), low impact height (h=2d), and high impact height (h=5.5d)，this study systematically reveals the flow field structure, pressure distribution, and thermal erosion behavior on the ground under different configurations. Results indicate：(1) The small-spacing layout induces strong jet interference in the absence of ground effect, resulting in a “multi-peak-slow-recovery” pressure recovery characteristic that significantly delays the flow field relaxation process. (2) The coupling effect between ground effect and interference is dominated by impact height. At low impact height, jet impact induces violent vortex restructuring and fragmentation, forming wall jets with velocities up to 960 m/s. Peak surface temperatures reach 1286.6 K with sustained high temperatures, significantly increasing track ablation risks. In contrast, high impact heights effectively suppress ground effects, leading to a more uniform and stable flow field structure. Peak surface temperatures decrease by approximately 65%, maximum flow velocities reduce by 58%, and ablation risks are significantly mitigated. (3) The rocket skid initial phase (0-8 m) represents the most severe thermal-mechanical loading zone. During this stage, the average acceleration reaches 832.7 m/s², coupled with a prolonged duration per unit distance of 1.84 ms/m. This interaction with transient complex flow fields constitutes the highest risk for orbital ablation. Numerical simulation results closely matched high-speed photography test outcomes in flow field morphology, shock height, and vortex core location, validating the reliability of the established “internal ballistics-external ballistics-flow field” coupled model. This study elucidates the complex flow patterns of a multi-nozzle parallel system under severe constraints, providing crucial theoretical foundations and design parameters for structural layout optimization and thermal protection design in high-acceleration, heavy-load rocket sled test systems.
To investigate the complex wake field characteristics of multi-motor parallel rocket sleds, this study focuses on analyzing the mechanisms by which horizontal nozzle center distance and impact height influence flow structures and ground effects. By comparing four operating conditions including large spacing (l=7d), small spacing (l=1d), low impact height (h=2d), and high impact height (h=5.5d)，this study systematically reveals the flow field structure, pressure distribution, and thermal erosion behavior on the ground under different configurations. Results indicate：(1) The small-spacing layout induces strong jet interference in the absence of ground effect, resulting in a “multi-peak-slow-recovery” pressure recovery characteristic that significantly delays the flow field relaxation process. (2) The coupling effect between ground effect and interference is dominated by impact height. At low impact height, jet impact induces violent vortex restructuring and fragmentation, forming wall jets with velocities up to 960 m/s. Peak surface temperatures reach 1286.6 K with sustained high temperatures, significantly increasing track ablation risks. In contrast, high impact heights effectively suppress ground effects, leading to a more uniform and stable flow field structure. Peak surface temperatures decrease by approximately 65%, maximum flow velocities reduce by 58%, and ablation risks are significantly mitigated. (3) The rocket skid initial phase (0-8 m) represents the most severe thermal-mechanical loading zone. During this stage, the average acceleration reaches 832.7 m/s², coupled with a prolonged duration per unit distance of 1.84 ms/m. This interaction with transient complex flow fields constitutes the highest risk for orbital ablation. Numerical simulation results closely matched high-speed photography test outcomes in flow field morphology, shock height, and vortex core location, validating the reliability of the established “internal ballistics-external ballistics-flow field” coupled model. This study elucidates the complex flow patterns of a multi-nozzle parallel system under severe constraints, providing crucial theoretical foundations and design parameters for structural layout optimization and thermal protection design in high-acceleration, heavy-load rocket sled test systems.
, Available online ,
doi: 10.11883/bzycj-2025-0415
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Abstract:
To investigate the dynamic characteristics of structures breaking through ice sheets and entering water, a series of vertical ice-breaking water-entry experiments were conducted using a water-entry experimental platform combined with high-speed photography. The experiments considered an ice-free condition and three ice sheet thicknesses equal to 1.5, 2.5, and 3.5 times the structure diameter (D0). The effects of ice sheet thickness on cavity evolution, ice failure modes, and motion characteristics of the structure were systematically analyzed. The results show that the presence of the ice sheet significantly alters the cavity evolution during water entry. The ice sheet accelerates cavity surface closure, suppresses radial cavity expansion, and promotes a rapid collapse of the cavity at later stages. When the ice thickness is 1.5D0, the cavity is able to fully envelop the structure, whereas for thicker ice sheets (2.5D0 and 3.5D0), the cavity fails to completely wrap around the structure. After the structure penetrates the ice sheet, conical craters are formed on both the upper and lower ice surfaces. For thinner ice sheets, the craters are symmetrically distributed around the penetration hole. In contrast, when the ice thickness reaches 3.5D0, an obvious asymmetry in crater geometry is observed due to the structure’s deflection during the ice-breaking process. Compared with the ice-free condition, the presence of the ice sheet leads to pronounced velocity attenuation and trajectory deviation during water entry. However, thicker ice sheets result in a reduction of the hydrodynamic resistance experienced by the structure in the subsequent underwater stage, indicating that the ice-breaking process plays a crucial role in modifying the downstream flow field and the overall water-entry dynamics.
To investigate the dynamic characteristics of structures breaking through ice sheets and entering water, a series of vertical ice-breaking water-entry experiments were conducted using a water-entry experimental platform combined with high-speed photography. The experiments considered an ice-free condition and three ice sheet thicknesses equal to 1.5, 2.5, and 3.5 times the structure diameter (D0). The effects of ice sheet thickness on cavity evolution, ice failure modes, and motion characteristics of the structure were systematically analyzed. The results show that the presence of the ice sheet significantly alters the cavity evolution during water entry. The ice sheet accelerates cavity surface closure, suppresses radial cavity expansion, and promotes a rapid collapse of the cavity at later stages. When the ice thickness is 1.5D0, the cavity is able to fully envelop the structure, whereas for thicker ice sheets (2.5D0 and 3.5D0), the cavity fails to completely wrap around the structure. After the structure penetrates the ice sheet, conical craters are formed on both the upper and lower ice surfaces. For thinner ice sheets, the craters are symmetrically distributed around the penetration hole. In contrast, when the ice thickness reaches 3.5D0, an obvious asymmetry in crater geometry is observed due to the structure’s deflection during the ice-breaking process. Compared with the ice-free condition, the presence of the ice sheet leads to pronounced velocity attenuation and trajectory deviation during water entry. However, thicker ice sheets result in a reduction of the hydrodynamic resistance experienced by the structure in the subsequent underwater stage, indicating that the ice-breaking process plays a crucial role in modifying the downstream flow field and the overall water-entry dynamics.
, Available online ,
doi: 10.11883/bzycj-2025-0212
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Abstract:
To investigate the effects of inlet pressure perturbations on the propagation characteristics of rotating detonation waves (RDWs), numerical simulations were conducted using the OpenFOAM platform and the two-dimensional Euler equations coupled with detailed chemical kinetics. A two-dimensional unfolded rotating detonation combustor model was established to represent the annular chamber. Periodic boundary conditions were applied in the circumferential direction, and non-reflecting boundary conditions were imposed at the outlet. Discretized premixed injection units were specified at the inlet to simulate the reactant supply process. High-frequency, small-amplitude pressure perturbations with a frequency of 5 kHz and an amplitude of 0.1 MPa were superimposed on the inlet total pressure with a mean value of 1 MPa, while the inlet total temperature was fixed at 300 K. Hydrogen–air mixtures with equivalence ratios ranging from 0.6 to 1.6 were considered to examine the influence of reactant composition on RDW behavior under perturbed inlet conditions. The governing equations were solved using a density-based compressible reacting-flow solver with a finite-volume discretization scheme. Convective fluxes were calculated using the KNP central-upwind scheme with a van Leer limiter, and time integration was performed using a second-order Crank–Nicolson method. A detailed hydrogen–air chemical reaction mechanism consisting of 27 elementary reactions was employed to capture detonation dynamics. The results indicate that the RDW wavenumber and propagation mode exhibit significant responses to inlet pressure perturbations at different equivalence ratios, which are mainly governed by the dual-wave collision process and the reactant replenishment characteristics ahead of the detonation front. The combustor adaptively balances the energy release and stable RDW propagation, allowing the system to stabilize at different wavenumbers through a nonlinear dynamic equilibrium. Under inlet pressure perturbations, flow parameters and RDW characteristics exhibit periodic responses at the perturbation frequency, with the RDW structure being more sensitive to the perturbations. The equivalence ratio and RDW propagation mode jointly determine the combustion heat release level and the outlet thrust, whereas the specific impulse is primarily controlled by the equivalence ratio and shows a weak correlation with the RDW wavenumber. High-frequency, small-amplitude inlet pressure perturbations mainly affect the wave structure and propagation mode of RDWs, while the mean performance parameters are only weakly influenced.
To investigate the effects of inlet pressure perturbations on the propagation characteristics of rotating detonation waves (RDWs), numerical simulations were conducted using the OpenFOAM platform and the two-dimensional Euler equations coupled with detailed chemical kinetics. A two-dimensional unfolded rotating detonation combustor model was established to represent the annular chamber. Periodic boundary conditions were applied in the circumferential direction, and non-reflecting boundary conditions were imposed at the outlet. Discretized premixed injection units were specified at the inlet to simulate the reactant supply process. High-frequency, small-amplitude pressure perturbations with a frequency of 5 kHz and an amplitude of 0.1 MPa were superimposed on the inlet total pressure with a mean value of 1 MPa, while the inlet total temperature was fixed at 300 K. Hydrogen–air mixtures with equivalence ratios ranging from 0.6 to 1.6 were considered to examine the influence of reactant composition on RDW behavior under perturbed inlet conditions. The governing equations were solved using a density-based compressible reacting-flow solver with a finite-volume discretization scheme. Convective fluxes were calculated using the KNP central-upwind scheme with a van Leer limiter, and time integration was performed using a second-order Crank–Nicolson method. A detailed hydrogen–air chemical reaction mechanism consisting of 27 elementary reactions was employed to capture detonation dynamics. The results indicate that the RDW wavenumber and propagation mode exhibit significant responses to inlet pressure perturbations at different equivalence ratios, which are mainly governed by the dual-wave collision process and the reactant replenishment characteristics ahead of the detonation front. The combustor adaptively balances the energy release and stable RDW propagation, allowing the system to stabilize at different wavenumbers through a nonlinear dynamic equilibrium. Under inlet pressure perturbations, flow parameters and RDW characteristics exhibit periodic responses at the perturbation frequency, with the RDW structure being more sensitive to the perturbations. The equivalence ratio and RDW propagation mode jointly determine the combustion heat release level and the outlet thrust, whereas the specific impulse is primarily controlled by the equivalence ratio and shows a weak correlation with the RDW wavenumber. High-frequency, small-amplitude inlet pressure perturbations mainly affect the wave structure and propagation mode of RDWs, while the mean performance parameters are only weakly influenced.
, Available online ,
doi: 10.11883/bzycj-2025-0388
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Abstract:
To address the collision protection requirements in fields such as aerospace, transportation, and civil engineering, a novel design method for the corrugated multi-cell gradient hexagonal tube (CMGHT) is proposed: sinusoidal corrugated ribs are introduced into a conventional hexagonal tube, integrated with the functional gradient design concept to enhance the structural crashworthiness. First, the FE model of the structure was established and numerical simulation analysis was conducted. Results indicate that under the same wall thickness condition, the key energy absorption indicators of CMGHT outperform existing structures significantly. Compared with the hexagonal tube (HT), the energy absorption (EA), specific energy absorption (SEA), mean crushing force (MCF), and crushing force efficiency (CFE) are improved by 395%, 76%, 45%, and 395%, respectively; Compared with the multi-cell hexagonal tube (MHT), the aforementioned indicators are increased by 102%, 57%, 120%, and 48%, respectively; Relative to a corrugated multi-cell hexagonal tube (CMHT), the enhancements are 8%, 7%, 8%, and 32% respectively, while the initial peak crushing force (IPCF) is decreased by 18%. These results fully demonstrate its superior energy absorption performance. Subsequently, the geometric parameters of the ribs and outer tube were selected as design variables. A total of 540 sample sets were generated via full factorial experimental design, and a support vector machine (SVM) surrogate model was constructed. Combined with the crested porcupine optimization (CPO) algorithm, model optimization was completed to achieve accurate prediction of CMGHT’s crashworthiness. Finally, the multi-objective coati optimization algorithm (MOCOA) was adopted for multi-objective optimization to obtain the optimal combination of characteristic parameters. Optimization results show that compared with the initial structure, the SEA of the optimized structure is increased by 22%, the CFE by 53%, and the MCF by 270%, further verifying the effectiveness of the proposed design method.
To address the collision protection requirements in fields such as aerospace, transportation, and civil engineering, a novel design method for the corrugated multi-cell gradient hexagonal tube (CMGHT) is proposed: sinusoidal corrugated ribs are introduced into a conventional hexagonal tube, integrated with the functional gradient design concept to enhance the structural crashworthiness. First, the FE model of the structure was established and numerical simulation analysis was conducted. Results indicate that under the same wall thickness condition, the key energy absorption indicators of CMGHT outperform existing structures significantly. Compared with the hexagonal tube (HT), the energy absorption (EA), specific energy absorption (SEA), mean crushing force (MCF), and crushing force efficiency (CFE) are improved by 395%, 76%, 45%, and 395%, respectively; Compared with the multi-cell hexagonal tube (MHT), the aforementioned indicators are increased by 102%, 57%, 120%, and 48%, respectively; Relative to a corrugated multi-cell hexagonal tube (CMHT), the enhancements are 8%, 7%, 8%, and 32% respectively, while the initial peak crushing force (IPCF) is decreased by 18%. These results fully demonstrate its superior energy absorption performance. Subsequently, the geometric parameters of the ribs and outer tube were selected as design variables. A total of 540 sample sets were generated via full factorial experimental design, and a support vector machine (SVM) surrogate model was constructed. Combined with the crested porcupine optimization (CPO) algorithm, model optimization was completed to achieve accurate prediction of CMGHT’s crashworthiness. Finally, the multi-objective coati optimization algorithm (MOCOA) was adopted for multi-objective optimization to obtain the optimal combination of characteristic parameters. Optimization results show that compared with the initial structure, the SEA of the optimized structure is increased by 22%, the CFE by 53%, and the MCF by 270%, further verifying the effectiveness of the proposed design method.
, Available online ,
doi: 10.11883/bzycj-2025-0186
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Abstract:
Round-ended concrete-filled steel tube (RE-CFST) members, commonly used in bridge piers and main towers, are often subjected to impacts from vessels, vehicles, floating debris, and other potential collisions. Therefore, this paper focuses on the residual mechanical performance of RE-CFST columns exposed to the combined effect of eccentric compression and impact loading. The post-impact compression tests were conducted, and the failure modes, load-midspan displacement, and load-longitudinal strain curves under different eccentricity ratios and axial-load ratios were obtained. The results showed that the RE-CFST beam-columns primarily presented global deformation under lateral impact. Under eccentric compression, pronounced local buckling was observed in the outer steel tube on the compression side. The load-lateral displacement curve of the column under eccentric compression showed a gentle decrease, indicating good ductility of the specimen. As the eccentricity ratio and axial-load ratio increased, the residual resistance of the specimen decreased. In addition, based on ABAQUS software, a total of 144 finite element (FE) models were established to analyze the lateral impact behavior and residual resistance of RE-CFST columns. The effects of impact velocity, eccentricity ratio, axial-load ratio, aspect ratio, and steel ratio were emphatically studied. Results indicate that with the increase in steel ratio and aspect ratio, the post-impact residual deflection of the specimens decreases, while the residual bearing capacity improves. Finally, based on response surface analysis, formulas for the residual deformation after an impact and residual resistance coefficients of these specimens under the interaction of multiple factors were proposed. The results show that the aspect ratio is a key factor affecting both post-impact residual deflection and residual bearing capacity coefficients. Furthermore, the interaction between aspect ratio and eccentricity ratio, as well as between aspect ratio and impact velocity are significant. The proposed formulas can well predict the post-impact residual deformation and residual bearing capacity coefficients of RE-CFST columns.
Round-ended concrete-filled steel tube (RE-CFST) members, commonly used in bridge piers and main towers, are often subjected to impacts from vessels, vehicles, floating debris, and other potential collisions. Therefore, this paper focuses on the residual mechanical performance of RE-CFST columns exposed to the combined effect of eccentric compression and impact loading. The post-impact compression tests were conducted, and the failure modes, load-midspan displacement, and load-longitudinal strain curves under different eccentricity ratios and axial-load ratios were obtained. The results showed that the RE-CFST beam-columns primarily presented global deformation under lateral impact. Under eccentric compression, pronounced local buckling was observed in the outer steel tube on the compression side. The load-lateral displacement curve of the column under eccentric compression showed a gentle decrease, indicating good ductility of the specimen. As the eccentricity ratio and axial-load ratio increased, the residual resistance of the specimen decreased. In addition, based on ABAQUS software, a total of 144 finite element (FE) models were established to analyze the lateral impact behavior and residual resistance of RE-CFST columns. The effects of impact velocity, eccentricity ratio, axial-load ratio, aspect ratio, and steel ratio were emphatically studied. Results indicate that with the increase in steel ratio and aspect ratio, the post-impact residual deflection of the specimens decreases, while the residual bearing capacity improves. Finally, based on response surface analysis, formulas for the residual deformation after an impact and residual resistance coefficients of these specimens under the interaction of multiple factors were proposed. The results show that the aspect ratio is a key factor affecting both post-impact residual deflection and residual bearing capacity coefficients. Furthermore, the interaction between aspect ratio and eccentricity ratio, as well as between aspect ratio and impact velocity are significant. The proposed formulas can well predict the post-impact residual deformation and residual bearing capacity coefficients of RE-CFST columns.
, Available online ,
doi: 10.11883/bzycj-2025-0234
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Abstract:
To address the bottlenecks of traditional metal materials such as low energy release efficiency and insufficient dynamic response under high-speed impact, this study focuses on Ti-Zr-Nb-V based refractory high-entropy alloys. By utilizing their multi-component synergistic effect, a single-phase BCC structure high-entropy alloy (Ti2Zr)1.5NbVAl0.5 was developed, with a lattice constant of 3.3501Å and an average grain size of 336.7μm. Subsequently, quasi-static/dynamic mechanical tests and direct ballistic experiments were carried out. The results show that the alloy has a good strength-ductility synergy, with a yield strength of 885.2MPa. When the compressive strain rate increases from 0.001s-1 to 6000s-1, the yield strength increases by 123%, and the sensitivity to strain rate at low temperatures is significantly higher than that at high temperatures. When the impact velocity increases from 734m/s to 1375m/s, the fragmentation degree of the projectile intensifies, the temperature field in the quasi-closed container rises continuously to a peak value of 2124.15K, and the corresponding energy release duration extends from 5ms to 12ms. The FEM-SPH algorithm was used to reproduce the penetration temperature rise and fragmentation behavior of the high-entropy alloy, verifying the reliability of the fitted Johnson-Cook constitutive parameters and Grunsien equation of state. Microscopic analysis reveals that the energy release of the (Ti2Zr)1.5NbVAl0.5 high-entropy alloy originates from dislocation recombination in the adiabatic shear band. Under high-speed impact, the suppression of cross-slip leads to dislocation saturation, which triggers local lattice instability and further causes overall structural failure. However, under low-speed impact, dynamic recrystallization can effectively delay the failure process.
To address the bottlenecks of traditional metal materials such as low energy release efficiency and insufficient dynamic response under high-speed impact, this study focuses on Ti-Zr-Nb-V based refractory high-entropy alloys. By utilizing their multi-component synergistic effect, a single-phase BCC structure high-entropy alloy (Ti2Zr)1.5NbVAl0.5 was developed, with a lattice constant of 3.3501Å and an average grain size of 336.7μm. Subsequently, quasi-static/dynamic mechanical tests and direct ballistic experiments were carried out. The results show that the alloy has a good strength-ductility synergy, with a yield strength of 885.2MPa. When the compressive strain rate increases from 0.001s-1 to 6000s-1, the yield strength increases by 123%, and the sensitivity to strain rate at low temperatures is significantly higher than that at high temperatures. When the impact velocity increases from 734m/s to 1375m/s, the fragmentation degree of the projectile intensifies, the temperature field in the quasi-closed container rises continuously to a peak value of 2124.15K, and the corresponding energy release duration extends from 5ms to 12ms. The FEM-SPH algorithm was used to reproduce the penetration temperature rise and fragmentation behavior of the high-entropy alloy, verifying the reliability of the fitted Johnson-Cook constitutive parameters and Grunsien equation of state. Microscopic analysis reveals that the energy release of the (Ti2Zr)1.5NbVAl0.5 high-entropy alloy originates from dislocation recombination in the adiabatic shear band. Under high-speed impact, the suppression of cross-slip leads to dislocation saturation, which triggers local lattice instability and further causes overall structural failure. However, under low-speed impact, dynamic recrystallization can effectively delay the failure process.
, Available online ,
doi: 10.11883/bzycj-2025-0342
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Abstract:
Achieving efficient plane wave loading on the test specimen is one of key technical issues to be addressed in the design of blast load simulator. In order to develop a safe, economical, and reusable blast wave simulator, numerical simulations were conducted. Based on existing testing device, large-scale shock tube test data, and LS-DYNA software, the numerical models of blast wave propagation in blast wave simulators were established. A quantitative method for assessing the uniformity of overpressure load on the loading area was proposed. Numerical analyses were performed to investigate the influence of the shape and length of expansion sections and the length of conditioning sections on the uniformity of overpressure loads on the loading area. The wall thickness of expansion and conditioning sections and the spacing and height of stiffeners, were numerically optimized to achieve an optimal geometric and structural design. It is found that the established numerical model can reproduce the blast wave propagation accurately and the prediction results show good agreement with the testing data. Taking the errors of overpressure peak value and arriving time as factors, a quantitative evaluation method of overpressure load uniformity on the loading area is achieved. Considering the balance between technical and economic factors, the developed blast load simulator is designed with a symmetrically configured expansion section with a length of 3 m, while the conditioning section length can be extended as much as practically feasible depending on the investment. Based on the numerical results, the wall thickness of both the expansion and conditioning sections is determined to be 30 mm, while the height and spacing of the stiffeners are set at 150 mm, respectively. Experimental validation confirms that the design meets the requirements of the blast load and structural blast resistance, demonstrating the simulator suitable for component-level blast tests.
Achieving efficient plane wave loading on the test specimen is one of key technical issues to be addressed in the design of blast load simulator. In order to develop a safe, economical, and reusable blast wave simulator, numerical simulations were conducted. Based on existing testing device, large-scale shock tube test data, and LS-DYNA software, the numerical models of blast wave propagation in blast wave simulators were established. A quantitative method for assessing the uniformity of overpressure load on the loading area was proposed. Numerical analyses were performed to investigate the influence of the shape and length of expansion sections and the length of conditioning sections on the uniformity of overpressure loads on the loading area. The wall thickness of expansion and conditioning sections and the spacing and height of stiffeners, were numerically optimized to achieve an optimal geometric and structural design. It is found that the established numerical model can reproduce the blast wave propagation accurately and the prediction results show good agreement with the testing data. Taking the errors of overpressure peak value and arriving time as factors, a quantitative evaluation method of overpressure load uniformity on the loading area is achieved. Considering the balance between technical and economic factors, the developed blast load simulator is designed with a symmetrically configured expansion section with a length of 3 m, while the conditioning section length can be extended as much as practically feasible depending on the investment. Based on the numerical results, the wall thickness of both the expansion and conditioning sections is determined to be 30 mm, while the height and spacing of the stiffeners are set at 150 mm, respectively. Experimental validation confirms that the design meets the requirements of the blast load and structural blast resistance, demonstrating the simulator suitable for component-level blast tests.
, Available online ,
doi: 10.11883/bzycj-2025-0307
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Abstract:
To explore the ice-breaking effect of underwater explosion in polar low-temperature environments, the LS-DYNA software was used to conduct numerical analysis on the underwater explosion ice-breaking process. Considering the temperature gradient of ice layers in polar low-temperature environments, the dynamic response process and failure mechanism of ice layers during the shock wave stage and bubble pulsation stage were analyzed. The influencing factors of underwater explosion ice-breaking effect and their changes in the failure mode were discussed. The influence laws and reasons of each factor were analyzed from the perspectives of stress wave propagation and energy release. The research results show that under complete typical working conditions, the dynamic response process of ice layers under underwater explosion loads can be roughly divided into five stages: the stress wave action stage, the initial crack initiation stage, the local bending deformation stage, the overall rebound stage, and the jet penetration stage. Increasing the charge mass brings limited improvement to the ice-breaking effect. The blast distance can directly affect the energy transfer efficiency, and there exists an optimal blast distance that makes the fragmentation zone effect the best, while the optimal blast distance for the crack zone is larger. The influence of ice layer thickness is nonlinear. As the thickness increases, the range of the fragmentation zone gradually decreases and tends to be stable, while the range of the crack zone dominated by bubble movement may increase under certain conditions. Through numerical simulation methods, it was found that the failure modes of temperature gradient ice layers and equivalent temperature ice layers are similar, but the fragmentation effects under the same explosion loads are slightly different.
To explore the ice-breaking effect of underwater explosion in polar low-temperature environments, the LS-DYNA software was used to conduct numerical analysis on the underwater explosion ice-breaking process. Considering the temperature gradient of ice layers in polar low-temperature environments, the dynamic response process and failure mechanism of ice layers during the shock wave stage and bubble pulsation stage were analyzed. The influencing factors of underwater explosion ice-breaking effect and their changes in the failure mode were discussed. The influence laws and reasons of each factor were analyzed from the perspectives of stress wave propagation and energy release. The research results show that under complete typical working conditions, the dynamic response process of ice layers under underwater explosion loads can be roughly divided into five stages: the stress wave action stage, the initial crack initiation stage, the local bending deformation stage, the overall rebound stage, and the jet penetration stage. Increasing the charge mass brings limited improvement to the ice-breaking effect. The blast distance can directly affect the energy transfer efficiency, and there exists an optimal blast distance that makes the fragmentation zone effect the best, while the optimal blast distance for the crack zone is larger. The influence of ice layer thickness is nonlinear. As the thickness increases, the range of the fragmentation zone gradually decreases and tends to be stable, while the range of the crack zone dominated by bubble movement may increase under certain conditions. Through numerical simulation methods, it was found that the failure modes of temperature gradient ice layers and equivalent temperature ice layers are similar, but the fragmentation effects under the same explosion loads are slightly different.
, Available online ,
doi: 10.11883/bzycj-2025-0309
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Abstract:
Cortical bone, as the core load-bearing component of the skeletal systems of humans and many other vertebrates, is frequently exposed to fracture risks under impact loading during daily activities. Existing research has predominantly focused on fracture behavior under quasi-static loading conditions, yet the influence of cortical bone’s notable strain rate sensitivity on its fracture mechanisms remains inadequately explored. Using a universal testing machine and a split Hopkinson pressure bar(SHPB), uniaxial compression tests were conducted on chicken femoral cortical bone under quasi-static (0.001 s-1) and dynamic (350 s-1 and 700 s-1) conditions. Chicken femoral cortical bone specimens were obtained via cutting and grinding, with high-contrast speckle patterns prepared on them. Images of cortical bone during the experiment were recorded synchronously with two cameras, with the acquisition frequency set to 5 Hz for the quasi-static test and 150 kHz for the dynamic test. Full-field strain distributions were obtained using digital image correlation (DIC), and fracture micro-morphology was observed via scanning electron microscopy (SEM) to analyze the effect of strain rate on fracture behavior. The experimental results show that the failure stress of cortical bone exhibits a non-monotonic trend with increasing strain rate, with average values of 99.6 MPa, 195.5 MPa and 171.3 MPa at 0.001 s-1, 350 s-1 and 700 s-1, respectively, demonstrating an “increase-then-decrease” tendency. A similar trend was observed for fracture strain. Under quasi-static loading, the macroscopic crack propagation path aligns with the maximum shear strain region, and the fracture surface exhibits typical shear failure characteristics (layered delamination and abundant debris), indicating shear strain as the primary fracture driver. In contrast, under dynamic loading, the macroscopic crack correlates more closely with the maximum tensile strain region, and the fracture surface appears smooth, characteristic of tensile fracture morphology, confirming tensile strain as the dominant mechanism. Strain rate exerts a significant influence on the fracture mechanism by regulating the fracture-inducing factor, which may account for one of the key reasons for the variation in fracture stress of cortical bone under dynamic conditions. This study reveals, from a macro-micro correlated perspective, the shift in fracture mechanisms of cortical bone from shear dominance to tensile dominance with increasing strain rate, which provides an experimental evidence for understanding the fracture mechanism of bone under impact loading and reference for the design of bone biomimetic materials and the development of orthopedic protective equipment.
Cortical bone, as the core load-bearing component of the skeletal systems of humans and many other vertebrates, is frequently exposed to fracture risks under impact loading during daily activities. Existing research has predominantly focused on fracture behavior under quasi-static loading conditions, yet the influence of cortical bone’s notable strain rate sensitivity on its fracture mechanisms remains inadequately explored. Using a universal testing machine and a split Hopkinson pressure bar(SHPB), uniaxial compression tests were conducted on chicken femoral cortical bone under quasi-static (0.001 s-1) and dynamic (350 s-1 and 700 s-1) conditions. Chicken femoral cortical bone specimens were obtained via cutting and grinding, with high-contrast speckle patterns prepared on them. Images of cortical bone during the experiment were recorded synchronously with two cameras, with the acquisition frequency set to 5 Hz for the quasi-static test and 150 kHz for the dynamic test. Full-field strain distributions were obtained using digital image correlation (DIC), and fracture micro-morphology was observed via scanning electron microscopy (SEM) to analyze the effect of strain rate on fracture behavior. The experimental results show that the failure stress of cortical bone exhibits a non-monotonic trend with increasing strain rate, with average values of 99.6 MPa, 195.5 MPa and 171.3 MPa at 0.001 s-1, 350 s-1 and 700 s-1, respectively, demonstrating an “increase-then-decrease” tendency. A similar trend was observed for fracture strain. Under quasi-static loading, the macroscopic crack propagation path aligns with the maximum shear strain region, and the fracture surface exhibits typical shear failure characteristics (layered delamination and abundant debris), indicating shear strain as the primary fracture driver. In contrast, under dynamic loading, the macroscopic crack correlates more closely with the maximum tensile strain region, and the fracture surface appears smooth, characteristic of tensile fracture morphology, confirming tensile strain as the dominant mechanism. Strain rate exerts a significant influence on the fracture mechanism by regulating the fracture-inducing factor, which may account for one of the key reasons for the variation in fracture stress of cortical bone under dynamic conditions. This study reveals, from a macro-micro correlated perspective, the shift in fracture mechanisms of cortical bone from shear dominance to tensile dominance with increasing strain rate, which provides an experimental evidence for understanding the fracture mechanism of bone under impact loading and reference for the design of bone biomimetic materials and the development of orthopedic protective equipment.
