冲击加载下孔洞贯通的微观机理研究

利用分子动力学方法计算模拟了沿〈100〉晶向冲击加载下单晶铜中双孔洞的贯通过程.发现孔洞周围发射剪切型位错环是孔洞塌缩和增长的原因.在拉伸阶段，孔洞首先分别独立增长，随后其周围塑性变形区开始交叠和相互作用，最后两个孔洞开始直接贯通.这种贯通模式和实验对延性材料中孔洞贯通过程的显微观察结果一致.对四种不同θ值（θ为两个孔洞中心连线与冲击加载方向之间的夹角）的模型分别进行了计算模拟，发现在相同的冲击加载强度下，θ＝0°和θ＝30°的孔洞之间没有相互贯通； 关键词： 纳米孔洞 分子动力学 冲击加载 贯通

Microscopic mechanism of void coalescence under shock loading

The influence of void configuration on void coalescence in single crystal copper under shock loading along ［100］ direction has been investigated with molecular dynamics （MD） simulation. The results reveal that the voids collapse and grow by means of emission of shear dislocation loops. In the tension stage, the voids first grow independently, then the plastic zone around the voids begin to interact and overlap, leading to the void coalescence. The pattern of void coalescence observed in our simulations coincides with the microscopic experimental results. We calculated for four different configurations, characterized by the angle （θ） formed by shock direction and the line connecting the two centers of voids, and found that among the four configurations，the coalescence of the voids prefers to occur where θ is 60°. Based on the resolved shear stress model around the void, we can clearly explain the simulation results.