2024 Vol. 44, No. 11
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2024, 44(11): 111001.
doi: 10.11883/bzycj-2023-0459
Abstract:
The layered protective structure composed of a bursting layer, distribution layer, and structure layer is usually used to resist the penetration and blast waves induced by advanced earth-penetrating weapons (EPWs). The defect of a traditional layered protective structure with medium/coarse sand as the distribution layer is that it is difficult to reliably control the load on the structure layer. To solve this issue, an alternative approach is presented by replacing the material of the distribution layer from the frequently used medium/coarse sand to foam concrete. A blast test on the layered composite target composed of a CF120 concrete (a fiber-reinforced high-strength concrete) bursting layer, a C5 foam concrete distribution layer, and a C40 reinforced concrete structure layer was first conducted in the present study to investigate the blast resistance of layered protective structure sandwiched by foam concrete (named composite protective structure), in which the damage and failure in the layered composite target and blast waves at specific locations were a major concern and were accurately recorded. Then, based on the concrete material model established by Kong and Fang and the smoothed particle Galerkin (SPG) algorithm available in the LS-DYNA, a corresponding numerical model was developed and validated against the test data. Using the validated numerical model, the propagation and attenuation of blast waves and damage and failure in the composite protective structure induced by cylindrical charge explosion are discussed in detail. It is found that the blast resistance mechanism of the composite protective structure is attributed to the extreme wave impedance mismatch between the bursting layer and the foam concrete layer, which greatly reduces the propagation of blast waves into the foam concrete layer, leading to a transformation of more blast energy to the bursting layer, so that the blast load and energy on the structure layer can be greatly reduced. The research results can provide an important reference for the design of protective structures against EPWs.
The layered protective structure composed of a bursting layer, distribution layer, and structure layer is usually used to resist the penetration and blast waves induced by advanced earth-penetrating weapons (EPWs). The defect of a traditional layered protective structure with medium/coarse sand as the distribution layer is that it is difficult to reliably control the load on the structure layer. To solve this issue, an alternative approach is presented by replacing the material of the distribution layer from the frequently used medium/coarse sand to foam concrete. A blast test on the layered composite target composed of a CF120 concrete (a fiber-reinforced high-strength concrete) bursting layer, a C5 foam concrete distribution layer, and a C40 reinforced concrete structure layer was first conducted in the present study to investigate the blast resistance of layered protective structure sandwiched by foam concrete (named composite protective structure), in which the damage and failure in the layered composite target and blast waves at specific locations were a major concern and were accurately recorded. Then, based on the concrete material model established by Kong and Fang and the smoothed particle Galerkin (SPG) algorithm available in the LS-DYNA, a corresponding numerical model was developed and validated against the test data. Using the validated numerical model, the propagation and attenuation of blast waves and damage and failure in the composite protective structure induced by cylindrical charge explosion are discussed in detail. It is found that the blast resistance mechanism of the composite protective structure is attributed to the extreme wave impedance mismatch between the bursting layer and the foam concrete layer, which greatly reduces the propagation of blast waves into the foam concrete layer, leading to a transformation of more blast energy to the bursting layer, so that the blast load and energy on the structure layer can be greatly reduced. The research results can provide an important reference for the design of protective structures against EPWs.
2024, 44(11): 111101.
doi: 10.11883/bzycj-2023-0418
Abstract:
Hydrogen is crucial in the global shift towards clean energy and is gaining significance in the energy industry, while its high flammability and explosive hazard make its safety a research hotspot. It is crucial to thoroughly investigate and assess the safety of hydrogen as it progresses toward commercialization in the energy sector. This article reviews the latest advancements in hydrogen explosion suppression conducted by researchers around the world, aiming at offering a scientific foundation and technical approach to efficiently manage and reduce the damaging impacts of hydrogen explosion incidents. The article focuses on the study of hydrogen explosion suppression materials and their suppression mechanisms, so as to provide scientific understanding and technical support for the safe application of hydrogen. Firstly, it systematically introduces the research progress in hydrogen explosion suppression by discussing four significant categories, i.e., gas, liquid, solid, and multiphase composite explosion suppression materials. By comparing and analyzing the effects, key performance parameters, and the variation rules of these materials, the current research status and effectiveness of various explosion suppression materials are sorted out, helping to deepen the understanding of the explosion suppression effects of these materials. Secondly, focusing on the suppression mechanism, the research delves into the vital role of explosion suppression materials in suppressing hydrogen explosions. Starting from three dimensions, i.e., physical suppression, chemical suppression, and physicochemical comprehensive suppression, it elucidates the mechanisms of action of explosion suppression materials in the suppression process, contributing to a deeper understanding of the role of explosion suppression materials in suppressing or mitigating hydrogen explosions. Finally, the article looks forward to the future development directions of hydrogen explosion suppression materials, especially emphasizing the importance of further studies on the high-efficiency explosion suppression materials and the challenges faced in practical applications. This review is aimed to provide scientific reference and inspiration for the research, development, and application of new hydrogen explosion suppression materials.
