2008 Vol. 28, No. 1
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2008, 28(1): 1-9.
doi: 10.11883/1001-1455(2008)01-0001-09
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Abstract:
An advanced earth penetrating weapon (EPW) penetrates targets at higher velocity and achieves much deeper depth of penetration compared with a common EPW. The present paper introduces the experimental method of high-speed impact fired by artillery and the launch technique of sub-caliber projectile. An experimental study on the deep penetration of reduced-scale advanced EPW was conducted, and the highest impact velocity reached about 1.2 km/s. Analyses on the deformation and failure of projectiles and concrete targets were given in detail. Researched results confirm the feasibility of the concept of advanced EPW.
An advanced earth penetrating weapon (EPW) penetrates targets at higher velocity and achieves much deeper depth of penetration compared with a common EPW. The present paper introduces the experimental method of high-speed impact fired by artillery and the launch technique of sub-caliber projectile. An experimental study on the deep penetration of reduced-scale advanced EPW was conducted, and the highest impact velocity reached about 1.2 km/s. Analyses on the deformation and failure of projectiles and concrete targets were given in detail. Researched results confirm the feasibility of the concept of advanced EPW.
2008, 28(1): 10-16.
doi: 10.11883/1001-1455(2008)01-0010-07
Abstract:
On the non-powder two-stage light gas gun facilities, high-velocity impact experiments were carried out to analyze the effects of bumper lateral size on the damage to Whipple shield and explore the feasibility of using bumper whose size is smaller than that of rear wall on Whipple shield in high-velocity impact tests. The configuration of Whipple shields consisted of 1-mm-thickness bumpers and 3-mm-thickness rear wall with 10-cm space between the bumper and the rear wall. The bumpers were 2A12 aluminum square plates with different side lines such as 8, 12, 16 and 20 cm. The rear wall was 5A06 Aluminum square plate with 20-cm side lines. All tests were performed by shooting aluminum projectile 4 mm in diameter at the velocity ranging from 1.45 to 1.71 km/s. Test results show that the mean velocity of 6 projectiles impacting on the Whipple shields is independent of bumper size when the perforation percentage of rear wall was over 80. It is found that the diameters of perforation holes both in front and in back of bumper are independent of bumper size too. However, the deflection on the bumper surface is dependent on bumper size obviously.
On the non-powder two-stage light gas gun facilities, high-velocity impact experiments were carried out to analyze the effects of bumper lateral size on the damage to Whipple shield and explore the feasibility of using bumper whose size is smaller than that of rear wall on Whipple shield in high-velocity impact tests. The configuration of Whipple shields consisted of 1-mm-thickness bumpers and 3-mm-thickness rear wall with 10-cm space between the bumper and the rear wall. The bumpers were 2A12 aluminum square plates with different side lines such as 8, 12, 16 and 20 cm. The rear wall was 5A06 Aluminum square plate with 20-cm side lines. All tests were performed by shooting aluminum projectile 4 mm in diameter at the velocity ranging from 1.45 to 1.71 km/s. Test results show that the mean velocity of 6 projectiles impacting on the Whipple shields is independent of bumper size when the perforation percentage of rear wall was over 80. It is found that the diameters of perforation holes both in front and in back of bumper are independent of bumper size too. However, the deflection on the bumper surface is dependent on bumper size obviously.
2008, 28(1): 17-22.
doi: 10.11883/1001-1455(2008)01-0017-06
Abstract:
The characteristic of shaped charge with jetting projectiles formed by two types of liner structure and their penetration capability to concrete were studied by X-ray flash radiographs and penetration effect test. The penetration parameters of different charges were measured and compared for semi-infinite and multi-layer concrete targets respectively. Results show that two types of liner structure can form ideal shaped charge with jetting projectile and generate penetration holes with both reasonable depth and width in the concrete targets.
The characteristic of shaped charge with jetting projectiles formed by two types of liner structure and their penetration capability to concrete were studied by X-ray flash radiographs and penetration effect test. The penetration parameters of different charges were measured and compared for semi-infinite and multi-layer concrete targets respectively. Results show that two types of liner structure can form ideal shaped charge with jetting projectile and generate penetration holes with both reasonable depth and width in the concrete targets.
