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2026, 46(6): 061401.
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 400 m/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
2026, 46(6): 061411.
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.
2026, 46(6): 061412.
doi: 10.11883/bzycj-2026-0010
Abstract:
Steel truss bridges are typically composed of a large number of slender members and represent one of the primary structural forms of railway bridges, facing the threat of overall collapse caused by explosions from unmanned aerial vehicles. Numerical simulation analysis was conducted on the failure mode and residual bearing capacity degradation law of railway steel truss bridges subjected to contact explosions. Firstly, the reliability of the numerical simulation method was verified by existing explosion tests on stiffened steel plates and steel box arches, as well as the residual bearing capacity of I-shaped steel column after explosion. Subsequently, mesh sensitivity analyses were performed for the damage and failure of upper chord member under contact explosions and for the residual bearing capacity of the entire bridge. Then, the most critical member of the bridge was identified by evaluating its residual performance under 100 kg TNT equivalent explosions at different locations. Furthermore, the variation of the residual bearing capacity with explosion yield was investigated. Finally, the evolution mechanism of damage and failure of the entire bridge under multi-point explosions was discussed. The results show as follows. (1) Under contact explosions, steel truss girder bridges are mainly characterized by localized member damage. For an explosive charge of 100 kg, the overall bridge bearing capacity decreases by 29.8% and 18.0% when the explosion occurs on the side and top surfaces of the upper chord member. The side explosion on the upper chord is the most unfavorable scenario. (2) As the charge weight for side explosion on upper chord increases from 25 kg to 150 kg, the reduction in residual bearing capacity of the entire bridge increases from 8.8% to 33.4%. Taking the ratio of bearing capacity loss to the ultimate bearing capacity of intact bridge as the damage index, a quantitative relationship between the entire bridge damage index and the explosive charge weight is established. (3) Under multi-point explosion scenarios, the damage factor increases to 0.452, indicating the structural redundancy and residual bearing capacity are significantly reduced compared with those under single-point explosion conditions.
Steel truss bridges are typically composed of a large number of slender members and represent one of the primary structural forms of railway bridges, facing the threat of overall collapse caused by explosions from unmanned aerial vehicles. Numerical simulation analysis was conducted on the failure mode and residual bearing capacity degradation law of railway steel truss bridges subjected to contact explosions. Firstly, the reliability of the numerical simulation method was verified by existing explosion tests on stiffened steel plates and steel box arches, as well as the residual bearing capacity of I-shaped steel column after explosion. Subsequently, mesh sensitivity analyses were performed for the damage and failure of upper chord member under contact explosions and for the residual bearing capacity of the entire bridge. Then, the most critical member of the bridge was identified by evaluating its residual performance under 100 kg TNT equivalent explosions at different locations. Furthermore, the variation of the residual bearing capacity with explosion yield was investigated. Finally, the evolution mechanism of damage and failure of the entire bridge under multi-point explosions was discussed. The results show as follows. (1) Under contact explosions, steel truss girder bridges are mainly characterized by localized member damage. For an explosive charge of 100 kg, the overall bridge bearing capacity decreases by 29.8% and 18.0% when the explosion occurs on the side and top surfaces of the upper chord member. The side explosion on the upper chord is the most unfavorable scenario. (2) As the charge weight for side explosion on upper chord increases from 25 kg to 150 kg, the reduction in residual bearing capacity of the entire bridge increases from 8.8% to 33.4%. Taking the ratio of bearing capacity loss to the ultimate bearing capacity of intact bridge as the damage index, a quantitative relationship between the entire bridge damage index and the explosive charge weight is established. (3) Under multi-point explosion scenarios, the damage factor increases to 0.452, indicating the structural redundancy and residual bearing capacity are significantly reduced compared with those under single-point explosion conditions.
2026, 46(6): 061413.
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.
2026, 46(6): 061414.
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.
2026, 46(6): 061421.
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 (SHPB) 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 (SHPB) 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.
2026, 46(6): 061422.