Hydrogen is crucial in the global shift towards clean energy and is gaining significance in the energy industry, while its high flammability and explosive hazard make its safety a research hotspot. It is crucial to thoroughly investigate and assess the safety of hydrogen as it progresses toward commercialization in the energy sector. This article reviews the latest advancements in hydrogen explosion suppression conducted by researchers around the world, aiming at offering a scientific foundation and technical approach to efficiently manage and reduce the damaging impacts of hydrogen explosion incidents. The article focuses on the study of hydrogen explosion suppression materials and their suppression mechanisms, so as to provide scientific understanding and technical support for the safe application of hydrogen. Firstly, it systematically introduces the research progress in hydrogen explosion suppression by discussing four significant categories, i.e., gas, liquid, solid, and multiphase composite explosion suppression materials. By comparing and analyzing the effects, key performance parameters, and the variation rules of these materials, the current research status and effectiveness of various explosion suppression materials are sorted out, helping to deepen the understanding of the explosion suppression effects of these materials. Secondly, focusing on the suppression mechanism, the research delves into the vital role of explosion suppression materials in suppressing hydrogen explosions. Starting from three dimensions, i.e., physical suppression, chemical suppression, and physicochemical comprehensive suppression, it elucidates the mechanisms of action of explosion suppression materials in the suppression process, contributing to a deeper understanding of the role of explosion suppression materials in suppressing or mitigating hydrogen explosions. Finally, the article looks forward to the future development directions of hydrogen explosion suppression materials, especially emphasizing the importance of further studies on the high-efficiency explosion suppression materials and the challenges faced in practical applications. This review is aimed to provide scientific reference and inspiration for the research, development, and application of new hydrogen explosion suppression materials.
2024, 44(11): 112101.
doi: 10.11883/bzycj-2023-0404
Abstract:
To study the explosion process of carbon-iron nanomaterials synthesized by gaseous detonation, the effects of different molar ratios of hydrogen to oxygen (2∶1, 3∶1, 4∶1) on the peak value time-history curve of detonation parameters (detonation velocity, detonation temperature, and detonation pressure) and the morphology of carbon-iron nanomaterials were studied by combination of hydrogen-oxygen experiments and numerical simulations. The explosion experiments used hydrogen and oxygen with a purity of 99.999% in a closed detonation tube. The precursor was ferrocene with a purity of 99%. A high-speed camera was used to observe in the middle of the tube. After the experiments, the samples were collected and characterized by transmission electron microscopy. The numerical simulation used ICEM software for modeling and meshing and then used Fluent software to verify the rationality of the mesh size, and then performed simulation calculations after confirming the optimal mesh size. The results indicate that hydrogen-oxygen explosion inside a detonation tube involves two processes: the propagation of detonation waves and the attenuation of combustion waves, and the hydrogen-oxygen molar ratio has a significant impact on the peak time history curves of detonation velocity, detonation temperature, and detonation pressure. With the increase of the molar ratio of hydrogen to oxygen, the detonation velocity, detonation temperature, detonation pressure, and attenuation rate of the detonation wave all decrease. The molar ratio of hydrogen to oxygen affects the morphology growth of carbon-iron nanomaterials by influencing the propagation and attenuation of detonation waves. At zero oxygen balance, the sample consists of carbon-coated iron nanoparticles. As the hydrogen-oxygen molar ratio increases, the number of carbon nanotubes in the sample gradually increases. Adjusting the molar ratio of hydrogen to oxygen can achieve control over the propagation and attenuation process of detonation waves, and also achieve the goal of controlling the preparation of carbon iron nanomaterials with specific morphologies through gaseous detonation.
To study the explosion process of carbon-iron nanomaterials synthesized by gaseous detonation, the effects of different molar ratios of hydrogen to oxygen (2∶1, 3∶1, 4∶1) on the peak value time-history curve of detonation parameters (detonation velocity, detonation temperature, and detonation pressure) and the morphology of carbon-iron nanomaterials were studied by combination of hydrogen-oxygen experiments and numerical simulations. The explosion experiments used hydrogen and oxygen with a purity of 99.999% in a closed detonation tube. The precursor was ferrocene with a purity of 99%. A high-speed camera was used to observe in the middle of the tube. After the experiments, the samples were collected and characterized by transmission electron microscopy. The numerical simulation used ICEM software for modeling and meshing and then used Fluent software to verify the rationality of the mesh size, and then performed simulation calculations after confirming the optimal mesh size. The results indicate that hydrogen-oxygen explosion inside a detonation tube involves two processes: the propagation of detonation waves and the attenuation of combustion waves, and the hydrogen-oxygen molar ratio has a significant impact on the peak time history curves of detonation velocity, detonation temperature, and detonation pressure. With the increase of the molar ratio of hydrogen to oxygen, the detonation velocity, detonation temperature, detonation pressure, and attenuation rate of the detonation wave all decrease. The molar ratio of hydrogen to oxygen affects the morphology growth of carbon-iron nanomaterials by influencing the propagation and attenuation of detonation waves. At zero oxygen balance, the sample consists of carbon-coated iron nanoparticles. As the hydrogen-oxygen molar ratio increases, the number of carbon nanotubes in the sample gradually increases. Adjusting the molar ratio of hydrogen to oxygen can achieve control over the propagation and attenuation process of detonation waves, and also achieve the goal of controlling the preparation of carbon iron nanomaterials with specific morphologies through gaseous detonation.
