Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.Thi...Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.This study investigates the blasting effects and underlying mechanisms of concrete frustums subjected to contact explosions,employing both numerical simulations and field tests.It focuses on the effects of top and side blasting,with particular emphasis on fracture modes,damage patterns,and fragment sizes,as well as the causes of different failure modes and the propagation of stress waves.The study also explores the blasting effects of detonating explosives at varying positions along the side and with different charge amounts.The results show that side-blasting leads to complete fragmentation,with tensile waves playing a significant role in creating extensive damage zones that propagate parallel to the frustum's outer surface,concentrating damage near the surface.During top-blasting,the upper half of the frustum undergoes fragmentation,while the lower half experiences cracking.Tensile waves propagate from the top to the bottom surface,forming larger blocks in regions with lower wave intensity.Three distinct damage zones within the frustum were identified,and a series of mathematical formulas were derived to describe the relationship between the maximum fragment size and charge mass.As the charge mass increased from 1.0 kg to 4.0 kg,the maximum fragment size decreased.Detonation at the center of the frustum's side resulted in the most severe fragmentation,with a 51.8%reduction in fragment size compared to other detonation positions.Finally,four broken modes were classified,each influenced by charge mass and explosive location.This study provides valuable insights for optimizing civil blasting operations and designing protective engineering structures.展开更多
To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyur...To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion tests.The reliability of the numerical simulation using LS-DYNA software was verified by the test results.The effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were studied.The results show that the polyurea coating can effectively enhance the anti-explosion performance of the girder.The top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local dent.The peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen G.For the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of fracture.With the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more significant.The optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn.展开更多
Layered concrete media with different wave impedance materials under one-dimensional strain are studied by numerical simulation. The four typical prototypes are analyzed,including concrete foam,air,steel plate and con...Layered concrete media with different wave impedance materials under one-dimensional strain are studied by numerical simulation. The four typical prototypes are analyzed,including concrete foam,air,steel plate and concrete as the middle layer,and the upper and lower layers are concrete materials. The propagation characteristics of plane blast wave in the concrete structure are illustrated,including the propagation and attenuation of stress wave across the different interlayers,the wave reflection and transmission at layered interfaces,the peak value of stress in the lower concrete and the total energy distribution in various medium layers. The result shows that the role of soft interlayer in concrete structure is mainly due to its low wave impedance,the waveform of incident wave is changed,the stress wavelength is pull wide,the radial diffusion of energy is enhanced,and the stress amplitude of and the energy input into the third layer are reduced. Meanwhile,it has been also proved that the air interlayer is able to reduce the peak value of explosion wave which is obviously different from that of foamed material. As a result,it should be concerned about stress amplitude and energy in order to get the best protective structure.展开更多
To quickly break through a reinforced concrete wall and meet the damage range requirements of rescuers entering the building,the combined damage characteristics of the reinforced concrete wall caused by EFP penetratio...To quickly break through a reinforced concrete wall and meet the damage range requirements of rescuers entering the building,the combined damage characteristics of the reinforced concrete wall caused by EFP penetration and explosion shock wave were studied.Based on LS-DYNA finite element software and RHT model with modified parameters,a 3D large-scale numerical model was established for simulation analysis,and the rationality of the material model parameters and numerical simulation algorithm were verified.On this basis,the combined damage effect of EFP penetration and explosion shock wave on reinforced concrete wall was studied,the effect of steel bars on the penetration of EFP was highlighted,and the effect of impact positions on the damage of the reinforced concrete wall was also examined.The results reveal that the designed shaped charge can form a crater with