, Available online ,
doi: 10.11883/bzycj-2025-0330
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Abstract:
With the continuous increase in the suddenness and frequency of explosion accidents, the rapid acquisition of the explosion yield, as a key parameter for evaluating the explosion power, plays a crucial role in damage assessment and emergency response. Therefore, this paper proposes a method for inverting the explosion yield based on audio and video information of the explosion. By analyzing the time difference between the appearance of firelight and the arrival of the wave, a quantitative assessment of the explosion power is achieved. Based on the Hopkinson-Cranz proportionality law, the Rankine-Hugoniot equation, and the free-field and near-ground overpressure models, the critical proportion distance parameter during the attenuation of the shock wave to the sound wave stage is introduced, and a theoretical model for yield inversion based on the travel time of the two waves is constructed. Through near-ground and air explosion experiments, the wave velocity variation laws under the two conditions are revealed, the validity and applicability of the established model are verified, and the influences of explosion height, frame rate, and frame extraction method on the prediction accuracy of the three models are analyzed. The results show that in the near-ground explosion condition, the ground reflection effect significantly increases the propagation speed of the explosion wave. Compared with the empirical formula based on the travel time of the shock wave and the improved formula combining the travel time of the sound wave, the dual-wave theoretical model proposed in this paper fully considers the differences in the propagation characteristics of the shock wave and the sound wave and the ground reflection effect in near-ground explosions. Under the influence of multiple factors such as explosion height, frame rate, and frame extraction method, it shows better stability and higher prediction accuracy. The audio-video fusion inversion method proposed in this study provides a new technical approach for the rapid assessment of the explosion yield and has broad application prospects in the field of public safety emergency response and protection.
With the continuous increase in the suddenness and frequency of explosion accidents, the rapid acquisition of the explosion yield, as a key parameter for evaluating the explosion power, plays a crucial role in damage assessment and emergency response. Therefore, this paper proposes a method for inverting the explosion yield based on audio and video information of the explosion. By analyzing the time difference between the appearance of firelight and the arrival of the wave, a quantitative assessment of the explosion power is achieved. Based on the Hopkinson-Cranz proportionality law, the Rankine-Hugoniot equation, and the free-field and near-ground overpressure models, the critical proportion distance parameter during the attenuation of the shock wave to the sound wave stage is introduced, and a theoretical model for yield inversion based on the travel time of the two waves is constructed. Through near-ground and air explosion experiments, the wave velocity variation laws under the two conditions are revealed, the validity and applicability of the established model are verified, and the influences of explosion height, frame rate, and frame extraction method on the prediction accuracy of the three models are analyzed. The results show that in the near-ground explosion condition, the ground reflection effect significantly increases the propagation speed of the explosion wave. Compared with the empirical formula based on the travel time of the shock wave and the improved formula combining the travel time of the sound wave, the dual-wave theoretical model proposed in this paper fully considers the differences in the propagation characteristics of the shock wave and the sound wave and the ground reflection effect in near-ground explosions. Under the influence of multiple factors such as explosion height, frame rate, and frame extraction method, it shows better stability and higher prediction accuracy. The audio-video fusion inversion method proposed in this study provides a new technical approach for the rapid assessment of the explosion yield and has broad application prospects in the field of public safety emergency response and protection.
, Available online ,
doi: 10.11883/bzycj-2025-0406
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Abstract:
To comprehensively investigate the impact of length-to-diameter ratio on hydrogen explosion within confined slender pipelines, an integrated methodology combining experimental approaches with three-dimensional numerical simulations was implemented. The influence of the equivalence ratio and length-to-diameter ratio on hydrogen explosion overpressure, flame propagation velocity, and flame structure was systematically examined. Based on the findings, an interval prediction theoretical model for the maximum explosion pressure rise rate of hydrogen in narrow pipelines was developed. The results indicate that the number of flame acceleration events is proportional to the length-to-diameter ratio of pipeline, and the flame propagation velocity is highly dependent on the evolution of flame morphology. Specifically, the flame propagation velocity increases when the flame front protrudes outward and decreases when it concaves inward. During the process of hydrogen explosion, pressure waves propagate faster than the flame front. These waves continuously reflect within the pipeline and interact with the flame front, altering the flame structure and resulting in high-frequency oscillations in the pressure curve. Under high length-to-diameter ratios, the explosion overpressure peak generated at both ends of the pipeline is greater than that generated in the middle. Both the explosion overpressure peak and pressure oscillation amplitude of the explosion exhibit a decreasing trend as the length-to-diameter ratio of the pipeline increases. The theoretical value of the explosion overpressure peak is not influenced by the pipeline length-to-diameter ratio and reaches its maximum under stoichiometric conditions. However, there are heat losses during the experiments, and these losses are more significant at higher length-to-diameter ratios, leading to a reduction in the explosion overpressure peak. Furthermore, the experimentally measured maximum pressure rise rate falls within the range predicted by the interval prediction theoretical model. This demonstrates that hydrogen explosion in narrow pipelines are not purely laminar or turbulent processes but rather complex phenomena intermediate between the two.
To comprehensively investigate the impact of length-to-diameter ratio on hydrogen explosion within confined slender pipelines, an integrated methodology combining experimental approaches with three-dimensional numerical simulations was implemented. The influence of the equivalence ratio and length-to-diameter ratio on hydrogen explosion overpressure, flame propagation velocity, and flame structure was systematically examined. Based on the findings, an interval prediction theoretical model for the maximum explosion pressure rise rate of hydrogen in narrow pipelines was developed. The results indicate that the number of flame acceleration events is proportional to the length-to-diameter ratio of pipeline, and the flame propagation velocity is highly dependent on the evolution of flame morphology. Specifically, the flame propagation velocity increases when the flame front protrudes outward and decreases when it concaves inward. During the process of hydrogen explosion, pressure waves propagate faster than the flame front. These waves continuously reflect within the pipeline and interact with the flame front, altering the flame structure and resulting in high-frequency oscillations in the pressure curve. Under high length-to-diameter ratios, the explosion overpressure peak generated at both ends of the pipeline is greater than that generated in the middle. Both the explosion overpressure peak and pressure oscillation amplitude of the explosion exhibit a decreasing trend as the length-to-diameter ratio of the pipeline increases. The theoretical value of the explosion overpressure peak is not influenced by the pipeline length-to-diameter ratio and reaches its maximum under stoichiometric conditions. However, there are heat losses during the experiments, and these losses are more significant at higher length-to-diameter ratios, leading to a reduction in the explosion overpressure peak. Furthermore, the experimentally measured maximum pressure rise rate falls within the range predicted by the interval prediction theoretical model. This demonstrates that hydrogen explosion in narrow pipelines are not purely laminar or turbulent processes but rather complex phenomena intermediate between the two.
, Available online ,
doi: 10.11883/bzycj-2025-0390
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Abstract:
The study of local instability of metals under ultra-low temperature and high strain rate is of crucial importance for the safety assessment of aerospace structures. To achieve the ultra-low temperature environment, a refrigeration system based on liquid helium circulation was developed. The specimen to be tested was cooled by a contact-conduction method to achieve the temperature in the liquid helium temperature range. Combined with the Hopkinson pressure bar experiment, impact compression experiments were conducted on titanium alloy specimens to study the dynamic properties of titanium alloys as low as the liquid helium temperature range (30K). The titanium alloy specimens adopted a circular ring structure, with the hollow structure having sufficient deformation space, which is conducive to the generation of shear bands. The experimental results show that: low temperature enhances the dynamic strength of titanium alloys; the material as a whole exhibits brittle deformation characteristics, and low temperature makes shear bands more likely to occur in titanium alloys; the width of shear bands gradually narrows with the decrease in temperature; Conjugate shear bands are more likely to occur under ultra-low temperature and high strain rate. Based on the generalized variational principle and constitutive relation incorporating microstructural evolution, a governing equation for localized dynamic instability was established. From this governing equation, an angular criterion for shear band formation was derived, which effectively characterizes the formation of shear bands. And the three development stages of localized shear bands were studied (i.e., shear deformation, shear band, and shear fracture). The results show that: low temperature changes the plastic stiffness of the material, promoting the generation of shear bands at lower strains; shear bands form before the peak point of the stress-strain curve. This work provides experimental and theoretical references for ultra-low temperature experimental techniques and the plastic instability of titanium alloys under ultra-low temperature and high strain rate.
The study of local instability of metals under ultra-low temperature and high strain rate is of crucial importance for the safety assessment of aerospace structures. To achieve the ultra-low temperature environment, a refrigeration system based on liquid helium circulation was developed. The specimen to be tested was cooled by a contact-conduction method to achieve the temperature in the liquid helium temperature range. Combined with the Hopkinson pressure bar experiment, impact compression experiments were conducted on titanium alloy specimens to study the dynamic properties of titanium alloys as low as the liquid helium temperature range (30K). The titanium alloy specimens adopted a circular ring structure, with the hollow structure having sufficient deformation space, which is conducive to the generation of shear bands. The experimental results show that: low temperature enhances the dynamic strength of titanium alloys; the material as a whole exhibits brittle deformation characteristics, and low temperature makes shear bands more likely to occur in titanium alloys; the width of shear bands gradually narrows with the decrease in temperature; Conjugate shear bands are more likely to occur under ultra-low temperature and high strain rate. Based on the generalized variational principle and constitutive relation incorporating microstructural evolution, a governing equation for localized dynamic instability was established. From this governing equation, an angular criterion for shear band formation was derived, which effectively characterizes the formation of shear bands. And the three development stages of localized shear bands were studied (i.e., shear deformation, shear band, and shear fracture). The results show that: low temperature changes the plastic stiffness of the material, promoting the generation of shear bands at lower strains; shear bands form before the peak point of the stress-strain curve. This work provides experimental and theoretical references for ultra-low temperature experimental techniques and the plastic instability of titanium alloys under ultra-low temperature and high strain rate.
, Available online ,
doi: 10.11883/bzycj-2025-0263
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Abstract:
To evaluate the crater damage effect of cylinder charge contact explosions on steel fiber reinforced concrete (SFRC) structures, a numerical model of an SFRC target was developed by the coupling method of smooth particle Galerkin and structured arbitrary Lagrange-Euler (SPG-S-ALE). This coupling method effectively simulates the extreme deformation, fragmentation, and fluid-structure interaction characteristic c of near-field explosions. The validity of the simulation was verified through comparison with experimental results. On this basis, a systematic investigation was conducted to analyze the failure modes and damage extent of SFRC targets under the combined influence of charge mass and charge length-to-diameter ratio. Based on contact explosion theory and dimensional analysis, crater diameter coefficient K1 and depth coefficient K2 were introduced to formulate a predictivemodel that describes the front-face crater diameter and depth as functions of the effective charge mass. Results indicate that thenumerical simulation results are in good agreement with the experiment results, which verifies the effectiveness of the simulation method. The crater formation of SFRC targets is the primary failure mode under the combined effects of charge mass and charge length-to-diameter ratio. For a constant charge mass, increasing the length-to-diameter ratio from 1 to 5 reduces both the craterdiameter and depth by approximately 50%, highlighting the pronounced influence of charge geometry on damage localization. Within the range of effective charge mass up to 16 kg, K1 and /Kz exhibit a power-function decay with the increase in the effective charge mass. Conversely, the crater diameter and depth follow a power-law growth relationship with the effective charge mass. Moreover, under identical effective charge mass conditions, the damaging effect is more concentrated on the lateral expansion than on its penetration depth. The established predictive model enables rapid and reasonably accurate estimation of crater dimensions in SFRC with different strengths and under varying effective charge mass. The above research results can provide a valuable theoretical basis and a practical computational tool for the anti-explosion design and performance assessment of SFRC protective structures.
To evaluate the crater damage effect of cylinder charge contact explosions on steel fiber reinforced concrete (SFRC) structures, a numerical model of an SFRC target was developed by the coupling method of smooth particle Galerkin and structured arbitrary Lagrange-Euler (SPG-S-ALE). This coupling method effectively simulates the extreme deformation, fragmentation, and fluid-structure interaction characteristic c of near-field explosions. The validity of the simulation was verified through comparison with experimental results. On this basis, a systematic investigation was conducted to analyze the failure modes and damage extent of SFRC targets under the combined influence of charge mass and charge length-to-diameter ratio. Based on contact explosion theory and dimensional analysis, crater diameter coefficient K1 and depth coefficient K2 were introduced to formulate a predictivemodel that describes the front-face crater diameter and depth as functions of the effective charge mass. Results indicate that thenumerical simulation results are in good agreement with the experiment results, which verifies the effectiveness of the simulation method. The crater formation of SFRC targets is the primary failure mode under the combined effects of charge mass and charge length-to-diameter ratio. For a constant charge mass, increasing the length-to-diameter ratio from 1 to 5 reduces both the craterdiameter and depth by approximately 50%, highlighting the pronounced influence of charge geometry on damage localization. Within the range of effective charge mass up to 16 kg, K1 and /Kz exhibit a power-function decay with the increase in the effective charge mass. Conversely, the crater diameter and depth follow a power-law growth relationship with the effective charge mass. Moreover, under identical effective charge mass conditions, the damaging effect is more concentrated on the lateral expansion than on its penetration depth. The established predictive model enables rapid and reasonably accurate estimation of crater dimensions in SFRC with different strengths and under varying effective charge mass. The above research results can provide a valuable theoretical basis and a practical computational tool for the anti-explosion design and performance assessment of SFRC protective structures.
, Available online ,
doi: 10.11883/bzycj-2025-0287
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Abstract:
Underwater explosion shock wave loads exhibit significant variability and uncertainty in their physical characteristics. Classical deterministic empirical models such as the Cole formula neglect these attributes, leading to marked discrepancies between computed outcomes and experimental measurements. This investigation analyzes 682 sets of underwater explosion test data to quantify uncertainties in key blast load parameters: peak pressure(pm), time constant(θ), impulse(I), and specific shock wave energy density(es). A Bayesian probabilistic framework integrating Cole’s empirical model was developed, with parameters calibrated through Bayesian inference to enable probabilistic characterization of shock wave loads. The results demonstrate that Model parameters exhibit variation coefficients of 0.03–0.48, while modeling errors demonstrate coefficients spanning 0.19–0.38. Only pm modeling errors follow approximately normal distribution, while θ, I, and es errors manifest skewed distributions. Remarkably, all modeling errors stabilize significantly with increasing scaled distance. The Bayesian probabilistic approach demonstrates superior sample efficiency in engineering applications. As sample sizes increase, posterior variances for θ, pm, I, and es parameters exhibit systematic contraction. Sampling optimization thresholds were identified: θ, I, es models achieve optimal accuracy at 20% data usage, while pm models require 30–60% sampling. Despite minimal Cov fluctuation in most models under varying samples, es Bayesian models displayed significant Cov reduction compared to Cole's baseline. The developed Bayesian model comprehensively characterizes blast load uncertainty through joint point estimates and uncertainty quantification, surpassing Cole’s prior model. This approach generates stochastic input fields accommodating load variability for blast-resistant structural reliability designs. The extensible modeling framework facilitates probabilistic risk assessment across diverse explosion scenarios, providing enhanced information completeness for engineering decision-making. Methodologically, Bayesian inference achieves improved parameter estimation accuracy under limited experimental data conditions while effectively controlling model uncertainty. The probabilistic characterization demonstrates practical utility by balancing computational precision with experimental resource optimization requirements.
, Available online ,
doi: 10.11883/bzycj-2025-0355
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Abstract:
The design of blast wave simulators for prototype or large-scale tests must carefully balance risk, cost, and performance. To address this challenge, a simulator driven by methane-air deflagration is developed in this study. Numerical models of methane-air deflagration in large-scale tubes were established by using the CFD software OpenFOAM and validated by comparing with testing data. Numerical simulations were conducted to analyze the effects of gas cloud length, venting conditions, and obstacle arrangement on overpressure loads. The mechanisms of blast wave and flame propagation in blast wave simulators were revealed and the experimental scheme was proposed. It is found that the numerical model can predict the overpressure time history and spatial distribution reasonably. Increasing the gas cloud volume and arranging obstacles near the ignition zone enhance deflagration intensity significantly. Side venting separates the pressure wave from the flame, thereby avoiding high-temperature distortion in the loading area. An optimized loading scheme was proposed for the developed blast wave simulator, employing four obstacles (1×50% + 3×25%, spaced 3 m apart) and variable gas cloud lengths (1.5 m - 6 m). The measured peak overpressure of blast wave simulator tests is in close agreement with the numerical predictions, with a deviation of less than 12%, good uniformity and high repeatability. The developed blast wave simulator is suitable for blast testing of components such as RC slabs.
The design of blast wave simulators for prototype or large-scale tests must carefully balance risk, cost, and performance. To address this challenge, a simulator driven by methane-air deflagration is developed in this study. Numerical models of methane-air deflagration in large-scale tubes were established by using the CFD software OpenFOAM and validated by comparing with testing data. Numerical simulations were conducted to analyze the effects of gas cloud length, venting conditions, and obstacle arrangement on overpressure loads. The mechanisms of blast wave and flame propagation in blast wave simulators were revealed and the experimental scheme was proposed. It is found that the numerical model can predict the overpressure time history and spatial distribution reasonably. Increasing the gas cloud volume and arranging obstacles near the ignition zone enhance deflagration intensity significantly. Side venting separates the pressure wave from the flame, thereby avoiding high-temperature distortion in the loading area. An optimized loading scheme was proposed for the developed blast wave simulator, employing four obstacles (1×50% + 3×25%, spaced 3 m apart) and variable gas cloud lengths (1.5 m - 6 m). The measured peak overpressure of blast wave simulator tests is in close agreement with the numerical predictions, with a deviation of less than 12%, good uniformity and high repeatability. The developed blast wave simulator is suitable for blast testing of components such as RC slabs.
, Available online ,
doi: 10.11883/bzycj-2025-0365
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Abstract:
All-terrain vehicles (ATVs) are widely used in border patrol, disaster relief transportation, forest fire protection and other fields due to their excellent environmental adaptability and off-road capabilities. Major emergencies often lead to a significant decline in regional accessibility, putting forward clear requirements for the repeated airdrop operation capability of ATVs. However, the airdrop landing process exerts intense impact on the vehicle, and repeated airdrops are more likely to cause cumulative damage to the vehicle, thereby affecting its operational reliability. To address this issue, this paper establishes a numerical simulation model for the airdrop system of a certain type of ATV. First, the low-cycle fatigue analysis method is adopted to evaluate the airdrop lifespan, and then combined with the J-C damage model, the evolution law of airdrop impact damage and life characteristics of the vehicle under multiple landing scenarios are systematically studied. The results show that the initial maximum damage of the ATV is concentrated on the chassis crossbeams; as the number of airdrops increases, the location of maximum damage shifts to structures such as upright columns. Under ideal airdrop conditions, the airdrop life of the vehicle is 10 times, and the life decreases with the increase of landing speed, among which the impact of oblique landing speed is the most significant. When the longitudinal, oblique, transverse and vertical landing speeds reach 1m/s, 1.5m/s, 3m/s and15 m/s respectively, airdrop operations are not recommended. The relevant research results provide important technical support for ensuring the repeated airdrop operation capability of ATVs under multiple landing scenarios.
All-terrain vehicles (ATVs) are widely used in border patrol, disaster relief transportation, forest fire protection and other fields due to their excellent environmental adaptability and off-road capabilities. Major emergencies often lead to a significant decline in regional accessibility, putting forward clear requirements for the repeated airdrop operation capability of ATVs. However, the airdrop landing process exerts intense impact on the vehicle, and repeated airdrops are more likely to cause cumulative damage to the vehicle, thereby affecting its operational reliability. To address this issue, this paper establishes a numerical simulation model for the airdrop system of a certain type of ATV. First, the low-cycle fatigue analysis method is adopted to evaluate the airdrop lifespan, and then combined with the J-C damage model, the evolution law of airdrop impact damage and life characteristics of the vehicle under multiple landing scenarios are systematically studied. The results show that the initial maximum damage of the ATV is concentrated on the chassis crossbeams; as the number of airdrops increases, the location of maximum damage shifts to structures such as upright columns. Under ideal airdrop conditions, the airdrop life of the vehicle is 10 times, and the life decreases with the increase of landing speed, among which the impact of oblique landing speed is the most significant. When the longitudinal, oblique, transverse and vertical landing speeds reach 1m/s, 1.5m/s, 3m/s and15 m/s respectively, airdrop operations are not recommended. The relevant research results provide important technical support for ensuring the repeated airdrop operation capability of ATVs under multiple landing scenarios.
, Available online ,
doi: 10.11883/bzycj-2025-0273
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Abstract:
Sodium-ion batteries(SIBS) have emerged as a promising candidate for energy storage applications owing to their material abundance and cost-effectiveness. However, safety concerns under mechanical abuse conditions remain inadequately addressed. This study systematically examines the failure mechanisms of commercial 18650 sodium-ion batteries under radial compression through integrated experimental and numerical approaches. A homogenized finite element model is developed to simulate dynamic crushing responses at impact velocities ranging from 1 to 35 m/s, with failure mechanisms elucidated through stress wave theory. Results demonstrate coincident peak load and failure points under quasi-static loading. Increasing compression velocity elevates peak load and failure displacement, while exhibiting negligible influence on temperature rise for batteries at 0% State of Charge (SOC). Under dynamic impact conditions, failure displacement decreases with impact velocity, showing a sharp decline beyond 20 m/s. Crack localization displays distinct velocity dependence: initiating at the central region for low velocities (<15 m/s), shifting to the bottom at 20 m/s, and transitioning to the impact end above 30 m/s. This behavioral transition is primarily governed by stress wave propagation and superposition effects. The study concludes that sodium-ion battery failure originates from structural instability-induced internal short circuits, with SOC dictating thermal behavior at low velocities while stress wave effects dominate high-speed failure characteristics. The established model demonstrates strong predictive capability for macroscopic mechanical responses, providing valuable insights for enhanced battery safety design.
, Available online ,
doi: 10.11883/bzycj-2025-0373
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Abstract:
The gradient structure has superior strength-ductility synergy due to its unique design strategy. This synergistic effect is mainly attributed to the heterogeneous deformation induced (HDI) strengthening caused by plastic strain gradient. The quasi-static mechanical behavior of gradient structures has been extensively revealed, but research on their mechanical property under dynamic conditions is almost blank, and the mechanical behavior of gradient structures under dynamic impact is not clear, which limits the application scope of gradient structures. Therefore, this study used the cyclic torsion method to prepare deep gradient structures on low carbon steel and the compression tests were conducted under a wide strain rate range (10-4-103 /s). The results indicate that the gradient structure significantly improves the yield strength of low carbon steel. At a strain rate of 0.001 /s, the yield strengths of GS1 and GS2 samples were 407.5 and 483.6 MPa, respectively. Compared to the initial state (203.2 MPa), the yield strengths increased by 100.5% and 137.9%, respectively. Moreover, as the strain rate increases, the yield strength also gradually increases, exhibiting significant sensitivity to positive strain rate. Under dynamic conditions, the strain rate sensitivity of GS1 and GS2 samples increases sharply, reaching 0.129 and 0.1097, respectively, which is almost an order of magnitude higher than quasi-static conditions. In addition, the degree of gradient will have an impact on the deformation mechanism: samples with a higher degree of gradient mainly consume the work hardening ability of the central soft domain during the deformation process, while the hardening effect of the edge region is weakened. Under dynamic conditions, due to the adiabatic temperature rise effect, the dislocation density of the edge hard domain is actually reduced. This study deeply reveals the mechanical response and deformation mechanism related to strain rate in heterogeneous regions of gradient structures. On the one hand, it provides reference for the design of gradient structures, and on the other hand, it provides theoretical value for the future application of gradient structures in extreme service environments such as dynamic impact.
The gradient structure has superior strength-ductility synergy due to its unique design strategy. This synergistic effect is mainly attributed to the heterogeneous deformation induced (HDI) strengthening caused by plastic strain gradient. The quasi-static mechanical behavior of gradient structures has been extensively revealed, but research on their mechanical property under dynamic conditions is almost blank, and the mechanical behavior of gradient structures under dynamic impact is not clear, which limits the application scope of gradient structures. Therefore, this study used the cyclic torsion method to prepare deep gradient structures on low carbon steel and the compression tests were conducted under a wide strain rate range (10-4-103 /s). The results indicate that the gradient structure significantly improves the yield strength of low carbon steel. At a strain rate of 0.001 /s, the yield strengths of GS1 and GS2 samples were 407.5 and 483.6 MPa, respectively. Compared to the initial state (203.2 MPa), the yield strengths increased by 100.5% and 137.9%, respectively. Moreover, as the strain rate increases, the yield strength also gradually increases, exhibiting significant sensitivity to positive strain rate. Under dynamic conditions, the strain rate sensitivity of GS1 and GS2 samples increases sharply, reaching 0.129 and 0.1097, respectively, which is almost an order of magnitude higher than quasi-static conditions. In addition, the degree of gradient will have an impact on the deformation mechanism: samples with a higher degree of gradient mainly consume the work hardening ability of the central soft domain during the deformation process, while the hardening effect of the edge region is weakened. Under dynamic conditions, due to the adiabatic temperature rise effect, the dislocation density of the edge hard domain is actually reduced. This study deeply reveals the mechanical response and deformation mechanism related to strain rate in heterogeneous regions of gradient structures. On the one hand, it provides reference for the design of gradient structures, and on the other hand, it provides theoretical value for the future application of gradient structures in extreme service environments such as dynamic impact.
, Available online ,
doi: 10.11883/bzycj-2025-0357
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Abstract:
Due to the challenges associated with material acquisition and high costs in penetration tests on granite targets, research on the equivalence between reinforced concrete (RC) and granite targets has been conducted. This study employs dimensional analysis and a modified compensation method, with the residual velocity as the equivalence criterion, to derive a computational approach for equivalent thickness. Based on existing experimental studies, a numerical model for medium-velocity projectile penetration into targets is established using LS-DYNA software and numerical simulation techniques. By considering projectile dimensions, impact velocity, and target thickness as variables, typical working conditions are designed. Through data fitting, a specific equivalent design formula for granite and reinforced concrete targets is obtained. The results indicate that the developed numerical simulation model accurately captures the residual velocity of the projectile and the failure characteristics of the targets during penetration. In the penetration process, compared to reinforced concrete targets, granite targets exhibit a smaller compaction zone and tunnel diameter, finer and longer cracks with higher propagation speeds, larger crack areas on the target surface, and a tendency to form larger spalling craters. Under identical penetration conditions, the failure characteristics of granite and equivalent-thickness reinforced concrete targets are similar, with both targets exhibiting five distinct failure regions. Using dimensional analysis and the compensation correction method, a dimensionless residual velocity function for projectiles penetrating reinforced concrete and granite targets is derived, along with an equivalent thickness formula for the two target types. The fitted equivalent thickness coefficient between granite and reinforced concrete is determined to be 1.69966. Validation of the equivalent thickness design formula using this coefficient shows that the error in residual velocity between the prototype and model targets does not exceed 5%. The findings of this study provide a valuable reference for the equivalent design of rock targets subjected to medium-velocity projectile penetration. The present work contributes to the field by offering a systematic methodology for substituting
Due to the challenges associated with material acquisition and high costs in penetration tests on granite targets, research on the equivalence between reinforced concrete (RC) and granite targets has been conducted. This study employs dimensional analysis and a modified compensation method, with the residual velocity as the equivalence criterion, to derive a computational approach for equivalent thickness. Based on existing experimental studies, a numerical model for medium-velocity projectile penetration into targets is established using LS-DYNA software and numerical simulation techniques. By considering projectile dimensions, impact velocity, and target thickness as variables, typical working conditions are designed. Through data fitting, a specific equivalent design formula for granite and reinforced concrete targets is obtained. The results indicate that the developed numerical simulation model accurately captures the residual velocity of the projectile and the failure characteristics of the targets during penetration. In the penetration process, compared to reinforced concrete targets, granite targets exhibit a smaller compaction zone and tunnel diameter, finer and longer cracks with higher propagation speeds, larger crack areas on the target surface, and a tendency to form larger spalling craters. Under identical penetration conditions, the failure characteristics of granite and equivalent-thickness reinforced concrete targets are similar, with both targets exhibiting five distinct failure regions. Using dimensional analysis and the compensation correction method, a dimensionless residual velocity function for projectiles penetrating reinforced concrete and granite targets is derived, along with an equivalent thickness formula for the two target types. The fitted equivalent thickness coefficient between granite and reinforced concrete is determined to be 1.69966. Validation of the equivalent thickness design formula using this coefficient shows that the error in residual velocity between the prototype and model targets does not exceed 5%. The findings of this study provide a valuable reference for the equivalent design of rock targets subjected to medium-velocity projectile penetration. The present work contributes to the field by offering a systematic methodology for substituting
, Available online ,
doi: 10.11883/bzycj-2025-0394
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Abstract:
The speed of underground blasting driving is primarily determined by the effectiveness of cutting blasting. To address the low cavity forming efficiency of parallel cutting in deep hole blasting driving, a solution involving delayed detonation of the bottom charge in the empty hole was proposed. Firstly, theoretical analysis, model experiments, and numerical simulations were conducted to investigate the influences of delayed detonation of empty hole bottom charge on the cavity forming efficiency. Subsequently, combined with high speed photography and numerical simulations of rock throwing process, the cavity forming mechanism under the synergistic effect of charge blasting in two types of blasting holes was revealed. Finally, field tests were performed to verify its actual application effects. The results indicate that delayed detonation of the empty hole bottom charge could significantly eliminate residual stumps at the bottom of the cutting cavity, increasing the cavity forming efficiency from less than 80 % to over 95 %. During the blasting stage of cutting holes, the strong clamping effect of surrounding rock leads to residual stumps in the cavity, but the newly formed free face could facilitate the throw of stumps subsequently. During the blasting stage of empty hole bottom charge, the weakened clamping effect of surrounding rock enables the residual stumps to be thrown out at the relatively high velocity, thereby achieving an excellent cavity forming effect. The rock throwing velocity during the empty hole blasting is about 2.0 m·s⁻1 higher than that during cutting hole blasting. Compared with the traditional parallel cutting technique, the proposed method increases the cycle footage by 0.35 m and reduces the specific charge by 0.43 kg·m⁻³. This confirms that the improved parallel cutting technique is conducive to enhancing driving efficiency and reducing driving costs. The research findings could provide theoretical supports and practical references for the optimization of deep hole cutting blasting in underground engineering.
The speed of underground blasting driving is primarily determined by the effectiveness of cutting blasting. To address the low cavity forming efficiency of parallel cutting in deep hole blasting driving, a solution involving delayed detonation of the bottom charge in the empty hole was proposed. Firstly, theoretical analysis, model experiments, and numerical simulations were conducted to investigate the influences of delayed detonation of empty hole bottom charge on the cavity forming efficiency. Subsequently, combined with high speed photography and numerical simulations of rock throwing process, the cavity forming mechanism under the synergistic effect of charge blasting in two types of blasting holes was revealed. Finally, field tests were performed to verify its actual application effects. The results indicate that delayed detonation of the empty hole bottom charge could significantly eliminate residual stumps at the bottom of the cutting cavity, increasing the cavity forming efficiency from less than 80 % to over 95 %. During the blasting stage of cutting holes, the strong clamping effect of surrounding rock leads to residual stumps in the cavity, but the newly formed free face could facilitate the throw of stumps subsequently. During the blasting stage of empty hole bottom charge, the weakened clamping effect of surrounding rock enables the residual stumps to be thrown out at the relatively high velocity, thereby achieving an excellent cavity forming effect. The rock throwing velocity during the empty hole blasting is about 2.0 m·s⁻1 higher than that during cutting hole blasting. Compared with the traditional parallel cutting technique, the proposed method increases the cycle footage by 0.35 m and reduces the specific charge by 0.43 kg·m⁻³. This confirms that the improved parallel cutting technique is conducive to enhancing driving efficiency and reducing driving costs. The research findings could provide theoretical supports and practical references for the optimization of deep hole cutting blasting in underground engineering.