2024, 44(11): 112201.
doi: 10.11883/bzycj-2023-0440
Abstract:
There is a lack of reliable calculation theory for the transmission and reflection pressures of shock waves at the water-soil interface. Using the mass conservation equation, momentum conservation equation, and the equations of state of water and soil, the Hugoniot relationship and p-u curve of the propagation of shock waves in water and soil medium are derived, and then the transmission and reflection pressures of the shock wave at the water-soil interface can be analyzed theoretically. Two-dimensional numerical models of the free field in water and water-soil layered medium field are established, in which the water and soil parameters are consistent with those in the three-phase medium saturated soil model used in the theoretical derivation. The calculation results show that the theoretical and numerical solutions of the water-soil interface transmission and reflection pressures are highly consistent. When using 80 g TNT explosives and exploding at 0.1–0.9 m from the water-soil interface (proportional burst distance of 0.232–2.089 m/kg1/3), the error of the theoretical and numerical solutions for transmission and reflection pressures is less than 7%, and the coefficient of the reflection pressure is in the range of 1.6–1.8 according to the analytical solution of the reflection pressure and the ratio of the incident pressure in the water. When exploding at 0.5 m from the water-soil interface and the gas content of the saturated soil varies in the range of 0–10%, the transmission and reflection pressures are 63.8–70.0 MPa, and the reflection pressure coefficients are in the range of 1.55–1.70 at this time. The calculation method for the shock wave transmission and reflection pressure at the water-soil interface has a clear physical meaning and high precision and can provide a theoretical basis for the soil damage assessment of engineering structures in submerged soil caused by underwater explosions.
There is a lack of reliable calculation theory for the transmission and reflection pressures of shock waves at the water-soil interface. Using the mass conservation equation, momentum conservation equation, and the equations of state of water and soil, the Hugoniot relationship and p-u curve of the propagation of shock waves in water and soil medium are derived, and then the transmission and reflection pressures of the shock wave at the water-soil interface can be analyzed theoretically. Two-dimensional numerical models of the free field in water and water-soil layered medium field are established, in which the water and soil parameters are consistent with those in the three-phase medium saturated soil model used in the theoretical derivation. The calculation results show that the theoretical and numerical solutions of the water-soil interface transmission and reflection pressures are highly consistent. When using 80 g TNT explosives and exploding at 0.1–0.9 m from the water-soil interface (proportional burst distance of 0.232–2.089 m/kg1/3), the error of the theoretical and numerical solutions for transmission and reflection pressures is less than 7%, and the coefficient of the reflection pressure is in the range of 1.6–1.8 according to the analytical solution of the reflection pressure and the ratio of the incident pressure in the water. When exploding at 0.5 m from the water-soil interface and the gas content of the saturated soil varies in the range of 0–10%, the transmission and reflection pressures are 63.8–70.0 MPa, and the reflection pressure coefficients are in the range of 1.55–1.70 at this time. The calculation method for the shock wave transmission and reflection pressure at the water-soil interface has a clear physical meaning and high precision and can provide a theoretical basis for the soil damage assessment of engineering structures in submerged soil caused by underwater explosions.
2024, 44(11): 112202.
doi: 10.11883/bzycj-2023-0342
Abstract:
Based on the Kong-Fang concrete material model and the multi-material arbitrary Lagrangian-Eulerian (MM-ALE) algorithm available in the LS-DYNA, the attenuation law of stress waves in CF120 concrete subjected to cylindrical cased charge explosion was numerically investigated in this paper. Firstly, the numerical algorithm and material model parameters were validated against two sets of cylindrical charge explosion tests. Then a series of fully enclosed and partially buried cylindrical charge explosion numerical models were established, in which different aspect ratios, shell thicknesses, and charge buried depths were considered to analyze the influence of charge shape and shell thickness on stress waves in concrete. Finally, an empirical formula for peak stress of compression wave in concrete induced by cylindrical cased charge explosion was presented based on curve-fitting the numerical data. Numerical results demonstrate that the larger the aspect ratio, the higher the peak stress in the near region, while the opposite law takes on in the far region. Besides, increasing the shell thickness will make the peak stress higher, but there is a threshold. The influence of charge shape, shell thickness, and charge buried depth on the peak stress can be quantified by defining the length-diameter ratio, thickness-diameter ratio, and coupling factor of peak stress. The empirical formula for peak stress of compression wave in concrete is valid for varied aspect ratio, shell thickness, and charge buried depth, which can provide a reliable estimation the peak stress induced by cylindrical cased charge explosion.
Based on the Kong-Fang concrete material model and the multi-material arbitrary Lagrangian-Eulerian (MM-ALE) algorithm available in the LS-DYNA, the attenuation law of stress waves in CF120 concrete subjected to cylindrical cased charge explosion was numerically investigated in this paper. Firstly, the numerical algorithm and material model parameters were validated against two sets of cylindrical charge explosion tests. Then a series of fully enclosed and partially buried cylindrical charge explosion numerical models were established, in which different aspect ratios, shell thicknesses, and charge buried depths were considered to analyze the influence of charge shape and shell thickness on stress waves in concrete. Finally, an empirical formula for peak stress of compression wave in concrete induced by cylindrical cased charge explosion was presented based on curve-fitting the numerical data. Numerical results demonstrate that the larger the aspect ratio, the higher the peak stress in the near region, while the opposite law takes on in the far region. Besides, increasing the shell thickness will make the peak stress higher, but there is a threshold. The influence of charge shape, shell thickness, and charge buried depth on the peak stress can be quantified by defining the length-diameter ratio, thickness-diameter ratio, and coupling factor of peak stress. The empirical formula for peak stress of compression wave in concrete is valid for varied aspect ratio, shell thickness, and charge buried depth, which can provide a reliable estimation the peak stress induced by cylindrical cased charge explosion.