a large diameter and high depth on the reinforced concrete wall.The average crater diameter is greater than 67 cm(5.58 times of charge diameter),and crater depth is greater than 22 cm(1.83 times of charge diameter).The failure of the reinforced concrete wall is mainly caused by EFP penetration.When only EFP penetration is considered,the average diameter and depth of the crater are 54.0 cm(4.50 times of charge diameter)and 23.7 cm(1.98 times of charge diameter),respectively.The effect of explosion shock wave on crater depth is not significant,resulting in a slight increase in crater depth.The average crater depth is 24.5 cm(2.04 times of charge diameter)when the explosion shock wave is considered.The effect of explosion shock wave on the crater diameter is obvious,which can aggravate the damage range of the crater,and the effect gradually decreases with the increase of standoff distance.Compared with the results for a plain concrete wall,the crater diameter and crater depth of the reinforced concrete wall are reduced by 5.94%and 9.96%,respectively.Compared to the case in which the steel bar is not hit,when the EFP hit one steel bar and the intersection of two steel bars,the crater diameter decreases by 1.36%and 5.45%respectively,the crater depth decreases by 4.92%and 14.02%respectively.The EFP will be split by steel bar during the penetration process,resulting in an irregular trajectory.展开更多
Based on the low inductance technology and parallel-plate transmission principle,an experimental apparatus of small-scale slapper initiating primary high explosives driven by electrical explosion is designed and estab...Based on the low inductance technology and parallel-plate transmission principle,an experimental apparatus of small-scale slapper initiating primary high explosives driven by electrical explosion is designed and established.The problem of instantaneously and continuously measuring the velocity of the small-scale slapper is successfully solved by using the technique of laser interference.Compared with the results published on the literatures at home and abroad,data of the experimental and the numerical simulation shown in this paper are more proper to reflect the physical process of electrical explosion driving slapper.One-dimensional numerical simulation of electrical explosion driving slapper is done using the hydrodynamic code.The experimental results are consistent with the computed ones by introducing a power correction factor.In the end,the introduced power correction factor is discussed.展开更多
A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including ...A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including deforming,fracturing,forming a local high-temperature region and igniting,were simulated using a coupled mechanical-thermo-chemical model integrating micro-defects evolution.A novel evaluation method for impact sensitivity is established using the relation between the input kinetic energy and the output energy due to deformation,crushing energy,local hot spot energy and ignition.The effects of impact velocity on sensitivity were analyzed and the critical local ignition impact velocity is determined as 4.0-4.5 m/s.The simulated results show that shear-crack friction heating is the dominant ignition mechanism.The region along the boundary of PBXs sample is the most hazardous regions where ignition first occur.The propagation of stress wave in PBXs causes shear-crack hotspot and bulk temperature exhibiting an approximate 45°direction evolution path,which is the main reason that dominated damage-ignition region transits from the boundary to the central of sample.展开更多
爆炸作用下地面建筑目标的破坏分析对制定实战打击策略和工程防护具有重要的实践指导意义。采用LS-DYNA有限元分析软件对已有含填充墙钢筋混凝土(reinforced concrete,RC)框架结构的近区爆炸试验进行复现,充分验证了所采用的精细化数值...爆炸作用下地面建筑目标的破坏分析对制定实战打击策略和工程防护具有重要的实践指导意义。采用LS-DYNA有限元分析软件对已有含填充墙钢筋混凝土(reinforced concrete,RC)框架结构的近区爆炸试验进行复现,充分验证了所采用的精细化数值仿真方法的适用性。结合建筑结构混合单元建模方法,对典型三层含填充墙RC框架结构在典型战斗部(100 kg和200 kg TNT当量)爆炸作用下的动态响应开展了仿真分析,考察了爆炸波在结构内部的传播和结构损伤特性。基于等效单自由度(single-degree-of-freedom,SDOF)方法预测了爆炸荷载作用下框架结构梁、柱、板和填充墙等构件的损伤等级,建立了内爆炸作用下建筑目标的破坏简化分析方法,并通过与精细化数值仿真结果对比检验其适用性。结果表明,在100 kg和200 kg TNT爆炸工况下,精细化数值仿真分析中建筑物整体功能性和结构性毁伤等级均为中度和轻度,等效SDOF简化分析得到的相应毁伤等级与数值仿真结果一致。此外,从各构件的毁伤等级可以看出,相比于板、梁和柱等承重构件,砌体填充墙更易发生破坏,从而导致爆炸波在层内水平方向房间的毁伤破坏范围更大。展开更多
In order to study and apply the penetration performance of jetting penetrator charge at long stand-off distance, three jetting penetrator charges(JPC), including spherical cone liner, truncated wide-angle liner and sp...In order to study and apply the penetration performance of jetting penetrator charge at long stand-off distance, three jetting penetrator charges(JPC), including spherical cone liner, truncated wide-angle liner and spherical segment liner, are designed. The numerical simulation analysis of the formation, elongation and penetration processes of rod-like jet is conducted by using LS-DYNA software. And the penetrating test is carried out at long stand-off distance. The test results show that the rod-like jet formed by the optimized spherical segment liner can pierce through a 90mm thick 45# steel target at 20 charge diameters(CD) stand-off distance when the charge detonation mode is a central point initiation, and the penetration depth can be up to 1.6CD. It is concluded that, at 20 CD stand-off distance, the penetration performance of JPC with spherical segment liner is the best, that of truncated wide-angle liner takes second place, and that of spherical cone liner is the worst.展开更多