, Available online ,
doi: 10.11883/bzycj-2025-0305
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Abstract:
In order to study the blast performance of ultra-high performance concrete (UHPC) panels under intermedium-to-far-field explosion loading, a combined experimental and numerical simulation approach was adopted. This study specifically utilized explosion tests to evaluate the dynamic response of the panels, followed by residual load capacity tests to assess their post-blast and residual strength. Deterministic finite element models and equivalent Single Degree of Freedom (SDOF) models were established to simulate and analyze the mid-span peak deflection of the panels under different scaled distances. Establish a random finite element model using Gaussian auto-correlation random fields to examine the influence of spatial uncertainty in material property distribution. The results indicate that, UHPC panels maintain structural integrity under intermedium-to-far-field explosion, exhibiting a typical flexural damage mode; damage on the back-blast surface was concentrated in the mid-span region; the residual load capacity of the panel at a scaled distance of 1.0 even exceeded that of the unblasted specimen, demonstrating excellent blast resistance. The deterministic finite element model accurately predicted the blast response of the UHPC panel. The SDOF method showed high accuracy in predicting mid-span peak deflection but tended to overestimate it under minor damage conditions. The random finite element model, by incorporating Gaussian auto-correlated random fields, accounted for the uncertainty in mechanical properties of the material and demonstrated superior simulation results. Increasing the compressive strength of UHPC helps reduce mid-span peak deflection and structural damage. Furthermore, when the auto-correlation length of the random field was within the range of 10 mm to 20 mm, the damage characteristics predicted by the model were highly consistent with the actual observations. This study verifies the excellent blast resistance of UHPC under intermedium-to-far-range explosions, demonstrates the high fidelity and effectiveness of the random finite element model, and reveals the significant influence of material variability on the blast resistance assessment of UHPC structures.
In order to study the blast performance of ultra-high performance concrete (UHPC) panels under intermedium-to-far-field explosion loading, a combined experimental and numerical simulation approach was adopted. This study specifically utilized explosion tests to evaluate the dynamic response of the panels, followed by residual load capacity tests to assess their post-blast and residual strength. Deterministic finite element models and equivalent Single Degree of Freedom (SDOF) models were established to simulate and analyze the mid-span peak deflection of the panels under different scaled distances. Establish a random finite element model using Gaussian auto-correlation random fields to examine the influence of spatial uncertainty in material property distribution. The results indicate that, UHPC panels maintain structural integrity under intermedium-to-far-field explosion, exhibiting a typical flexural damage mode; damage on the back-blast surface was concentrated in the mid-span region; the residual load capacity of the panel at a scaled distance of 1.0 even exceeded that of the unblasted specimen, demonstrating excellent blast resistance. The deterministic finite element model accurately predicted the blast response of the UHPC panel. The SDOF method showed high accuracy in predicting mid-span peak deflection but tended to overestimate it under minor damage conditions. The random finite element model, by incorporating Gaussian auto-correlated random fields, accounted for the uncertainty in mechanical properties of the material and demonstrated superior simulation results. Increasing the compressive strength of UHPC helps reduce mid-span peak deflection and structural damage. Furthermore, when the auto-correlation length of the random field was within the range of 10 mm to 20 mm, the damage characteristics predicted by the model were highly consistent with the actual observations. This study verifies the excellent blast resistance of UHPC under intermedium-to-far-range explosions, demonstrates the high fidelity and effectiveness of the random finite element model, and reveals the significant influence of material variability on the blast resistance assessment of UHPC structures.
, Available online ,
doi: 10.11883/bzycj-2025-0358
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Abstract:
Pathological detonation is a kind of non-ideal detonation that chemical reaction heat release cannot be fully used to support the propagation of detonation wave. It is common in the practical processes, and the study on propagation stability of the detonation is of great significance. In this study, the pathological detonation process is realized by using a single-step reaction with a reduced molar number. The oscillation instability process of one-dimensional pathological detonation wave propagation is numerically simulated by using one-dimensional reactive Euler equation and high-resolution numerical scheme. The effects of piston-driven speed and activation energy on the stability of pathological detonation wave are systematically investigated, and the relationship between the stability of detonation wave and the reaction zone structure is analyzed. The results show that the pathological detonation is more unstable than the ideal detonation wave under the same reaction exothermic conditions. The increase of piston-driven speed is beneficial to the stability of the pathological detonation wave, while the increase of activation energy can lead to the instability of the pathological detonation wave. The high-frequency and low-amplitude oscillation of overdriven pathological detonation has little change in the structure of the reaction zone; the low-frequency and low-amplitude oscillation of detonation wave under the condition of strong solution is caused by the alternation of two configurations of strong solution in the reaction zone. The low-frequency and high-amplitude oscillation characteristics of overdriven pathological detonation are characterized by the alternating occurrence of reaction zone structures such as weak solution, strong solution and overdriven solution.
Pathological detonation is a kind of non-ideal detonation that chemical reaction heat release cannot be fully used to support the propagation of detonation wave. It is common in the practical processes, and the study on propagation stability of the detonation is of great significance. In this study, the pathological detonation process is realized by using a single-step reaction with a reduced molar number. The oscillation instability process of one-dimensional pathological detonation wave propagation is numerically simulated by using one-dimensional reactive Euler equation and high-resolution numerical scheme. The effects of piston-driven speed and activation energy on the stability of pathological detonation wave are systematically investigated, and the relationship between the stability of detonation wave and the reaction zone structure is analyzed. The results show that the pathological detonation is more unstable than the ideal detonation wave under the same reaction exothermic conditions. The increase of piston-driven speed is beneficial to the stability of the pathological detonation wave, while the increase of activation energy can lead to the instability of the pathological detonation wave. The high-frequency and low-amplitude oscillation of overdriven pathological detonation has little change in the structure of the reaction zone; the low-frequency and low-amplitude oscillation of detonation wave under the condition of strong solution is caused by the alternation of two configurations of strong solution in the reaction zone. The low-frequency and high-amplitude oscillation characteristics of overdriven pathological detonation are characterized by the alternating occurrence of reaction zone structures such as weak solution, strong solution and overdriven solution.
, Available online ,
doi: 10.11883/bzycj-2025-0227
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Abstract:
At present, there is a lack of research on the correlation between the impact design load specified in GJB1060.1-1991 and the test load corresponding to the test conditions specified in GJB150.18-1986 in China. Without a clear understanding of the severity of design loads and test loads, it is impossible to accurately guide the anti-shock design, evaluation and testing of ship equipment. Taking the medium-weight impact test specified in GJB150.18-1986 standard as the object, a multi-degree-of-freedom mass stiffness damping dynamic model is established. Aiming at the single-degree-of-freedom rigid installation equipment installed on the hull ( the equipment itself is assumed to be rigid ), the impact test load calculation under the standard conditions can be carried out. It can be found that there are upper and lower limits for the impact spectrum velocity of the test load anvil, the lower limit is about 1.75 m / s, and the upper limit is about 2.40 m / s, and the calculation formula of the impact test spectrum velocity is fitted. Through the DDAM method and the impact design spectrum value specified in GJB1060.1-1991, the impact design spectrum velocity calculated is compared with the impact test load, and the influence of equipment installation frequency, equipment quality and pendulum height on the design load and test load is analyzed. Based on the comparison results, overall, the impact design load is more severe than the test load. However, when the channel steel span is relatively large (greater than 90 cm) and the equipment installation frequency is relatively high (greater than 80 Hz), the impact test load may be more severe. In addition, the quantitative ratio between the velocity of the impact design spectrum and that of the impact test spectrum is provided.The research results prove the correlation between the impact design load and the test load, which can provide reference for the impact resistance design and test of the equipment and the revision of relevant standards.
At present, there is a lack of research on the correlation between the impact design load specified in GJB1060.1-1991 and the test load corresponding to the test conditions specified in GJB150.18-1986 in China. Without a clear understanding of the severity of design loads and test loads, it is impossible to accurately guide the anti-shock design, evaluation and testing of ship equipment. Taking the medium-weight impact test specified in GJB150.18-1986 standard as the object, a multi-degree-of-freedom mass stiffness damping dynamic model is established. Aiming at the single-degree-of-freedom rigid installation equipment installed on the hull ( the equipment itself is assumed to be rigid ), the impact test load calculation under the standard conditions can be carried out. It can be found that there are upper and lower limits for the impact spectrum velocity of the test load anvil, the lower limit is about 1.75 m / s, and the upper limit is about 2.40 m / s, and the calculation formula of the impact test spectrum velocity is fitted. Through the DDAM method and the impact design spectrum value specified in GJB1060.1-1991, the impact design spectrum velocity calculated is compared with the impact test load, and the influence of equipment installation frequency, equipment quality and pendulum height on the design load and test load is analyzed. Based on the comparison results, overall, the impact design load is more severe than the test load. However, when the channel steel span is relatively large (greater than 90 cm) and the equipment installation frequency is relatively high (greater than 80 Hz), the impact test load may be more severe. In addition, the quantitative ratio between the velocity of the impact design spectrum and that of the impact test spectrum is provided.The research results prove the correlation between the impact design load and the test load, which can provide reference for the impact resistance design and test of the equipment and the revision of relevant standards.
, Available online ,
doi: 10.11883/bzycj-2025-0220
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Abstract:
This study addresses critical safety concerns in wind-resistant design of building envelope systems, aiming to quantify secondary fragmentation effects and potential risks from tempered glass breakage under wind-borne debris impact. Through systematically designed hybrid orthogonal impact tests, it comprehensively investigates the influence of key parameters—including impact type, velocity, angle, boundary conditions, glass thickness, and dimensions—on failure modes and fragment mass distribution. Range analysis and variance decomposition of the experimental matrix quantitatively reveal the sensitivity weights of each parameter on glass fracture characteristics, impactor velocity attenuation rate, and fragment mass distribution. A dimensionless functional framework characterizing fragment mass distribution was established using the principle of dimensional homogeneity and Buckingham's Π theorem. Parameter values for the semi-empirical predictive formula were determined via an orthogonal distance regression iterative algorithm, verifying the formula's physical significance and predictive reliability. Results demonstrate: boundary conditions dominantly control glass fracture extent and fragment dispersion (exposed framing support yielding minimal fragment mass - optimal solution); structural glazing support exhibits maximum kinetic energy attenuation yet moderate fragment quantities; point fixing induces complete fragmentation (high-risk scenario); impact angle, glass dimensions, and velocity also exert significant influences. The developed formula accurately characterizes tempered glass fracture patterns, with parameters for exposed framing and structural glazing supports both falling within the order of 10⁰, enabling their combination into a unified framed-type support system model, thereby providing crucial theoretical foundations for wind-resistant design of building envelopes.
This study addresses critical safety concerns in wind-resistant design of building envelope systems, aiming to quantify secondary fragmentation effects and potential risks from tempered glass breakage under wind-borne debris impact. Through systematically designed hybrid orthogonal impact tests, it comprehensively investigates the influence of key parameters—including impact type, velocity, angle, boundary conditions, glass thickness, and dimensions—on failure modes and fragment mass distribution. Range analysis and variance decomposition of the experimental matrix quantitatively reveal the sensitivity weights of each parameter on glass fracture characteristics, impactor velocity attenuation rate, and fragment mass distribution. A dimensionless functional framework characterizing fragment mass distribution was established using the principle of dimensional homogeneity and Buckingham's Π theorem. Parameter values for the semi-empirical predictive formula were determined via an orthogonal distance regression iterative algorithm, verifying the formula's physical significance and predictive reliability. Results demonstrate: boundary conditions dominantly control glass fracture extent and fragment dispersion (exposed framing support yielding minimal fragment mass - optimal solution); structural glazing support exhibits maximum kinetic energy attenuation yet moderate fragment quantities; point fixing induces complete fragmentation (high-risk scenario); impact angle, glass dimensions, and velocity also exert significant influences. The developed formula accurately characterizes tempered glass fracture patterns, with parameters for exposed framing and structural glazing supports both falling within the order of 10⁰, enabling their combination into a unified framed-type support system model, thereby providing crucial theoretical foundations for wind-resistant design of building envelopes.
, Available online ,
doi: 10.11883/bzycj-2025-0348
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Abstract:
To effectively mitigate bedrock damage caused by blasting excavation in sea-crossing projects, this study systematically investigates the damage control effectiveness of a composite bottom cushion charging structure in underwater drilling blasts. By integrating a case study of embedded open caisson blasting excavation for a sea-crossing bridge, field sampling and underwater explosion model tests were conducted. The influence of iron-sand concrete with different wave impedances in the composite bottom cushion on rock sample damage was quantitatively analyzed using a piezoelectric ceramic detection system. Based on fractal dimension and damage theory, the propagation behavior of cracks on the top of rock samples under various working conditions was quantitatively evaluated. Results indicate that the composite bottom cushion effectively suppresses the propagation of macroscopic cracks in rock samples, reduces the number of top cracks, and decreases the axial propagation depth of cracks. Analysis of axial damage in rock samples shows that with increasing wave impedance, the maximum axial damage factor in the borehole region (0-12 cm) can be reduced by up to 9.95%, while the reduction in the bedrock region (12-28 cm) reaches 40.23%-92.1%. The research demonstrates that employing a composite bottom cushion charging structure in underwater drilling blasting can significantly alleviate blast-induced damage to bedrock, and effectively control axial damage in rock samples by adjusting the wave impedance of iron-sand concrete.
To effectively mitigate bedrock damage caused by blasting excavation in sea-crossing projects, this study systematically investigates the damage control effectiveness of a composite bottom cushion charging structure in underwater drilling blasts. By integrating a case study of embedded open caisson blasting excavation for a sea-crossing bridge, field sampling and underwater explosion model tests were conducted. The influence of iron-sand concrete with different wave impedances in the composite bottom cushion on rock sample damage was quantitatively analyzed using a piezoelectric ceramic detection system. Based on fractal dimension and damage theory, the propagation behavior of cracks on the top of rock samples under various working conditions was quantitatively evaluated. Results indicate that the composite bottom cushion effectively suppresses the propagation of macroscopic cracks in rock samples, reduces the number of top cracks, and decreases the axial propagation depth of cracks. Analysis of axial damage in rock samples shows that with increasing wave impedance, the maximum axial damage factor in the borehole region (0-12 cm) can be reduced by up to 9.95%, while the reduction in the bedrock region (12-28 cm) reaches 40.23%-92.1%. The research demonstrates that employing a composite bottom cushion charging structure in underwater drilling blasting can significantly alleviate blast-induced damage to bedrock, and effectively control axial damage in rock samples by adjusting the wave impedance of iron-sand concrete.
, Available online ,
doi: 10.11883/bzycj-2025-0336
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Abstract:
To explore the feasibility of replacing detonators with nano-aluminothermic agents in mixed biomass blasting agent systems for stable initiation and their differences in detonation performance, wood powder and peanut shell powder (1:1) were used as the core raw materials. Three initiation methods were selected: digital electronic detonators (S0), Al/CuO aluminothermic agent (S1), and Al/Bi2O3 aluminothermic agent (S2). Traditional industrial explosive performance testing methods were employed to conduct orthogonal tests on aluminothermic agent trial detonations, explosion velocity, and brisance, as well as underwater explosion and blasting crater tests to investigate their explosive performance patterns. The trial detonation tests confirmed that aluminothermic agent initiation is a typical high-temperature deflagration energy release process, featuring an extended reaction zone but high energy density, enabling effective energy coupling within limited constraints to trigger the overall explosive reaction of the biomass blasting agent, thus demonstrating reliable initiation capability. Orthogonal tests on explosion velocity and brisance revealed that oxygen pressure is the dominant factor influencing both parameters, followed by steel pipe wall thickness, while the initiation method has a relatively weaker effect. By increasing oxygen pressure and optimizing confinement conditions, synergistic enhancement of explosion velocity and brisance in biomass blasting agents can be achieved, resulting in superior explosive performance combinations. Underwater explosion tests showed that S0 exhibits higher peak pressure, impulse, and specific shock energy than S1 and S2 initiation methods, with the S2 system demonstrating better energy release and impact effects compared to the S1 system. Blasting crater tests indicated that the largest crater volume (0.33m3) was formed by S0 initiation, followed by S2 initiation (0.24m3), and the smallest by S1 initiation (0.21m3). All three initiation methods successfully detonated the mixed biomass blasting agent, with the initiation performance ranking as follows: digital electronic detonator (S0) > Al/Bi2O3 aluminothermic agent (S2) > Al/CuO aluminothermic agent (S1). This study provides experimental support for the optimization and application of biomass blasting technology.
To explore the feasibility of replacing detonators with nano-aluminothermic agents in mixed biomass blasting agent systems for stable initiation and their differences in detonation performance, wood powder and peanut shell powder (1:1) were used as the core raw materials. Three initiation methods were selected: digital electronic detonators (S0), Al/CuO aluminothermic agent (S1), and Al/Bi2O3 aluminothermic agent (S2). Traditional industrial explosive performance testing methods were employed to conduct orthogonal tests on aluminothermic agent trial detonations, explosion velocity, and brisance, as well as underwater explosion and blasting crater tests to investigate their explosive performance patterns. The trial detonation tests confirmed that aluminothermic agent initiation is a typical high-temperature deflagration energy release process, featuring an extended reaction zone but high energy density, enabling effective energy coupling within limited constraints to trigger the overall explosive reaction of the biomass blasting agent, thus demonstrating reliable initiation capability. Orthogonal tests on explosion velocity and brisance revealed that oxygen pressure is the dominant factor influencing both parameters, followed by steel pipe wall thickness, while the initiation method has a relatively weaker effect. By increasing oxygen pressure and optimizing confinement conditions, synergistic enhancement of explosion velocity and brisance in biomass blasting agents can be achieved, resulting in superior explosive performance combinations. Underwater explosion tests showed that S0 exhibits higher peak pressure, impulse, and specific shock energy than S1 and S2 initiation methods, with the S2 system demonstrating better energy release and impact effects compared to the S1 system. Blasting crater tests indicated that the largest crater volume (0.33m3) was formed by S0 initiation, followed by S2 initiation (0.24m3), and the smallest by S1 initiation (0.21m3). All three initiation methods successfully detonated the mixed biomass blasting agent, with the initiation performance ranking as follows: digital electronic detonator (S0) > Al/Bi2O3 aluminothermic agent (S2) > Al/CuO aluminothermic agent (S1). This study provides experimental support for the optimization and application of biomass blasting technology.
, Available online ,
doi: 10.11883/bzycj-2025-0304
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Abstract:
In order to study the disturbance caused by blasting in the surrounding rock of the deep tunnel during the tunneling process, it is urgent to understand the mechanical response, failure mode and energy dissipation characteristics of the surrounding rock under dynamic load. In this study, the dynamic compression test of red sandstone samples under confining pressure was carried out by using the self-developed Hopkinson pressu re bar (SHPB) test system equipped with active confining pressure control device to explore the dynamic mechanical response, failure mode and energy dissipation mechanism of red sandstone under blasting impact load. The test results show that the dynamic stress-strain curve of the rock sample without confining pressure shows the characteristics of "two-stage" change, while the "three-stage" evolution law is obvious under confining pressure. The confining pressure significantly increases the dynamic compressive strength and peak strain of red sandstone, and the two show obvious strain rate and confining effects. In terms of failure mode and energy dissipation, when there is no confining pressure, the rock specimens undergo crushing failure under the action of higher strain rate. Under the confining pressure condition, the damage degree of the specimen was significantly reduced, and finally the compression and shear failure mode was reduced. At the same time, under the same strain rate, the energy absorption capacity of the confining pressure specimen is significantly higher than that without confining pressure. When the incident energy is similar, the specific energy absorption value (SEA) of red sandstone increases with the increase of confining pressure level.
In order to study the disturbance caused by blasting in the surrounding rock of the deep tunnel during the tunneling process, it is urgent to understand the mechanical response, failure mode and energy dissipation characteristics of the surrounding rock under dynamic load. In this study, the dynamic compression test of red sandstone samples under confining pressure was carried out by using the self-developed Hopkinson pressu re bar (SHPB) test system equipped with active confining pressure control device to explore the dynamic mechanical response, failure mode and energy dissipation mechanism of red sandstone under blasting impact load. The test results show that the dynamic stress-strain curve of the rock sample without confining pressure shows the characteristics of "two-stage" change, while the "three-stage" evolution law is obvious under confining pressure. The confining pressure significantly increases the dynamic compressive strength and peak strain of red sandstone, and the two show obvious strain rate and confining effects. In terms of failure mode and energy dissipation, when there is no confining pressure, the rock specimens undergo crushing failure under the action of higher strain rate. Under the confining pressure condition, the damage degree of the specimen was significantly reduced, and finally the compression and shear failure mode was reduced. At the same time, under the same strain rate, the energy absorption capacity of the confining pressure specimen is significantly higher than that without confining pressure. When the incident energy is similar, the specific energy absorption value (SEA) of red sandstone increases with the increase of confining pressure level.
, Available online ,
doi: 10.11883/bzycj-2025-0229
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Abstract:
In view of the rockfall impact threat faced by buried pipelines in high-risk areas of geological disasters, in order to further explore its dynamic response characteristics, this paper systematically studied the dynamic response characteristics of buried pipelines through the combination of scale model test and numerical simulation. Its purpose is to dig deep into these characteristics. During the experiment, this study, firstly, constructed a test model at a geometric scale ratio of 1:10. And at the same time, a drop hammer impact test device combined with LS-DYNA finite element analysis was used. Based on these above, the influence laws of pipe burial depth, wall thickness, impact parameters, pipe parameters, and soil properties (including soil elastic modulus and pipe-soil friction coefficient) on buried pipelines were explored. The test results show that at the same impact height, the peak strain decreases as the pipeline’s burial depth and wall thickness increase. When facing the eccentric drop hammer impacts, the influence on the upper and lower cross-sections of the pipeline diminishes as the impact point deviates from the pipeline center. Additionally, a higher impact height corresponds to a greater peak strain in the middle section of the pipeline.The numerical simulation results indicate that the maximum stress and strain of the pipeline are positively correlated with pipeline diameter, internal pressure, and impact velocity, while negatively correlated with impact eccentricity, soil elastic modulus, and pipeline burial depth. Moreover, the increase in the pipe-soil friction coefficient has a limited impact on pipeline stress and strain, and this effect becomes negligible when it exceeds 0.3.Based on Pearson correlation analysis, the order of influence degree of each parameter is impact eccentricity first, then pipeline internal pressure, then pipeline diameter, then soil elastic modulus, then pipe-soil friction coefficient last. Among them, pipeline internal pressure, pipeline diameter, and pipe-soil friction coefficient are positively correlated with strain, while soil elastic modulus and impact eccentricity are negatively correlated with strain. The rockfall impact eccentricity and pipeline internal pressure have a moderate to strong correlation with the impact on buried pipelines.The research results can provide a basis for the safety design of buried pipelines in high-risk areas.
In view of the rockfall impact threat faced by buried pipelines in high-risk areas of geological disasters, in order to further explore its dynamic response characteristics, this paper systematically studied the dynamic response characteristics of buried pipelines through the combination of scale model test and numerical simulation. Its purpose is to dig deep into these characteristics. During the experiment, this study, firstly, constructed a test model at a geometric scale ratio of 1:10. And at the same time, a drop hammer impact test device combined with LS-DYNA finite element analysis was used. Based on these above, the influence laws of pipe burial depth, wall thickness, impact parameters, pipe parameters, and soil properties (including soil elastic modulus and pipe-soil friction coefficient) on buried pipelines were explored. The test results show that at the same impact height, the peak strain decreases as the pipeline’s burial depth and wall thickness increase. When facing the eccentric drop hammer impacts, the influence on the upper and lower cross-sections of the pipeline diminishes as the impact point deviates from the pipeline center. Additionally, a higher impact height corresponds to a greater peak strain in the middle section of the pipeline.The numerical simulation results indicate that the maximum stress and strain of the pipeline are positively correlated with pipeline diameter, internal pressure, and impact velocity, while negatively correlated with impact eccentricity, soil elastic modulus, and pipeline burial depth. Moreover, the increase in the pipe-soil friction coefficient has a limited impact on pipeline stress and strain, and this effect becomes negligible when it exceeds 0.3.Based on Pearson correlation analysis, the order of influence degree of each parameter is impact eccentricity first, then pipeline internal pressure, then pipeline diameter, then soil elastic modulus, then pipe-soil friction coefficient last. Among them, pipeline internal pressure, pipeline diameter, and pipe-soil friction coefficient are positively correlated with strain, while soil elastic modulus and impact eccentricity are negatively correlated with strain. The rockfall impact eccentricity and pipeline internal pressure have a moderate to strong correlation with the impact on buried pipelines.The research results can provide a basis for the safety design of buried pipelines in high-risk areas.
, Available online ,
doi: 10.11883/bzycj-2025-0225
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Abstract:
In the national defense and civilian fields, equipment and structures will inevitably be subjected to intermittent, high loading rates, and repetitive severe impact loads, which are the so-called repeated impacts or impact fatigue. To study the impact fatigue behavior of equipment or structures, it is necessary to first establish a reliable impact fatigue testing techniques or methodologies. This study modifies and enhances the conventional Hopkinson bar impact loading technique to meet this need. The stress wave propagation characteristics in the loading bar, specimen, and fixtures under successive impacts are analyzed in detail. The amplitude, pulse width, and waveform configuration of the impact loading pulses applied to the specimen are systematically analyzed and controlled. And a theoretical analysis on how to achieve single pulse loading in impact fatigue testing is provided. Effective control of the amplitude, pulse width, and the stress wave pulse configuration of the loading wave is realized by optimizing and modifying the impact velocity, length, and geometric shape of the projectile. This research primarily proposeds a simple and rapid single pulse loading method suitable for impact fatigue testing. The principle involves designing the length and material parameters of the loading bar such that the end surfaces of the specimen and the bar act in coordination and then separate, thereby preventing irregular and random secondary or multiple loadings caused by reflected stress waves. This design ensures that each individual impact in a continuous impact sequence results in a single loading on the specimen. The effectiveness and feasibility of the proposed impact fatigue testing technique have been verified through numerical simulations and experiments. Finally, a loading device for shear impact fatigue was established, and the shear impact fatigue stress-life curve of TC4 titanium alloy was obtained.
In the national defense and civilian fields, equipment and structures will inevitably be subjected to intermittent, high loading rates, and repetitive severe impact loads, which are the so-called repeated impacts or impact fatigue. To study the impact fatigue behavior of equipment or structures, it is necessary to first establish a reliable impact fatigue testing techniques or methodologies. This study modifies and enhances the conventional Hopkinson bar impact loading technique to meet this need. The stress wave propagation characteristics in the loading bar, specimen, and fixtures under successive impacts are analyzed in detail. The amplitude, pulse width, and waveform configuration of the impact loading pulses applied to the specimen are systematically analyzed and controlled. And a theoretical analysis on how to achieve single pulse loading in impact fatigue testing is provided. Effective control of the amplitude, pulse width, and the stress wave pulse configuration of the loading wave is realized by optimizing and modifying the impact velocity, length, and geometric shape of the projectile. This research primarily proposeds a simple and rapid single pulse loading method suitable for impact fatigue testing. The principle involves designing the length and material parameters of the loading bar such that the end surfaces of the specimen and the bar act in coordination and then separate, thereby preventing irregular and random secondary or multiple loadings caused by reflected stress waves. This design ensures that each individual impact in a continuous impact sequence results in a single loading on the specimen. The effectiveness and feasibility of the proposed impact fatigue testing technique have been verified through numerical simulations and experiments. Finally, a loading device for shear impact fatigue was established, and the shear impact fatigue stress-life curve of TC4 titanium alloy was obtained.
, Available online ,
doi: 10.11883/bzycj-2025-0297
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Abstract:
To investigate the influences of cutting cavity depth on subsequent rock breaking properties in driving sections, driving sections with different depths of cutting cavities were simplified as sandstone specimens with different depths of cavities. A series of dynamic compression tests were conducted using the split Hopkinson pressure bar (SHPB) testing system. Then, the dynamic mechanical properties, energy dissipation characteristics, and fracture patterns of the specimens were analyzed as the cavity depth varied, and the field cutting blasting parameters were optimized accordingly. The results demonstrate that for sandstone specimens with cavity diameters of 10 mm and 20 mm, as the cavity depth increases, the dynamic peak stress decreases by 17.69% and 39.05%, the dynamic peak strain increases by 7.58% and 18.56%, the dissipation energy increases by 22.87% and 45.92%, the dissipation energy density increases by 26.92% and 73.08%, respectively. And the fragmentation size of the specimens gradually decreases. These findings indicate that increasing cutting cavity depth could reduce the rock mass's resistance to failure, enhance its deformation capacity and energy utilization efficiency, and improve its fragmentation effects. When the cavity diameter is 20 mm, the dynamic mechanical properties and energy dissipation characteristics of the specimens change at a faster rate with the increase of cavity depth, and the fragmentation size is smaller. This indicates that increasing the cutting cavity diameter is also beneficial for rock breaking. In the field, the cutting blasting technique with hole-inner and hole-outer composite delays is adopted, which can increase the cavity depth and diameter to provide sufficient free surfaces for subsequent borehole blasting, thereby increasing the hole utilization rate of the full section blasting to 96.1%, and ensuring uniform and reasonable rock fragmentation degree.
To investigate the influences of cutting cavity depth on subsequent rock breaking properties in driving sections, driving sections with different depths of cutting cavities were simplified as sandstone specimens with different depths of cavities. A series of dynamic compression tests were conducted using the split Hopkinson pressure bar (SHPB) testing system. Then, the dynamic mechanical properties, energy dissipation characteristics, and fracture patterns of the specimens were analyzed as the cavity depth varied, and the field cutting blasting parameters were optimized accordingly. The results demonstrate that for sandstone specimens with cavity diameters of 10 mm and 20 mm, as the cavity depth increases, the dynamic peak stress decreases by 17.69% and 39.05%, the dynamic peak strain increases by 7.58% and 18.56%, the dissipation energy increases by 22.87% and 45.92%, the dissipation energy density increases by 26.92% and 73.08%, respectively. And the fragmentation size of the specimens gradually decreases. These findings indicate that increasing cutting cavity depth could reduce the rock mass's resistance to failure, enhance its deformation capacity and energy utilization efficiency, and improve its fragmentation effects. When the cavity diameter is 20 mm, the dynamic mechanical properties and energy dissipation characteristics of the specimens change at a faster rate with the increase of cavity depth, and the fragmentation size is smaller. This indicates that increasing the cutting cavity diameter is also beneficial for rock breaking. In the field, the cutting blasting technique with hole-inner and hole-outer composite delays is adopted, which can increase the cavity depth and diameter to provide sufficient free surfaces for subsequent borehole blasting, thereby increasing the hole utilization rate of the full section blasting to 96.1%, and ensuring uniform and reasonable rock fragmentation degree.
, Available online ,
doi: 10.11883/bzycj-2025-0295
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Abstract:
To investigate the influence of inter-hole delay on the intensity and frequency characteristics of blasting vibrations, an effective simulation of single-hole blasting vibration waveforms was achieved based on a single-hole blasting vibration prediction model. Subsequently, incorporating Blair's nonlinear superposition theory, a group-hole blasting vibration prediction model capable of reflecting the nonlinear vibration relationship between holes was constructed. Using a copper mine in Jiangxi Province as the engineering context, the constrained-traversal algorithm was employed to optimize the parameters of the single-hole prediction model. The simulated waveform output by this model exhibits a peak velocity error of 0.7% compared to the measured single-hole waveform, with identical predictions for the dominant frequency. The peak velocity error between the simulated waveform output by the group-hole blast vibration prediction model and the measured group-hole waveform is 3.9%, with the main frequency prediction being completely consistent. This fully validates the effectiveness of both the single-hole and group-hole blast vibration prediction models. Based on dual-hole blasting vibration experiments, employing Monte Carlo methodology, the model generated 1000 sets of single-hole simulated waveforms. From these, 500 sets of dual-hole blasting vibration waveform characteristics (peak velocity, dominant frequency, and energy distribution across frequency bands) were extracted to construct a sample set. Subsequently, statistical analysis was conducted on the damping rate, dominant frequency, and energy distribution across frequency bands for the superimposed vibration waves of dual-hole blasts at different delay times and blast center distances, using the upper limit of the 95% confidence interval and the mean value. Results indicate that at the same blast center distance, as the delay time increases, the damping rate first increases and then stabilizes, while the dominant frequency gradually decreases, with high-frequency energy progressively shifting toward low-frequency energy. At different blast centers, as the blast center distance increases, the damping rate generally decreases across various delay times, the dominant frequency shifts toward lower frequencies, low-frequency energy shows an overall increase, and high-frequency energy exhibits an overall decrease. The Monte Carlo method, based on extensive simulations and statistical analysis, not only reveals the random characteristics of blasting vibration signals but also enables quantitative analysis of their time-domain and frequency-domain features, holding significant theoretical and engineering value.