2024, 44(11): 113101.
doi: 10.11883/bzycj-2-23-0466
Abstract:
Coral concrete is a material with severely asymmetric tensile and compressive strengths. Therefore, studying the dynamic tensile mechanical properties of coral concrete is of great significance for island reef protective engineering. To investigate the dynamic tensile mechanical properties of carbon fiber (CF) and stainless steel fiber (SSF) reinforced coral sand cement mortar under impact loading, dynamic splitting tests were conducted using a 100 mm diameter split Hopkinson pressure bar (SHPB) device. Comparative analysis was carried out on the dynamic tensile strength and energy dissipation patterns of coral sand cement mortars with different fiber contents at various strain rates. In the SHPB tests, cement mortar specimens with different fiber contents were prepared: no fiber, 1.5% CF, 1.5% CF with 0.5% SSF, 1.5% CF with 1.0% SSF, and 1.5% CF with 1.5% SSF. The specimens were subjected to four impact velocities: 3.45, 4.86, 6.54, and 7.34 m/s. This allowed for impact-splitting tests conducted at different strain-rate ranges. In addition, scanning electron microscope (SEM) tests were performed to reveal the action mechanism of the hybrid fibers. The results indicate that the static and dynamic tensile strengths of CF and SSF-reinforced coral sand cement mortar specimens are significantly improved, with a maximum dynamic tensile strength increase ratio of 66.03%. At the same strain rate, the dynamic tensile strength of the specimens positively correlates with the fiber content, while the fragmentation degree negatively correlates with the fiber content. The fiber bridging effect effectively suppresses the development of cracks in the specimens. Under the same fiber content, the dynamic increase factor increases significantly with the increase of strain rate, with a maximum increase factor of 2.44, demonstrating a clear tensile strain rate effect. The fragmentation degree and dissipated energy of coral sand cement mortar specimens positively correlate with the strain rate, and samples with higher fiber dosages require more energy to dissipate during failure.
Coral concrete is a material with severely asymmetric tensile and compressive strengths. Therefore, studying the dynamic tensile mechanical properties of coral concrete is of great significance for island reef protective engineering. To investigate the dynamic tensile mechanical properties of carbon fiber (CF) and stainless steel fiber (SSF) reinforced coral sand cement mortar under impact loading, dynamic splitting tests were conducted using a 100 mm diameter split Hopkinson pressure bar (SHPB) device. Comparative analysis was carried out on the dynamic tensile strength and energy dissipation patterns of coral sand cement mortars with different fiber contents at various strain rates. In the SHPB tests, cement mortar specimens with different fiber contents were prepared: no fiber, 1.5% CF, 1.5% CF with 0.5% SSF, 1.5% CF with 1.0% SSF, and 1.5% CF with 1.5% SSF. The specimens were subjected to four impact velocities: 3.45, 4.86, 6.54, and 7.34 m/s. This allowed for impact-splitting tests conducted at different strain-rate ranges. In addition, scanning electron microscope (SEM) tests were performed to reveal the action mechanism of the hybrid fibers. The results indicate that the static and dynamic tensile strengths of CF and SSF-reinforced coral sand cement mortar specimens are significantly improved, with a maximum dynamic tensile strength increase ratio of 66.03%. At the same strain rate, the dynamic tensile strength of the specimens positively correlates with the fiber content, while the fragmentation degree negatively correlates with the fiber content. The fiber bridging effect effectively suppresses the development of cracks in the specimens. Under the same fiber content, the dynamic increase factor increases significantly with the increase of strain rate, with a maximum increase factor of 2.44, demonstrating a clear tensile strain rate effect. The fragmentation degree and dissipated energy of coral sand cement mortar specimens positively correlate with the strain rate, and samples with higher fiber dosages require more energy to dissipate during failure.
2024, 44(11): 113102.
doi: 10.11883/bzycj-2023-0296
Abstract:
The dynamic mechanical behavior of a metallic hierarchical corrugated sandwich beam subjected to foam projectile impact was systematically studied. After verifying the reliability of the numerical method, the dynamic deformation evolution, quantitative deflection results, deformation failure modes, and energy absorption characteristics of the metallic hierarchical corrugated sandwich beam under different projectile momentum levels were analyzed using Abaqus-Explicit simulations. Subsequently, three metallic single-layer empty corrugated sandwich beams with different geometric parameters were designed, aiming to compare the shock resistance between single-layer and hierarchical corrugated sandwich beams under equal mass conditions. The results showed that the degree of crushing of the secondary corrugated core on the impact side and the first-order corrugated core of the hierarchical sandwich beam was always greater than that of the rear sandwich’s secondary corrugated core. The final mid-span deflection of the rear face of the hierarchical corrugated sandwich beam was always smaller than the corresponding deflection value of the equivalent mass single-level empty corrugated sandwich beam, demonstrating the superior impact protection performance of the hierarchical sandwich beam. This enhancement mechanism is mainly attributed to the increased energy absorption because of the added cellular cores, which protects the rear face sheet. Besides, the plastic longitudinal stretching strength of the hierarchical sandwich beam remains almost unchanged, while the plastic bending strength increases due to the increase in the total beam thickness, thereby enlarging the plastic yield surface of the sandwich structure.