To study a new shaped charge of perforator, the jet formation and penetration processes in concrete targets are simulated numerically by using LS-DYNA finite element analysis software. The results show that the cylind...To study a new shaped charge of perforator, the jet formation and penetration processes in concrete targets are simulated numerically by using LS-DYNA finite element analysis software. The results show that the cylindrical liner can form jet and most materials on top of liner form the tip of jet, while the others form the tail of jet. The jet has a better continuity, and the ratio of cumulative jet length to the liner diameter can reach to 7.56. Furthermore, the ratio of bore diameter to the liner diameter is from 0.36 and 1, and the ratio of penetration depth to the liner diameter can be up to 5.5.展开更多
For shaped charges,LS-DYNA software was adopted to explore the influence of number of initiation points on the penetrator formation numerically.Changed the number of initiation points from 4 to 36,the performance of p...For shaped charges,LS-DYNA software was adopted to explore the influence of number of initiation points on the penetrator formation numerically.Changed the number of initiation points from 4 to 36,the performance of penetrator under four different kinds of typical charge diameter was analyzed,and the effect of detonation wave pressure on the liner was discussed.The minimum number of initiation points to substitute for annular initiation was obtained for each of four warheads with different charge diameters,and the curve representing the relation between the number of initiation points and charge diameter was found out also by using polynomial fitting.The simulation result provides a reference for the design of multimode warhead.展开更多
基金the support provided by the Technology Innovation Project (Grant No. KYGYZB002201) for the research work
文摘Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.This study investigates the blasting effects and underlying mechanisms of concrete frustums subjected to contact explosions,employing both numerical simulations and field tests.It focuses on the effects of top and side blasting,with particular emphasis on fracture modes,damage patterns,and fragment sizes,as well as the causes of different failure modes and the propagation of stress waves.The study also explores the blasting effects of detonating explosives at varying positions along the side and with different charge amounts.The results show that side-blasting leads to complete fragmentation,with tensile waves playing a significant role in creating extensive damage zones that propagate parallel to the frustum's outer surface,concentrating damage near the surface.During top-blasting,the upper half of the frustum undergoes fragmentation,while the lower half experiences cracking.Tensile waves propagate from the top to the bottom surface,forming larger blocks in regions with lower wave intensity.Three distinct damage zones within the frustum were identified,and a series of mathematical formulas were derived to describe the relationship between the maximum fragment size and charge mass.As the charge mass increased from 1.0 kg to 4.0 kg,the maximum fragment size decreased.Detonation at the center of the frustum's side resulted in the most severe fragmentation,with a 51.8%reduction in fragment size compared to other detonation positions.Finally,four broken modes were classified,each influenced by charge mass and explosive location.This study provides valuable insights for optimizing civil blasting operations and designing protective engineering structures.
基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20200494)China Postdoctoral Science Foundation(Grant No.2021M701725)+3 种基金Jiangsu Postdoctoral Research Funding Program(Grant No.2021K522C)Fundamental Research Funds for the Central Universities(Grant No.30919011246)National Natural Science Foundation of China(Grant No.52278188)Natural Science Foundation of Jiangsu Province(Grant No.BK20211196)。
文摘To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion tests.The reliability of the numerical simulation using LS-DYNA software was verified by the test results.The effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were studied.The results show that the polyurea coating can effectively enhance the anti-explosion performance of the girder.The top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local dent.The peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen G.For the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of fracture.With the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more significant.The optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn.
