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, Available online , doi: 10.11883/bzycj-2025-0273
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Sodium-ion batteries (SIBs) have emerged as a promising candidate for energy storage applications owing to their material abundance and cost-effectiveness; however, safety issues under mechanical abuse conditions remain insufficiently understood. This study systematically investigates the failure mechanisms of commercial18650 sodium-ion batteries subjected to radial compression by integrating experimental and numerical approaches. Experiments were conducted using an electronic universal testing machine to characterize the mechanical–electrical–thermal responses at different compression speeds and states of charge (SOC), with synchronous measurements of load, voltage, and temperature. A homogenized finite element model was established to simulate the dynamic crushing behavior at impact velocities ranging from 1 to 35 m/s. The failure mechanisms were interpreted based on stress wave theory, and the failure criteria were calibrated using the experimental results. The results indicate that under quasi-static loading, the battery exhibits a four-stage deformation process, in which the peak load coincides with the onset of failure. With increasing compression velocity, both the peak load and the failure displacement increase, while the temperature rise of batteries at 0% SOC is only weakly affected. In contrast, higher SOC significantly intensifies the temperature rise and advances the occurrence of failure. Under dynamic impact conditions, the failure displacement decreases with increasing impact velocity and shows a pronounced reduction beyond 20 m/s, whereas the load–displacement curve exhibits a distinct plateau at high velocities. The crack initiation location displays a strong dependence on impact velocity: it originates in the central region at low velocities (<15 m/s), shifts to the bottom at approximately 20 m/s, and moves to the impact end when the velocity exceeds 30 m/s. This transition is mainly governed by the propagation, reflection, and superposition of stress waves. Overall, the results indicate that failure of sodium-ion batteries is triggered by structural instability leading to internal short circuits. The SOC primarily controls the thermal response under low-speed compression, whereas stress wave effects dominate the failure behavior at high impact velocities. The proposed model demonstrates good predictive capability for the macroscopic mechanical response and provides valuable insights for the safety design of sodium-ion batteries.
Sodium-ion batteries (SIBs) have emerged as a promising candidate for energy storage applications owing to their material abundance and cost-effectiveness; however, safety issues under mechanical abuse conditions remain insufficiently understood. This study systematically investigates the failure mechanisms of commercial
, Available online , doi: 10.11883/bzycj-2025-0102
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-2026-0018
Abstract:
To investigate the failure and damage modes of shallow-buried reinforced concrete (RC) oil depots under coupled shock wave and oil-gas explosion, a scaled model of a shallow-buried reinforced concrete oil depot was designed. The influence mechanisms of the oil depot structure, oil type and content, and explosion source location on the damage and failure modes of the concrete oil depot were studied. The results show that the blast shock wave acting on the oil depot cover causes punching-perforation failure on the blast-facing side and spalling failure on the blast-opposite side. The damage of the cover containing 50% diesel is more severe than that at 100% diesel content. For 100% diesel with the cover installed, two peaks appear during the overpressure rise stage of the shock wave. For 50% diesel with the cover installed, due to interface reflections in internal cavity, three peaks appear during the overpressure rise stage compared with the full-oil case, and the positive pressure duration of the shock wave is significantly prolonged. When the explosion is initiated at the bottom of the depot, both the cover and the entire depot structure are severely damaged. Reflected wave superposition at the corners leads to significant shear cracking at the edges of the main structure. Compared with the explosion of 50% diesel, the explosion of 50% gasoline produces a larger fireball and a longer combustion duration, but does not cause damage to the main structure of the oil depot.
To investigate the failure and damage modes of shallow-buried reinforced concrete (RC) oil depots under coupled shock wave and oil-gas explosion, a scaled model of a shallow-buried reinforced concrete oil depot was designed. The influence mechanisms of the oil depot structure, oil type and content, and explosion source location on the damage and failure modes of the concrete oil depot were studied. The results show that the blast shock wave acting on the oil depot cover causes punching-perforation failure on the blast-facing side and spalling failure on the blast-opposite side. The damage of the cover containing 50% diesel is more severe than that at 100% diesel content. For 100% diesel with the cover installed, two peaks appear during the overpressure rise stage of the shock wave. For 50% diesel with the cover installed, due to interface reflections in internal cavity, three peaks appear during the overpressure rise stage compared with the full-oil case, and the positive pressure duration of the shock wave is significantly prolonged. When the explosion is initiated at the bottom of the depot, both the cover and the entire depot structure are severely damaged. Reflected wave superposition at the corners leads to significant shear cracking at the edges of the main structure. Compared with the explosion of 50% diesel, the explosion of 50% gasoline produces a larger fireball and a longer combustion duration, but does not cause damage to the main structure of the oil depot.