To investigate the influence of inter-hole delay on the intensity and frequency characteristics of blasting vibrations, an effective simulation of single-hole blasting vibration waveforms was achieved based on a single-hole blasting vibration prediction model. Subsequently, incorporating Blair's nonlinear superposition theory, a group-hole blasting vibration prediction model capable of reflecting the nonlinear vibration relationship between holes was constructed. Using a copper mine in Jiangxi Province as the engineering context, the constrained-traversal algorithm was employed to optimize the parameters of the single-hole prediction model. The simulated waveform output by this model exhibits a peak velocity error of 0.7% compared to the measured single-hole waveform, with identical predictions for the dominant frequency. The peak velocity error between the simulated waveform output by the group-hole blast vibration prediction model and the measured group-hole waveform is 3.9%, with the main frequency prediction being completely consistent. This fully validates the effectiveness of both the single-hole and group-hole blast vibration prediction models. Based on dual-hole blasting vibration experiments, employing Monte Carlo methodology, the model generated 1000 sets of single-hole simulated waveforms. From these, 500 sets of dual-hole blasting vibration waveform characteristics (peak velocity, dominant frequency, and energy distribution across frequency bands) were extracted to construct a sample set. Subsequently, statistical analysis was conducted on the damping rate, dominant frequency, and energy distribution across frequency bands for the superimposed vibration waves of dual-hole blasts at different delay times and blast center distances, using the upper limit of the 95% confidence interval and the mean value. Results indicate that at the same blast center distance, as the delay time increases, the damping rate first increases and then stabilizes, while the dominant frequency gradually decreases, with high-frequency energy progressively shifting toward low-frequency energy. At different blast centers, as the blast center distance increases, the damping rate generally decreases across various delay times, the dominant frequency shifts toward lower frequencies, low-frequency energy shows an overall increase, and high-frequency energy exhibits an overall decrease. The Monte Carlo method, based on extensive simulations and statistical analysis, not only reveals the random characteristics of blasting vibration signals but also enables quantitative analysis of their time-domain and frequency-domain features, holding significant theoretical and engineering value.
, Available online ,
doi: 10.11883/bzycj-2025-0081
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Abstract:
In modern counter - terrorism operations, rapid indoor entry often requires breaching doors. Door breaching rounds can destroy locks or chains to facilitate this. However, traditional shotgun-fired breaching rounds may cause collateral damage with their steel shot and fragments. So, this paper presents a new LCD (Low Collateral Damage) breaching round. It uses an internally ribbed porous thin-walled non-metallic cylinder as the carrier and is filled with high density metal powder. This structure ensures stability during firing, boosting penetration. After breaching, the metal powder quickly loses kinetic energy, reducing collateral damage. Ballistic tests and numerical simulations were done to study the breaching and collateral damage of this new round on steel targets. The effects of powder material, initial kinetic energy, and internal ribs were examined. The penetration and energy-absorption mechanisms of the porous cylinder with metal powder were analyzed. Results showed that a 2-order ribbed breaching round needs less initial kinetic energy and causes non-lethal collateral damage. This round, with its internal support, maintains stability during firing, enhancing penetration. After breaching, the metal powder's kinetic energy rapidly diminishes, lowering collateral damage. The study found that the 2-order ribbed round is efficient, needing less initial kinetic energy and causing non-lethal damage.
In modern counter - terrorism operations, rapid indoor entry often requires breaching doors. Door breaching rounds can destroy locks or chains to facilitate this. However, traditional shotgun-fired breaching rounds may cause collateral damage with their steel shot and fragments. So, this paper presents a new LCD (Low Collateral Damage) breaching round. It uses an internally ribbed porous thin-walled non-metallic cylinder as the carrier and is filled with high density metal powder. This structure ensures stability during firing, boosting penetration. After breaching, the metal powder quickly loses kinetic energy, reducing collateral damage. Ballistic tests and numerical simulations were done to study the breaching and collateral damage of this new round on steel targets. The effects of powder material, initial kinetic energy, and internal ribs were examined. The penetration and energy-absorption mechanisms of the porous cylinder with metal powder were analyzed. Results showed that a 2-order ribbed breaching round needs less initial kinetic energy and causes non-lethal collateral damage. This round, with its internal support, maintains stability during firing, enhancing penetration. After breaching, the metal powder's kinetic energy rapidly diminishes, lowering collateral damage. The study found that the 2-order ribbed round is efficient, needing less initial kinetic energy and causing non-lethal damage.
, Available online ,
doi: 10.11883/bzycj-2025-0312
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Abstract:
During the high-speed water entry of a projectile, cavitation occurs, forming a cavity bubble that alters the flow field and subsequently affects the projectile’s motion stability. Our study investigates the characteristics of flow field changes after double-cone projectiles with different head cone angles traverse the free surface. High-speed water entry experiments were conducted by using an electromagnetic launch device, and a numerical simulation model of high-speed water entry was established basing on the overset mesh technique and the VOF multiphase flow model. The validity of the simulation model was verified through experiments, and the flow field characteristics after the vertical water entry of projectiles with different head shapes were obtained. The research findings are as follows: After the vertical water entry of a double-cone projectile, the cavity bubble develops symmetrically. Following surface closure of the cavity bubble, its total length increases while its maximum width gradually decreases. As the head cone angle of the projectile's cavitator increases: during the initial entry phase, the closure point and wetted surface position move closer to the tail; the cavity contour becomes wider; the resistance experienced at the moment of entry and during underwater motion increases, leading to faster velocity decay; the time of surface closure for the cavity bubble is delayed. At the same moment during underwater motion, the length of the tail cavity bubble is longer, while the length of the vortex structures within the water domain is shorter.
During the high-speed water entry of a projectile, cavitation occurs, forming a cavity bubble that alters the flow field and subsequently affects the projectile’s motion stability. Our study investigates the characteristics of flow field changes after double-cone projectiles with different head cone angles traverse the free surface. High-speed water entry experiments were conducted by using an electromagnetic launch device, and a numerical simulation model of high-speed water entry was established basing on the overset mesh technique and the VOF multiphase flow model. The validity of the simulation model was verified through experiments, and the flow field characteristics after the vertical water entry of projectiles with different head shapes were obtained. The research findings are as follows: After the vertical water entry of a double-cone projectile, the cavity bubble develops symmetrically. Following surface closure of the cavity bubble, its total length increases while its maximum width gradually decreases. As the head cone angle of the projectile's cavitator increases: during the initial entry phase, the closure point and wetted surface position move closer to the tail; the cavity contour becomes wider; the resistance experienced at the moment of entry and during underwater motion increases, leading to faster velocity decay; the time of surface closure for the cavity bubble is delayed. At the same moment during underwater motion, the length of the tail cavity bubble is longer, while the length of the vortex structures within the water domain is shorter.
, Available online ,
doi: 10.11883/bzycj-2025-0278
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Abstract:
This paper investigates the cloud ignition margin under the condition where the secondary initiation explosive charge is positioned at the periphery of the cloud formed after the dispersion of the fuel-air explosive (FAE). Through a combination of experimental study, empirical formula, and numerical simulation, the research focuses on determining the threshold value of the peak overpressure at the cloud edge. A prototype containing 12.5 kg of FAE was designed, and dispersion tests were conducted to identify the maximum radius of the cloud. A 1 kg-class HMX-based explosive was employed as the secondary initiation explosive charge. Experimental studies were carried out to establish the relationship between the distance of the charge from the cloud edge and the cloud ignition state, ultimately determining a distance threshold. The peak overpressure at the cloud edge was selected as a metric to evaluate the magnitude of the initiation energy required for cloud ignition. Based on an empirical formula and numerical simulations, the threshold value of the peak overpressure at the cloud edge necessary to satisfy the cloud ignition conditions was investigated. Moreover, the peak overpressure was validated in accordance with the critical energy flow criterion. The results demonstrate that positioning a 1 kg-class HMX-based explosive at the periphery of the cloud can also induce detonation of the cloud, provided that the distance from the cloud edge does not exceed 0.5 meters. Furthermore, when the energy of the secondary initiation charge column reaches a level sufficient to enable the cloud to experience stable detonation, the position of the secondary initiation charge column exerts minimal influence on the detonation overpressure. To ensure reliable cloud ignition performance, the edge peak overpressure of the cloud generated by the secondary initiation explosive charge should not be less than 5 MPa. This study considers the stringent conditions required for cloud ignition and provides valuable insights and data for the design of secondary initiation explosive charges. The research findings can serve as a technical foundation for optimizing the performance of secondary initiation systems in practical applications.
This paper investigates the cloud ignition margin under the condition where the secondary initiation explosive charge is positioned at the periphery of the cloud formed after the dispersion of the fuel-air explosive (FAE). Through a combination of experimental study, empirical formula, and numerical simulation, the research focuses on determining the threshold value of the peak overpressure at the cloud edge. A prototype containing 12.5 kg of FAE was designed, and dispersion tests were conducted to identify the maximum radius of the cloud. A 1 kg-class HMX-based explosive was employed as the secondary initiation explosive charge. Experimental studies were carried out to establish the relationship between the distance of the charge from the cloud edge and the cloud ignition state, ultimately determining a distance threshold. The peak overpressure at the cloud edge was selected as a metric to evaluate the magnitude of the initiation energy required for cloud ignition. Based on an empirical formula and numerical simulations, the threshold value of the peak overpressure at the cloud edge necessary to satisfy the cloud ignition conditions was investigated. Moreover, the peak overpressure was validated in accordance with the critical energy flow criterion. The results demonstrate that positioning a 1 kg-class HMX-based explosive at the periphery of the cloud can also induce detonation of the cloud, provided that the distance from the cloud edge does not exceed 0.5 meters. Furthermore, when the energy of the secondary initiation charge column reaches a level sufficient to enable the cloud to experience stable detonation, the position of the secondary initiation charge column exerts minimal influence on the detonation overpressure. To ensure reliable cloud ignition performance, the edge peak overpressure of the cloud generated by the secondary initiation explosive charge should not be less than 5 MPa. This study considers the stringent conditions required for cloud ignition and provides valuable insights and data for the design of secondary initiation explosive charges. The research findings can serve as a technical foundation for optimizing the performance of secondary initiation systems in practical applications.
, Available online ,
doi: 10.11883/bzycj-2025-0248
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Abstract:
When a projectile impacts a thin plate at hypervelocity, the projectile material usually undergoes deformation, fragmentation, or even phase transition phenomenon under the action of complex wave system, forming a secondary debris cloud. For rod-shaped projectiles, it has been shown that their aspect ratio is an important factor affecting the fragmentation of rod-shaped projectiles. In this paper, a series of SPH numerical simulations of impacts by the rods with flat head, hemispherical head and cone head are carried out. The results show that, in terms of different head shapes, large obtuse cone head and flat head impact with thin plate produce the strongest shock wave, more intense projectile fragmentation, larger projectile kinetic energy loss. Combined with the analysis of the shock wave during the impact, the phenomenon is qualitatively explained. At the same time, it is predicted that for the cone head, there exists a critical half-cone angle (related to the impact velocity and the target material), which makes the fragmentation of the rod projectile the most violent. The prediction is in line with the existing simulation results. This paper can provide some theoretical references for hypervelocity collision related research such as protection design of non-spherical space debris.
When a projectile impacts a thin plate at hypervelocity, the projectile material usually undergoes deformation, fragmentation, or even phase transition phenomenon under the action of complex wave system, forming a secondary debris cloud. For rod-shaped projectiles, it has been shown that their aspect ratio is an important factor affecting the fragmentation of rod-shaped projectiles. In this paper, a series of SPH numerical simulations of impacts by the rods with flat head, hemispherical head and cone head are carried out. The results show that, in terms of different head shapes, large obtuse cone head and flat head impact with thin plate produce the strongest shock wave, more intense projectile fragmentation, larger projectile kinetic energy loss. Combined with the analysis of the shock wave during the impact, the phenomenon is qualitatively explained. At the same time, it is predicted that for the cone head, there exists a critical half-cone angle (related to the impact velocity and the target material), which makes the fragmentation of the rod projectile the most violent. The prediction is in line with the existing simulation results. This paper can provide some theoretical references for hypervelocity collision related research such as protection design of non-spherical space debris.
, Available online ,
doi: 10.11883/bzycj-2025-0294
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Abstract:
Magnesium powder, as a commonly used metal material, frequently causes combustion and explosion accidents during production processes. To seek efficient explosion suppressants for magnesium powder, six bimetallic supramolecular compounds were synthesized using the co-precipitation and their flame suppression effects on magnesium powder flames were compared based on flame morphology and flame propagation velocity using Hartmann tube, alongside a comparison with the traditional suppressant sodium bicarbonate. In the experiments, magnesium powder was pre-mixed with seven suppressants at a ratio of 1:6 and then ignited in the Hartmann tube. The average flame propagation velocity was calculated using the tube length and the time taken for the flame to reach the top of the tube, and the flame propagation velocity was calculated by measuring the flame height at different times. A larger average velocity and a faster flame front propagation velocity indicate a poorer suppression effect of the suppressant. However, when ranking the suppression performance of the seven suppressants according to these two parameters, the results were not entirely consistent. For example, the average velocity corresponding to MgAl-Cl was lower than that of NaHCO3, whereas the maximum flame propagation velocity showed the opposite trend. This is because some suppressants had a weak inhibitory effect on the magnesium powder flame, leading to rapid flame propagation in the area close to the tube outlet due to sufficient oxygen availability. Based on a comprehensive analysis of the average velocity and the maximum flame propagation velocity, the suppression effectiveness of the seven suppressants was ranked from weakest to strongest as follows: NaHCO3, MgAl-Cl, ZnCr-CO3, CaFe-Cl, MgAl-CO3, CuAl-CO3, CaFe-CO3. Furthermore, the percentage reduction in average velocity for the four bimetallic supramolecular compounds: MgAl-Cl versus MgAl-CO3, and CaFe-Cl versus CaFe-CO3, on the deflagration flame of magnesium powder was calculated to be 17.95%, 27.30%, 23.82%, and 50.76%. Thus, it is concluded that bimetallic supramolecular compounds with carbonate as the interlayer anion have a superior suppression effect on magnesium powder deflagration compared to those with chloride as the interlayer anion. Analysis of the products via SEM, XRD, and the TG-DSC curves of the bimetallic supramolecular compounds revealed that during the decomposition process, bimetallic supramolecular compounds reduce the flame temperature through the desorption of interlayer water molecules and the heat absorption associated with the decomposition of the layered structure. Moreover, the inert gases and metal oxides generated during decomposition can block heat transfer and inhibit the volatilization of combustible gases from the surface of magnesium powder particles. Meanwhile, the metal ions and interlayer anions participate in the combustion reaction, consuming free radicals and interrupting the chain reaction, thereby achieving the explosion suppression effect.
Magnesium powder, as a commonly used metal material, frequently causes combustion and explosion accidents during production processes. To seek efficient explosion suppressants for magnesium powder, six bimetallic supramolecular compounds were synthesized using the co-precipitation and their flame suppression effects on magnesium powder flames were compared based on flame morphology and flame propagation velocity using Hartmann tube, alongside a comparison with the traditional suppressant sodium bicarbonate. In the experiments, magnesium powder was pre-mixed with seven suppressants at a ratio of 1:6 and then ignited in the Hartmann tube. The average flame propagation velocity was calculated using the tube length and the time taken for the flame to reach the top of the tube, and the flame propagation velocity was calculated by measuring the flame height at different times. A larger average velocity and a faster flame front propagation velocity indicate a poorer suppression effect of the suppressant. However, when ranking the suppression performance of the seven suppressants according to these two parameters, the results were not entirely consistent. For example, the average velocity corresponding to MgAl-Cl was lower than that of NaHCO3, whereas the maximum flame propagation velocity showed the opposite trend. This is because some suppressants had a weak inhibitory effect on the magnesium powder flame, leading to rapid flame propagation in the area close to the tube outlet due to sufficient oxygen availability. Based on a comprehensive analysis of the average velocity and the maximum flame propagation velocity, the suppression effectiveness of the seven suppressants was ranked from weakest to strongest as follows: NaHCO3, MgAl-Cl, ZnCr-CO3, CaFe-Cl, MgAl-CO3, CuAl-CO3, CaFe-CO3. Furthermore, the percentage reduction in average velocity for the four bimetallic supramolecular compounds: MgAl-Cl versus MgAl-CO3, and CaFe-Cl versus CaFe-CO3, on the deflagration flame of magnesium powder was calculated to be 17.95%, 27.30%, 23.82%, and 50.76%. Thus, it is concluded that bimetallic supramolecular compounds with carbonate as the interlayer anion have a superior suppression effect on magnesium powder deflagration compared to those with chloride as the interlayer anion. Analysis of the products via SEM, XRD, and the TG-DSC curves of the bimetallic supramolecular compounds revealed that during the decomposition process, bimetallic supramolecular compounds reduce the flame temperature through the desorption of interlayer water molecules and the heat absorption associated with the decomposition of the layered structure. Moreover, the inert gases and metal oxides generated during decomposition can block heat transfer and inhibit the volatilization of combustible gases from the surface of magnesium powder particles. Meanwhile, the metal ions and interlayer anions participate in the combustion reaction, consuming free radicals and interrupting the chain reaction, thereby achieving the explosion suppression effect.
, Available online ,
doi: 10.11883/bzycj-2025-0280
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Abstract:
Rock materials are widely used in protective engineering and various civil engineering structures such as tunnels, and the research on their dynamic mechanical properties is of great significance. In this paper, red sandstone from a stone mine in Jinan, Shandong Province was taken as the research object. Triaxial testing machines and split Hopkinson pressure bar (SHPB) devices were used to study the mechanical properties of red sandstone under different confining pressures and strain rates, respectively. Based on the static and dynamic mechanical tests, the parameters of the Holmquist-Johnson-Cook (HJC) constitutive model for red sandstone were calibrated. Using the calibrated parameters of the HJC constitutive model for red sandstone, a finite element model of the SHPB dynamic compression test was established to verify the parameters. The results show that: Under the confining pressure environment, the propagation direction and extent of internal cracks in red sandstone are restricted, making it difficult for cracks to penetrate rapidly. Thus, the peak stress increases with the increase of hydrostatic pressure. Under loading with different air pressures, red sandstone exhibits an obvious rate effect. The dynamic compressive and splitting tensile strengths are positively correlated with the average strain rate. Through the research and analysis of the dynamic increase factor for compressive strength (DIFc) and dynamic increase factor for tensile strength (DIFt), the rate effect of the dynamic tensile peak stress is more significant. The calibrated HJC constitutive model parameters can well simulate the damage and failure process of red sandstone under dynamic impact in LS-DYNA. Before reaching the maximum peak stress, the stress-strain curves from the numerical simulation results are basically consistent with those from the test results. The calibrated parameters for dense and high-strength red sandstone in this paper can provide a reference for the research on the dynamic mechanical properties of red sandstone and its engineering applications.
Rock materials are widely used in protective engineering and various civil engineering structures such as tunnels, and the research on their dynamic mechanical properties is of great significance. In this paper, red sandstone from a stone mine in Jinan, Shandong Province was taken as the research object. Triaxial testing machines and split Hopkinson pressure bar (SHPB) devices were used to study the mechanical properties of red sandstone under different confining pressures and strain rates, respectively. Based on the static and dynamic mechanical tests, the parameters of the Holmquist-Johnson-Cook (HJC) constitutive model for red sandstone were calibrated. Using the calibrated parameters of the HJC constitutive model for red sandstone, a finite element model of the SHPB dynamic compression test was established to verify the parameters. The results show that: Under the confining pressure environment, the propagation direction and extent of internal cracks in red sandstone are restricted, making it difficult for cracks to penetrate rapidly. Thus, the peak stress increases with the increase of hydrostatic pressure. Under loading with different air pressures, red sandstone exhibits an obvious rate effect. The dynamic compressive and splitting tensile strengths are positively correlated with the average strain rate. Through the research and analysis of the dynamic increase factor for compressive strength (DIFc) and dynamic increase factor for tensile strength (DIFt), the rate effect of the dynamic tensile peak stress is more significant. The calibrated HJC constitutive model parameters can well simulate the damage and failure process of red sandstone under dynamic impact in LS-DYNA. Before reaching the maximum peak stress, the stress-strain curves from the numerical simulation results are basically consistent with those from the test results. The calibrated parameters for dense and high-strength red sandstone in this paper can provide a reference for the research on the dynamic mechanical properties of red sandstone and its engineering applications.
, Available online ,
doi: 10.11883/bzycj-2025-0148
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Abstract:
Aiming at the impact protection problem of heavy-loaded unmanned platform landing, a buffer airbag system is designed to achieve safe landing. Based on the theoretical model, the airbag geometric parameters and vent area were initially determined, and a finite element simulation model was established using the controlled volume method (CVM) to simulate the airbag cushioning process and analyze the impact dynamics and cushioning performance during the landing attenuation process. Through single parameter analysis, the influence laws of vent hole size, critical exhaust pressure, airbag bottom area and height on cushioning performance are revealed. It is found that there is a conflict between the above parameters reducing the maximum overload and increasing the specific energy absorption. In order to solve this problem, the optimal Latin hypercube design sampling is used, and the neural network is combined to build an objective function proxy model. The accuracy of the constructed proxy model is analyzed, and the NSGA-II genetic algorithm is integrated for multi-objective optimization. The results show that the root-mean-square error between the maximum overload value and specific energy absorption of the proxy model are 0.4895 and 0.7262, and the coefficient of determination (R2) are 0.9833 and 0.9364, both greater than the industry benchmark of 0.9. When the size of the exhaust hole is 3952mm2, the critical exhaust pressure is 158kPa, and the airbag bottom area is 1.08m2, the maximum overload is reduced from 16.8g to 14.5g, and the specific absorption energy is stable at 1529J/kg. Experimental verification shows that the maximum overload test value is 15.2g, and the error from the simulation results is only 4.8%, confirming the reliability of the optimization scheme. This research provides efficient and low-cost design technical support for unmanned platform soft landing systems and improves the safety and efficiency of combat deployment.
Aiming at the impact protection problem of heavy-loaded unmanned platform landing, a buffer airbag system is designed to achieve safe landing. Based on the theoretical model, the airbag geometric parameters and vent area were initially determined, and a finite element simulation model was established using the controlled volume method (CVM) to simulate the airbag cushioning process and analyze the impact dynamics and cushioning performance during the landing attenuation process. Through single parameter analysis, the influence laws of vent hole size, critical exhaust pressure, airbag bottom area and height on cushioning performance are revealed. It is found that there is a conflict between the above parameters reducing the maximum overload and increasing the specific energy absorption. In order to solve this problem, the optimal Latin hypercube design sampling is used, and the neural network is combined to build an objective function proxy model. The accuracy of the constructed proxy model is analyzed, and the NSGA-II genetic algorithm is integrated for multi-objective optimization. The results show that the root-mean-square error between the maximum overload value and specific energy absorption of the proxy model are 0.4895 and 0.7262, and the coefficient of determination (R2) are 0.9833 and 0.9364, both greater than the industry benchmark of 0.9. When the size of the exhaust hole is 3952mm2, the critical exhaust pressure is 158kPa, and the airbag bottom area is 1.08m2, the maximum overload is reduced from 16.8g to 14.5g, and the specific absorption energy is stable at 1529J/kg. Experimental verification shows that the maximum overload test value is 15.2g, and the error from the simulation results is only 4.8%, confirming the reliability of the optimization scheme. This research provides efficient and low-cost design technical support for unmanned platform soft landing systems and improves the safety and efficiency of combat deployment.
, Available online ,
doi: 10.11883/bzycj-2025-0102
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Abstract:
The Mie-Grüneisen mixture model is conveniently used in the multi-component problem with Mie-Grüneisen EOS (equation of states). In the Mie-Grüneisen EOS, the isentropic and Hugoniot curves are two typical reference states curves. However, the curves of these two reference states contain singularity points and cause difficulty when the interface is treated by volume fraction, which is accustomed used as a color function in traditional model. The difficulty lies in that the volume fraction model produces fragments of fluid volumes near the interface due to its diffused style, these volume fragments may encounter the singularity points and make the sound velocity abnormally high at the interface in some isentropic reference curves. On the other side, the singularity points may cause the sound velocity negative for some Hugoniot reference states and interrupt the calculation. To avoid volumes fragments near the interface area, the volume fraction is replaced by mass fraction, and the relative volume is defined by the reciprocal of proportional density of fluid component. This definition makes the relative volume no less than which of fluids mixture. Thanks to the reconstructed relative volume, the sound velocity forms a trough shape at the interface and does not cause high peak value. Moreover, some equations in Mie-Grüneisen mixture model contains the derivatives items of reference states parameters, when these items are defined as weighted average mixture at the interface, they often become negative if weighted average of mass fraction are directly used. To prevent the negative value at the interface, the reference states are optimized at the interface. Numerical examples show that the mass fraction has tiny improvement on the accuracy of results, it makes the sound velocity steady on the isentropic reference states of medium and spend less time steps than volume fraction model. And the mass fraction can be used to correct the negative sound velocity in Hugoniot reference states. Then the calculation is kept smooth and accurate.
The Mie-Grüneisen mixture model is conveniently used in the multi-component problem with Mie-Grüneisen EOS (equation of states). In the Mie-Grüneisen EOS, the isentropic and Hugoniot curves are two typical reference states curves. However, the curves of these two reference states contain singularity points and cause difficulty when the interface is treated by volume fraction, which is accustomed used as a color function in traditional model. The difficulty lies in that the volume fraction model produces fragments of fluid volumes near the interface due to its diffused style, these volume fragments may encounter the singularity points and make the sound velocity abnormally high at the interface in some isentropic reference curves. On the other side, the singularity points may cause the sound velocity negative for some Hugoniot reference states and interrupt the calculation. To avoid volumes fragments near the interface area, the volume fraction is replaced by mass fraction, and the relative volume is defined by the reciprocal of proportional density of fluid component. This definition makes the relative volume no less than which of fluids mixture. Thanks to the reconstructed relative volume, the sound velocity forms a trough shape at the interface and does not cause high peak value. Moreover, some equations in Mie-Grüneisen mixture model contains the derivatives items of reference states parameters, when these items are defined as weighted average mixture at the interface, they often become negative if weighted average of mass fraction are directly used. To prevent the negative value at the interface, the reference states are optimized at the interface. Numerical examples show that the mass fraction has tiny improvement on the accuracy of results, it makes the sound velocity steady on the isentropic reference states of medium and spend less time steps than volume fraction model. And the mass fraction can be used to correct the negative sound velocity in Hugoniot reference states. Then the calculation is kept smooth and accurate.
, Available online ,
doi: 10.11883/bzycj-2025-0139
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Abstract:
Integrated with related penetrating test results and mesoscopic finite element simulation analysis, the deformation and failure characteristics of tungsten fiber reinforced metallic glass matrix (WF/MG) composite long rods with different fiber diameters were investigated systematically, and the similarities and differences among the ‘self-sharpening’ behavior as well as the corresponding penetration / perforation performance of various composite long rods were discussed, then the transformation of deformation and failure modes of projectiles under different impact velocities was analyzed in detail. Related analysis demonstrated that due to the differences in the mechanical properties among the tungsten fibers with different diameters, i.e., bending resistance and shear resistance, etc., the corresponding composite long rods exhibit different failure characteristics during the penetration process, and it further affects their penetration / perforation performance. The impact velocity also plays an important role on the deformation and failure modes of composite long rods and the corresponding penetration / perforation performance: when the impact velocity is relatively low, the fibers in the nose of composite rod projectile exhibits unstable buckling phenomenon and gradually disperse during the penetration process, which makes the projectile nose blunt at a certain extent, and induces the increase in the penetration resistance and decrease in the penetration performance; along with the impact velocity increases, in the case that the fiber diameter is small, the fibers on the outer side of projectile nose refluxes back, and when the fiber diameter is large, the fibers mainly behave as shear failure, and it further strengthen the ‘self-sharpening’ behavior as well as the penetration performance of projectile; when the impact velocity and fiber diameter reach a certain upper threshold values, The thickness of ‘edge layer’ in the rod nose is sharply reduced, and thus the ‘self-sharpening’ property is weakened, and the penetration performance of projectile is decayed again. Related research is beneficial to predicting the penetration / perforation performance of WF/MG composite long rods with different fiber diameters under different impact velocities, and optimizing the structural design of projectile as well as the impact velocity, etc.
Integrated with related penetrating test results and mesoscopic finite element simulation analysis, the deformation and failure characteristics of tungsten fiber reinforced metallic glass matrix (WF/MG) composite long rods with different fiber diameters were investigated systematically, and the similarities and differences among the ‘self-sharpening’ behavior as well as the corresponding penetration / perforation performance of various composite long rods were discussed, then the transformation of deformation and failure modes of projectiles under different impact velocities was analyzed in detail. Related analysis demonstrated that due to the differences in the mechanical properties among the tungsten fibers with different diameters, i.e., bending resistance and shear resistance, etc., the corresponding composite long rods exhibit different failure characteristics during the penetration process, and it further affects their penetration / perforation performance. The impact velocity also plays an important role on the deformation and failure modes of composite long rods and the corresponding penetration / perforation performance: when the impact velocity is relatively low, the fibers in the nose of composite rod projectile exhibits unstable buckling phenomenon and gradually disperse during the penetration process, which makes the projectile nose blunt at a certain extent, and induces the increase in the penetration resistance and decrease in the penetration performance; along with the impact velocity increases, in the case that the fiber diameter is small, the fibers on the outer side of projectile nose refluxes back, and when the fiber diameter is large, the fibers mainly behave as shear failure, and it further strengthen the ‘self-sharpening’ behavior as well as the penetration performance of projectile; when the impact velocity and fiber diameter reach a certain upper threshold values, The thickness of ‘edge layer’ in the rod nose is sharply reduced, and thus the ‘self-sharpening’ property is weakened, and the penetration performance of projectile is decayed again. Related research is beneficial to predicting the penetration / perforation performance of WF/MG composite long rods with different fiber diameters under different impact velocities, and optimizing the structural design of projectile as well as the impact velocity, etc.
, Available online ,
doi: 10.11883/bzycj-2025-0138
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Abstract:
Industrial electronic detonators are usually filled with relatively sensitive detonation agents, which makes electronic detonators in the production and application process, prone to accidental explosion, there is a certain safety risk. Target:In order to meet the needs of industry safety and market, this paper studies a new no-primary electronic detonator. Methods: The main methods used were theoretical analysis of working mechanism, numerical simulation of blade speed, high-speed photography and underwater explosion test methods for product initiation capability.Conclusion:The rationality of its structure is proved through a series of tests. If the lead plate perforation test shows that the electronic detonator is 400mg, the second main charge is 200mg, and the third main charge is 320mg, The pressure density is 1.56 g/cm3, At the pressure density of the second load is 1.41 g/cm3, Three-pack in bulk, The detonation transmission of the detonator is relatively stable, Can form a stable detonation; In contrast with the traditional nonexplosive detonator, It shows that the axial detonator of this structure is large; The closing diameter of the pilot generator is controlled in the 5.6~5.7mm range, Can realize the combustion to detonation and obtain a reliable detonator flying speed. The product structure design of the study eliminated four drugs compared with the traditional detonator structure, which both simplifies the production process and improves the safety. The rationality and advantages of the structure are verified by lead plate test and underwater explosion test.