基金sponsored by the National Natural Science Foundation of China (Grant No.11202028,11172071)the project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology (Grant No.QNKT1006)
文摘Layered concrete media with different wave impedance materials under one-dimensional strain are studied by numerical simulation. The four typical prototypes are analyzed,including concrete foam,air,steel plate and concrete as the middle layer,and the upper and lower layers are concrete materials. The propagation characteristics of plane blast wave in the concrete structure are illustrated,including the propagation and attenuation of stress wave across the different interlayers,the wave reflection and transmission at layered interfaces,the peak value of stress in the lower concrete and the total energy distribution in various medium layers. The result shows that the role of soft interlayer in concrete structure is mainly due to its low wave impedance,the waveform of incident wave is changed,the stress wavelength is pull wide,the radial diffusion of energy is enhanced,and the stress amplitude of and the energy input into the third layer are reduced. Meanwhile,it has been also proved that the air interlayer is able to reduce the peak value of explosion wave which is obviously different from that of foamed material. As a result,it should be concerned about stress amplitude and energy in order to get the best protective structure.
基金supported by the Scientific and Technological Innovation Project(Grant No.KYGYZB0019003)。
文摘To quickly break through a reinforced concrete wall and meet the damage range requirements of rescuers entering the building,the combined damage characteristics of the reinforced concrete wall caused by EFP penetration and explosion shock wave were studied.Based on LS-DYNA finite element software and RHT model with modified parameters,a 3D large-scale numerical model was established for simulation analysis,and the rationality of the material model parameters and numerical simulation algorithm were verified.On this basis,the combined damage effect of EFP penetration and explosion shock wave on reinforced concrete wall was studied,the effect of steel bars on the penetration of EFP was highlighted,and the effect of impact positions on the damage of the reinforced concrete wall was also examined.The results reveal that the designed shaped charge can form a crater with a large diameter and high depth on the reinforced concrete wall.The average crater diameter is greater than 67 cm(5.58 times of charge diameter),and crater depth is greater than 22 cm(1.83 times of charge diameter).The failure of the reinforced concrete wall is mainly caused by EFP penetration.When only EFP penetration is considered,the average diameter and depth of the crater are 54.0 cm(4.50 times of charge diameter)and 23.7 cm(1.98 times of charge diameter),respectively.The effect of explosion shock wave on crater depth is not significant,resulting in a slight increase in crater depth.The average crater depth is 24.5 cm(2.04 times of charge diameter)when the explosion shock wave is considered.The effect of explosion shock wave on the crater diameter is obvious,which can aggravate the damage range of the crater,and the effect gradually decreases with the increase of standoff distance.Compared with the results for a plain concrete wall,the crater diameter and crater depth of the reinforced concrete wall are reduced by 5.94%and 9.96%,respectively.Compared to the case in which the steel bar is not hit,when the EFP hit one steel bar and the intersection of two steel bars,the crater diameter decreases by 1.36%and 5.45%respectively,the crater depth decreases by 4.92%and 14.02%respectively.The EFP will be split by steel bar during the penetration process,resulting in an irregular trajectory.
基金Sponsored by the Foundation of Institute of Fluid Physics of China Academy of Engineering Physics
文摘Based on the low inductance technology and parallel-plate transmission principle,an experimental apparatus of small-scale slapper initiating primary high explosives driven by electrical explosion is designed and established.The problem of instantaneously and continuously measuring the velocity of the small-scale slapper is successfully solved by using the technique of laser interference.Compared with the results published on the literatures at home and abroad,data of the experimental and the numerical simulation shown in this paper are more proper to reflect the physical process of electrical explosion driving slapper.One-dimensional numerical simulation of electrical explosion driving slapper is done using the hydrodynamic code.The experimental results are consistent with the computed ones by introducing a power correction factor.In the end,the introduced power correction factor is discussed.
