冲击压缩下非均质脆性固体的弛豫破坏研究

通过平板冲击实验研究了富含微缺陷的非均质脆性固体的冲击压缩响应特性.选取“强角闪石化橄榄二辉岩”作为样品材料，利用激光速度干涉仪测量样品后自由面的速度历史，在冲击加载应力远低于样品材料Hugoniot弹性极限的条件下，观测到了表征破坏波出现的再加载信号，并且该破坏波的速度远大于玻璃中破坏波的速度，以接近于冲击波的速度在样品内向前传播，其形成机理与玻璃样品中的破坏机理不同，称之为“就位扩展机理”.采用同一冲击加载应力(～3.9GPa)作用于不同厚度的样品,获得了破坏波穿过样品的运动过程，确定出样品中破坏波的轨迹线近似为一条不过原点的直线，相应的产生此破坏波的弛豫时间约为0.5 μs.

A delayed failure of inhomogenous brittle material under shock wave compression

The failure property of inhomogenous brittle materials under plate impact experiment has been studied by using AOW (amphibolized olivine websterite) rock as a representative sample. A small recompression signal was observed in the VISAR record of the rear free surface velocity at shock stress much below σ_HEL, indicating the generation of the failure wave. By using samples with different thickness but impacted at approximately the same shock stress of 3.9 GPa, the trajectory of the propagation of the failure wave through the stressed sample has been determined. The failure wave is generated with a delay time of about 0.5 μs behind the shock wave front, and propagates into the stressed material with a velocity comparable to that of the shock wave front. A physical mechanism involving the “in situ activation and growth” of the originally existing micro-cracks due to the local shear stress under shock wave compression is suggested for these observations.