The dynamic mechanical behavior of a metallic hierarchical corrugated sandwich beam subjected to foam projectile impact was systematically studied. After verifying the reliability of the numerical method, the dynamic deformation evolution, quantitative deflection results, deformation failure modes, and energy absorption characteristics of the metallic hierarchical corrugated sandwich beam under different projectile momentum levels were analyzed using Abaqus-Explicit simulations. Subsequently, three metallic single-layer empty corrugated sandwich beams with different geometric parameters were designed, aiming to compare the shock resistance between single-layer and hierarchical corrugated sandwich beams under equal mass conditions. The results showed that the degree of crushing of the secondary corrugated core on the impact side and the first-order corrugated core of the hierarchical sandwich beam was always greater than that of the rear sandwich’s secondary corrugated core. The final mid-span deflection of the rear face of the hierarchical corrugated sandwich beam was always smaller than the corresponding deflection value of the equivalent mass single-level empty corrugated sandwich beam, demonstrating the superior impact protection performance of the hierarchical sandwich beam. This enhancement mechanism is mainly attributed to the increased energy absorption because of the added cellular cores, which protects the rear face sheet. Besides, the plastic longitudinal stretching strength of the hierarchical sandwich beam remains almost unchanged, while the plastic bending strength increases due to the increase in the total beam thickness, thereby enlarging the plastic yield surface of the sandwich structure.
2024, 44(11): 113103.
doi: 10.11883/bzycj-2023-0460
Abstract:
To address the issue of peak load reduction for impact loads in engineering technology, the energy absorption characteristics of axial series energy absorbing tubes was investigated through a combination of numerical simulation and experimentation. Firstly, the Johnson-Cook dynamic constitutive parameters of the material 06Cr18Ni11Ti GB/T1220-2007 of energy absorbing tubes were established and evaluated based on high-speed tensile tests which indicates 06Cr18Ni11Ti has obvious strain rate hardening effect. Subsequently, numerical simulation and high-speed impact tests were conducted to examine the energy absorption characteristics of energy absorption tubes, with an evaluation of consistency between numerical simulation and test results. The numerical simulation was based on the time-step ABAQUS/Explicit finite element simulation platform. The high speed impact test system used the high pressure gas inside the air actuated piston cylinder as the power source, which could accelerate the mass block to a speed of 30 m/s. Finally, the energy absorption evaluation indexes between the axial series configuration and the single configuration of the energy absorption tube were compared and analyzed by numerical simulation. The analysis demonstrates that deformation mode, load curve, and energy absorption evaluation indexes from both numerical simulations and impact tests exhibit good agreement. The accuracy of material performance parameters confirms the effectiveness of simulation prediction methods while validating reasonability and reliability of high-speed impact test schemes. Compared to axial series configurations with identical structural parameters, single-tube configurations display asymmetric and unstable twist deformations during compression processes. Single-tube configurations experience a 13% reduction in effective compression stroke along with a 33.4% increase in peak load, 15% increase in instantaneous impact load, 13% increase in average compression force, as well as a 17.7% increase in peak-to-average load ratio. Consequently, axial series configurations prove to be more ideal energy absorbing structures.
To address the issue of peak load reduction for impact loads in engineering technology, the energy absorption characteristics of axial series energy absorbing tubes was investigated through a combination of numerical simulation and experimentation. Firstly, the Johnson-Cook dynamic constitutive parameters of the material 06Cr18Ni11Ti GB/T1220-2007 of energy absorbing tubes were established and evaluated based on high-speed tensile tests which indicates 06Cr18Ni11Ti has obvious strain rate hardening effect. Subsequently, numerical simulation and high-speed impact tests were conducted to examine the energy absorption characteristics of energy absorption tubes, with an evaluation of consistency between numerical simulation and test results. The numerical simulation was based on the time-step ABAQUS/Explicit finite element simulation platform. The high speed impact test system used the high pressure gas inside the air actuated piston cylinder as the power source, which could accelerate the mass block to a speed of 30 m/s. Finally, the energy absorption evaluation indexes between the axial series configuration and the single configuration of the energy absorption tube were compared and analyzed by numerical simulation. The analysis demonstrates that deformation mode, load curve, and energy absorption evaluation indexes from both numerical simulations and impact tests exhibit good agreement. The accuracy of material performance parameters confirms the effectiveness of simulation prediction methods while validating reasonability and reliability of high-speed impact test schemes. Compared to axial series configurations with identical structural parameters, single-tube configurations display asymmetric and unstable twist deformations during compression processes. Single-tube configurations experience a 13% reduction in effective compression stroke along with a 33.4% increase in peak load, 15% increase in instantaneous impact load, 13% increase in average compression force, as well as a 17.7% increase in peak-to-average load ratio. Consequently, axial series configurations prove to be more ideal energy absorbing structures.
2024, 44(11): 113301.
doi: 10.11883/bzycj-2023-0208
Abstract:
In order to solve the problem of high-performance lightweight bulletproof inserts protection of penetration of light weapon killing elements, this paper carried out penetration experiments on ultra-high molecular weight polyethylene (UHMWPE) laminated sheet, analyzed the deformation and failure characteristics of the UHMWPE sheet after penetration and compared the damage morphology of light weapon killing element. A numerical model of UHMWPE laminate against the penetration of light weapon killers was established by using the finite element software LS-DYNA, and the validity of the numerical model was verified by the experimental results of the damage morphology of the target plate, the depth of the depression and the deformation of the warhead. On this basis, the failure mode of the UHMWPE thin plate subjected to oblique penetration by the projectile is investigated by numerical methods, and the influence of the incidence angle on the ricochet phenomenon and the damage morphology of UHMWPE thin plate under the penetration of three kinds of light weapon killing elements is revealed. The results show that the ricochet angles of 7.62 mm×25 mm steel-core bullets and 7.62 mm×39 mm ordinary bullets (steel-core) obliquely penetrating UHMWPE plates are located in the range of 45°–50°; 7.62 mm×25 mm lead-core bullets can be completely ricocheted out when the angle of incidence is greater than 70°, and the rest of the bullets are in the form of broken shrapnel splinters, and the destruction of the bullet body has an effect on the ricochet condition; the oblique penetration bullets produce a large area and a large number of damage patterns at a smaller angle of incidence; the oblique penetration bullets produce a larger area and a larger number of damage patterns in the UHMWPE plates. When the angle of incidence is small, the oblique penetration bullet will produce a larger area and a certain depth of the crater, the next bullet will be easier to penetrate the crater weakness of the fiber plate, and the oblique penetration effect on the thin plate by the secondary penetration of the negative impact, the angle of incidence is larger, the bullet will be more complete ricochet and has a high residual velocity, which will produce a secondary killing of personnel. The research results can be used for UHMWPE thin plate for lightweight military bulletproof insert design to provide reference.