基金China National Nature Science Foundation(Grant No.11872119)Foundation Strengthening Project(Grant No.2020-JCJQ-GFJQ2126-007)+1 种基金Pre-research Program of Armament(Grant No.6142A03202002)China Postdoctoral Science Foundation(Grant No.BX20200046)for supporting this project。
文摘A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including deforming,fracturing,forming a local high-temperature region and igniting,were simulated using a coupled mechanical-thermo-chemical model integrating micro-defects evolution.A novel evaluation method for impact sensitivity is established using the relation between the input kinetic energy and the output energy due to deformation,crushing energy,local hot spot energy and ignition.The effects of impact velocity on sensitivity were analyzed and the critical local ignition impact velocity is determined as 4.0-4.5 m/s.The simulated results show that shear-crack friction heating is the dominant ignition mechanism.The region along the boundary of PBXs sample is the most hazardous regions where ignition first occur.The propagation of stress wave in PBXs causes shear-crack hotspot and bulk temperature exhibiting an approximate 45°direction evolution path,which is the main reason that dominated damage-ignition region transits from the boundary to the central of sample.
文摘爆炸作用下地面建筑目标的破坏分析对制定实战打击策略和工程防护具有重要的实践指导意义。采用LS-DYNA有限元分析软件对已有含填充墙钢筋混凝土(reinforced concrete,RC)框架结构的近区爆炸试验进行复现,充分验证了所采用的精细化数值仿真方法的适用性。结合建筑结构混合单元建模方法,对典型三层含填充墙RC框架结构在典型战斗部(100 kg和200 kg TNT当量)爆炸作用下的动态响应开展了仿真分析,考察了爆炸波在结构内部的传播和结构损伤特性。基于等效单自由度(single-degree-of-freedom,SDOF)方法预测了爆炸荷载作用下框架结构梁、柱、板和填充墙等构件的损伤等级,建立了内爆炸作用下建筑目标的破坏简化分析方法,并通过与精细化数值仿真结果对比检验其适用性。结果表明,在100 kg和200 kg TNT爆炸工况下,精细化数值仿真分析中建筑物整体功能性和结构性毁伤等级均为中度和轻度,等效SDOF简化分析得到的相应毁伤等级与数值仿真结果一致。此外,从各构件的毁伤等级可以看出,相比于板、梁和柱等承重构件,砌体填充墙更易发生破坏,从而导致爆炸波在层内水平方向房间的毁伤破坏范围更大。
文摘In order to study and apply the penetration performance of jetting penetrator charge at long stand-off distance, three jetting penetrator charges(JPC), including spherical cone liner, truncated wide-angle liner and spherical segment liner, are designed. The numerical simulation analysis of the formation, elongation and penetration processes of rod-like jet is conducted by using LS-DYNA software. And the penetrating test is carried out at long stand-off distance. The test results show that the rod-like jet formed by the optimized spherical segment liner can pierce through a 90mm thick 45# steel target at 20 charge diameters(CD) stand-off distance when the charge detonation mode is a central point initiation, and the penetration depth can be up to 1.6CD. It is concluded that, at 20 CD stand-off distance, the penetration performance of JPC with spherical segment liner is the best, that of truncated wide-angle liner takes second place, and that of spherical cone liner is the worst.
文摘To study a new shaped charge of perforator, the jet formation and penetration processes in concrete targets are simulated numerically by using LS-DYNA finite element analysis software. The results show that the cylindrical liner can form jet and most materials on top of liner form the tip of jet, while the others form the tail of jet. The jet has a better continuity, and the ratio of cumulative jet length to the liner diameter can reach to 7.56. Furthermore, the ratio of bore diameter to the liner diameter is from 0.36 and 1, and the ratio of penetration depth to the liner diameter can be up to 5.5.
文摘For shaped charges,LS-DYNA software was adopted to explore the influence of number of initiation points on the penetrator formation numerically.Changed the number of initiation points from 4 to 36,the performance of penetrator under four different kinds of typical charge diameter was analyzed,and the effect of detonation wave pressure on the liner was discussed.The minimum number of initiation points to substitute for annular initiation was obtained for each of four warheads with different charge diameters,and the curve representing the relation between the number of initiation points and charge diameter was found out also by using polynomial fitting.The simulation result provides a reference for the design of multimode warhead.