, Available online , doi: 10.11883/bzycj-2025-0229
Abstract:
In view of the rockfall impact threat faced by buried pipelines in high-risk areas of geological disasters, this study systematically investigated the dynamic response characteristics of buried pipelines through a combination of scale model test and numerical simulation to further explore its dynamic response characteristics and dig deep into their intrinsic mechanisms. A test model with a geometric scale ratio of 1:10 was constructed. Meanwhile, a drop hammer impact test device combined with LS-DYNA finite element analysis was used. Based on these above, the influence laws of pipeline burial depth, wall thickness, impact parameters, pipeline 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. Under 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, pipeline internal pressure, pipeline diameter, ,soil elastic modulus,, and pipe-soil friction coefficient,. 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 response of 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, this study systematically investigated the dynamic response characteristics of buried pipelines through a combination of scale model test and numerical simulation to further explore its dynamic response characteristics and dig deep into their intrinsic mechanisms. A test model with a geometric scale ratio of 1:10 was constructed. Meanwhile, a drop hammer impact test device combined with LS-DYNA finite element analysis was used. Based on these above, the influence laws of pipeline burial depth, wall thickness, impact parameters, pipeline 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. Under 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, pipeline internal pressure, pipeline diameter, ,soil elastic modulus,, and pipe-soil friction coefficient,. 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 response of buried pipelines.The research results can provide a basis for the safety design of buried pipelines in high-risk areas.
Experimental study on damage effects of RC frame structures with masonry walls under explosion loads
, Available online , doi: 10.11883/bzycj-2025-0378
Abstract:
Reinforced concrete (RC) frame structures are the most widely adopted structural form in civil infrastructure, government facilities, commercial buildings and critical public premises, undertaking irreplaceable roles in normal political and economic operations. However, with the growing frequency of terrorist explosion attacks, accidental industrial and gas explosion incidents, alongside the complex and volatile global security environment, RC frame structures have become both high-priority attack targets and the critical line of defense for personnel protection. To investigate the damage effects of multiple explosion scenarios on RC frame structures, a full-scale two-story RC frame structure with infill masonry walls, designed in line with current building design codes, was constructed. A series of field explosion tests, including external and internal explosion scenarios with TNT equivalents of 11.573 kg and 20 kg, were conducted on this structure. 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 remains limited. In contrast, under internal explosion, the floor slabs and masonry walls show global shear failure, with more severe damage compared to the RC columns and beams. In addition to the shock wave loading, the explosive ejection of wall and slab fragments from the detonation room is the primary cause of damage to the masonry walls and slabs along the shock wave propagation path. Finally, based on damage assessment criteria, the damage levels of components, rooms, and the RC structure for each test were determined. The damage severity and affected range of the RC structure under internal explosion are significantly greater than those under external explosion with the same equivalent.
Reinforced concrete (RC) frame structures are the most widely adopted structural form in civil infrastructure, government facilities, commercial buildings and critical public premises, undertaking irreplaceable roles in normal political and economic operations. However, with the growing frequency of terrorist explosion attacks, accidental industrial and gas explosion incidents, alongside the complex and volatile global security environment, RC frame structures have become both high-priority attack targets and the critical line of defense for personnel protection. To investigate the damage effects of multiple explosion scenarios on RC frame structures, a full-scale two-story RC frame structure with infill masonry walls, designed in line with current building design codes, was constructed. A series of field explosion tests, including external and internal explosion scenarios with TNT equivalents of 11.573 kg and 20 kg, were conducted on this structure. 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 remains limited. In contrast, under internal explosion, the floor slabs and masonry walls show global shear failure, with more severe damage compared to the RC columns and beams. In addition to the shock wave loading, the explosive ejection of wall and slab fragments from the detonation room is the primary cause of damage to the masonry walls and slabs along the shock wave propagation path. Finally, based on damage assessment criteria, the damage levels of components, rooms, and the RC structure for each test were determined. The damage severity and affected range of the RC structure under internal explosion are significantly greater than those under external explosion with the same equivalent.
, 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.
Dynamic response and failure mechanism for urban continuous beam bridges under far-field blast loads
, Available online , doi: 10.11883/bzycj-2025-0170
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
