We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity penetration.Meanwhile, we define different instances of penetratio...We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity penetration.Meanwhile, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.展开更多
A simplified approximate model considering rod/target material's compressibility is proposed for hypervelocity penetration.We study the effect of shockwaves on hypervelocity penetration whenever the compressibilit...A simplified approximate model considering rod/target material's compressibility is proposed for hypervelocity penetration.We study the effect of shockwaves on hypervelocity penetration whenever the compressibility of the rod is much larger,analogously,and much less than that of the target,respectively.The results show that the effect of shockwaves is insignificant up to 12 km/s,so the shockwave is neglected in the present approximate model.The Murnaghan equation of state is adopted to simulate the material behaviors in penetration and its validity is proved.The approximate model is finally reduced to an equation depending only on the penetration velocity and a simple approximate solution is achieved.The solution of the approximate model is in agreement with the result of the complete compressible model.In addition,the effect of shockwaves on hypervelocity penetration is shown to weaken material's compressibility and reduce the interface pressure of the rod/target,and thus the striking/protective performance of the rod/target is weakened,respectively.We also conduct an error analysis of the interface pressure and penetration efficiency.With a velocity change of 1.6 times the initial sound speed for the rod or target,the error of the approximate model is very small.For metallic rod-target combinations,the approximate model is applicable even at an impact velocity of 12 km/s.展开更多
Using theoretical analysis and mumerical calculation method,the axial adiabatic compression of a spinning non-ideal gas in a cylinder with a smooth surface is investigated.We show that the axial pressure of a spinning...Using theoretical analysis and mumerical calculation method,the axial adiabatic compression of a spinning non-ideal gas in a cylinder with a smooth surface is investigated.We show that the axial pressure of a spinning gas will gradually become lower than that of a stationary gas during continuous compression,even though the initial axial pressure of the spining gas is larger than that of the stationary gas at the same initial temperature and average density.This phenomenon indicates that the axial compressibility of gas is improved in a rotating system.In addition,the effect of different forms of virial coefficient B(T)on pressure and temperature changes in spinning and stationary gases are investigated.Research on the axial compressibility of spinning non ideal gas can provide useful references for fields that require high compression of gases,such as laser fusion,laboratory astrophysics,and Z-pinch experiments.展开更多
文摘We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity penetration.Meanwhile, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.
基金The work was supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(11521202)the National Outstanding Young Scientist Foundation of China(11225213)the Key Subject'Computational Solid Mechanics'of China Academy of Engineering Physics.
文摘A simplified approximate model considering rod/target material's compressibility is proposed for hypervelocity penetration.We study the effect of shockwaves on hypervelocity penetration whenever the compressibility of the rod is much larger,analogously,and much less than that of the target,respectively.The results show that the effect of shockwaves is insignificant up to 12 km/s,so the shockwave is neglected in the present approximate model.The Murnaghan equation of state is adopted to simulate the material behaviors in penetration and its validity is proved.The approximate model is finally reduced to an equation depending only on the penetration velocity and a simple approximate solution is achieved.The solution of the approximate model is in agreement with the result of the complete compressible model.In addition,the effect of shockwaves on hypervelocity penetration is shown to weaken material's compressibility and reduce the interface pressure of the rod/target,and thus the striking/protective performance of the rod/target is weakened,respectively.We also conduct an error analysis of the interface pressure and penetration efficiency.With a velocity change of 1.6 times the initial sound speed for the rod or target,the error of the approximate model is very small.For metallic rod-target combinations,the approximate model is applicable even at an impact velocity of 12 km/s.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.11805061)the Natural Science Foundation of Hunan Province,China(Grant No.2019JJ50072)+1 种基金the Science Challenge Project(Grant No.TZ2016005)the Fundamental Research Funds for the Central Universities.
文摘Using theoretical analysis and mumerical calculation method,the axial adiabatic compression of a spinning non-ideal gas in a cylinder with a smooth surface is investigated.We show that the axial pressure of a spinning gas will gradually become lower than that of a stationary gas during continuous compression,even though the initial axial pressure of the spining gas is larger than that of the stationary gas at the same initial temperature and average density.This phenomenon indicates that the axial compressibility of gas is improved in a rotating system.In addition,the effect of different forms of virial coefficient B(T)on pressure and temperature changes in spinning and stationary gases are investigated.Research on the axial compressibility of spinning non ideal gas can provide useful references for fields that require high compression of gases,such as laser fusion,laboratory astrophysics,and Z-pinch experiments.