Industrial electronic detonators are usually filled with relatively sensitive detonation agents, which makes electronic detonators in the production and application process, prone to accidental explosion, there is a certain safety risk. Target:In order to meet the needs of industry safety and market, this paper studies a new no-primary electronic detonator. Methods: The main methods used were theoretical analysis of working mechanism, numerical simulation of blade speed, high-speed photography and underwater explosion test methods for product initiation capability.Conclusion:The rationality of its structure is proved through a series of tests. If the lead plate perforation test shows that the electronic detonator is 400mg, the second main charge is 200mg, and the third main charge is 320mg, The pressure density is 1.56 g/cm3, At the pressure density of the second load is 1.41 g/cm3, Three-pack in bulk, The detonation transmission of the detonator is relatively stable, Can form a stable detonation; In contrast with the traditional nonexplosive detonator, It shows that the axial detonator of this structure is large; The closing diameter of the pilot generator is controlled in the 5.6~5.7mm range, Can realize the combustion to detonation and obtain a reliable detonator flying speed. The product structure design of the study eliminated four drugs compared with the traditional detonator structure, which both simplifies the production process and improves the safety. The rationality and advantages of the structure are verified by lead plate test and underwater explosion test.
, Available online ,
doi: 10.11883/bzycj-2025-0052
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Abstract:
For the purpose of preventing propylene explosion risk in production and use, propylene explosion limit was tested by 12L spherical exlosion device to study the relationship between explosion limits and various initial temperature（20~180℃）or pressure（0.1~0.9MPa）in air. The study found that with the initial temperature and pressure rising,the upper explosion limit obviously elevate,but the low explosion limit decrease slightly,the explosion limit expand. At an initial temperature of 180℃, as the pressure increases the increase of the upper explosion limit of propylene is significantly higher than the linear increase, the content of carbon powder in the explosion products increased significantly, and the lower explosion limit of propylene changed from linear to slide-like curve. The coupling effect of initial temperature and initial pressure is obviously higher than that of single factor, and the influence on the upper explosion limit is obviously higher than that of the lower explosion limit. In the range of test temperature and pressure, the coupling effect is as follows : the upper explosion limit increases by 108 %, and the lower explosion limit decreases by 18.05 %. The single factor effect of initial temperature : the upper explosion limit increased by 3.8 %, and the lower explosion limit decreased by 3.41 %.The single factor effect of initial pressure : the upper explosion limit increased by 51.3 %, and the lower explosion limit decreased by 2.44 %. In this paper, the influence surface and fitting formula of initial temperature and initial pressure on the explosion limits of propylene-air mixtures are provided.
For the purpose of preventing propylene explosion risk in production and use, propylene explosion limit was tested by 12L spherical exlosion device to study the relationship between explosion limits and various initial temperature（20~180℃）or pressure（0.1~0.9MPa）in air. The study found that with the initial temperature and pressure rising,the upper explosion limit obviously elevate,but the low explosion limit decrease slightly,the explosion limit expand. At an initial temperature of 180℃, as the pressure increases the increase of the upper explosion limit of propylene is significantly higher than the linear increase, the content of carbon powder in the explosion products increased significantly, and the lower explosion limit of propylene changed from linear to slide-like curve. The coupling effect of initial temperature and initial pressure is obviously higher than that of single factor, and the influence on the upper explosion limit is obviously higher than that of the lower explosion limit. In the range of test temperature and pressure, the coupling effect is as follows : the upper explosion limit increases by 108 %, and the lower explosion limit decreases by 18.05 %. The single factor effect of initial temperature : the upper explosion limit increased by 3.8 %, and the lower explosion limit decreased by 3.41 %.The single factor effect of initial pressure : the upper explosion limit increased by 51.3 %, and the lower explosion limit decreased by 2.44 %. In this paper, the influence surface and fitting formula of initial temperature and initial pressure on the explosion limits of propylene-air mixtures are provided.
, Available online ,
doi: 10.11883/bzycj-2025-0095
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Abstract:
Novel low-yield earth-penetrating nuclear warheads utilizing multi-point focused explosions pose a severe threat to deep underground structures. Addressing the critical challenge that traditional single-point simulations fail to replicate the synergistic damage effects inherent in such multi-point detonations, this paper innovatively designs and develops a vacuum chamber-based simulation test system for large-yield multi-point focused explosion cratering effects. The core innovation lies in the unique application of vacuum chamber technology, enabling efficient, cost-effective simulation of these complex phenomena with high result repeatability. Based on vacuum chamber explosion simulation theory, we established the similarity laws governing large-yield multi-point explosion cratering, determining key parameters including vacuum chamber pressure and simulated multi-source cavity pressure, while synchronization tests verified simultaneity across explosive sources. Referencing the US "Palanquin" underground nuclear test, we conducted vacuum chamber simulations for three-point sources under deep burial (4.3 kt, 85 m depth) and shallow burial (5 kt, 20 m depth) scenarios, comparing results with single-point explosion prototype data and empirical formulas. Results demonstrate that multi-point explosions significantly enhance crater radius, volume, and free-surface projection area compared to single-point events, dramatically expanding the damage zone, with explosive burial depth profoundly influencing the effect. This study pioneers a first-of-its-kind vacuum chamber multi-point explosion simulation system, providing an indispensable experimental platform and robust theoretical foundation for accurately assessing damage mechanisms and effectiveness of earth-penetrating nuclear multi-point strikes on deep underground engineering, holding substantial value for protective structure design and related engineering applications.
Novel low-yield earth-penetrating nuclear warheads utilizing multi-point focused explosions pose a severe threat to deep underground structures. Addressing the critical challenge that traditional single-point simulations fail to replicate the synergistic damage effects inherent in such multi-point detonations, this paper innovatively designs and develops a vacuum chamber-based simulation test system for large-yield multi-point focused explosion cratering effects. The core innovation lies in the unique application of vacuum chamber technology, enabling efficient, cost-effective simulation of these complex phenomena with high result repeatability. Based on vacuum chamber explosion simulation theory, we established the similarity laws governing large-yield multi-point explosion cratering, determining key parameters including vacuum chamber pressure and simulated multi-source cavity pressure, while synchronization tests verified simultaneity across explosive sources. Referencing the US "Palanquin" underground nuclear test, we conducted vacuum chamber simulations for three-point sources under deep burial (4.3 kt, 85 m depth) and shallow burial (5 kt, 20 m depth) scenarios, comparing results with single-point explosion prototype data and empirical formulas. Results demonstrate that multi-point explosions significantly enhance crater radius, volume, and free-surface projection area compared to single-point events, dramatically expanding the damage zone, with explosive burial depth profoundly influencing the effect. This study pioneers a first-of-its-kind vacuum chamber multi-point explosion simulation system, providing an indispensable experimental platform and robust theoretical foundation for accurately assessing damage mechanisms and effectiveness of earth-penetrating nuclear multi-point strikes on deep underground engineering, holding substantial value for protective structure design and related engineering applications.
, Available online ,
doi: 10.11883/bzycj-2025-0129
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Abstract:
To investigate the coupled effects of trajectory angle and pitch angle on the deflection characteristics of projectiles penetrating thin concrete targets, an extensive numerical simulation study was systematically conducted, focusing primarily on the oblique penetration scenarios of single-layer concrete thin targets. The projectile was divided into six distinct segments (the nose section comprising 2 segments and the body section divided into 4 segments) for detailed force analysis to accurately capture its dynamic response. Various combinations of trajectory angles (ranging from 5° to 30°) and pitch angles (ranging from -6° to 6°) with different magnitudes and directions were selected to examine their individual and combined influences. The reliability of the numerical simulation method was rigorously verified based on the penetration test results of projectiles with different trajectory angles and pitch angles into two-layer spaced concrete targets. The results indicate that the deflection of the projectile is jointly caused by the reversal of the force direction on the projectile head and the change in the direction of the deflection moment induced by the forward motion of the projectile body during penetration. Under positive trajectory angle conditions, the trajectory exhibits an upward deflection. If a pitch angle is present, the sign of the pitch angle determines the direction of the trajectory deflection. When the trajectory angle and pitch angle are in the same direction, the attitude angle of the projectile after exiting the target first decreases and then increases in the opposite direction. Conversely, when the trajectory angle and pitch angle are in opposite directions, a smaller pitch angle causes the attitude angle of the projectile to continuously increase after exiting the target. In this scenario, a larger trajectory angle leads to the projectile undergoing three deflections during penetration. If the pitch angle exceeds 2°, the attitude angle of the projectile after exiting the target first decreases and then increases in the opposite direction.
To investigate the coupled effects of trajectory angle and pitch angle on the deflection characteristics of projectiles penetrating thin concrete targets, an extensive numerical simulation study was systematically conducted, focusing primarily on the oblique penetration scenarios of single-layer concrete thin targets. The projectile was divided into six distinct segments (the nose section comprising 2 segments and the body section divided into 4 segments) for detailed force analysis to accurately capture its dynamic response. Various combinations of trajectory angles (ranging from 5° to 30°) and pitch angles (ranging from -6° to 6°) with different magnitudes and directions were selected to examine their individual and combined influences. The reliability of the numerical simulation method was rigorously verified based on the penetration test results of projectiles with different trajectory angles and pitch angles into two-layer spaced concrete targets. The results indicate that the deflection of the projectile is jointly caused by the reversal of the force direction on the projectile head and the change in the direction of the deflection moment induced by the forward motion of the projectile body during penetration. Under positive trajectory angle conditions, the trajectory exhibits an upward deflection. If a pitch angle is present, the sign of the pitch angle determines the direction of the trajectory deflection. When the trajectory angle and pitch angle are in the same direction, the attitude angle of the projectile after exiting the target first decreases and then increases in the opposite direction. Conversely, when the trajectory angle and pitch angle are in opposite directions, a smaller pitch angle causes the attitude angle of the projectile to continuously increase after exiting the target. In this scenario, a larger trajectory angle leads to the projectile undergoing three deflections during penetration. If the pitch angle exceeds 2°, the attitude angle of the projectile after exiting the target first decreases and then increases in the opposite direction.
, Available online ,
doi: 10.11883/bzycj-2025-0133
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Abstract:
In order to quantitatively evaluate the overload stability of defective charges, a charge overload test system that can take into account both high overload pressure and wide pulse was innovatively established, and the overload stability of charges with different defects was tested. By quantifying the influence of the experimental system on the characteristic value of charge load, the correlation mechanism between charge response behavior and image gray level was revealed. By introducing the conversion factor of testing device, the overload stability evaluation model of defective charge was proposed, and the response critical pressure threshold of different defective charge was predicted. The results indicate that the overload peak value greater than 1GPa and high impulse pulse width greater than 100μs can be achieved. With the increase of defect diameter, the response level of loading response increases significantly. The critical pressure of combustion reaction decreases from 0.71gpa to 0.26gpa with the increase of charge defect diameter from 0mm to 12mm. When the defect diameter of the charge reaches 10mm, the critical pressure of deflagration reaction is 1.56GPa. With the increase of defect diameter, the critical pressure of deflagration reaction decreases to 1.25GPa when the defect is Φ12mm. The reaction critical pressure predicted by the model is within the confidence range of the experimental data surrounded by the minimum reaction overload pressure and the maximum unreacted overload pressure, which verifies the reliability of the model, and provides theoretical and experimental data support for the safe service of defective charge.
In order to quantitatively evaluate the overload stability of defective charges, a charge overload test system that can take into account both high overload pressure and wide pulse was innovatively established, and the overload stability of charges with different defects was tested. By quantifying the influence of the experimental system on the characteristic value of charge load, the correlation mechanism between charge response behavior and image gray level was revealed. By introducing the conversion factor of testing device, the overload stability evaluation model of defective charge was proposed, and the response critical pressure threshold of different defective charge was predicted. The results indicate that the overload peak value greater than 1GPa and high impulse pulse width greater than 100μs can be achieved. With the increase of defect diameter, the response level of loading response increases significantly. The critical pressure of combustion reaction decreases from 0.71gpa to 0.26gpa with the increase of charge defect diameter from 0mm to 12mm. When the defect diameter of the charge reaches 10mm, the critical pressure of deflagration reaction is 1.56GPa. With the increase of defect diameter, the critical pressure of deflagration reaction decreases to 1.25GPa when the defect is Φ12mm. The reaction critical pressure predicted by the model is within the confidence range of the experimental data surrounded by the minimum reaction overload pressure and the maximum unreacted overload pressure, which verifies the reliability of the model, and provides theoretical and experimental data support for the safe service of defective charge.
, Available online ,
doi: 10.11883/bzycj-2025-0146
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Abstract:
In order to explore the propagation characteristics of P wave in nonlinear oblique joints rock mass, the method combing theoretical analysis, comparative verification and numerical calculation is adopted. Firstly, the hyperbolic joint model with normal nonlinear deformation and tangential linear deformation is introduced. Based on the interaction relationship between stress wave and linear joint, the propagation equation of P wave incident oblique joints is deduced according to the wave theory, Snell theorem, conservation principle of wave front momentum, displacement discontinuity theory and superposition principle. Then, based on the parameters of incident P wave and the conditions of jointed rock mass in literature, the transmission and reflection coefficients are calculated and found to be very close, which verified the accuracy and feasibility of the theoretical model. Furthermore, the auxiliary function ofδ function is selected as the incident P wave to analysis influence rule of waveform, duration and joint stiffness on the propagation characteristics of P wave in oblique joints rock mass through parameter research. The results indicated that the phenomenon of amplitude reduction, amplitude-time delay and duration extension is significant when the auxiliary function of δ function incident on oblique joints, which can better reflect the mutation characteristics and nonlinear attenuation feature of P wave in short time. The duration of incident P wave in oblique joints rock mass can significantly improve the transmission performance of P wave and slightly reduce the reflection characteristics of P wave and S wave. But the increase of duration is very weak impact on the transmission of S wave. P waves are prone to transmission but difficult to reflection and S waves are prone to reflection but difficult to transmission when P wave transmit to oblique joints. As k n0 and k s increase, the reflection coefficient R sc decay in concave surface shape, while the transmission coefficient T pc increase in convex surface shape. The transmission performance of P wave is closely related to the normal stiffness of joint, while the reflection characteristics of S wave is significantly affected by the second joint in the oblique joints. The research results are beneficial for developing the mechanical properties and dynamic response of natural jointed rock mass.
In order to explore the propagation characteristics of P wave in nonlinear oblique joints rock mass, the method combing theoretical analysis, comparative verification and numerical calculation is adopted. Firstly, the hyperbolic joint model with normal nonlinear deformation and tangential linear deformation is introduced. Based on the interaction relationship between stress wave and linear joint, the propagation equation of P wave incident oblique joints is deduced according to the wave theory, Snell theorem, conservation principle of wave front momentum, displacement discontinuity theory and superposition principle. Then, based on the parameters of incident P wave and the conditions of jointed rock mass in literature, the transmission and reflection coefficients are calculated and found to be very close, which verified the accuracy and feasibility of the theoretical model. Furthermore, the auxiliary function of
, Available online ,
doi: 10.11883/bzycj-2025-0039
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Abstract:
A high-pressure physical property research technology for metal powders was established based on laser driving method. Through target optimization design and experimental verification, while achieving the regulation of shock wave loading characteristics, the technical difficulties caused by the lack of fixed geometric shapes in powder materials for measurement have been solved; The use of local coating method in the target structure solves the influence of adhesive on the thickness measurement of quartz standard material, ensuring the authenticity of the data. By utilizing three-dimensional CT imaging technology to characterize the assembly quality of experimental targets, micro targets that meet the requirements of laser driven metal powder high-pressure physical property diagnosis were obtained through improved assembly methods, and the development of targets with different initial densities was also achieved. The experimental results show good data consistency, which is consistent with the independently calculated WEOS simulation results and can effectively distinguish the data trends under different initial densities. This experimental technique can be extended to the study of high-pressure physical properties of other powder particles.
A high-pressure physical property research technology for metal powders was established based on laser driving method. Through target optimization design and experimental verification, while achieving the regulation of shock wave loading characteristics, the technical difficulties caused by the lack of fixed geometric shapes in powder materials for measurement have been solved; The use of local coating method in the target structure solves the influence of adhesive on the thickness measurement of quartz standard material, ensuring the authenticity of the data. By utilizing three-dimensional CT imaging technology to characterize the assembly quality of experimental targets, micro targets that meet the requirements of laser driven metal powder high-pressure physical property diagnosis were obtained through improved assembly methods, and the development of targets with different initial densities was also achieved. The experimental results show good data consistency, which is consistent with the independently calculated WEOS simulation results and can effectively distinguish the data trends under different initial densities. This experimental technique can be extended to the study of high-pressure physical properties of other powder particles.
, Available online ,
doi: 10.11883/bzycj-2025-0045
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Abstract:
Coal dust explosion has become one of the most serious accidents in underground coal mines due to its powerful destructive force and extensive damage range. Using the Box-Behnken experimental design method, the influence of multi-factor coupling effects on the intensity of coal dust explosion during the transient explosion reaction process was studied. A total of 45 groups of 20L spherical explosion tests were conducted, observing the macroscopic characteristics of the intensity of coal dust explosion under the coupling effects of five factors: coal dust concentration (A), coal dust particle size (B), coal volatile matter (C), ignition energy (D), and ignition delay (E). The explosion process was monitored by measuring pressure changes, and the maximum explosion pressure (response value Y1) and the maximum explosion pressure rise rate (response value Y2) were determined from the pressure-time curve. The Design-Expert software was used to analyze the experimental results to establish a quadratic regression model for response values Y1 and Y2. The results show that in the variance analysis (ANOVA), the coefficient of determination (R) for Y1 and Y2 is 0.9771 and 0.9258, respectively, indicating a good fit between the model and experimental data. The single factor that has the greatest influence on the maximum explosion pressure (Y1) is ignition energy and ignition delay, and the single factor that has the greatest influence on the rise rate of the maximum explosion pressure (Y2) is coal dust particle size and ignition delay. In the quadratic regression model, the significant two-factor interaction affecting Y1 are AB, AD, AE, BC, CD, CE, and DE, while significant two-factor interaction affecting Y2 are AE, BC, BE, CE, and DE. Among them, ignition delay plays a decisive role in response values Y1 and Y2.The research results can provide a theoretical basis for dust explosion prevention work in underground coal mines.
Coal dust explosion has become one of the most serious accidents in underground coal mines due to its powerful destructive force and extensive damage range. Using the Box-Behnken experimental design method, the influence of multi-factor coupling effects on the intensity of coal dust explosion during the transient explosion reaction process was studied. A total of 45 groups of 20L spherical explosion tests were conducted, observing the macroscopic characteristics of the intensity of coal dust explosion under the coupling effects of five factors: coal dust concentration (A), coal dust particle size (B), coal volatile matter (C), ignition energy (D), and ignition delay (E). The explosion process was monitored by measuring pressure changes, and the maximum explosion pressure (response value Y1) and the maximum explosion pressure rise rate (response value Y2) were determined from the pressure-time curve. The Design-Expert software was used to analyze the experimental results to establish a quadratic regression model for response values Y1 and Y2. The results show that in the variance analysis (ANOVA), the coefficient of determination (R) for Y1 and Y2 is 0.9771 and 0.9258, respectively, indicating a good fit between the model and experimental data. The single factor that has the greatest influence on the maximum explosion pressure (Y1) is ignition energy and ignition delay, and the single factor that has the greatest influence on the rise rate of the maximum explosion pressure (Y2) is coal dust particle size and ignition delay. In the quadratic regression model, the significant two-factor interaction affecting Y1 are AB, AD, AE, BC, CD, CE, and DE, while significant two-factor interaction affecting Y2 are AE, BC, BE, CE, and DE. Among them, ignition delay plays a decisive role in response values Y1 and Y2.The research results can provide a theoretical basis for dust explosion prevention work in underground coal mines.
, Available online ,
doi: 10.11883/bzycj-2025-0067
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Abstract:
The calculation method of explosion relief area for lithium-ion battery thermal runaway (LIBTR) environmental structures is still unclear. Using an 8L cylindrical explosion test device, five discharge diameters of 10.5mm, 15mm, 21.2mm, 30mm and 60mm were set to simulate the explosion relief law of LIBTR environmental structures. The results show that the explosion relief pressure Pred of the gas (BVG) released by thermal runaway of lithium-ion batteries is higher than the Pred of the BVG-graphite powder mixture, and the influence of solid particles ejected by thermal runaway can be ignored; Pred decays exponentially with the increase of the discharge diameter and grows logarithmically with the opening pressure Pstat of the explosion relief device; combined with the specifications, the calculation formula for the explosion relief area of lithium-ion battery structures is obtained, and the commonly used pressure relief ratio C is given as 0.11. The research results provide a reference for the explosion relief of lithium battery environmental constructure.
The calculation method of explosion relief area for lithium-ion battery thermal runaway (LIBTR) environmental structures is still unclear. Using an 8L cylindrical explosion test device, five discharge diameters of 10.5mm, 15mm, 21.2mm, 30mm and 60mm were set to simulate the explosion relief law of LIBTR environmental structures. The results show that the explosion relief pressure Pred of the gas (BVG) released by thermal runaway of lithium-ion batteries is higher than the Pred of the BVG-graphite powder mixture, and the influence of solid particles ejected by thermal runaway can be ignored; Pred decays exponentially with the increase of the discharge diameter and grows logarithmically with the opening pressure Pstat of the explosion relief device; combined with the specifications, the calculation formula for the explosion relief area of lithium-ion battery structures is obtained, and the commonly used pressure relief ratio C is given as 0.11. The research results provide a reference for the explosion relief of lithium battery environmental constructure.
, Available online ,
doi: 10.11883/bzycj-2025-0071
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Abstract:
In order to study the anti-explosion performance of a single-room reinforced concrete building under internal explosion loads, a full-scale reinforced concrete single-room building, whose dimensions were 4m×4m×3m, was designed and constructed. For the internal explosion test, 3kg TNT was placed in the geometric center of the room. Sensors were installed at the center of the shear wall and roof to record data and analyze the damage characteristics of the single-room structure. In addition, an anti-explosion numerical model of the reinforced concrete single-room structure was established and verified using the LS-DYNA software. The weight of the explosives in the numerical model was changed to study the damage process and shock wave propagation law of the single-room building. Based on the experimental and simulation results, the damage modes of the single room structure were categorized by the dimensionless weighted parameter Dr, and relevant empirical formulas were obtained through data fitting. The results show that when 3kg TNT explodes in the geometric center of the room structure, the single-room structure exhibits roof bulging, with long cracks appearing along the roof edges. However, the whole structure does not collapse; Under the internal explosion condition, the local damage characteristics of reinforced concrete buildings are not only closely related to the explosive yield, but also significantly affected by the design of structural connection nodes and structural details; Due to the delayed dynamic response of reinforced concrete, the next shock wave has acted on the building before the last shock wave has reacted obviously, which subjects it to multiple impacts within a very short time; By varying the charge weight, five damage-aggravating modes (Model I to Model V) were identified. The five damage modes were quantitatively defined using the weighted parameter Dr, and a function curve relating it to the explosive equivalent was fitted. These research findings can provide a reference for damage assessment of shear wall-structured rooms.
In order to study the anti-explosion performance of a single-room reinforced concrete building under internal explosion loads, a full-scale reinforced concrete single-room building, whose dimensions were 4m×4m×3m, was designed and constructed. For the internal explosion test, 3kg TNT was placed in the geometric center of the room. Sensors were installed at the center of the shear wall and roof to record data and analyze the damage characteristics of the single-room structure. In addition, an anti-explosion numerical model of the reinforced concrete single-room structure was established and verified using the LS-DYNA software. The weight of the explosives in the numerical model was changed to study the damage process and shock wave propagation law of the single-room building. Based on the experimental and simulation results, the damage modes of the single room structure were categorized by the dimensionless weighted parameter Dr, and relevant empirical formulas were obtained through data fitting. The results show that when 3kg TNT explodes in the geometric center of the room structure, the single-room structure exhibits roof bulging, with long cracks appearing along the roof edges. However, the whole structure does not collapse; Under the internal explosion condition, the local damage characteristics of reinforced concrete buildings are not only closely related to the explosive yield, but also significantly affected by the design of structural connection nodes and structural details; Due to the delayed dynamic response of reinforced concrete, the next shock wave has acted on the building before the last shock wave has reacted obviously, which subjects it to multiple impacts within a very short time; By varying the charge weight, five damage-aggravating modes (Model I to Model V) were identified. The five damage modes were quantitatively defined using the weighted parameter Dr, and a function curve relating it to the explosive equivalent was fitted. These research findings can provide a reference for damage assessment of shear wall-structured rooms.
, Available online ,
doi: 10.11883/bzycj-2025-0053
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Abstract:
In order to study the influence of constraint conditions on the reaction characteristics of CL-20-based PBX explosive after non-impact ignition, a variable constraint ignition test device was designed. Combined with high-speed camera and pressure sensor, the reaction intensity, reaction pressure growth and air shock wave overpressure of CL-20-based PBX explosive under different constraints were analyzed. Furthermore, the relationship between the constraint conditions and the reactivity of explosive charge is analyzed by comparing with the peak value of complete detonation air overpressure. The results show that the non-impact ignition reaction process of CL-20-based PBX explosive under constraint conditions is divided into two stages : slow growth of reaction pressure and rapid growth of reaction pressure. With the increase of constraint strength, the distinction between the two reaction stages is gradually not obvious. The constraint conditions have a significant effect on the reactivity of explosive charge. When the shell thickness is 6mm and the strength of bursting disc is 2MPa and 50MPa, the reactivity of explosive is 0.11 and 0.14 respectively. When the shell thickness is 20 mm and the bursting strength is 2 MPa, the charge reactivity is 0.31. It can be seen that the reaction intensity of CL-20-based PBX explosive can be effectively reduced by weakening the mechanical constraint strength.
In order to study the influence of constraint conditions on the reaction characteristics of CL-20-based PBX explosive after non-impact ignition, a variable constraint ignition test device was designed. Combined with high-speed camera and pressure sensor, the reaction intensity, reaction pressure growth and air shock wave overpressure of CL-20-based PBX explosive under different constraints were analyzed. Furthermore, the relationship between the constraint conditions and the reactivity of explosive charge is analyzed by comparing with the peak value of complete detonation air overpressure. The results show that the non-impact ignition reaction process of CL-20-based PBX explosive under constraint conditions is divided into two stages : slow growth of reaction pressure and rapid growth of reaction pressure. With the increase of constraint strength, the distinction between the two reaction stages is gradually not obvious. The constraint conditions have a significant effect on the reactivity of explosive charge. When the shell thickness is 6mm and the strength of bursting disc is 2MPa and 50MPa, the reactivity of explosive is 0.11 and 0.14 respectively. When the shell thickness is 20 mm and the bursting strength is 2 MPa, the charge reactivity is 0.31. It can be seen that the reaction intensity of CL-20-based PBX explosive can be effectively reduced by weakening the mechanical constraint strength.
, Available online ,
doi: 10.11883/bzycj-2025-0042
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Abstract:
Small sample size and unavoidable uncertainty seriously hinders the research of detonation experiments with multi-physical attributes. Probability learning on manifold (PLoM) involves diffusion map and Ito projection sampling, which can generate sufficient dataset satisfying the detonation physical mechanism. And uncertainty quantification of experiment can be fulfilled through PLoM. To begin with, scale transformation is implemented on the experimental data with multi-physical asset of insensitive high explosive PBX 9502. The training set is then obtained through the normalization of the scale matrix by means of principal component analysis. To make it further, an altered high-dimensional Gaussian kernel density estimation is utilized to derive the probability measure of the random matrix associated with the training dataset. Meanwhile, diffusion map is used to deduce the nonlinear manifold based on the training dataset. Sampling on the manifold is fulfilled through Itô-MCMC generator defined by a dissipative Hamilton system driven by the Wiener process. At last, the learning set is obtained via inverse transformation. The result shows that the Gaussian statistics obtained from random numbers generated from PLoM coincide with the statistical information of density of PBX 9502 calibrated by Los Alamos National Laboratory (LANL) and Prof. Chengwei Sun. Furthermore, the double logarithm model related to the distance to detonation and initial impact stress is constructed through the data generated. It also holds for the relationship between the time of detonation and initial shock stress. Fitting precision of the curve is almost equivalent to the accuracy of LANL, however the cost is negligible. More accurate digital test result is obtained through the learning and processing of existing experimental data via PLoM. PLoM is general enough to extend to detonation experiment of other type of explosives.
Small sample size and unavoidable uncertainty seriously hinders the research of detonation experiments with multi-physical attributes. Probability learning on manifold (PLoM) involves diffusion map and Ito projection sampling, which can generate sufficient dataset satisfying the detonation physical mechanism. And uncertainty quantification of experiment can be fulfilled through PLoM. To begin with, scale transformation is implemented on the experimental data with multi-physical asset of insensitive high explosive PBX 9502. The training set is then obtained through the normalization of the scale matrix by means of principal component analysis. To make it further, an altered high-dimensional Gaussian kernel density estimation is utilized to derive the probability measure of the random matrix associated with the training dataset. Meanwhile, diffusion map is used to deduce the nonlinear manifold based on the training dataset. Sampling on the manifold is fulfilled through Itô-MCMC generator defined by a dissipative Hamilton system driven by the Wiener process. At last, the learning set is obtained via inverse transformation. The result shows that the Gaussian statistics obtained from random numbers generated from PLoM coincide with the statistical information of density of PBX 9502 calibrated by Los Alamos National Laboratory (LANL) and Prof. Chengwei Sun. Furthermore, the double logarithm model related to the distance to detonation and initial impact stress is constructed through the data generated. It also holds for the relationship between the time of detonation and initial shock stress. Fitting precision of the curve is almost equivalent to the accuracy of LANL, however the cost is negligible. More accurate digital test result is obtained through the learning and processing of existing experimental data via PLoM. PLoM is general enough to extend to detonation experiment of other type of explosives.
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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, Available online ,
doi: 10.11883/bzycj-2025-0270
Abstract:
In order to investigate the coupled enhancement effects of shock wave and temperature generated by thermobaric explosives in confined spaces, internal explosion experiments were conducted with 100−400 g charges in a confined building space. Pressure sensors and thermocouples were employed to obtain the explosion pressure and temperature data at different locations within the confined space. The experiments revealed the evolution characteristics and propagation patterns of the shock wave and temperature field produced by the thermobaric explosive. The results show that the temperature generated by the internal explosion of the thermobaric explosive exhibits significant secondary heating and prolonged duration characteristics. A decay model for the initial peak temperature based on the scaled distance was established. The TNT equivalence coefficient of the shock wave from the internal explosion of the thermobaric explosive exhibits a concave hyperbolic trend with increasing scaled distance. At a scaled distance of 1.7 m/kg1/3, the TNT equivalence coefficient of the shock wave overpressure reaches a minimum value of 1.43, indicating that this position is the turning point where the energy from aerobic afterburn combustion exerts a significant effect on the peak overpressure. A two-stage prediction model for the peak overpressure was established, describing the contributions of non-ideal detonation and the aerobic afterburn effect of aluminum powder to the shock wave in different regions. Based on the pressure rise caused by the expansion of detonation products and the temperature rise due to afterburn combustion, a quasi-static pressure prediction model for the internal explosion of thermobaric explosives was established. Taking the quasi-static pressure of the 100 g charge as the reference, the quasi-static pressures for the 200, 300, and 400 g charges increased to 2.27, 3.21, and 4.18 times the reference value, respectively, showing a nonlinear growth under the coupled effect of detonation product expansion and afterburn temperature rise.