In order to solve the problem of high-performance lightweight bulletproof inserts protection of penetration of light weapon killing elements, this paper carried out penetration experiments on ultra-high molecular weight polyethylene (UHMWPE) laminated sheet, analyzed the deformation and failure characteristics of the UHMWPE sheet after penetration and compared the damage morphology of light weapon killing element. A numerical model of UHMWPE laminate against the penetration of light weapon killers was established by using the finite element software LS-DYNA, and the validity of the numerical model was verified by the experimental results of the damage morphology of the target plate, the depth of the depression and the deformation of the warhead. On this basis, the failure mode of the UHMWPE thin plate subjected to oblique penetration by the projectile is investigated by numerical methods, and the influence of the incidence angle on the ricochet phenomenon and the damage morphology of UHMWPE thin plate under the penetration of three kinds of light weapon killing elements is revealed. The results show that the ricochet angles of 7.62 mm×25 mm steel-core bullets and 7.62 mm×39 mm ordinary bullets (steel-core) obliquely penetrating UHMWPE plates are located in the range of 45°–50°; 7.62 mm×25 mm lead-core bullets can be completely ricocheted out when the angle of incidence is greater than 70°, and the rest of the bullets are in the form of broken shrapnel splinters, and the destruction of the bullet body has an effect on the ricochet condition; the oblique penetration bullets produce a large area and a large number of damage patterns at a smaller angle of incidence; the oblique penetration bullets produce a larger area and a larger number of damage patterns in the UHMWPE plates. When the angle of incidence is small, the oblique penetration bullet will produce a larger area and a certain depth of the crater, the next bullet will be easier to penetrate the crater weakness of the fiber plate, and the oblique penetration effect on the thin plate by the secondary penetration of the negative impact, the angle of incidence is larger, the bullet will be more complete ricochet and has a high residual velocity, which will produce a secondary killing of personnel. The research results can be used for UHMWPE thin plate for lightweight military bulletproof insert design to provide reference.
2024, 44(11): 113302.
doi: 10.11883/bzycj-2024-0063
Abstract:
Reactive fragments are composed of multifunctional impact reactive structural materials. After reactive fragments penetrate the front target of warhead, the debris cloud generated by the sufficient reaction of reactive material will damage the medium behind the target in the form of kinetic energy-chemical energy coupling damage. Ballistic impact experiments and finite element simulations were conducted to investigate the impact damage effect of reactive fragments on cased charge. Based on the criteria for failure levels of cased charge characterized by equivalent fragments initial velocity and equivalent gurney velocity, the ratio of the equivalent gurney velocity under abnormal detonation conditions to gurney velocity or the ratio of the equivalent fragments initial velocity under abnormal detonation conditions to the fragments initial velocity is used to measure the reaction violence of the cased charge. Equivalent gurney velocity of cased charge under impact of inert fragments and reactive fragments, response duration of cased charge, the damage of the authentication target, and the peak pressure of explosive layer are compared. The influence of energy release characteristics of reactive fragments on the failure of cased charge is also analyzed. The results show that explosive detonate under the impact of inert fragments, while explosive deflagrate or explode under the impact of reactive fragments. The steel verification target only presents significant circular pit during explosive detonation. The explosive detonation process captured by high-speed photography is on the microsecond scale, while the explosive explosion or deflagration process is on the millisecond scale. Under the penetration of six reactive fragments, the corresponding ratio of equivalent gurney velocity to gurney velocity ranges from 0.014 to 0.233, which is far below the ratio of equivalent gurney velocity to gurney velocity under the condition of inert fragments penetrating cased charges. By using AUTODYN, the peak pressure at the observation point on the axis of the cased charge during detonation failure under the penetration of inert fragments ranges from 17.3 to 34.5 GPa, while the peak pressure of cased charge during deflagration failure under the penetration of reactive fragments ranges from 1.04 to 3.62 GPa, which is far below the critical detonation pressure. Based on the ratio of the equivalent gurney velocity to gurney velocity, the peak pressure of explosive and superimposed effect of kinetic energy and chemical energy of reactive fragments, the idea that it is difficult to detonate cased charge under the penetration of reactive fragments is proposed.