2008, 28(1): 23-27.
doi: 10.11883/1001-1455(2008)01-0023-05
Abstract:
对自行研制的电磁加速等离子体喷涂技术（Electromagnetically accelerated plasma spraying,EMAPS）从原理上进行了分析，建立了等离子体的运动方程，得到了脉冲电流作用下等离子体上任一点的磁感应强度的计算公式和等离子体及它所压缩周围空气的速度表达式；并分析了粉末粒子与冲击波的相互作用，得到了粉末粒子的喷涂速度与喷枪长度、粉末粒子直径以及电流强度之间的关系；同时还对喷枪的长度进行了设计。
对自行研制的电磁加速等离子体喷涂技术（Electromagnetically accelerated plasma spraying,EMAPS）从原理上进行了分析，建立了等离子体的运动方程，得到了脉冲电流作用下等离子体上任一点的磁感应强度的计算公式和等离子体及它所压缩周围空气的速度表达式；并分析了粉末粒子与冲击波的相互作用，得到了粉末粒子的喷涂速度与喷枪长度、粉末粒子直径以及电流强度之间的关系；同时还对喷枪的长度进行了设计。
2008, 28(1): 28-31.
doi: 10.11883/1001-1455(2008)01-0028-05
Abstract:
An exploding foil initiator was designed. The question of the velocity measurement of small-size flyer was effectively solved by adopting the measures as follows: (1) accurately control the orientation of bridge foil, flyer and barrel; (2) put a thin aluminum film on the surface of the flyer and the mass of the aluminum film can be neglected compared with that of the flyer; (3) reasonably choose the work distance of the VISAR probe and the fringe constants related with the time delay of interference cavity; (4) shield measuring system and use the optical filter. The velocity measurement results of the flyers with two different sizes of 0.7 mm0.025mm and 0.5 mm0.025 mm were given. Compared with the results by Weingart R C, the obtained results after taking the measures above are with good signal-to-noise ratios, and can reflect the physical essence of exploding foil initiator driving flyer.
An exploding foil initiator was designed. The question of the velocity measurement of small-size flyer was effectively solved by adopting the measures as follows: (1) accurately control the orientation of bridge foil, flyer and barrel; (2) put a thin aluminum film on the surface of the flyer and the mass of the aluminum film can be neglected compared with that of the flyer; (3) reasonably choose the work distance of the VISAR probe and the fringe constants related with the time delay of interference cavity; (4) shield measuring system and use the optical filter. The velocity measurement results of the flyers with two different sizes of 0.7 mm0.025mm and 0.5 mm0.025 mm were given. Compared with the results by Weingart R C, the obtained results after taking the measures above are with good signal-to-noise ratios, and can reflect the physical essence of exploding foil initiator driving flyer.
2008, 28(1): 33-37.
doi: 10.11883/1001-1455(2008)01-0033-05
Abstract:
The modified dynamic damage model for modeling penetration into concrete or reinforced concrete was implemented into the three-dimensional transient dynamic explicit finite element code LS-DYNA with the user-defined material function. The model includes two parts: tension part described by TCK model indicating the strain rate sensitivity to tension process and the compression part described by HJC model. This model considers tension damage, compressive damage, strain softening, hydrostatic pressure and strain rate effects. By using the propsoed method, simulation on yawed penetration was carried out and compared with the experimental results. In simulation of penetration process the deformation and the velocity variation of the projectile and damage of the target were analyzed. Calculated results show that the model can predict the process of the yawed penetration into concrete well with the test data.
The modified dynamic damage model for modeling penetration into concrete or reinforced concrete was implemented into the three-dimensional transient dynamic explicit finite element code LS-DYNA with the user-defined material function. The model includes two parts: tension part described by TCK model indicating the strain rate sensitivity to tension process and the compression part described by HJC model. This model considers tension damage, compressive damage, strain softening, hydrostatic pressure and strain rate effects. By using the propsoed method, simulation on yawed penetration was carried out and compared with the experimental results. In simulation of penetration process the deformation and the velocity variation of the projectile and damage of the target were analyzed. Calculated results show that the model can predict the process of the yawed penetration into concrete well with the test data.
