中文摘要：

基于Y/G及G/B为常数的假设,构建了7种高压与高应变率本构模型,采用所构建的7种本构模型对于高导无氧铜（OFHC）的平面冲击波试验进行了数值模拟。结果表明,平面冲击波载荷下OFHC的屈服强度对于压力、密度、温度以及塑性应变的依赖性是本构描述的关键。由Hopkinson试验取得的OFHC高应变率本构模型,并不适合描述平面冲击波载荷下的本构特性。采用层裂过程中的应力松弛方程,建立了一种基于空穴聚集的延性层裂模型,依赖于应力的层裂空隙度方程被耦合计及损伤的总体控制方程。数值模拟了多种材料的平面冲击致层裂试验。采用Hopkinson拉伸装置和一种基于一级气体炮的高速冲击拉伸断裂装置,研究了OFHC铜杆在一系列冲击拉伸速度下的断裂。一种受单轴冲击拉伸荷载的中心含椭球空穴的样本体积单元用于数值模拟空穴的增长与失稳,以空穴形状演化为判据,比较了空穴失稳时的单元平均径向应变与无凹槽杆的冲击断裂应变。

英文摘要：

Assumed Y/G = constant and G/B = constant, seven constitutive models for the ductile materials at high pressure and high strain rates are constructed, respectively, where Y denotes the yield strength, G the shear modulus, and B the bulk modulus, and are applied in the numerical simulations of planar shock test for oxygen-free high conductive （OFHC） copper. The results indicate that the pressure, density, temperature and plastic strain dependences of the yield strength for OFHC copper subjected to planar shock loading are essential to the constitutive descriptions. It seems that the strength models of OFHC copper obtained from SHPB test and/or torsion test are not suitable to describe the constitutive properties under planar shock loading. The stress relaxation equations in the spallation process are adopt- ed and a void coalescence-based spallation model is presented in which the equations for stress dependent spall porosities are combined with the governing equations. The spallation tests for some materials under planar shock are numerically simulated by using the presented void coalescence-based spallation models. A series of tensile tests for OFHC copper at different tensile velocities are carried out on the Hopkinson tensile bar in tension mode and a novel facility for high speed tensile test based on a single gas gun sysem. A representative volume element is modeled by circular cylinder with containing a ellipsoid void at its center and dynamically loaded by single axis velocity at the top of the cell. The processes from the void growth through void instability in OFHC copper are simulated numerically. The conditions of dynamic void instability are discussed and a criterion based on the void shape evolution is presented. The average radial strains of the cell at void instability are compared with the experimental localized fracture strains of OFHC copper bars under single axis impact tension.