Reactive fragments are composed of multifunctional impact reactive structural materials. After reactive fragments penetrate the front target of warhead, the debris cloud generated by the sufficient reaction of reactive material will damage the medium behind the target in the form of kinetic energy-chemical energy coupling damage. Ballistic impact experiments and finite element simulations were conducted to investigate the impact damage effect of reactive fragments on cased charge. Based on the criteria for failure levels of cased charge characterized by equivalent fragments initial velocity and equivalent gurney velocity, the ratio of the equivalent gurney velocity under abnormal detonation conditions to gurney velocity or the ratio of the equivalent fragments initial velocity under abnormal detonation conditions to the fragments initial velocity is used to measure the reaction violence of the cased charge. Equivalent gurney velocity of cased charge under impact of inert fragments and reactive fragments, response duration of cased charge, the damage of the authentication target, and the peak pressure of explosive layer are compared. The influence of energy release characteristics of reactive fragments on the failure of cased charge is also analyzed. The results show that explosive detonate under the impact of inert fragments, while explosive deflagrate or explode under the impact of reactive fragments. The steel verification target only presents significant circular pit during explosive detonation. The explosive detonation process captured by high-speed photography is on the microsecond scale, while the explosive explosion or deflagration process is on the millisecond scale. Under the penetration of six reactive fragments, the corresponding ratio of equivalent gurney velocity to gurney velocity ranges from 0.014 to 0.233, which is far below the ratio of equivalent gurney velocity to gurney velocity under the condition of inert fragments penetrating cased charges. By using AUTODYN, the peak pressure at the observation point on the axis of the cased charge during detonation failure under the penetration of inert fragments ranges from 17.3 to 34.5 GPa, while the peak pressure of cased charge during deflagration failure under the penetration of reactive fragments ranges from 1.04 to 3.62 GPa, which is far below the critical detonation pressure. Based on the ratio of the equivalent gurney velocity to gurney velocity, the peak pressure of explosive and superimposed effect of kinetic energy and chemical energy of reactive fragments, the idea that it is difficult to detonate cased charge under the penetration of reactive fragments is proposed.
2024, 44(11): 113901.
doi: 10.11883/bzycj-2023-0260
Abstract:
Based on the computational fluid dynamics (CFD) numerical methods, a set of reliable and effective numerical methods for investigating the flow field and evolution characteristics of motion during the process of falling vehicle with boost floatation aids impacting the water in wave environment was established coupled with volume of fluid (VOF) multiphase flow model, k-ω SST turbulence model, Schnerr-Sauer cavitation model and Stokes fifth-order nonlinear wave theory. The numerical simulation of the process of falling into water under a horizontal cylinder showed that the difference between the experimental results and the numerical results in falling displacement was small, which verifies the validity of the numerical method of water falling impact. The wave generation results obtained by the velocity boundary numerical wave generation method were in good agreement with Stokes fifth-order nonlinear wave theory. Based on the established numerical method, numerical simulation was carried out on the water falling impact process of the vehicle with boost floatation aids under different wave sea states. The kinematic and dynamic parameters of the vehicle and evolution of water-entry cavity flow field during the impact process were analyzed, and the water falling impact characteristics of the vehicle with boost floatation aids under wave environment were summarized. The results show that the impact of wave environment on the falling impact process is mainly reflected in the motion attenuation section. The horizontal impact is much more affected by the wave environment than the vertical impact and the influence of different sea conditions on the horizontal impact of the vehicle is mainly achieved by influencing the formation and collapse of the water-entry cavity. The calculated displacement, velocity, acceleration and boost floatation aids force during the impact process of vehicle with boost floatation aids can be provided as a reference for the structural design and safety test guidance of the vehicle recovery under wave environment.
Based on the computational fluid dynamics (CFD) numerical methods, a set of reliable and effective numerical methods for investigating the flow field and evolution characteristics of motion during the process of falling vehicle with boost floatation aids impacting the water in wave environment was established coupled with volume of fluid (VOF) multiphase flow model, k-ω SST turbulence model, Schnerr-Sauer cavitation model and Stokes fifth-order nonlinear wave theory. The numerical simulation of the process of falling into water under a horizontal cylinder showed that the difference between the experimental results and the numerical results in falling displacement was small, which verifies the validity of the numerical method of water falling impact. The wave generation results obtained by the velocity boundary numerical wave generation method were in good agreement with Stokes fifth-order nonlinear wave theory. Based on the established numerical method, numerical simulation was carried out on the water falling impact process of the vehicle with boost floatation aids under different wave sea states. The kinematic and dynamic parameters of the vehicle and evolution of water-entry cavity flow field during the impact process were analyzed, and the water falling impact characteristics of the vehicle with boost floatation aids under wave environment were summarized. The results show that the impact of wave environment on the falling impact process is mainly reflected in the motion attenuation section. The horizontal impact is much more affected by the wave environment than the vertical impact and the influence of different sea conditions on the horizontal impact of the vehicle is mainly achieved by influencing the formation and collapse of the water-entry cavity. The calculated displacement, velocity, acceleration and boost floatation aids force during the impact process of vehicle with boost floatation aids can be provided as a reference for the structural design and safety test guidance of the vehicle recovery under wave environment.
2024, 44(11): 114101.
doi: 10.11883/bzycj-2023-0195
Abstract:
Based on the basic principles of electromagnetic induction, an impact device is proposed that generates high-amplitude and long-pulse acceleration loads driven by electromagnetic forces. The impact device goes to make up for the shortcomings of the current stage of ground impact test technology. The disadvantages of the current stage of ground impact test technology include mainly time-consuming, high cost, low repeatability and controllability, and it is difficult to continuously improve the pulse width of acceleration load. Acceleration impact tests were performed using an electromagnetic Hopkinson bar, and the working process of the device from the generation of electromagnetic force to its transformation into impact load was analyzed. In the acceleration impact test, the stress on the bar was obtained by strain gauges and the acceleration loads at the end of the bar were obtained by acceleration transducers. A plurality of test results without loss of repeatability. The classical one-dimensional stress wave theory for predicting the relationship between acceleration and stress in slender bars is developed. Comparative analysis against experimental data are presented to demonstrate the effectiveness of the present approach. The electromagnetic Hopkinson bar acceleration impact test was numerically simulated using COMSOL finite element software, and the simulation results showed good consistency with the experimental results, indicating that the numerical model could simulate this kind of impact test more accurately and verifying the accuracy of the numerical model. Based on this finite element model, an impact device that generates high-amplitude, long-pulse acceleration is proposed, and numerical simulations of the device are carried out at different voltages and capacitances. The simulation results show that the device is able to generate the required acceleration. The acceleration amplitude increases with increasing capacitance voltage and the acceleration pulse width increases with increasing capacitance value. By regulating the values of the circuit parameters, the device can generate acceleration loads with different amplitudes and pulse widths.