2008, 28(1): 38-41.
doi: 1.011883/1001-1455(2008)01-0038-06
Abstract:
A new reaction rate function model was developed to represent explosive initiation process based on Kim elastic-plastic pore collapse hot spot reaction model by analyzing explosive reaction rate function models. Parameters of the developed reaction rate function model were determined by using genetic algorithms as well as one dimensional Lagrangian shock to detonation pressure curv. The new model was validitied by comparision of simulation results between the new model and the Forest-Fire reaction rate function model. PBX-9404 shock initiation and detonation process was numerically simulated by embedding the new reaction rate function model into finite element analysis program. Influences of porosity and grain size change on initiation and detonation behaviours of explosive were analyzed by the numerical simulation results in the event that explosive was loaded by applied shock.
A new reaction rate function model was developed to represent explosive initiation process based on Kim elastic-plastic pore collapse hot spot reaction model by analyzing explosive reaction rate function models. Parameters of the developed reaction rate function model were determined by using genetic algorithms as well as one dimensional Lagrangian shock to detonation pressure curv. The new model was validitied by comparision of simulation results between the new model and the Forest-Fire reaction rate function model. PBX-9404 shock initiation and detonation process was numerically simulated by embedding the new reaction rate function model into finite element analysis program. Influences of porosity and grain size change on initiation and detonation behaviours of explosive were analyzed by the numerical simulation results in the event that explosive was loaded by applied shock.
2008, 28(1): 44-49.
doi: 10.11883/1001-1455(2008)01-0044-06
Abstract:
A theoretical model of 3D transient heat conduction in a multilayer cylinder irradiated by high power laser was developed in which the action of air flow around the exterior surface and the compatibilities of both temperature and heat transfer at the interfaces were taken into consideration. By using eigenvalue method and Bessel functions, the closed solutions of 3D transient temperature field in each layer of the cylinder were deduced. As a simple example, the axisymmetric transient temperature field was analytically computed and the effect rules of some parameters such as surface heat-exchange coefficient on the temperature field were obtained. The theoretical solutions of transient temperature field can be further used to analyze 3D thermo-mechanical effects of multilayer cylinders and can also be used as basis of modification of numerical models in related numerical simulations.
A theoretical model of 3D transient heat conduction in a multilayer cylinder irradiated by high power laser was developed in which the action of air flow around the exterior surface and the compatibilities of both temperature and heat transfer at the interfaces were taken into consideration. By using eigenvalue method and Bessel functions, the closed solutions of 3D transient temperature field in each layer of the cylinder were deduced. As a simple example, the axisymmetric transient temperature field was analytically computed and the effect rules of some parameters such as surface heat-exchange coefficient on the temperature field were obtained. The theoretical solutions of transient temperature field can be further used to analyze 3D thermo-mechanical effects of multilayer cylinders and can also be used as basis of modification of numerical models in related numerical simulations.
2008, 28(1): 50-56.
doi: 10.11883/1001-1455(2008)01-0050-07
Abstract:
Some liner and explosive charge configurations have evolved because of the constrains and requirements of the particular weapon system (typically smart munition, multipurpose shaped charge warhead and tandem warhead). Recent developments in shaped charge technology and application are reviewed in this paper. Shaped charges include not only traditional shaped charges but also explosively formed projectile and high-velocity rod-shaped projectile. A discussion about the development trend and potential application of shaped charge is given.
Some liner and explosive charge configurations have evolved because of the constrains and requirements of the particular weapon system (typically smart munition, multipurpose shaped charge warhead and tandem warhead). Recent developments in shaped charge technology and application are reviewed in this paper. Shaped charges include not only traditional shaped charges but also explosively formed projectile and high-velocity rod-shaped projectile. A discussion about the development trend and potential application of shaped charge is given.
2008, 28(1): 57-62.
doi: 10.11883/1001-1455(2008)01-0057-05
Abstract:
The penetration ballistics of a high-speed-rotating bullet on the moving sheet-metal plate is numerically studied by using of LS-DYNA. Because of the high-speed motion of the sheet-metal plate, the bullet direction will turn aside, and its trajectory becomes deflective. A method is provided to calculate the bullet turning angle. In the simulation, the bullet moving speed is 300 m/s, rotating speed is 0, 3 600 and 6 370 r/s. The sheet-metal plate moving speed is 0, 40 and 80 m/s. The head of bullet is a hemispheroid with the diameter of 7.62 mm, the sheet-metal plate is a steel sheet with the diameter of 80 mm and the thickness of 2 mm. The Johnson-Cook material model is introduced to characterize the material effects in strain hardening, strain rate hardening and thermal softening. The bullets final velocity, its turning angle and the ballistic trajectorys offset on various bullets rotating speeds and the moving speeds of steel sheets are analyzed by the simulated results.
