动态拉伸加载下高纯铝破坏的临界行为

以高纯铝(99.999%)作为延性金属的模拟材料，在一级气体炮上开展了一维应变平面冲击波加载实验.通过对不完全层裂的回收样品进行细观微损伤统计分析，讨论了高纯铝动态破坏时发生的临界行为.文中定义拉伸应力和拉伸作用时间的乘积为拉伸(作用)冲量，统计发现：随着拉伸冲量的增加，样品中的损伤呈现明显的临界行为特征：当拉伸冲量较小时，损伤以线性方式缓慢增长，当拉伸冲量足够大，且超过一定的临界阈值以后，损伤以幂指数形式快速增长.初步实验结果表明，高纯铝的拉伸冲量临界阈值约为0.34GPa·μs，对应的损伤临界值约为0.12.

Critical fracture behavior of high purity aluminum under impact loading

One-dimensional strain impact experiments were performed for the high purity aluminum (HPA) (99.999%). The spall characteristics of HPA in dynamic tensile fracture have been discussed according to the quantitative metallographic analysis of the shock recover of samples. By defining the product of the tensile stress and the time as a parameter called tensile impulse (I), the statistic resultsindicate that an obvious critical behavior for the damage evolution appears with the increasing of I. When the I is low, the damage grows slowly with alinear increment. Once the I reaches a critical value, the damage grows rapidly and an exponential increase is observed. Our preliminary results indicate that the critical value of I for HPA is about 0.34 GPa·μs and the corresponding critical damage is about 0.12.