金属材料再加载“准弹性”响应的实验验证

 用波反射法设计了一维应变冲击实验，由时间分辨VISAR系统（Velocity Interferometer System for Any Reflection）测量了镁铝合金的冲击-再加载速度波剖面。结果显示，在排除窗口反射稀疏波的情况下，从24 GPa冲击态开始的再加载存在明显的“准弹性”响应，证实了Asay等报道的二次压缩“准弹性”响应是材料本征特性。并对金属材料高压本构参量实验测量的关键技术进行了探讨。

Experimental Validation of "Quasi-Elastic" Response of Metal during Reloading Process

An uniaxial strain experiment of a magnesium alloy(brand:MB2) disk under shock loading and reloading was designed by a wave reflection method.Time-resolved interfacial velocity between the MB2 sample and a LiF window was measured by a VISAR(Velocity Interferometer System for Any Reflection) probe during the dynamic loading.Our result reveals that,under a better test condition with no rarefaction disturbing from the window(present in previous experiments),an elastic-plastic response does exist in the process of reloading from an initial shock state(24 GPa).This validates that the "quasi-elastic" response of metals under recompression,which had been reported by Asay et al,is an intrinsic character of the materials.Some discussion about the experimental technique for measuring the constitutive parameters of metals at high pressures will be presented also.