The penetration ballistics of a high-speed-rotating bullet on the moving sheet-metal plate is numerically studied by using of LS-DYNA. Because of the high-speed motion of the sheet-metal plate, the bullet direction will turn aside, and its trajectory becomes deflective. A method is provided to calculate the bullet turning angle. In the simulation, the bullet moving speed is 300 m/s, rotating speed is 0, 3 600 and 6 370 r/s. The sheet-metal plate moving speed is 0, 40 and 80 m/s. The head of bullet is a hemispheroid with the diameter of 7.62 mm, the sheet-metal plate is a steel sheet with the diameter of 80 mm and the thickness of 2 mm. The Johnson-Cook material model is introduced to characterize the material effects in strain hardening, strain rate hardening and thermal softening. The bullets final velocity, its turning angle and the ballistic trajectorys offset on various bullets rotating speeds and the moving speeds of steel sheets are analyzed by the simulated results.
2008, 28(1): 62-66.
doi: 10.11883/1001-1455(2008)01-0062-05
Abstract:
The material and structure of a crisp airproof lid was determined. Numerical calculations on the crisp airproof lid impacted by rocket projectile and fired-gas streams were carried out by the finite element method, and simulated results were experimentally validated. Fracture effects and performances of the airproof lid were obtained. Researched results show as follows： (1) The airproof lid can fracture along the preset slot, satisfies the reliability of the fuze and doesnt influence the natural work of the rocket. (2)Impact forces of fired-gas streams have so little effect on the airproof lid that the airproof lid cannt be destroyed.
The material and structure of a crisp airproof lid was determined. Numerical calculations on the crisp airproof lid impacted by rocket projectile and fired-gas streams were carried out by the finite element method, and simulated results were experimentally validated. Fracture effects and performances of the airproof lid were obtained. Researched results show as follows： (1) The airproof lid can fracture along the preset slot, satisfies the reliability of the fuze and doesnt influence the natural work of the rocket. (2)Impact forces of fired-gas streams have so little effect on the airproof lid that the airproof lid cannt be destroyed.
2008, 28(1): 67-74.
doi: 10.11883/1001-1455(2008)01-0067-08
Abstract:
The kinematic relational expression in the near zone of an explosion was introduced. Energy consumption in elastic medium was considered when the surface of radial crack was formed. By analyzing the distortion and failure for the near zone of the explosion, the dynamics calculation sketch was proposed by adopting different main stress functions. Through researching the characteristic of each zone development and the change relation, the coefficients of compression and failure radii about RPC concrete under contact explosion were obtained. Comparison between the test results and the empirical formulas shows the practicability and reliability of the proposed formula.
The kinematic relational expression in the near zone of an explosion was introduced. Energy consumption in elastic medium was considered when the surface of radial crack was formed. By analyzing the distortion and failure for the near zone of the explosion, the dynamics calculation sketch was proposed by adopting different main stress functions. Through researching the characteristic of each zone development and the change relation, the coefficients of compression and failure radii about RPC concrete under contact explosion were obtained. Comparison between the test results and the empirical formulas shows the practicability and reliability of the proposed formula.
2008, 28(1): 75-79.
doi: 10.11883/1001-1455(2008)01-0075-05
Abstract:
To reduce the CPU time cost by reactive flow calculations, the direct integral (DI) of chemical reactions is replaced by an in situ adaptive tabulation (ISAT) method. The ISAT method with two enlargement criterions of calculated error is used to numerically simulate the gaseous detonation process for H2/O2 mixture. The calculated pressure, temperature and mass fractions of species by ISAT are compared with those by DI to verify the accuracy of the ISAT. The computed CPU time and find, enlargement and record process of data in ISAT, which represent the calculated efficiency of ISAT, are discussed. Compared with those by DI method, the calculated errors by ISAT method are no more than 3% and the calculated efficiency of ISAT is improved 8 times. It is concluded that the ISAT method shows the advantage in the calculations of detonation wave propagation.