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
2026, 46(6): 061423.
doi: 10.11883/bzycj-2025-0399
Abstract:
Crack propagation in rock blasting exhibits strong randomness, making directional fracture control difficult and leading to low energy utilization efficiency, which remains a key issue in controlled blasting. To improve the energy utilization efficiency in directional fracturing, a composite shaped charge liner with a “slotting + shaped-charge” structure was designed. A combination of dynamic caustics experiments and numerical simulations was employed to investigate the effects of liner opening angle on crack propagation and energy release. In the experimental study, dynamic caustics technique was used to capture the initiation and evolution of cracks under blasting loading, and key dynamic parameters such as crack propagation velocity and stress intensity factor were obtained from caustic patterns. Meanwhile, fractal dimension analysis was introduced to quantitatively characterize the complexity and directional distribution of blast-induced cracks. In the numerical study, a fluid-structure coupled model was established to simulate the blasting process, enabling further analysis of stress wave propagation, energy release behavior, and the formation and penetration characteristics of the shaped charge jet under different opening angles. The results show that the composite shaped charge liner significantly enhances crack propagation in the energy-focused direction while suppressing damage in non-focused directions. The shaped-charge effect first increases and then decreases with increasing opening angle. When the opening angle is 60°, the crack propagation length, propagation velocity, the ratio of fractal dimensions between focused and non-focused directions, and the dynamic stress intensity factor all reach their peak values, indicating the optimal directional fracturing performance. The energy release rate increases with the opening angle and reaches 746.05 N/m at 75°. Numerical simulations indicate that, at an opening angle of 60°, the formed metal jet exhibits the most coherent morphology and the highest jet-tip velocity, with the penetration depth and inlet aperture reaching 21.5 mm and 14.1 mm, respectively.
Crack propagation in rock blasting exhibits strong randomness, making directional fracture control difficult and leading to low energy utilization efficiency, which remains a key issue in controlled blasting. To improve the energy utilization efficiency in directional fracturing, a composite shaped charge liner with a “slotting + shaped-charge” structure was designed. A combination of dynamic caustics experiments and numerical simulations was employed to investigate the effects of liner opening angle on crack propagation and energy release. In the experimental study, dynamic caustics technique was used to capture the initiation and evolution of cracks under blasting loading, and key dynamic parameters such as crack propagation velocity and stress intensity factor were obtained from caustic patterns. Meanwhile, fractal dimension analysis was introduced to quantitatively characterize the complexity and directional distribution of blast-induced cracks. In the numerical study, a fluid-structure coupled model was established to simulate the blasting process, enabling further analysis of stress wave propagation, energy release behavior, and the formation and penetration characteristics of the shaped charge jet under different opening angles. The results show that the composite shaped charge liner significantly enhances crack propagation in the energy-focused direction while suppressing damage in non-focused directions. The shaped-charge effect first increases and then decreases with increasing opening angle. When the opening angle is 60°, the crack propagation length, propagation velocity, the ratio of fractal dimensions between focused and non-focused directions, and the dynamic stress intensity factor all reach their peak values, indicating the optimal directional fracturing performance. The energy release rate increases with the opening angle and reaches 746.05 N/m at 75°. Numerical simulations indicate that, at an opening angle of 60°, the formed metal jet exhibits the most coherent morphology and the highest jet-tip velocity, with the penetration depth and inlet aperture reaching 21.5 mm and 14.1 mm, respectively.
2026, 46(6): 061424.
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.
2026, 46(6): 061431.
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.
2026, 46(6): 061432.
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.
2026, 46(6): 061441.
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.
2026, 46(6): 061442.
doi: 10.11883/bzycj-2025-0388
Abstract:
To address the collision protection requirements in fields such as aeronautics and space, traffic transportation, and civil construction, a novel design method for the corrugated multi-cell gradient hexagonal tube (CMGHT) was proposed. The sinusoidal corrugated ribs were introduced into a conventional hexagonal tube, integrated with the functional gradient design concept to improve the energy absorption performance of the structure. First, the finite element model of the structure was established and numerical simulation analysis was conducted. Results indicate that under the same wall thickness condition, the key energy absorption indicators of CMGHT outperform existing structures significantly. Compared with the hexagonal tube (HT), the energy absorption (Ea), specific energy absorption (Esa), mean crushing force (\begin{document}$ \overline{F} $\end{document} \begin{document}$ \overline{F} $\end{document}
To address the collision protection requirements in fields such as aeronautics and space, traffic transportation, and civil construction, a novel design method for the corrugated multi-cell gradient hexagonal tube (CMGHT) was proposed. The sinusoidal corrugated ribs were introduced into a conventional hexagonal tube, integrated with the functional gradient design concept to improve the energy absorption performance of the structure. First, the finite element model of the structure was established and numerical simulation analysis was conducted. Results indicate that under the same wall thickness condition, the key energy absorption indicators of CMGHT outperform existing structures significantly. Compared with the hexagonal tube (HT), the energy absorption (Ea), specific energy absorption (Esa), mean crushing force (