Based on the basic principles of electromagnetic induction, an impact device is proposed that generates high-amplitude and long-pulse acceleration loads driven by electromagnetic forces. The impact device goes to make up for the shortcomings of the current stage of ground impact test technology. The disadvantages of the current stage of ground impact test technology include mainly time-consuming, high cost, low repeatability and controllability, and it is difficult to continuously improve the pulse width of acceleration load. Acceleration impact tests were performed using an electromagnetic Hopkinson bar, and the working process of the device from the generation of electromagnetic force to its transformation into impact load was analyzed. In the acceleration impact test, the stress on the bar was obtained by strain gauges and the acceleration loads at the end of the bar were obtained by acceleration transducers. A plurality of test results without loss of repeatability. The classical one-dimensional stress wave theory for predicting the relationship between acceleration and stress in slender bars is developed. Comparative analysis against experimental data are presented to demonstrate the effectiveness of the present approach. The electromagnetic Hopkinson bar acceleration impact test was numerically simulated using COMSOL finite element software, and the simulation results showed good consistency with the experimental results, indicating that the numerical model could simulate this kind of impact test more accurately and verifying the accuracy of the numerical model. Based on this finite element model, an impact device that generates high-amplitude, long-pulse acceleration is proposed, and numerical simulations of the device are carried out at different voltages and capacitances. The simulation results show that the device is able to generate the required acceleration. The acceleration amplitude increases with increasing capacitance voltage and the acceleration pulse width increases with increasing capacitance value. By regulating the values of the circuit parameters, the device can generate acceleration loads with different amplitudes and pulse widths.
2024, 44(11): 115401.
doi: 10.11883/bzycj-2023-0340
Abstract:
In order to improve the explosion suppression efficiency of liquefied petroleum gas (LPG), a self-designed semi-open organic glass pipeline was used to build the N2/water mist explosion suppression experimental platform. The explosion suppression effect of N2/water mist containing modified chlorine compounds was analyzed from four aspects: explosion overpressure, flame propagation velocity and its peak arrival time, and flame structure. The results show that the chlorine compounds are selective to surfactants. The synergistic effect between KCl, NaCl and NH4Cl and fatty alcohol polyoxyethylene ether (AeO9) and silicone surfactant (Sicare2235) is better. The maximum explosion overpressure and flame propagation velocity are obviously reduced, and their arrival time is obviously prolonged. When sodium dodecyl sulfate (SDS) only interacts with NaCl, the explosion suppression effect is significantly improved. While when SDS interacts with the other three chloride salts, there is no synergistic effect or even explosion-promoting effect. Explosion enhancement occurs when FeCl2 cooperates with surfactants. When the chlorine compound and the surfactant act together, there is an optimal value for the surface tension value, when the surface tension is 20 mN/m, the explosion suppression efficiency is the best. The numerical simulation results of chemical kinetics show that the modified chlorine compound N2 water mist can effectively reduce the adiabatic flame temperature, consume key free radicals, and interrupt the combustion chain reaction. The synergistic mechanism of explosion suppression is mainly reflected in three aspects: N2 inerting dilution, surfactant regulation of water mist particle size increase cooling effect and inhibition of chain reaction. The research results will provide technical guidance for the prevention and suppression of liquefied petroleum gas explosion accidents in China.
In order to improve the explosion suppression efficiency of liquefied petroleum gas (LPG), a self-designed semi-open organic glass pipeline was used to build the N2/water mist explosion suppression experimental platform. The explosion suppression effect of N2/water mist containing modified chlorine compounds was analyzed from four aspects: explosion overpressure, flame propagation velocity and its peak arrival time, and flame structure. The results show that the chlorine compounds are selective to surfactants. The synergistic effect between KCl, NaCl and NH4Cl and fatty alcohol polyoxyethylene ether (AeO9) and silicone surfactant (Sicare2235) is better. The maximum explosion overpressure and flame propagation velocity are obviously reduced, and their arrival time is obviously prolonged. When sodium dodecyl sulfate (SDS) only interacts with NaCl, the explosion suppression effect is significantly improved. While when SDS interacts with the other three chloride salts, there is no synergistic effect or even explosion-promoting effect. Explosion enhancement occurs when FeCl2 cooperates with surfactants. When the chlorine compound and the surfactant act together, there is an optimal value for the surface tension value, when the surface tension is 20 mN/m, the explosion suppression efficiency is the best. The numerical simulation results of chemical kinetics show that the modified chlorine compound N2 water mist can effectively reduce the adiabatic flame temperature, consume key free radicals, and interrupt the combustion chain reaction. The synergistic mechanism of explosion suppression is mainly reflected in three aspects: N2 inerting dilution, surfactant regulation of water mist particle size increase cooling effect and inhibition of chain reaction. The research results will provide technical guidance for the prevention and suppression of liquefied petroleum gas explosion accidents in China.