To reduce the CPU time cost by reactive flow calculations, the direct integral (DI) of chemical reactions is replaced by an in situ adaptive tabulation (ISAT) method. The ISAT method with two enlargement criterions of calculated error is used to numerically simulate the gaseous detonation process for H2/O2 mixture. The calculated pressure, temperature and mass fractions of species by ISAT are compared with those by DI to verify the accuracy of the ISAT. The computed CPU time and find, enlargement and record process of data in ISAT, which represent the calculated efficiency of ISAT, are discussed. Compared with those by DI method, the calculated errors by ISAT method are no more than 3% and the calculated efficiency of ISAT is improved 8 times. It is concluded that the ISAT method shows the advantage in the calculations of detonation wave propagation.
2008, 28(1): 80-85.
doi: 10.11883/1001-1455(2008)01-0080-06
Abstract:
Rigid and fluid interaction problems are solved by the level set method with the RKDG method. The system of the Eluer equations are solved by the RKDG method while the level set equation which describes the motion of the interface are solved by high-resolution WENO finite difference scheme. The extended ghost fluid method is used to deal with the solid and fluid boundary. Numerical tests on two dimensional flow are carried ou and satisfactory results are obtained. This method can be extended to three dimensional questions since no mesh modification is needed.
Rigid and fluid interaction problems are solved by the level set method with the RKDG method. The system of the Eluer equations are solved by the RKDG method while the level set equation which describes the motion of the interface are solved by high-resolution WENO finite difference scheme. The extended ghost fluid method is used to deal with the solid and fluid boundary. Numerical tests on two dimensional flow are carried ou and satisfactory results are obtained. This method can be extended to three dimensional questions since no mesh modification is needed.
2008, 28(1): 86-91.
doi: 10.11883/1001-1455(2008)01-0086-06
Abstract:
The processes for the jet penetrating at different impact angles into a semi-infinite target with V-shaped sandwich explosive structure are simulated numerically by using the 3D finite element code (LS-DYNA). Simulated results are compared with the corresponding cases without sandwich explosive structure. After ignition of the V-shaped sandwich explosive，the active face and back plates have great disturbance and cutting effect on the jet, which make the jet deviated, bended and the penetration capability decreases about 30％～90％. Disturbance of V-shaped sandwich explosive structure on jet increases with the increase of the impact angle. Variations of V-shaped angles cant disturb observably penetration of jet.
The processes for the jet penetrating at different impact angles into a semi-infinite target with V-shaped sandwich explosive structure are simulated numerically by using the 3D finite element code (LS-DYNA). Simulated results are compared with the corresponding cases without sandwich explosive structure. After ignition of the V-shaped sandwich explosive，the active face and back plates have great disturbance and cutting effect on the jet, which make the jet deviated, bended and the penetration capability decreases about 30％～90％. Disturbance of V-shaped sandwich explosive structure on jet increases with the increase of the impact angle. Variations of V-shaped angles cant disturb observably penetration of jet.
2008, 28(1): 92-96.
doi: 10.11883/1001-1455(2008)01-0092-05
Abstract:
According to safety assessment of structures subjected to blasting-induced ground excitations, a time-history analysis method was proposed to assess safety of blast seismic waves. The model of structural elasto-plastic dynamic analysis based on precise integration algorithm was established. The precise integration codes of blast seismic structural elasto-plastic responses were programmed and the precision of algorithm was validated. Comparisons of calculted results with elastic and elasto-plastic analysis show that their displacement curves are similar but numerical results are different. The appropriate restoring force model and elasto-plastic analysis are suggested to be used to simulate structural dynamic response to blasting-induced ground excitations and assess blasting seism waves.
According to safety assessment of structures subjected to blasting-induced ground excitations, a time-history analysis method was proposed to assess safety of blast seismic waves. The model of structural elasto-plastic dynamic analysis based on precise integration algorithm was established. The precise integration codes of blast seismic structural elasto-plastic responses were programmed and the precision of algorithm was validated. Comparisons of calculted results with elastic and elasto-plastic analysis show that their displacement curves are similar but numerical results are different. The appropriate restoring force model and elasto-plastic analysis are suggested to be used to simulate structural dynamic response to blasting-induced ground excitations and assess blasting seism waves.