In order to investigate the coupled enhancement effects of shock wave and temperature generated by thermobaric explosives in confined spaces, internal explosion experiments were conducted with 100−400 g charges in a confined building space. Pressure sensors and thermocouples were employed to obtain the explosion pressure and temperature data at different locations within the confined space. The experiments revealed the evolution characteristics and propagation patterns of the shock wave and temperature field produced by the thermobaric explosive. The results show that the temperature generated by the internal explosion of the thermobaric explosive exhibits significant secondary heating and prolonged duration characteristics. A decay model for the initial peak temperature based on the scaled distance was established. The TNT equivalence coefficient of the shock wave from the internal explosion of the thermobaric explosive exhibits a concave hyperbolic trend with increasing scaled distance. At a scaled distance of 1.7 m/kg1/3, the TNT equivalence coefficient of the shock wave overpressure reaches a minimum value of 1.43, indicating that this position is the turning point where the energy from aerobic afterburn combustion exerts a significant effect on the peak overpressure. A two-stage prediction model for the peak overpressure was established, describing the contributions of non-ideal detonation and the aerobic afterburn effect of aluminum powder to the shock wave in different regions. Based on the pressure rise caused by the expansion of detonation products and the temperature rise due to afterburn combustion, a quasi-static pressure prediction model for the internal explosion of thermobaric explosives was established. Taking the quasi-static pressure of the 100 g charge as the reference, the quasi-static pressures for the 200, 300, and 400 g charges increased to 2.27, 3.21, and 4.18 times the reference value, respectively, showing a nonlinear growth under the coupled effect of detonation product expansion and afterburn temperature rise.
Abstract:
Urban bridges are frequently exposed to blast threats arising from accidental explosions and terrorist attacks. However, existing studies on bridge responses under blast loading remain limited, particularly for far-field blast conditions. To investigate the dynamic response and damage mechanisms of urban continuous beam bridges subjected to far-field blast loading, LS-DYNA was employed to efficiently apply blast loads and perform numerical simulations accounting for blast-induced fluid–structure interaction. Based on a typical continuous beam bridge, a refined numerical model was developed to analyze the response process and representative damage modes of the bridge under different blast scenarios. Furthermore, the effects of blast distance, explosive charge weight, and impact angle on structural response and damage were systematically examined. The results indicate that, under far-field blast loading, the continuous beam bridge exhibits a global structural response, with uplift of the superstructure and tilting of the bridge piers being the dominant characteristics. The uplift of the superstructure is primarily influenced by the blast load and the spatial geometric characteristics of the bridge, whereas the tilting of the piers is associated with the direct action of the blast wave and the displacement of the superstructure. Under perpendicular impact, typical damage modes include wet joint failure, flexural deformation of box girders, crushing damage at the tops and bases of piers, and bending cracks in bent caps. Under oblique blast loading, torsional deformation of pier columns is additionally observed in the substructure. A decrease in the impact angle or the scaled distance results in an increase in the overall damage of the bridge structure. Evaluation based on the proposed weighted damage factor indicates that, compared with the impact angle, the overall damage of the continuous beam bridge is more sensitive to variations in the scaled distance. The findings of this study provide useful analytical approaches and mechanistic insights for understanding blast responses and guiding the blast-resistant design of bridge structures.
Urban bridges are frequently exposed to blast threats arising from accidental explosions and terrorist attacks. However, existing studies on bridge responses under blast loading remain limited, particularly for far-field blast conditions. To investigate the dynamic response and damage mechanisms of urban continuous beam bridges subjected to far-field blast loading, LS-DYNA was employed to efficiently apply blast loads and perform numerical simulations accounting for blast-induced fluid–structure interaction. Based on a typical continuous beam bridge, a refined numerical model was developed to analyze the response process and representative damage modes of the bridge under different blast scenarios. Furthermore, the effects of blast distance, explosive charge weight, and impact angle on structural response and damage were systematically examined. The results indicate that, under far-field blast loading, the continuous beam bridge exhibits a global structural response, with uplift of the superstructure and tilting of the bridge piers being the dominant characteristics. The uplift of the superstructure is primarily influenced by the blast load and the spatial geometric characteristics of the bridge, whereas the tilting of the piers is associated with the direct action of the blast wave and the displacement of the superstructure. Under perpendicular impact, typical damage modes include wet joint failure, flexural deformation of box girders, crushing damage at the tops and bases of piers, and bending cracks in bent caps. Under oblique blast loading, torsional deformation of pier columns is additionally observed in the substructure. A decrease in the impact angle or the scaled distance results in an increase in the overall damage of the bridge structure. Evaluation based on the proposed weighted damage factor indicates that, compared with the impact angle, the overall damage of the continuous beam bridge is more sensitive to variations in the scaled distance. The findings of this study provide useful analytical approaches and mechanistic insights for understanding blast responses and guiding the blast-resistant design of bridge structures.
, Available online ,
doi: 10.11883/bzycj-2025-0258
Abstract:
To obtain the ballistic characteristics of the oblique penetration of an elliptical cross-section projectile into concrete, a systematic study was carried out using numerical simulation. A reliable finite element numerical simulation model was constructed. The oblique angle, attack angle and axis spin angle that affect the ballistic deflection were decoupling. Numerical simulations of the oblique penetration of an elliptical cross-section projectile into concrete under different drop angles were carried out. The evolution laws of ballistic deflection and spin were deeply analyzed, and the mechanisms of ballistic deflection and spin were explained. The results show that the oblique angle and attack angle lead to the asymmetry of the force-bearing areas on the upper and lower surfaces of the projectile, and the attack angle also leads to the asymmetry of the surface stress of the projectile, eventually generating a deflection torque that prompts the deflection of the projectile. The angular velocity, attitude angle and ballistic offset of the projectile increase with the increases of the oblique angle and attack angle. In the case of oblique penetration with an oblique angle, the projectile in the upright position (γ=0°) deflects slowly and for a long time, while the projectile in the lying position (γ=90°) deflects quickly and for a short time. There is no absolute superiority or inferiority between the two positions in terms of ballistic stability. In the case of oblique penetration with an attack angle, the ballistic stability of the projectile in the upright position is better than that of the projectile in the lying position. The combined effects of the axis spin angle and oblique angle lead to the asymmetry of the projectile-target intersection. Besides offset and deflection, the projectile also has a self-rotating motion around the axis. When the axis spin angle increases from 0° to 90°, the projectile-target intersection condition undergoes a transformation from symmetry to asymmetry and then back to symmetry. The offset in the horizontal direction and the axis spin angle increment of the projectile first increase and then decrease. The research results provide important references for the practical engineering application of the elliptical cross-section projectile.
To obtain the ballistic characteristics of the oblique penetration of an elliptical cross-section projectile into concrete, a systematic study was carried out using numerical simulation. A reliable finite element numerical simulation model was constructed. The oblique angle, attack angle and axis spin angle that affect the ballistic deflection were decoupling. Numerical simulations of the oblique penetration of an elliptical cross-section projectile into concrete under different drop angles were carried out. The evolution laws of ballistic deflection and spin were deeply analyzed, and the mechanisms of ballistic deflection and spin were explained. The results show that the oblique angle and attack angle lead to the asymmetry of the force-bearing areas on the upper and lower surfaces of the projectile, and the attack angle also leads to the asymmetry of the surface stress of the projectile, eventually generating a deflection torque that prompts the deflection of the projectile. The angular velocity, attitude angle and ballistic offset of the projectile increase with the increases of the oblique angle and attack angle. In the case of oblique penetration with an oblique angle, the projectile in the upright position (γ=0°) deflects slowly and for a long time, while the projectile in the lying position (γ=90°) deflects quickly and for a short time. There is no absolute superiority or inferiority between the two positions in terms of ballistic stability. In the case of oblique penetration with an attack angle, the ballistic stability of the projectile in the upright position is better than that of the projectile in the lying position. The combined effects of the axis spin angle and oblique angle lead to the asymmetry of the projectile-target intersection. Besides offset and deflection, the projectile also has a self-rotating motion around the axis. When the axis spin angle increases from 0° to 90°, the projectile-target intersection condition undergoes a transformation from symmetry to asymmetry and then back to symmetry. The offset in the horizontal direction and the axis spin angle increment of the projectile first increase and then decrease. The research results provide important references for the practical engineering application of the elliptical cross-section projectile.
, Available online ,
doi: 10.11883/bzycj-2025-0379
Abstract:
To reveal the local damage mechanism of natural gas pipelines subjected to high-velocity projectile penetration, a unified solution for the plastic radius of pipeline damage was established based on the unified strength theory, integrating penetration tests, numerical simulations, and theoretical analysis. Through projectile penetration tests on L415M pipeline steel, key parameters including impact feature on the impacted surface of the pipeline, plastic zone and plastic radius were obtained. Based on the experimental results and ANSYS/Workbench, a dynamic model was developed to numerically simulate the distribution of local stress fields and strains in the pipeline. Sensitivity analysis of the intermediate principal stress parameter\begin{document}$ b $\end{document} \begin{document}$ {r}_{\max } $\end{document} \begin{document}$ {\varepsilon }_{f} $\end{document} \begin{document}$ A $\end{document} \begin{document}$ b $\end{document} \begin{document}$ b=0.2 $\end{document}
To reveal the local damage mechanism of natural gas pipelines subjected to high-velocity projectile penetration, a unified solution for the plastic radius of pipeline damage was established based on the unified strength theory, integrating penetration tests, numerical simulations, and theoretical analysis. Through projectile penetration tests on L415M pipeline steel, key parameters including impact feature on the impacted surface of the pipeline, plastic zone and plastic radius were obtained. Based on the experimental results and ANSYS/Workbench, a dynamic model was developed to numerically simulate the distribution of local stress fields and strains in the pipeline. Sensitivity analysis of the intermediate principal stress parameter
, Available online ,
doi: 10.11883/bzycj-2026-0005
Abstract:
In the field of packaging design, the use of paper honeycomb structures largely relies on empirical experience, which often results in material waste. This study develops a rapid design method for packaging structures based on the fragility theory, under equal thickness constraints, utilizing the buffering characteristics of multi-layer paper honeycomb structures. By conducting static compression and dynamic impact tests, the force-displacement curves and energy absorption characteristics of different honeycomb configurations were obtained. Simultaneously, numerical simulation methods were used to reveal the deformation modes and mechanical response mechanisms of various configurations during the loading process. Based on the structural buffering characteristic data obtained from the experiments, a rapid parametric design of multi-layer honeycomb packaging structures was achieved, and the buffering performance of the design scheme was verified through finite element models. The results show that in the static compression test, the triple-layer paper honeycomb absorbs 65.1% more energy than the single-layer paper honeycomb structure, and its stress-strain curve exhibits multiple distinct plateau stress regions. Under impact loading, the triple-layer paper honeycomb does not enter the densification stage when subjected to an impact energy of less than 81.6 J, whereas the force value of the single-layer paper honeycomb structure increases sharply under an impact energy exceeding 53.8 J. These findings indicate that the multi-layer paper honeycomb structure possesses better energy absorption characteristics under impact. Based on the fragility and the experimentally obtained buffering characteristics of the multi-layer honeycomb structure, a reverse design method for structural packaging is developed and validated through finite element modeling, confirming the effectiveness of the design approach. Compared with existing honeycomb packaging structure design methods, this proposed approach demonstrates significantly higher efficiency and accuracy. It not only reduces redundant design iterations, but also holds considerable promise for applications in cushioning packaging structure design and other impact fields.
In the field of packaging design, the use of paper honeycomb structures largely relies on empirical experience, which often results in material waste. This study develops a rapid design method for packaging structures based on the fragility theory, under equal thickness constraints, utilizing the buffering characteristics of multi-layer paper honeycomb structures. By conducting static compression and dynamic impact tests, the force-displacement curves and energy absorption characteristics of different honeycomb configurations were obtained. Simultaneously, numerical simulation methods were used to reveal the deformation modes and mechanical response mechanisms of various configurations during the loading process. Based on the structural buffering characteristic data obtained from the experiments, a rapid parametric design of multi-layer honeycomb packaging structures was achieved, and the buffering performance of the design scheme was verified through finite element models. The results show that in the static compression test, the triple-layer paper honeycomb absorbs 65.1% more energy than the single-layer paper honeycomb structure, and its stress-strain curve exhibits multiple distinct plateau stress regions. Under impact loading, the triple-layer paper honeycomb does not enter the densification stage when subjected to an impact energy of less than 81.6 J, whereas the force value of the single-layer paper honeycomb structure increases sharply under an impact energy exceeding 53.8 J. These findings indicate that the multi-layer paper honeycomb structure possesses better energy absorption characteristics under impact. Based on the fragility and the experimentally obtained buffering characteristics of the multi-layer honeycomb structure, a reverse design method for structural packaging is developed and validated through finite element modeling, confirming the effectiveness of the design approach. Compared with existing honeycomb packaging structure design methods, this proposed approach demonstrates significantly higher efficiency and accuracy. It not only reduces redundant design iterations, but also holds considerable promise for applications in cushioning packaging structure design and other impact fields.
, Available online ,
doi: 10.11883/bzycj-2025-0023
Abstract:
The study aims to solve the problem of calculating the thickness limit of high-strength steel-concrete composite structures under the impact of slender thin-walled projectiles, a key consideration for protective engineering design. A series of impact tests on composite targets were carried out. These targets were composed of different high-strength steel plates and concrete backplates. Slender thin-walled projectiles were launched with a gas gun at controlled velocities, and the impact process were captured by high-speed cameras. The resulting damage to the structures and the failure modes of the projectiles were analyzed using both non-destructive and destructive testing methods. Based on test results, the protective mechanism of the composite structures and the failure modes of projectiles were analyzed. An improved thickness limit calculation model was then developed. Unlike the original model, this new model incorporated the structural strength of slender thin-walled projectiles, considering their wall thickness, material yield strength, and geometric dimensions, and was established based on force equilibrium and energy conservation principles. The results show that the high-strength steel in the composite structures provides material strength to resist penetration, while the concrete backplate offers support stiffness. As slender thin-walled projectiles are prone to compression and expansion cracking during impact, their structural strength must be factored into the calculation model. Moreover, the design of composite structures should consider both the mechanical properties of high-strength steel and the thickness limit. In conclusion, though the proposed model offers a new theoretical approach, it has limitations such as empirical parameters and conservative results. Further research is necessary to refine and enhance the model. The study's findings provide a theoretical basis for the design and application of high-strength steel-concrete composite structures in protective engineering.
The study aims to solve the problem of calculating the thickness limit of high-strength steel-concrete composite structures under the impact of slender thin-walled projectiles, a key consideration for protective engineering design. A series of impact tests on composite targets were carried out. These targets were composed of different high-strength steel plates and concrete backplates. Slender thin-walled projectiles were launched with a gas gun at controlled velocities, and the impact process were captured by high-speed cameras. The resulting damage to the structures and the failure modes of the projectiles were analyzed using both non-destructive and destructive testing methods. Based on test results, the protective mechanism of the composite structures and the failure modes of projectiles were analyzed. An improved thickness limit calculation model was then developed. Unlike the original model, this new model incorporated the structural strength of slender thin-walled projectiles, considering their wall thickness, material yield strength, and geometric dimensions, and was established based on force equilibrium and energy conservation principles. The results show that the high-strength steel in the composite structures provides material strength to resist penetration, while the concrete backplate offers support stiffness. As slender thin-walled projectiles are prone to compression and expansion cracking during impact, their structural strength must be factored into the calculation model. Moreover, the design of composite structures should consider both the mechanical properties of high-strength steel and the thickness limit. In conclusion, though the proposed model offers a new theoretical approach, it has limitations such as empirical parameters and conservative results. Further research is necessary to refine and enhance the model. The study's findings provide a theoretical basis for the design and application of high-strength steel-concrete composite structures in protective engineering.
, Available online ,
doi: 10.11883/bzycj-2025-0362
Abstract:
The advancement of titanium-based solid-state hydrogen storage technologies and titanium manufacturing processes inherently involves the formation of hydrogen/titanium dust hybrid mixtures, which present substantial explosion hazards. To investigate the explosion behavior of such two-phase systems, this study systematically examined the variation patterns of explosion intensity parameters in hydrogen/titanium dust hybrid systems using a standardized 20 L spherical explosion vessel. The experimental matrix covers hydrogen volume fraction ranging from 0% to 30% and titanium dust mass concentrations from 100 to 700 g/m3. Specifically, titanium dust concentrations were tested at seven discrete levels (100, 200, 300, 400, 500, 600, and 700 g/m3), while hydrogen concentrations were selected at eight critical values (4%, 5%, 10%, 15%, 20%, 25%, 29%, and 30%). Dynamic parameters, including explosion pressure and rate of explosion pressure rise, were synchronously recorded. Furthermore, the phase composition and surface chemical states of explosion residues were characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). This integrated approach provides in-depth insights into the macroscopic evolution of explosion intensity with varying gas-solid ratios and elucidates the underlying microscopic reaction mechanisms. Experimental results demonstrate that hydrogen concentration critically modulates explosion severity. The explosion pressure exhibits a characteristic three-stage dependence on hydrogen concentration: it initially decreases, reaching a minimum at 4% H2, subsequently increases to a maximum at 29% H2, and finally declines at higher concentrations. Correspondingly, the maximum rate of pressure rise rate decreases to its lowest value at 4% H2 before increasing continuously up to 30% H2. The maximum explosion pressure shows an analogous trend, peaking at 29% H2 after an initial reduction, while the maximum rate of pressure rise reaches its minimum at 4% H2 and peaks at 30% H2. Residue analysis indicates that at low hydrogen concentrations (<4%), incomplete oxidation of titanium predominates, thereby reducing explosion intensity. Beyond the critical threshold of 4% H2, hydrogen self-combustion promotes titanium-nitrogen reactions and facilitates the transition from heterogeneous to homogeneous combustion, significantly enhancing explosion severity. This investigation provides fundamental insights into the explosion dynamics of hydrogen/titanium dust mixtures and delivers essential parameters for risk assessment and safety mitigation in related industrial applications.
The advancement of titanium-based solid-state hydrogen storage technologies and titanium manufacturing processes inherently involves the formation of hydrogen/titanium dust hybrid mixtures, which present substantial explosion hazards. To investigate the explosion behavior of such two-phase systems, this study systematically examined the variation patterns of explosion intensity parameters in hydrogen/titanium dust hybrid systems using a standardized 20 L spherical explosion vessel. The experimental matrix covers hydrogen volume fraction ranging from 0% to 30% and titanium dust mass concentrations from 100 to 700 g/m3. Specifically, titanium dust concentrations were tested at seven discrete levels (100, 200, 300, 400, 500, 600, and 700 g/m3), while hydrogen concentrations were selected at eight critical values (4%, 5%, 10%, 15%, 20%, 25%, 29%, and 30%). Dynamic parameters, including explosion pressure and rate of explosion pressure rise, were synchronously recorded. Furthermore, the phase composition and surface chemical states of explosion residues were characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). This integrated approach provides in-depth insights into the macroscopic evolution of explosion intensity with varying gas-solid ratios and elucidates the underlying microscopic reaction mechanisms. Experimental results demonstrate that hydrogen concentration critically modulates explosion severity. The explosion pressure exhibits a characteristic three-stage dependence on hydrogen concentration: it initially decreases, reaching a minimum at 4% H2, subsequently increases to a maximum at 29% H2, and finally declines at higher concentrations. Correspondingly, the maximum rate of pressure rise rate decreases to its lowest value at 4% H2 before increasing continuously up to 30% H2. The maximum explosion pressure shows an analogous trend, peaking at 29% H2 after an initial reduction, while the maximum rate of pressure rise reaches its minimum at 4% H2 and peaks at 30% H2. Residue analysis indicates that at low hydrogen concentrations (<4%), incomplete oxidation of titanium predominates, thereby reducing explosion intensity. Beyond the critical threshold of 4% H2, hydrogen self-combustion promotes titanium-nitrogen reactions and facilitates the transition from heterogeneous to homogeneous combustion, significantly enhancing explosion severity. This investigation provides fundamental insights into the explosion dynamics of hydrogen/titanium dust mixtures and delivers essential parameters for risk assessment and safety mitigation in related industrial applications.
, Available online ,
doi: 10.11883/bzycj-2026-0017
Abstract:
Ceramic/metal composite armor has attracted extensive attention in lightweight protective structures because of its high hardness, excellent energy dissipation capability, and strong resistance to repeated impacts. However, most existing studies focus on uniformly distributed ceramic balls and single-impact scenarios, leaving the damage evolution and protective mechanisms of gradient ceramic-ball composites under multiple impacts insufficiently understood. To address these limitations, a gradient ceramic-ball metal composite structure was proposed to improve the multi-hit resistance of composite armor. Penetration experiments using 12.7 mm armor-piercing incendiary projectiles were conducted to investigate the ballistic response of the composite target. Based on the experimental conditions, numerical simulations were carried out using the LS-DYNA software to analyze the penetration behavior of successive projectiles impacting the composite target plate. A three-dimensional finite element model was established to reproduce the penetration process, in which the Johnson–Cook constitutive model was employed to describe the mechanical behavior of metallic components and the Johnson–Holmquist ceramic constitutive model was adopted to characterize the dynamic response and failure behavior of ceramic materials. Appropriate contact algorithms and erosion criteria were implemented to simulate the interaction, damage, and fragmentation processes between the projectile and the target materials. Parametric numerical simulations were further performed to analyze the penetration characteristics of successive projectiles during the multi-impact process. The effects of ceramic ball diameter, impact spacing between successive projectiles, and gradient arrangement direction of ceramic balls on the ballistic performance of the composite structure were systematically investigated. In addition, the penetration depth, energy absorption characteristics, damage morphology of the target, and projectile deflection behavior were analyzed to reveal the influence of structural heterogeneity and pre-existing damage on the penetration response. The results show that increasing the diameter of ceramic balls significantly enlarges the damage region and enhances the structural non-uniformity, thereby increasing the sensitivity of the structure to impact location. Under multiple projectile impact conditions, the pre-existing damage caused by the first projectile significantly reduces the energy absorption capacity of the target plate and alters the penetration behavior of the subsequent projectile, especially when the impact point of the latter is located within the damaged region. Within a certain range of impact spacing, projectile deflection induced by damage heterogeneity effectively reduces the penetration depth of the backing plate even when the absorbed kinetic energy remains nearly unchanged. Compared with the negative-gradient configuration, the positive-gradient ceramic-ball composite armor reduces the damage area of the first ceramic layer by 14.8%–57.8% under the same areal density and effectively restricts the expansion of the initial damage region, thereby maintaining higher structural integrity under repeated impacts. These results indicate that a properly designed gradient distribution of ceramic balls can significantly improve the multi-hit resistance of ceramic/metal composite armor and provide useful guidance for the lightweight design and structural optimization of gradient ceramic-ball composite armor.
Ceramic/metal composite armor has attracted extensive attention in lightweight protective structures because of its high hardness, excellent energy dissipation capability, and strong resistance to repeated impacts. However, most existing studies focus on uniformly distributed ceramic balls and single-impact scenarios, leaving the damage evolution and protective mechanisms of gradient ceramic-ball composites under multiple impacts insufficiently understood. To address these limitations, a gradient ceramic-ball metal composite structure was proposed to improve the multi-hit resistance of composite armor. Penetration experiments using 12.7 mm armor-piercing incendiary projectiles were conducted to investigate the ballistic response of the composite target. Based on the experimental conditions, numerical simulations were carried out using the LS-DYNA software to analyze the penetration behavior of successive projectiles impacting the composite target plate. A three-dimensional finite element model was established to reproduce the penetration process, in which the Johnson–Cook constitutive model was employed to describe the mechanical behavior of metallic components and the Johnson–Holmquist ceramic constitutive model was adopted to characterize the dynamic response and failure behavior of ceramic materials. Appropriate contact algorithms and erosion criteria were implemented to simulate the interaction, damage, and fragmentation processes between the projectile and the target materials. Parametric numerical simulations were further performed to analyze the penetration characteristics of successive projectiles during the multi-impact process. The effects of ceramic ball diameter, impact spacing between successive projectiles, and gradient arrangement direction of ceramic balls on the ballistic performance of the composite structure were systematically investigated. In addition, the penetration depth, energy absorption characteristics, damage morphology of the target, and projectile deflection behavior were analyzed to reveal the influence of structural heterogeneity and pre-existing damage on the penetration response. The results show that increasing the diameter of ceramic balls significantly enlarges the damage region and enhances the structural non-uniformity, thereby increasing the sensitivity of the structure to impact location. Under multiple projectile impact conditions, the pre-existing damage caused by the first projectile significantly reduces the energy absorption capacity of the target plate and alters the penetration behavior of the subsequent projectile, especially when the impact point of the latter is located within the damaged region. Within a certain range of impact spacing, projectile deflection induced by damage heterogeneity effectively reduces the penetration depth of the backing plate even when the absorbed kinetic energy remains nearly unchanged. Compared with the negative-gradient configuration, the positive-gradient ceramic-ball composite armor reduces the damage area of the first ceramic layer by 14.8%–57.8% under the same areal density and effectively restricts the expansion of the initial damage region, thereby maintaining higher structural integrity under repeated impacts. These results indicate that a properly designed gradient distribution of ceramic balls can significantly improve the multi-hit resistance of ceramic/metal composite armor and provide useful guidance for the lightweight design and structural optimization of gradient ceramic-ball composite armor.
, Available online ,
doi: 10.11883/bzycj-2025-0100
Abstract:
When a high-velocity fragment impacted the fuel tank, hydrodynamic ram occurred. The fuel spurt caused by hydrodynamic ram may result in the ignition or even explosion of the fuel tank, thus threatening the survivability of the high-value target. To study the characteristics of fuel spurt caused by the hydrodynamic ram event, an experiment of a high-velocity fragment impacting a simulated fuel tank was conducted, and the characteristics of velocity and spatial distribution of the fuel spurt were tested and analyzed. In order to quantitatively describe the initial motion velocity of the fuel spurt and the attenuation process of its movement in the air, the specific volume unit within the fuel was defined as fuel mass. The concepts of initial motion velocity v0 and dispersion velocity of the fuel mass were proposed. The process of fuel mass spurting from the penetration orifices was simplified into three stages: (1) the fuel mass was about to spurt out; (2) the fuel mass spurted from the penetration orifices; (3) the fuel mass was moving in the air and gradually became atomized. On this basis, the theoretical model of the distribution of fuel spurt was established. According to the cracks at the penetration orifices and the shape change of the material at the edge of the orifices, the value of the coefficient of discharge was classified, and the influence of the distribution of pressure in the fuel was also taken into account during the calculation. When v0≤737 m/s, the range of Cv is from 0.60 to 0.70. When 737 m/s<v0<906 m/s, Cv ranges from 0.25 to 0.55. When v0≥906 m/s, Cv ranges from 0.75 to 0.95. The research showed that the average error between the calculation results of the fuel spurt axial distance and the experimental results was less than 15%. The error between the calculation results of the corrected theoretical model of radial distance and the experimental results was about 5%. The calculated results of the theoretical model were in good agreement with the experimental results.
When a high-velocity fragment impacted the fuel tank, hydrodynamic ram occurred. The fuel spurt caused by hydrodynamic ram may result in the ignition or even explosion of the fuel tank, thus threatening the survivability of the high-value target. To study the characteristics of fuel spurt caused by the hydrodynamic ram event, an experiment of a high-velocity fragment impacting a simulated fuel tank was conducted, and the characteristics of velocity and spatial distribution of the fuel spurt were tested and analyzed. In order to quantitatively describe the initial motion velocity of the fuel spurt and the attenuation process of its movement in the air, the specific volume unit within the fuel was defined as fuel mass. The concepts of initial motion velocity v0 and dispersion velocity of the fuel mass were proposed. The process of fuel mass spurting from the penetration orifices was simplified into three stages: (1) the fuel mass was about to spurt out; (2) the fuel mass spurted from the penetration orifices; (3) the fuel mass was moving in the air and gradually became atomized. On this basis, the theoretical model of the distribution of fuel spurt was established. According to the cracks at the penetration orifices and the shape change of the material at the edge of the orifices, the value of the coefficient of discharge was classified, and the influence of the distribution of pressure in the fuel was also taken into account during the calculation. When v0≤737 m/s, the range of Cv is from 0.60 to 0.70. When 737 m/s<v0<906 m/s, Cv ranges from 0.25 to 0.55. When v0≥906 m/s, Cv ranges from 0.75 to 0.95. The research showed that the average error between the calculation results of the fuel spurt axial distance and the experimental results was less than 15%. The error between the calculation results of the corrected theoretical model of radial distance and the experimental results was about 5%. The calculated results of the theoretical model were in good agreement with the experimental results.
, Available online ,
doi: 10.11883/bzycj-2025-0269
Abstract:
Background-oriented schlieren (BOS) imaging, owing to its non-contact nature and high spatiotemporal resolution, has become an important measurement technique in field experiments of explosion mechanics. However, due to strong illumination interference, scattering from detonation products, and the inherently weak and morphologically complex shockwave signature, automatic and accurate extraction of the shock front from BOS images remains highly challenging. To address this issue, we propose a structure-aware weighted variational optical flow method (SAW-VF) for robust quantification of the high-speed transient displacement field of shockwaves. The proposed approach minimizes a purpose-designed energy functional. Specifically, the data fidelity term combines a first-order photometric constraint with a second-order Hessian-invariance constraint, substantially enhancing sensitivity to the local line-like geometric features of shock fronts. In addition, a spatially adaptive weighting mechanism driven by normalized cross-correlation (NCC) is introduced to dynamically suppress the adverse influence of severely distorted regions on the estimation. Moreover, an anisotropic regularization term inspired by Perona-Malik diffusion is employed to effectively preserve the sharp motion boundaries of the shock front. To cope with large displacements, the optimization is embedded in a coarse-to-fine Gaussian pyramid framework. Building upon the estimated displacement field, we further develop a physics model–driven shock-front fitting method, in which the shock front is accurately extracted via maximum-inlier-set optimization coupled with shockwave dynamical constraints. Finally, the shock radius and propagation velocity are estimated using geometric calibration and temporal information, and the overpressure is quantitatively determined in a non-contact manner based on the Rankine-Hugoniot theory. In TNT explosion experiments, the proposed method achieves a relative error of 0.93%—9.85% with respect to pressure sensor measurements, demonstrating its effectiveness and accuracy for non-intrusive overpressure measurement of shockwaves.
Background-oriented schlieren (BOS) imaging, owing to its non-contact nature and high spatiotemporal resolution, has become an important measurement technique in field experiments of explosion mechanics. However, due to strong illumination interference, scattering from detonation products, and the inherently weak and morphologically complex shockwave signature, automatic and accurate extraction of the shock front from BOS images remains highly challenging. To address this issue, we propose a structure-aware weighted variational optical flow method (SAW-VF) for robust quantification of the high-speed transient displacement field of shockwaves. The proposed approach minimizes a purpose-designed energy functional. Specifically, the data fidelity term combines a first-order photometric constraint with a second-order Hessian-invariance constraint, substantially enhancing sensitivity to the local line-like geometric features of shock fronts. In addition, a spatially adaptive weighting mechanism driven by normalized cross-correlation (NCC) is introduced to dynamically suppress the adverse influence of severely distorted regions on the estimation. Moreover, an anisotropic regularization term inspired by Perona-Malik diffusion is employed to effectively preserve the sharp motion boundaries of the shock front. To cope with large displacements, the optimization is embedded in a coarse-to-fine Gaussian pyramid framework. Building upon the estimated displacement field, we further develop a physics model–driven shock-front fitting method, in which the shock front is accurately extracted via maximum-inlier-set optimization coupled with shockwave dynamical constraints. Finally, the shock radius and propagation velocity are estimated using geometric calibration and temporal information, and the overpressure is quantitatively determined in a non-contact manner based on the Rankine-Hugoniot theory. In TNT explosion experiments, the proposed method achieves a relative error of 0.93%—9.85% with respect to pressure sensor measurements, demonstrating its effectiveness and accuracy for non-intrusive overpressure measurement of shockwaves.
, Available online ,
doi: 10.11883/bzycj-2025-0222
Abstract:
Although macroscopic finite-element simulations based on classical composite failure criteria such as Hashin’s can account for macroscopic damage mechanisms such as fiber fracture, matrix damage, and delamination, these approaches are unable to represent microscopic damage mechanisms within carbon-fiber-reinforced polymer (CFRP), particularly interfacial debonding between fibers and the matrix. To overcome this limitation, a multiphase micromechanical model was developed that explicitly incorporates distinct constituent phases-fiber, matrix, and interface. This model integrates multiple damage mechanisms such as fiber fracture, matrix failure, and interfacial debonding, enabling a more granular analysis of damage initiation and progression. Periodic boundary conditions were applied to the model to ensure kinematic consistency and mechanical representativeness. A mesh-convergence study was subsequently carried out on the basis of the predicted elastic moduli of CFRP in various material directions, leading to an optimized discretization strategy that balances accuracy and computational cost. Comprehensive validation was performed by comparing the model-predicted stress-strain responses with experimental data obtained from unidirectional CFRP (UD CFRP) under a range of loading conditions, including transverse tension and compression, longitudinal tension and compression, and in-plane and out-of-plane shear. The damage-evolution processes under these representative loading paths were systematically analyzed. The results indicate that the relative errors in peak stress and failure strain between simulations and experiments are less than 5 %. Moreover, the crack-propagation paths predicted by the model show strong agreement with observations from scanning electron microscopy, thereby confirming the accuracy of the proposed microstructure-aware micromechanical modeling framework. Furthermore, the model successfully captures the detailed damage evolution of UD CFRP under various loading scenarios. Under transverse tensile loading, damage is initiated by interfacial debonding, followed by plastic deformation and eventual failure of the matrix near debonded regions. In contrast, under transverse compression, interfacial debonding and matrix plastic deformation are observed to occur simultaneously. Under longitudinal loading, the dominant damage mechanism is identified as fiber fracture, whereas the damage patterns under in-plane and out-of-plane shear are found to be consistent with those under transverse compression and transverse tension, respectively. These insights offer significant engineering value for the development of damage-tolerant design criteria and structural-integrity evaluation frameworks for CFRP components and assemblies.
Although macroscopic finite-element simulations based on classical composite failure criteria such as Hashin’s can account for macroscopic damage mechanisms such as fiber fracture, matrix damage, and delamination, these approaches are unable to represent microscopic damage mechanisms within carbon-fiber-reinforced polymer (CFRP), particularly interfacial debonding between fibers and the matrix. To overcome this limitation, a multiphase micromechanical model was developed that explicitly incorporates distinct constituent phases-fiber, matrix, and interface. This model integrates multiple damage mechanisms such as fiber fracture, matrix failure, and interfacial debonding, enabling a more granular analysis of damage initiation and progression. Periodic boundary conditions were applied to the model to ensure kinematic consistency and mechanical representativeness. A mesh-convergence study was subsequently carried out on the basis of the predicted elastic moduli of CFRP in various material directions, leading to an optimized discretization strategy that balances accuracy and computational cost. Comprehensive validation was performed by comparing the model-predicted stress-strain responses with experimental data obtained from unidirectional CFRP (UD CFRP) under a range of loading conditions, including transverse tension and compression, longitudinal tension and compression, and in-plane and out-of-plane shear. The damage-evolution processes under these representative loading paths were systematically analyzed. The results indicate that the relative errors in peak stress and failure strain between simulations and experiments are less than 5 %. Moreover, the crack-propagation paths predicted by the model show strong agreement with observations from scanning electron microscopy, thereby confirming the accuracy of the proposed microstructure-aware micromechanical modeling framework. Furthermore, the model successfully captures the detailed damage evolution of UD CFRP under various loading scenarios. Under transverse tensile loading, damage is initiated by interfacial debonding, followed by plastic deformation and eventual failure of the matrix near debonded regions. In contrast, under transverse compression, interfacial debonding and matrix plastic deformation are observed to occur simultaneously. Under longitudinal loading, the dominant damage mechanism is identified as fiber fracture, whereas the damage patterns under in-plane and out-of-plane shear are found to be consistent with those under transverse compression and transverse tension, respectively. These insights offer significant engineering value for the development of damage-tolerant design criteria and structural-integrity evaluation frameworks for CFRP components and assemblies.
, Available online ,
doi: 10.11883/bzycj-2025-0216
Abstract:
In order to systematically evaluate the impact safety of human chest impacted by non-lethal kinetic projectiles (NLKP), an integrated three-rib thoracic physical model with a configurable structure was developed, which was compatible with both simulation and experimental testing. The projectile representation was first validated through rigid-wall impacts at 29 m/s and 61 m/s on a controllable gas-launch platform. The measured force–time histories agreed well with the NATO Allied Engineering Publication-99 (AEP-99), corridors, confirming the fidelity of the projectile model. Impact experiments on chest were then conducted using the validated projectile model at 56 m/s and 86.5 m/s. The measured chest-wall displacements and the maximum value of the viscous criterion (VCmax, βvc,max) fell within the validation corridors specified in the AEP-99, demonstrating that the proposed model exhibits dynamic-response consistency and predictive accuracy under medium- and low-velocity impacts at or below 90 m/s. Among them, the maximum relative errors between simulated and experimental displacements at 56 m/s and 86.5 m/s are 16% and 21%, respectively. A projectile hardness scan (soft/medium/hard) showed that VCmax increased from 0.298 m/s to 0.336 m/s at 56 m/s and from 0.765 m/s to 0.856 m/s at 86.5 m/s, indicating a more pronounced risk amplification at higher energies. When the rib spacing varies within the range of 80%−120% of the baseline rib spacing, its effect on the peak displacement and contact force is approximately ±6%, and VCmax fluctuates within 5.7%−6.2%, which is generally within the engineering acceptable range. Compared with the surrogate human thorax for impact model (SHTIM), the proposed model adhered more closely to the corridor mid-line at 56, 86.5 m/s, and yielded VCmax values of 0.308, 0.803 m/s (both within the recommended ranges), whereas the SHTIM slightly underestimated the high-energy case, confirming the model advantage in response fidelity and criterion consistency. A systematic simulation was conducted for impact responses by four typical projectiles (NS, CONDOR, SIR-X, and RB1FS) within the velocity range of 60–90 m/s, elucidating the influence mechanisms of projectile structure and material on thoracic injury risk. Under higher speed impact (100–120 m/s), the soft tissue layer of the model dominates energy absorption and dissipation, while the peak stress in the rib layer increases significantly with velocity and exceeds the yield limit, indicating a high risk of fracture. Thickness sensitivity analysis reveals that the thickness of the soft tissue layer plays the most prominent role in regulating energy absorption and deformation. These findings provide important theoretical and technical support for NLKP impact injury assessment and the optimization of protective equipment.
In order to systematically evaluate the impact safety of human chest impacted by non-lethal kinetic projectiles (NLKP), an integrated three-rib thoracic physical model with a configurable structure was developed, which was compatible with both simulation and experimental testing. The projectile representation was first validated through rigid-wall impacts at 29 m/s and 61 m/s on a controllable gas-launch platform. The measured force–time histories agreed well with the NATO Allied Engineering Publication-99 (AEP-99), corridors, confirming the fidelity of the projectile model. Impact experiments on chest were then conducted using the validated projectile model at 56 m/s and 86.5 m/s. The measured chest-wall displacements and the maximum value of the viscous criterion (VCmax, βvc,max) fell within the validation corridors specified in the AEP-99, demonstrating that the proposed model exhibits dynamic-response consistency and predictive accuracy under medium- and low-velocity impacts at or below 90 m/s. Among them, the maximum relative errors between simulated and experimental displacements at 56 m/s and 86.5 m/s are 16% and 21%, respectively. A projectile hardness scan (soft/medium/hard) showed that VCmax increased from 0.298 m/s to 0.336 m/s at 56 m/s and from 0.765 m/s to 0.856 m/s at 86.5 m/s, indicating a more pronounced risk amplification at higher energies. When the rib spacing varies within the range of 80%−120% of the baseline rib spacing, its effect on the peak displacement and contact force is approximately ±6%, and VCmax fluctuates within 5.7%−6.2%, which is generally within the engineering acceptable range. Compared with the surrogate human thorax for impact model (SHTIM), the proposed model adhered more closely to the corridor mid-line at 56, 86.5 m/s, and yielded VCmax values of 0.308, 0.803 m/s (both within the recommended ranges), whereas the SHTIM slightly underestimated the high-energy case, confirming the model advantage in response fidelity and criterion consistency. A systematic simulation was conducted for impact responses by four typical projectiles (NS, CONDOR, SIR-X, and RB1FS) within the velocity range of 60–90 m/s, elucidating the influence mechanisms of projectile structure and material on thoracic injury risk. Under higher speed impact (100–120 m/s), the soft tissue layer of the model dominates energy absorption and dissipation, while the peak stress in the rib layer increases significantly with velocity and exceeds the yield limit, indicating a high risk of fracture. Thickness sensitivity analysis reveals that the thickness of the soft tissue layer plays the most prominent role in regulating energy absorption and deformation. These findings provide important theoretical and technical support for NLKP impact injury assessment and the optimization of protective equipment.
, Available online ,
doi: 10.11883/bzycj-2025-0219
Abstract:
Deep coal rock blasting poses high risks, and hydraulic fracturing faces limitations, necessitating the development of controllable rock-breaking technologies. As an advanced high-energy gas fracturing technique, high-energy gas-generating agents demonstrate remarkable advantages in rock fragmentation, providing robust technical support for efficient and safe coal mining. This study focuses on the casing materials of high-energy gas-generating agents, investigating their impact on borehole wall pressure during coal rock fracturing. A comprehensive pressure monitoring system was established, employing three casing materials—transparent PVC, white PVC, and kraft paper tubes—for borehole wall pressure experiments. Attenuation indices and reliability were selected as evaluation metrics to analyze the influence of material physical properties on borehole wall pressure. Results indicate that the initiator, upon ignition, generates stress waves and a small amount of gas. The stress wave induces the first pressure peak, followed by a decline due to gas diffusion. The superposition of reflected stress waves and gas expansion waves forms the second peak, while gas expansion variations produce the third peak. Without the main agent, the initiator group exhibits the lowest pressure peak, shortest pressure rise time, minimal loading rate, limited energy release, and low transmission efficiency. For the three groups containing the main agent, pressure peaks near the high-energy gas-generating agent (10 cm away) approximate 200 MPa, with pressure rise times around 20 ms. The attenuation coefficients of pressure peaks for the three casing materials from the biggest to the smallest follow the order: transparent PVC, white PVC, and kraft paper tube. The attenuation coefficients of pressure rise times from the biggest to the smallest rank as: transparent PVC, kraft paper tube, and white PVC. For loading rate attenuation coefficients, the sequence from the biggest to the smallest is: white PVC, transparent PVC, and kraft paper tube. Because of its high elastic modulus and low Poisson’s ratio, white PVC casing demonstrates optimal performance in pressure peak, rise time, and loading rate near the high-energy gas-generating agent, achieving the highest energy transmission efficiency. Transparent PVC casing exhibits higher pressure peaks and loading rates than the paper tube near the agent but underperforms at longer distances, indicating strong directionality and concentration. The kraft paper tube ensures uniform energy distribution but exhibits the weakest overall energy concentration, along with the longest rise times and lowest loading rates. These findings provide a theoretical foundation for optimizing high-energy gas-generating agent designs and enhancing rock-breaking efficacy.
Deep coal rock blasting poses high risks, and hydraulic fracturing faces limitations, necessitating the development of controllable rock-breaking technologies. As an advanced high-energy gas fracturing technique, high-energy gas-generating agents demonstrate remarkable advantages in rock fragmentation, providing robust technical support for efficient and safe coal mining. This study focuses on the casing materials of high-energy gas-generating agents, investigating their impact on borehole wall pressure during coal rock fracturing. A comprehensive pressure monitoring system was established, employing three casing materials—transparent PVC, white PVC, and kraft paper tubes—for borehole wall pressure experiments. Attenuation indices and reliability were selected as evaluation metrics to analyze the influence of material physical properties on borehole wall pressure. Results indicate that the initiator, upon ignition, generates stress waves and a small amount of gas. The stress wave induces the first pressure peak, followed by a decline due to gas diffusion. The superposition of reflected stress waves and gas expansion waves forms the second peak, while gas expansion variations produce the third peak. Without the main agent, the initiator group exhibits the lowest pressure peak, shortest pressure rise time, minimal loading rate, limited energy release, and low transmission efficiency. For the three groups containing the main agent, pressure peaks near the high-energy gas-generating agent (10 cm away) approximate 200 MPa, with pressure rise times around 20 ms. The attenuation coefficients of pressure peaks for the three casing materials from the biggest to the smallest follow the order: transparent PVC, white PVC, and kraft paper tube. The attenuation coefficients of pressure rise times from the biggest to the smallest rank as: transparent PVC, kraft paper tube, and white PVC. For loading rate attenuation coefficients, the sequence from the biggest to the smallest is: white PVC, transparent PVC, and kraft paper tube. Because of its high elastic modulus and low Poisson’s ratio, white PVC casing demonstrates optimal performance in pressure peak, rise time, and loading rate near the high-energy gas-generating agent, achieving the highest energy transmission efficiency. Transparent PVC casing exhibits higher pressure peaks and loading rates than the paper tube near the agent but underperforms at longer distances, indicating strong directionality and concentration. The kraft paper tube ensures uniform energy distribution but exhibits the weakest overall energy concentration, along with the longest rise times and lowest loading rates. These findings provide a theoretical foundation for optimizing high-energy gas-generating agent designs and enhancing rock-breaking efficacy.
, Available online ,
doi: 10.11883/bzycj-2025-0140
Abstract:
Hydrogen energy, as a zero-carbon energy source, holds broad application prospects in critical defense systems because of its high energy density and zero carbon emissions. To enhance energy utilization efficiency and ensure operational safety, an integrated approach combining experimental and numerical simulations was adopted to systematically examine the effects of hydrogen concentration on explosion dynamics in a confined space. Experiments were carried out in a cylindrical chamber equipped with high-frequency pressure sensors and a high-speed camera to record transient overpressure and track flame propagation behavior. Complementing the experimental setup, computational fluid dynamics (CFD) simulations were implemented using a detailed 19-step hydrogen/air chemical reaction mechanism to accurately reproduce the spatiotemporal evolution of flow field velocity during the premixed gas explosion process. Results indicate that the maximum explosion pressure occurred at a hydrogen volume fraction of 30%, peaking at 0.623 94 MPa. The peak flame area was largest at both 30% and 45%, exceeding results at 15% and 60% by 14.6% and 6.3%, respectively. The 30 % condition also achieved the peak flame area in the shortest time, at 8.2 ms. Furthermore, geometric constraints at the junction of the cylindrical sidewall and the endwall led to accumulation of unburned hydrogen, causing localized increases in density and pressure and resulting in four clearly discernible high-velocity regions within the flow field. At 9 ms, the flow velocity profile along the centerline exhibited symmetry with a dual-peak structure appearing unilaterally. While the 45% condition showed an early transient velocity advantage due to intensified local heat release, the 30% condition demonstrated superior late-stage velocity recovery owing to more stable and sustained combustion near the stoichiometric ratio. These findings underscore the high combustion efficiency and stability achievable near stoichiometric conditions, providing a scientific foundation for the design and optimization of high-efficiency hydrogen combustion systems..
Hydrogen energy, as a zero-carbon energy source, holds broad application prospects in critical defense systems because of its high energy density and zero carbon emissions. To enhance energy utilization efficiency and ensure operational safety, an integrated approach combining experimental and numerical simulations was adopted to systematically examine the effects of hydrogen concentration on explosion dynamics in a confined space. Experiments were carried out in a cylindrical chamber equipped with high-frequency pressure sensors and a high-speed camera to record transient overpressure and track flame propagation behavior. Complementing the experimental setup, computational fluid dynamics (CFD) simulations were implemented using a detailed 19-step hydrogen/air chemical reaction mechanism to accurately reproduce the spatiotemporal evolution of flow field velocity during the premixed gas explosion process. Results indicate that the maximum explosion pressure occurred at a hydrogen volume fraction of 30%, peaking at 0.623 94 MPa. The peak flame area was largest at both 30% and 45%, exceeding results at 15% and 60% by 14.6% and 6.3%, respectively. The 30 % condition also achieved the peak flame area in the shortest time, at 8.2 ms. Furthermore, geometric constraints at the junction of the cylindrical sidewall and the endwall led to accumulation of unburned hydrogen, causing localized increases in density and pressure and resulting in four clearly discernible high-velocity regions within the flow field. At 9 ms, the flow velocity profile along the centerline exhibited symmetry with a dual-peak structure appearing unilaterally. While the 45% condition showed an early transient velocity advantage due to intensified local heat release, the 30% condition demonstrated superior late-stage velocity recovery owing to more stable and sustained combustion near the stoichiometric ratio. These findings underscore the high combustion efficiency and stability achievable near stoichiometric conditions, providing a scientific foundation for the design and optimization of high-efficiency hydrogen combustion systems..
, Available online ,
doi: 10.11883/bzycj-2025-0125
Abstract:
Layered rock masses were prone to bedding plane cracking or even large-scale collapse under impact loads such as blasting. In engineering practices, bolts or cables were commonly employed for anchoring support. To investigate the dynamic mechanical response of layered rock masses under impact loading and the effectiveness of bolt support, sandstone specimens with different bedding dip angles (0°, 15°, 30°, 45°, 60°, 75°, 90°) and bolt support methods (No-anchor, End-anchor, Semi-anchor, Full- anchor) were prepared. Dynamic impact tests were conducted using a split Hopkinson pressure bar system to analyze the coupling effects of bedding dip angle and bolt support method on the dynamic strength, energy evolution, and failure modes of the rock mass. Additionally, fractal theory was employed to quantitatively characterize the fracture characteristics of the specimens. The results indicate that the strength of unanchored specimens initially decreases and then increases with increasing bedding plane angle, exhibiting a V-shaped curve. After anchoring, the strength of specimens improves significantly, and as the anchor length increases, the curve transitions to an inverted V-shape. From an energy perspective, the transmitted energy trends of all four specimen types are similar to their strength trends. As the bedding plane angle increases, the reflected energy curve shows an inverted V-shape, the transmitted energy gradually decreases, while the dissipated energy increases. The anchoring method primarily affects the overall level of the curves. The fragments of the specimens after failure exhibit distinct fractal characteristics, with the fractal dimension curves showing an inverted V-shape influenced by the bedding plane angle. Full-anchor specimens display the least fragmentation, while No-anchor specimens experience the most severe damage. Based on this, the unit dissipated energy index was calculated, revealing a V-shaped curve. Full-anchor specimens exhibit the highest overall unit dissipated energy index, indicating their superior resistance to damage. The findings of this study can provide a reference for anchor support design in layered rock mass engineering.
Layered rock masses were prone to bedding plane cracking or even large-scale collapse under impact loads such as blasting. In engineering practices, bolts or cables were commonly employed for anchoring support. To investigate the dynamic mechanical response of layered rock masses under impact loading and the effectiveness of bolt support, sandstone specimens with different bedding dip angles (0°, 15°, 30°, 45°, 60°, 75°, 90°) and bolt support methods (No-anchor, End-anchor, Semi-anchor, Full- anchor) were prepared. Dynamic impact tests were conducted using a split Hopkinson pressure bar system to analyze the coupling effects of bedding dip angle and bolt support method on the dynamic strength, energy evolution, and failure modes of the rock mass. Additionally, fractal theory was employed to quantitatively characterize the fracture characteristics of the specimens. The results indicate that the strength of unanchored specimens initially decreases and then increases with increasing bedding plane angle, exhibiting a V-shaped curve. After anchoring, the strength of specimens improves significantly, and as the anchor length increases, the curve transitions to an inverted V-shape. From an energy perspective, the transmitted energy trends of all four specimen types are similar to their strength trends. As the bedding plane angle increases, the reflected energy curve shows an inverted V-shape, the transmitted energy gradually decreases, while the dissipated energy increases. The anchoring method primarily affects the overall level of the curves. The fragments of the specimens after failure exhibit distinct fractal characteristics, with the fractal dimension curves showing an inverted V-shape influenced by the bedding plane angle. Full-anchor specimens display the least fragmentation, while No-anchor specimens experience the most severe damage. Based on this, the unit dissipated energy index was calculated, revealing a V-shaped curve. Full-anchor specimens exhibit the highest overall unit dissipated energy index, indicating their superior resistance to damage. The findings of this study can provide a reference for anchor support design in layered rock mass engineering.
, Available online ,
doi: 10.11883/bzycj-2025-0301
Abstract:
Nuclear-grade stainless steel Z2CN18.10 is widely used in nuclear power plant piping systems. Its dynamic mechanical behavior under combined high strain rates and elevated temperatures is of great significance for assessing structural integrity under impact loads. To accurately characterize the mechanical behavior of Z2CN18.10 under dynamic loading, quasi-static and high-strain-rate tensile tests were conducted using a universal electronic testing machine and a conventional split Hopkinson tension bar system. The stress-strain responses of the material were obtained within temperature ranges from ambient (25 ℃) up to 400 ℃ and strain rates from 10−3 to 103 s−1. To overcome the limitation of conventional Hopkinson bar apparatus in achieving large-strain loading, an electromagnetically driven bidirectional Hopkinson tension bar system was employed to measure the failure strain of the material under different stress triaxialities. Based on the experimental data, parameters for the Johnson-Cook constitutive model and failure criterion were fitted, and the validity of the model was verified through high-speed impact tests using a gas gun. The results show that the differences between numerical simulations and experiments in terms of perforation diameter, peak strain, and support reaction force were 4.4%, 7.5%, and 2.3%, respectively, indicating good agreement. The established reliable dynamic constitutive model and failure criterion for Z2CN18.10 stainless steel provide an important methodological and data foundation for the impact-resistant design and safety assessment of nuclear power piping systems.
Nuclear-grade stainless steel Z2CN18.10 is widely used in nuclear power plant piping systems. Its dynamic mechanical behavior under combined high strain rates and elevated temperatures is of great significance for assessing structural integrity under impact loads. To accurately characterize the mechanical behavior of Z2CN18.10 under dynamic loading, quasi-static and high-strain-rate tensile tests were conducted using a universal electronic testing machine and a conventional split Hopkinson tension bar system. The stress-strain responses of the material were obtained within temperature ranges from ambient (25 ℃) up to 400 ℃ and strain rates from 10−3 to 103 s−1. To overcome the limitation of conventional Hopkinson bar apparatus in achieving large-strain loading, an electromagnetically driven bidirectional Hopkinson tension bar system was employed to measure the failure strain of the material under different stress triaxialities. Based on the experimental data, parameters for the Johnson-Cook constitutive model and failure criterion were fitted, and the validity of the model was verified through high-speed impact tests using a gas gun. The results show that the differences between numerical simulations and experiments in terms of perforation diameter, peak strain, and support reaction force were 4.4%, 7.5%, and 2.3%, respectively, indicating good agreement. The established reliable dynamic constitutive model and failure criterion for Z2CN18.10 stainless steel provide an important methodological and data foundation for the impact-resistant design and safety assessment of nuclear power piping systems.
, Available online ,
doi: 10.11883/bzycj-2025-0243
Abstract:
In the field of material dynamic mechanical properties research, it is significant to obtain reliable data of materials under complex stress states. To address the challenge of achieving a stable stress ratio during combined loading, this work developed a novel device based on the electromagnetic Hopkinson bar (ESHB) platform. This device uniquely enables unilateral synchronous tension/compression-torsion combined dynamic loading. The paper detailed the device’s configuration and loading principles. The core innovation of this device is the independent generation of trapezoidal tensile/compressive and torsional stress waves. A multi-circuit pulse shaper produced tensile/compressive waves, while shear waves were generated using an electromagnetic clamp with torque storage. Crucially, a high-precision digital delay generator (DDG) ensured wave synchronization. With triggering accuracy within 0.1 μs, it controlled the arrival time difference of these distinct waves at the specimen to within 5 μs. This overcame the challenge posed by their different propagation velocities. Additionally, it described the synchronization control methodology and the wave propagation analysis essential for timing calculations. To validate the apparatus, dynamic tension-torsion experiments were conducted on CoCrFeMnNi high-entropy alloy specimens. The results show that the device is highly reliable and effective. It successfully achieved a stable stress ratio of approximately 1.7 throughout the loading duration. Furthermore, the experiments conclusively showed a key finding. Trapezoidal wave loading significantly enhances stress-ratio stability during combined dynamic loading. This improvement contrasts with the effect of traditional sinusoidal wave loading. This advancement offers a robust and controllable experimental method. It enables the study of materials’ dynamic mechanical responses under complex stress states. These states involve high-strain rates and multiaxial loading. This capability is especially valuable for aerospace, impact engineering, and materials science applications. The successful implementation of constant stress-ratio loading opens avenues for more accurate characterization of material yield criteria and failure mechanisms under dynamic multiaxial conditions.
In the field of material dynamic mechanical properties research, it is significant to obtain reliable data of materials under complex stress states. To address the challenge of achieving a stable stress ratio during combined loading, this work developed a novel device based on the electromagnetic Hopkinson bar (ESHB) platform. This device uniquely enables unilateral synchronous tension/compression-torsion combined dynamic loading. The paper detailed the device’s configuration and loading principles. The core innovation of this device is the independent generation of trapezoidal tensile/compressive and torsional stress waves. A multi-circuit pulse shaper produced tensile/compressive waves, while shear waves were generated using an electromagnetic clamp with torque storage. Crucially, a high-precision digital delay generator (DDG) ensured wave synchronization. With triggering accuracy within 0.1 μs, it controlled the arrival time difference of these distinct waves at the specimen to within 5 μs. This overcame the challenge posed by their different propagation velocities. Additionally, it described the synchronization control methodology and the wave propagation analysis essential for timing calculations. To validate the apparatus, dynamic tension-torsion experiments were conducted on CoCrFeMnNi high-entropy alloy specimens. The results show that the device is highly reliable and effective. It successfully achieved a stable stress ratio of approximately 1.7 throughout the loading duration. Furthermore, the experiments conclusively showed a key finding. Trapezoidal wave loading significantly enhances stress-ratio stability during combined dynamic loading. This improvement contrasts with the effect of traditional sinusoidal wave loading. This advancement offers a robust and controllable experimental method. It enables the study of materials’ dynamic mechanical responses under complex stress states. These states involve high-strain rates and multiaxial loading. This capability is especially valuable for aerospace, impact engineering, and materials science applications. The successful implementation of constant stress-ratio loading opens avenues for more accurate characterization of material yield criteria and failure mechanisms under dynamic multiaxial conditions.
, 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
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2026, 46(4): 041001.
doi: 10.11883/bzycj-2025-0108
Abstract:
To investigate the impact of target damage on projectile penetration performance, a series of penetration experiments was conducted on a concrete target utilizing a former jet and a subsequent kinetic energy projectile. The critical factors influencing the performance of pre-damaged concrete penetrated by the projectile were analyzed. The relationship for the strength of the concrete materials in the pre-damaged concrete target was determined. Based on this, a semi-empirical model of projectile penetration of pre-damaged concrete was established by combining the aforementioned cavity expansion theory with the results of the preceding analysis. The impact of projectile and target parameters on the performance of secondary penetration of the projectile was then analyzed. The findings indicate that the influence of pre-damaged concrete on the depth of projectile penetration is contingent upon the discrepancy in crater volume and concrete damage. It can be posited that the damage to the target is the predominant influencing factor. When there is a finite-length damage zone within the concrete target and the diameter of the cavity of the target is between 0.3 and 0.5 times the diameter of the projectile, the effect is even less pronounced. When a finite-length damage zone exists within the target, the pre-damage cavity is 0.3–0.5 times the projectile diameter. In this instance, the gain in depth of penetration is most pronounced. In the event of penetrating damage to the target, a ratio of 0.3 between the diameter of the target tunnel and that of the projectile is observed. The difference in penetration depth between the pre-damaged target and the pre-drilled target is greater, with a gradual increase in this difference as the ratio increases further. When the damage state of the target is certain, decreasing the projectile diameter or increasing the CRH of the ogive-nosed projectile is more advantageous to increase the penetration depth.
To investigate the impact of target damage on projectile penetration performance, a series of penetration experiments was conducted on a concrete target utilizing a former jet and a subsequent kinetic energy projectile. The critical factors influencing the performance of pre-damaged concrete penetrated by the projectile were analyzed. The relationship for the strength of the concrete materials in the pre-damaged concrete target was determined. Based on this, a semi-empirical model of projectile penetration of pre-damaged concrete was established by combining the aforementioned cavity expansion theory with the results of the preceding analysis. The impact of projectile and target parameters on the performance of secondary penetration of the projectile was then analyzed. The findings indicate that the influence of pre-damaged concrete on the depth of projectile penetration is contingent upon the discrepancy in crater volume and concrete damage. It can be posited that the damage to the target is the predominant influencing factor. When there is a finite-length damage zone within the concrete target and the diameter of the cavity of the target is between 0.3 and 0.5 times the diameter of the projectile, the effect is even less pronounced. When a finite-length damage zone exists within the target, the pre-damage cavity is 0.3–0.5 times the projectile diameter. In this instance, the gain in depth of penetration is most pronounced. In the event of penetrating damage to the target, a ratio of 0.3 between the diameter of the target tunnel and that of the projectile is observed. The difference in penetration depth between the pre-damaged target and the pre-drilled target is greater, with a gradual increase in this difference as the ratio increases further. When the damage state of the target is certain, decreasing the projectile diameter or increasing the CRH of the ogive-nosed projectile is more advantageous to increase the penetration depth.
2026, 46(4): 041101.
doi: 10.11883/bzycj-2025-0040
Abstract:
Against the backdrop of rising global terrorism and industrial accidents, research on infrastructure safety under blast impact has become critically urgent. As a pivotal approach for investigating dynamic responses and damage characteristics of materials and structures subjected to explosive loading, the equivalent blast-loading techniques, which show safe, efficient, and accurate, have emerged as both a research frontier and challenge. This review synthesizes advancements in equivalent blast-loading techniques for far-field explosion simulation, encompassing explosive-driven shock tubes, high-pressure gas-driven shock tubes, drop-weight impact testing machines, and hydraulically-actuated simulators. While each technique exhibits distinct advantages and limitations in simulating blast shockwaves, all strive to establish controlled and secure experimental environments that reproduce high-velocity air flow fields and pressure waves generated by explosions. Through comparative assessment, their performance in load replication fidelity, applicability, and operational efficiency are elucidated, alongside discussions on implementation challenges and potential. Finally, a novel blast simulation technique leveraging liquid-gas phase-transition-driven expansion is introduced and the follow-up research directions are prospected.
Against the backdrop of rising global terrorism and industrial accidents, research on infrastructure safety under blast impact has become critically urgent. As a pivotal approach for investigating dynamic responses and damage characteristics of materials and structures subjected to explosive loading, the equivalent blast-loading techniques, which show safe, efficient, and accurate, have emerged as both a research frontier and challenge. This review synthesizes advancements in equivalent blast-loading techniques for far-field explosion simulation, encompassing explosive-driven shock tubes, high-pressure gas-driven shock tubes, drop-weight impact testing machines, and hydraulically-actuated simulators. While each technique exhibits distinct advantages and limitations in simulating blast shockwaves, all strive to establish controlled and secure experimental environments that reproduce high-velocity air flow fields and pressure waves generated by explosions. Through comparative assessment, their performance in load replication fidelity, applicability, and operational efficiency are elucidated, alongside discussions on implementation challenges and potential. Finally, a novel blast simulation technique leveraging liquid-gas phase-transition-driven expansion is introduced and the follow-up research directions are prospected.
2026, 46(4): 042201.
doi: 10.11883/bzycj-2024-0428
Abstract:
In order to study the distribution of blast wave load of building surface under surface burst, firstly, the fine scaled experiments under laboratory environment were conducted. The blast wave pressure-time curves on the surface of building model under the situation of surface burst of spherical charge as well as the distribution law of blast wave characteristic parameters were obtained. Subsequently, the numerical simulation method of blast wave propagation was developed and verified by the experimental data. Through simulation, the blast load distribution and time-histories of blast pressure on the rear face of building were analyzed. Finally, the theoretical method based on blast wave time-history analysis and superposition rule was proposed, and the quantitative analysis model of the blast load distribution on the rear face of building which was verified by numerical results was obtained. The results show that the maximum blast load on the front face of building located at the bottom of the building, which the overall distribution was relatively uniform. The blast load on the rear face of building was mainly concentrated on the two sides of the top angle and the central axis, which was formed by the superposition of the diffraction waves from top and side edges, and the maximum overpressure occurred at the intersection position of different diffraction shock waves, which is affected by the building size and explosion distance.
In order to study the distribution of blast wave load of building surface under surface burst, firstly, the fine scaled experiments under laboratory environment were conducted. The blast wave pressure-time curves on the surface of building model under the situation of surface burst of spherical charge as well as the distribution law of blast wave characteristic parameters were obtained. Subsequently, the numerical simulation method of blast wave propagation was developed and verified by the experimental data. Through simulation, the blast load distribution and time-histories of blast pressure on the rear face of building were analyzed. Finally, the theoretical method based on blast wave time-history analysis and superposition rule was proposed, and the quantitative analysis model of the blast load distribution on the rear face of building which was verified by numerical results was obtained. The results show that the maximum blast load on the front face of building located at the bottom of the building, which the overall distribution was relatively uniform. The blast load on the rear face of building was mainly concentrated on the two sides of the top angle and the central axis, which was formed by the superposition of the diffraction waves from top and side edges, and the maximum overpressure occurred at the intersection position of different diffraction shock waves, which is affected by the building size and explosion distance.
2026, 46(4): 042301.
doi: 10.11883/bzycj-2025-0190
Abstract:
To improve the mechanical behaviors and explosion performance of the Al/PTFE reactive materials, short-cut titanium fibers were added to Al/PTFE annular reactive materials, and subsequently assembled with RDX explosive column to form a composite charge. The effects of different titanium fiber contents on the mechanical behaviors of the annular reactive materials were investigated using a universal material testing machine and a split Hopkinson pressure bar. The influence of short-cut titanium fiber contents on the quasi-static pressure, shock wave parameters and thermal damage effects of the composite charge was studied in depth by the free-field explosion test system and spherical explosion container test system combined with the colorimetric temperature measurement technology. The temperature field of explosion flame was reconstructed by the colorimetric temperature measurement method with a high-speed camera, which was based on the gray-body radiation theory. A tungsten lamp calibrated the measurement accuracy of the temperature mapping system, and the fitting relationship between the temperatures and the gray values of the high-speed images was derived to obtain the conversion coefficient. The test results of mechanical properties showed that with the increase of titanium fiber content, the elastic modulus, yield strength and compressive strength of Al/PTFE annular reactive materials under quasi-static compression, as well as the yield strength and compressive strength under high-speed impact, all exhibited an initial increase, which were followed by a decrease, reaching the maximum values at 3% content. The experimental results of explosion performance showed that short-cut titanium fibers could significantly enhance the explosion performance of Al/PTFE-RDX composite charges. When the content of short-cut titanium fibers was 3%, the peak overpressure of the explosion shock wave, its positive phase duration and positive impulse were 37.68 kPa, 695.34 µs and 12.34 Pa·s, respectively. With 5% content of short-cut titanium fibers, the afterburning effect was the most significant. The maximum values of the explosion quasi-static pressure, average fireball temperature and fireball duration reached 70.50 kPa,2782 K and 1668.90 µs, respectively. Analysis of solid explosion products indicated that short-cut titanium fibers could enhance the mechanical strength of the Al/PTFE matrix, delay the fragmentation time of the Al/PTFE annular reactive materials, promote the interfacial reactions, and participate in high-temperature chemical reactions, generating a synergistic effect and positive feedback to improve the mechanical toughness and energy release efficiency of the reactive materials.
To improve the mechanical behaviors and explosion performance of the Al/PTFE reactive materials, short-cut titanium fibers were added to Al/PTFE annular reactive materials, and subsequently assembled with RDX explosive column to form a composite charge. The effects of different titanium fiber contents on the mechanical behaviors of the annular reactive materials were investigated using a universal material testing machine and a split Hopkinson pressure bar. The influence of short-cut titanium fiber contents on the quasi-static pressure, shock wave parameters and thermal damage effects of the composite charge was studied in depth by the free-field explosion test system and spherical explosion container test system combined with the colorimetric temperature measurement technology. The temperature field of explosion flame was reconstructed by the colorimetric temperature measurement method with a high-speed camera, which was based on the gray-body radiation theory. A tungsten lamp calibrated the measurement accuracy of the temperature mapping system, and the fitting relationship between the temperatures and the gray values of the high-speed images was derived to obtain the conversion coefficient. The test results of mechanical properties showed that with the increase of titanium fiber content, the elastic modulus, yield strength and compressive strength of Al/PTFE annular reactive materials under quasi-static compression, as well as the yield strength and compressive strength under high-speed impact, all exhibited an initial increase, which were followed by a decrease, reaching the maximum values at 3% content. The experimental results of explosion performance showed that short-cut titanium fibers could significantly enhance the explosion performance of Al/PTFE-RDX composite charges. When the content of short-cut titanium fibers was 3%, the peak overpressure of the explosion shock wave, its positive phase duration and positive impulse were 37.68 kPa, 695.34 µs and 12.34 Pa·s, respectively. With 5% content of short-cut titanium fibers, the afterburning effect was the most significant. The maximum values of the explosion quasi-static pressure, average fireball temperature and fireball duration reached 70.50 kPa,
2026, 46(4): 043101.
doi: 10.11883/bzycj-2024-0461
Abstract:
To enhance the anti-impact protective performance of armor systems and address the demands of lightweight armored vehicles and military equipment, a systematic study was conducted on the ballistic resistance of a silicon carbide (SiC) ceramic/novel TWIP (twinning-induced plasticity) steel composite structure. Samples of the SiC ceramic/TWIP steel composite and monolithic TWIP steel were fabricated for comparative analysis. Single-stage light gas gun plate impact experiments were performed at a flyer impact velocity of 500 m/s to obtain free-surface velocity profiles of both materials under high-velocity loading. The spall strength and strain rate sensitivity of the composite and monolithic steel were calculated from these profiles and statistically compared. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were employed to characterize the microstructural evolution and damage mechanisms, including microvoid nucleation, coalescence, and primary crack propagation, in the impacted samples. Numerical simulations were implemented using LS-DYNA, where the TWIP steel was modeled with the Johnson-Cook (J-C) constitutive equation, and a particle-based method was adopted to simulate the brittle ceramic phase. The simulations were extended to investigate spallation behavior at varying impact velocities and to evaluate the influence of different steel properties on composite performance. Experimental results demonstrate that the composite exhibits 22.76% and 7.09% enhancements in spall strength and strain rate sensitivity, respectively, compared to monolithic TWIP steel. Microstructural analysis reveals that both materials undergo ductile fracture characterized by microvoid coalescence; however, the composite shows significantly weaker spall damage, confirming its superior impact resistance. The numerical model achieves excellent agreement with experimental data, validating its predictive accuracy. Stress distribution analysis during the impact process identifies a critical crack-initiation velocity of approximately 225 m/s. Furthermore, the influence of steel properties on the anti-impact performance of the composite structure was analyzed, demonstrating that the novel TWIP steel exhibits superior performance.
To enhance the anti-impact protective performance of armor systems and address the demands of lightweight armored vehicles and military equipment, a systematic study was conducted on the ballistic resistance of a silicon carbide (SiC) ceramic/novel TWIP (twinning-induced plasticity) steel composite structure. Samples of the SiC ceramic/TWIP steel composite and monolithic TWIP steel were fabricated for comparative analysis. Single-stage light gas gun plate impact experiments were performed at a flyer impact velocity of 500 m/s to obtain free-surface velocity profiles of both materials under high-velocity loading. The spall strength and strain rate sensitivity of the composite and monolithic steel were calculated from these profiles and statistically compared. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were employed to characterize the microstructural evolution and damage mechanisms, including microvoid nucleation, coalescence, and primary crack propagation, in the impacted samples. Numerical simulations were implemented using LS-DYNA, where the TWIP steel was modeled with the Johnson-Cook (J-C) constitutive equation, and a particle-based method was adopted to simulate the brittle ceramic phase. The simulations were extended to investigate spallation behavior at varying impact velocities and to evaluate the influence of different steel properties on composite performance. Experimental results demonstrate that the composite exhibits 22.76% and 7.09% enhancements in spall strength and strain rate sensitivity, respectively, compared to monolithic TWIP steel. Microstructural analysis reveals that both materials undergo ductile fracture characterized by microvoid coalescence; however, the composite shows significantly weaker spall damage, confirming its superior impact resistance. The numerical model achieves excellent agreement with experimental data, validating its predictive accuracy. Stress distribution analysis during the impact process identifies a critical crack-initiation velocity of approximately 225 m/s. Furthermore, the influence of steel properties on the anti-impact performance of the composite structure was analyzed, demonstrating that the novel TWIP steel exhibits superior performance.
2026, 46(4): 043301.
doi: 10.11883/bzycj-2024-0440
Abstract:
To study the effects of parameters in smoothed particle hydrodynamics (SPH) simulations of hypervelocity impacts on basalt, numerical analysis and validation were performed using the Riemann-SPH method based on ground-based impact tests. By adjusting various simulation parameters, the influence of parameters on the simulation can be obtained. Results show that both algorithmic and material parameters significantly influence the simulation, with coupling between strength and damage models. Applying the artificial stress method helps suppress tensile instability in solid impacts. Using the Wendland C2 kernel with a target of 2.5 particles within the smoothing length optimizes both accuracy and efficiency, and variable-resolution particle distribution improves performance by over 20 times. In simulations, the impactor may undergo a phase transition, and different model and parameter combinations can yield similar responses. It is recommended to employ the Lundborg strength model and the Benz-Asphaug stochastic damage model, which better represent the mechanical behavior of rocky materials, and to account for phase transitions. Parameter search should be constrained by reasonably known values to avoid large errors or non-uniqueness. With reasonable parameters, simulated crater size and momentum transfer factor match experiments within 10%–20% error. These strategies support SPH applications in asteroid defense and parameter selection.
To study the effects of parameters in smoothed particle hydrodynamics (SPH) simulations of hypervelocity impacts on basalt, numerical analysis and validation were performed using the Riemann-SPH method based on ground-based impact tests. By adjusting various simulation parameters, the influence of parameters on the simulation can be obtained. Results show that both algorithmic and material parameters significantly influence the simulation, with coupling between strength and damage models. Applying the artificial stress method helps suppress tensile instability in solid impacts. Using the Wendland C2 kernel with a target of 2.5 particles within the smoothing length optimizes both accuracy and efficiency, and variable-resolution particle distribution improves performance by over 20 times. In simulations, the impactor may undergo a phase transition, and different model and parameter combinations can yield similar responses. It is recommended to employ the Lundborg strength model and the Benz-Asphaug stochastic damage model, which better represent the mechanical behavior of rocky materials, and to account for phase transitions. Parameter search should be constrained by reasonably known values to avoid large errors or non-uniqueness. With reasonable parameters, simulated crater size and momentum transfer factor match experiments within 10%–20% error. These strategies support SPH applications in asteroid defense and parameter selection.
2026, 46(4): 044201.
doi: 10.11883/bzycj-2024-0503
Abstract:
To meet the need for accurate and rapid prediction of overpressure generated by an explosion, a graph neural network (GNN)-based artificial intelligence model was proposed in this paper for predicting the spatial and temporal distribution of the blast overpressure. The model relies on high-fidelity training data generated through computational fluid dynamics (CFD) simulations using the open-source software blastFoam, and the numerical simulations was validated against experimental data from existing literature. In the simulations, the computational domain was discretized using hexahedral meshes, and key physical parameters—including pressure, velocity, and node type—were extracted and converted into structured graph data via mesh remapping technology. This approach enabled the construction of two specialized datasets: a free-field explosion dataset and a confined explosion dataset for TNT, which serve as the foundation for training and evaluating the GNN model. The GNN model contains three modules: an encoder, a processor and a decoder. The predicted results of the pressure field can be output through inputting the standard graph format data. The GNN model was trained using the two training datasets for the two specialized scenarios, separately. The root mean square error (
To meet the need for accurate and rapid prediction of overpressure generated by an explosion, a graph neural network (GNN)-based artificial intelligence model was proposed in this paper for predicting the spatial and temporal distribution of the blast overpressure. The model relies on high-fidelity training data generated through computational fluid dynamics (CFD) simulations using the open-source software blastFoam, and the numerical simulations was validated against experimental data from existing literature. In the simulations, the computational domain was discretized using hexahedral meshes, and key physical parameters—including pressure, velocity, and node type—were extracted and converted into structured graph data via mesh remapping technology. This approach enabled the construction of two specialized datasets: a free-field explosion dataset and a confined explosion dataset for TNT, which serve as the foundation for training and evaluating the GNN model. The GNN model contains three modules: an encoder, a processor and a decoder. The predicted results of the pressure field can be output through inputting the standard graph format data. The GNN model was trained using the two training datasets for the two specialized scenarios, separately. The root mean square error (
2026, 46(4): 045101.
doi: 10.11883/bzycj-2025-0072
Abstract:
To improve the explosion resistance of the blast wall, it is proposed to combine the negative Poisson’s ratio structure with ultra-high toughness cementitious composites (UHTCC), Through a combination of the explosion experiment and numerical simulation, the anti-explosive property of negative Poisson’s ratio slabs has been studied, to prove the superiority of the anti-explosive properties of the negative Poisson’s ratio UHTCC slabs. Firstly, a negative Poisson’s ratio structural slab was constructed using concrete 3D printing technology and optimizing the printing path, which verified the constructability of the negative Poisson’s ratio structural slab, and the negative Poisson’s slab was subjected to a contact explosion test. Using LS-DYNA software, a finite element model of fluid-solid coupling was established according to the explosion test conditions, and the finite element model was verified by comparison of the slab damage pattern in the contact explosion test and the simulation. On this basis, the verified finite element model was used to simulate and analyze the effects of different materials (concrete and UHTCC), structures (negative Poisson's ratio structure, positive Poisson’s ratio structure, and solid structure), cell concave angles, and solid layer thickness ratios on the anti-explosive properties of negative Poisson’s structural slabs under contact explosion. By comparing the slab damage patterns and the ability of energy absorption, which was determined by the value of the air overpressure behind the slabs, the design of a negative Poisson’s ratio structure target plate with the best anti-explosive properties was obtained. The results show that: (1) due to the high toughness, the explosion resistance of UHTCC slabs is significantly better than that of concrete slabs. The UHTCC slabs all remained intact, and the concrete target slabs were all penetrated. (2) The negative Poisson’s ratio slab has the best ability to absorb energy among the three kinds of structures, while the solid slab is better at maintaining the structural integrity. (3) When the negative Poisson’s ratio of the cell concave angle is 61°, the structure has optimal explosion resistance, and both smaller and larger angles reduce the explosion resistance of the structure. (4) When the thickness of the negative Poisson’s ratio structure is too large as a proportion of the total thickness, the slab is severely damaged. Increasing the solid layer thickness of the backburst surface of the slab, or simultaneously increasing the solid layer thickness of the explosion-facing and backburst surfaces, is conducive to weakening the blast shock wave and improving structural integrity. This study confirmed the superiority of the explosion resistance of negative Poisson’s ratio UHTCC slab, and provides a theoretical basis for the design of blast walls based on negative Poisson’s ratio structure.
To improve the explosion resistance of the blast wall, it is proposed to combine the negative Poisson’s ratio structure with ultra-high toughness cementitious composites (UHTCC), Through a combination of the explosion experiment and numerical simulation, the anti-explosive property of negative Poisson’s ratio slabs has been studied, to prove the superiority of the anti-explosive properties of the negative Poisson’s ratio UHTCC slabs. Firstly, a negative Poisson’s ratio structural slab was constructed using concrete 3D printing technology and optimizing the printing path, which verified the constructability of the negative Poisson’s ratio structural slab, and the negative Poisson’s slab was subjected to a contact explosion test. Using LS-DYNA software, a finite element model of fluid-solid coupling was established according to the explosion test conditions, and the finite element model was verified by comparison of the slab damage pattern in the contact explosion test and the simulation. On this basis, the verified finite element model was used to simulate and analyze the effects of different materials (concrete and UHTCC), structures (negative Poisson's ratio structure, positive Poisson’s ratio structure, and solid structure), cell concave angles, and solid layer thickness ratios on the anti-explosive properties of negative Poisson’s structural slabs under contact explosion. By comparing the slab damage patterns and the ability of energy absorption, which was determined by the value of the air overpressure behind the slabs, the design of a negative Poisson’s ratio structure target plate with the best anti-explosive properties was obtained. The results show that: (1) due to the high toughness, the explosion resistance of UHTCC slabs is significantly better than that of concrete slabs. The UHTCC slabs all remained intact, and the concrete target slabs were all penetrated. (2) The negative Poisson’s ratio slab has the best ability to absorb energy among the three kinds of structures, while the solid slab is better at maintaining the structural integrity. (3) When the negative Poisson’s ratio of the cell concave angle is 61°, the structure has optimal explosion resistance, and both smaller and larger angles reduce the explosion resistance of the structure. (4) When the thickness of the negative Poisson’s ratio structure is too large as a proportion of the total thickness, the slab is severely damaged. Increasing the solid layer thickness of the backburst surface of the slab, or simultaneously increasing the solid layer thickness of the explosion-facing and backburst surfaces, is conducive to weakening the blast shock wave and improving structural integrity. This study confirmed the superiority of the explosion resistance of negative Poisson’s ratio UHTCC slab, and provides a theoretical basis for the design of blast walls based on negative Poisson’s ratio structure.
2026, 46(4): 045102.
doi: 10.11883/bzycj-2024-0441
Abstract:
To investigate the dynamic response and damage assessment of reinforced concrete (RC) piers under lateral impact loads, high-fidelity finite element models of RC piers under lateral impact were developed using the explicit dynamic analysis software LS-DYNA. The finite element models were calibrated by using the test data from lateral impact tests of RC piers. The influences of impact velocity, impact mass, impact location, and axial compression ratio on the dynamic response and damage evolution of RC piers were investigated. Based on the residual load-carrying capacity and residual displacement, the indicators of relative residual deformation and relative residual load-carrying capacity were proposed. The corresponding values of relative residual load-carrying capacity for slight damage, moderate damage, severe damage, and collapse were determined. Moreover, a mapping relationship between relative residual deformation and relative residual load-carrying capacity of RC piers with various axial compression ratios and impacted at different impact locations was established. A damage assessment method for RC piers under impact load was proposed based on the mapping relationship. The research results indicate that RC piers subjected to impact at the mid-column position primarily exhibit flexural-shear failure, whereas local shear failure predominantly occurs when the impact is applied close to the column base. As the impact velocity and mass increase, the residual displacement increases significantly, while the residual bearing capacity decreases. The axial compression ratio within the range from 0.2 to 0.4 has a limited effect on the peak impact force and peak displacement but significantly affects the residual displacement when the impact occurs at the mid-column. When the mid-column position and the column base position are subjected to lateral impact, there exists an approximate linear relationship between relative residual deformation and relative residual load-carrying capacity, such that the greater the relative residual deformation, the smaller the relative residual load-carrying capacity. Under conditions of equal relative residual deformation, the relative residual load-carrying capacity of the base-column impact is lower than that of the mid-column impact, with a more significant decrease in load-carrying capacity.
To investigate the dynamic response and damage assessment of reinforced concrete (RC) piers under lateral impact loads, high-fidelity finite element models of RC piers under lateral impact were developed using the explicit dynamic analysis software LS-DYNA. The finite element models were calibrated by using the test data from lateral impact tests of RC piers. The influences of impact velocity, impact mass, impact location, and axial compression ratio on the dynamic response and damage evolution of RC piers were investigated. Based on the residual load-carrying capacity and residual displacement, the indicators of relative residual deformation and relative residual load-carrying capacity were proposed. The corresponding values of relative residual load-carrying capacity for slight damage, moderate damage, severe damage, and collapse were determined. Moreover, a mapping relationship between relative residual deformation and relative residual load-carrying capacity of RC piers with various axial compression ratios and impacted at different impact locations was established. A damage assessment method for RC piers under impact load was proposed based on the mapping relationship. The research results indicate that RC piers subjected to impact at the mid-column position primarily exhibit flexural-shear failure, whereas local shear failure predominantly occurs when the impact is applied close to the column base. As the impact velocity and mass increase, the residual displacement increases significantly, while the residual bearing capacity decreases. The axial compression ratio within the range from 0.2 to 0.4 has a limited effect on the peak impact force and peak displacement but significantly affects the residual displacement when the impact occurs at the mid-column. When the mid-column position and the column base position are subjected to lateral impact, there exists an approximate linear relationship between relative residual deformation and relative residual load-carrying capacity, such that the greater the relative residual deformation, the smaller the relative residual load-carrying capacity. Under conditions of equal relative residual deformation, the relative residual load-carrying capacity of the base-column impact is lower than that of the mid-column impact, with a more significant decrease in load-carrying capacity.
2026, 46(4): 045103.
doi: 10.11883/bzycj-2024-0474
Abstract:
To investigate the protective effect of ground concrete cushion layers on buried pipelines used for water transmission, field rockfall impact tests were conducted by pre-burying multi-section bell-and-spigot concrete pipelines and casting in-situ concrete cushions on the ground. Combined with the DH8302 dynamic strain testing system, the spatial distribution characteristics of dynamic strain in the pipeline body and the variation law of earth pressure at the bell-and-spigot joints were analyzed. The LS-DYNA numerical simulation software was used to establish a detailed model of the rockfall impact test, and the reliability of the numerical model was verified by comparing simulation results with test results. By increasing the impact energy of rockfalls, the failure characteristics of buried bell-and-spigot concrete pipelines were studied. The influence mechanism of concrete cushion parameters (thickness and strength) on the protective effect was further analyzed by varying these parameters. The results show that under the condition of a burial depth of 2 m, unstable crack propagation in the pipeline body is more likely to cause leakage of bell-and-spigot concrete pipelines under rockfall impact. The peak tensile strain in the pipeline body decreases nonlinearly with the increase of cushion thickness and strength. The cushion thickness must exceed a critical value (15 cm) to significantly dissipate energy, and there is an optimal strength range (C30−C35). Excessive strength enhancement will reduce protective efficiency. Cushion thickness accounts for 74% of the protective effect contribution, indicating that the design principle of “geometry prior to material” should be followed. It is recommended to use a concrete cushion with a strength of C30−C35 and a thickness large than 0.2 m, which can significantly reduce the risk of pipeline impact damage and provide a quantitative design basis for pipeline protection in mountainous areas.
To investigate the protective effect of ground concrete cushion layers on buried pipelines used for water transmission, field rockfall impact tests were conducted by pre-burying multi-section bell-and-spigot concrete pipelines and casting in-situ concrete cushions on the ground. Combined with the DH8302 dynamic strain testing system, the spatial distribution characteristics of dynamic strain in the pipeline body and the variation law of earth pressure at the bell-and-spigot joints were analyzed. The LS-DYNA numerical simulation software was used to establish a detailed model of the rockfall impact test, and the reliability of the numerical model was verified by comparing simulation results with test results. By increasing the impact energy of rockfalls, the failure characteristics of buried bell-and-spigot concrete pipelines were studied. The influence mechanism of concrete cushion parameters (thickness and strength) on the protective effect was further analyzed by varying these parameters. The results show that under the condition of a burial depth of 2 m, unstable crack propagation in the pipeline body is more likely to cause leakage of bell-and-spigot concrete pipelines under rockfall impact. The peak tensile strain in the pipeline body decreases nonlinearly with the increase of cushion thickness and strength. The cushion thickness must exceed a critical value (15 cm) to significantly dissipate energy, and there is an optimal strength range (C30−C35). Excessive strength enhancement will reduce protective efficiency. Cushion thickness accounts for 74% of the protective effect contribution, indicating that the design principle of “geometry prior to material” should be followed. It is recommended to use a concrete cushion with a strength of C30−C35 and a thickness large than 0.2 m, which can significantly reduce the risk of pipeline impact damage and provide a quantitative design basis for pipeline protection in mountainous areas.
2026, 46(4): 045104.
doi: 10.11883/bzycj-2025-0060
Abstract:
Reinforced concrete (RC) shed tunnel serves as an effective in-situ solution for rockfall protection along mountainous highways and railways. Using the commercial software LS-DYNA, refined numerical simulations were conducted to investigate the damage and failure assessment of a prototype framed T-beam type RC shed tunnel under rockfall impact. The simulations considered scenarios both with and without cushions, including 600 mm and1200 mm sand cushions, as well as 1200 mm sand-expandable polyethylene (EPE) composite cushion. Firstly, a refined finite element model of a prototype framed T-beam type RC shed tunnel located on the Shanghai-Kunming railway under rockfall impact was developed, of which the rockfall masses ranging from 1 t to 30 t and impact velocities ranging from 10 m/s to 57 m/s. Secondly, by comparing with the results of existing impact tests on bare RC slab, as well as RC slabs with sand and EPE cushions, the accuracy and reliability of the adopted material constitutive model, mesh size, contact algorithm, and corresponding parameters of the finite element model were validated. Furthermore, the damage patterns and dynamic responses of the prototype shed tunnel without cushion, with sand cushion, and with sand-EPE composite cushion were compared and analyzed. Finally, taking the maximum penetration depth of the rockfall reaching the total thickness of the roof slab and cushion as the failure threshold of the shed tunnel, the corresponding relationship between the rockfall mass and the critical impact velocity was established, which enabled rapid assessment of protective performance of shed tunnel. It indicates that: (1) Under the impact of a 15 t rockfall at velocities of 10 m/s and 25 m/s, the damage to the shed tunnel without cushion is primarily concentrated in the impact area of the roof slab. On average, the use of sand cushion and sand-EPE composite cushion reduces the peak impact force by 92.8% and 91.6%, respectively; (2) At impact velocity of 10 m/s, the sand-EPE composite cushion exhibits superior buffering and energy dissipation performance compared to the sand cushion. However, with impact velocity increasing to 25 m/s, the EPE in the composite cushion is rapidly compacted, leading to a diminished protective effect. In this scenario, the impact force and energy transferred to the roof slab with the composite cushion are 89.3% and 37.8% higher than those with the sand cushion, respectively; (3) The critical impact velocity of rockfall corresponding to the failure damage of the shed tunnel follows an exponential decay trend as the rockfall mass increases. The application of cushions can increase the critical impact velocity by 52% to 155%, significantly improving the protective performance of the shed tunnel.
Reinforced concrete (RC) shed tunnel serves as an effective in-situ solution for rockfall protection along mountainous highways and railways. Using the commercial software LS-DYNA, refined numerical simulations were conducted to investigate the damage and failure assessment of a prototype framed T-beam type RC shed tunnel under rockfall impact. The simulations considered scenarios both with and without cushions, including 600 mm and
2026, 46(4): 045201.
doi: 10.11883/bzycj-2025-0290
Abstract:
Hypergravity centrifuge model testing serves as an effective method for simulating prototype explosion effects, whose successful application relies on soil simulants capable of replicating the dynamic response of in-situ soil. To address the challenges of particle size effects and material similarity in centrifuge modeling of explosions in sandy gravel, this study aims to establish a systematic methodology for the preparation and validation of such simulants. Through theoretical analysis, the soil key parameters governing ground shock effects under explosions were identified as density and wave velocity (wave impedance), which are fundamentally controlled by the soil’s gradation characteristics. Based on this premise, twelve types of simulants with varying maximum particle sizes were systematically prepared using four scaling methods: the removal method, equal quantity replacement method, similar gradation method, and hybrid method. Through void ratio tests and bender element testing under effective confining pressure, quantitative relationships were revealed between the extreme void ratios of sandy gravel and its fines content and mean particle size. Based on this, an empirical predictive model for the small strain elastic modulus was established. Comparison of the model-predicted wave velocities with in-situ measured data indicates that the coefficient of uniformity, fines content, and mean particle size are the key controlling indices for achieving dynamic similarity in sandy gravel under explosion loading. Among these, the simulant prepared by the equal quantity replacement method, with a maximum particle size of 10 mm, demonstrated the closest equivalence to the in-situ soil in terms of the aforementioned indices. Hypergravity centrifuge explosion tests using this equivalent simulant further verified that the attenuation law of normalized peak accelerations within the source plane corresponds highly consistently with the in-situ data. This research confirms that by controlling key gradation indices and employing the equal quantity replacement method, it is possible to successfully prepare simulants that are equivalent to in-situ sandy gravel in their dynamic response to explosions. This provides a practical and effective technical pathway for centrifuge model testing in related fields.
Hypergravity centrifuge model testing serves as an effective method for simulating prototype explosion effects, whose successful application relies on soil simulants capable of replicating the dynamic response of in-situ soil. To address the challenges of particle size effects and material similarity in centrifuge modeling of explosions in sandy gravel, this study aims to establish a systematic methodology for the preparation and validation of such simulants. Through theoretical analysis, the soil key parameters governing ground shock effects under explosions were identified as density and wave velocity (wave impedance), which are fundamentally controlled by the soil’s gradation characteristics. Based on this premise, twelve types of simulants with varying maximum particle sizes were systematically prepared using four scaling methods: the removal method, equal quantity replacement method, similar gradation method, and hybrid method. Through void ratio tests and bender element testing under effective confining pressure, quantitative relationships were revealed between the extreme void ratios of sandy gravel and its fines content and mean particle size. Based on this, an empirical predictive model for the small strain elastic modulus was established. Comparison of the model-predicted wave velocities with in-situ measured data indicates that the coefficient of uniformity, fines content, and mean particle size are the key controlling indices for achieving dynamic similarity in sandy gravel under explosion loading. Among these, the simulant prepared by the equal quantity replacement method, with a maximum particle size of 10 mm, demonstrated the closest equivalence to the in-situ soil in terms of the aforementioned indices. Hypergravity centrifuge explosion tests using this equivalent simulant further verified that the attenuation law of normalized peak accelerations within the source plane corresponds highly consistently with the in-situ data. This research confirms that by controlling key gradation indices and employing the equal quantity replacement method, it is possible to successfully prepare simulants that are equivalent to in-situ sandy gravel in their dynamic response to explosions. This provides a practical and effective technical pathway for centrifuge model testing in related fields.
Founded in 1981 monthly
Sponsored byChinese Society of Theoretical and Applied Mechanics
Institude of Fluid Physics, CAEP
Editor-in-ChiefJianheng Zhao
