Spall damage of copper under supported and decaying shock loading
Spall damage of copper under supported and decaying shock loading
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DOI：
10.1063/1.3271414
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发表时间：
2009-12-15
影响因子：
3.2
通讯作者：
Tonks, Davis L.
中科院分区：
文献类型：
--
作者：
Luo, Sheng-Nian;Germann, Timothy C.;Tonks, Davis L.
利用分子动力学模拟方法研究了铜单晶在支撑冲击波（方波）和衰减冲击波（泰勒波）作用下的层裂损伤。改变靶板厚度比R（靶板厚度固定）和撞击速度，可以产生具有不同脉冲形状、持续时间和强度的方波和泰勒波，它们与层裂前损伤、层裂强度和层裂损伤有很好的相关性。在相同的冲击速度下，Taylor波加载的层裂强度比支撑冲击加载的层裂强度高，而在相同的自由表面峰值速度下，两种加载的层裂强度相似，但Taylor波加载的层裂损伤比方波加载的层裂损伤小。空洞形核之前的塑性和固态无序。在层裂早期，多个层裂事件似乎是相互独立的。在应用声学方法由自由表面速度历程推求层裂强度时，应考虑适当的声速和R。该方法对大R（泰勒波）比小R（方波）更有效。然而，这种方法可能会大大低估两种类型的负载的应变率。
We investigate spall damage of single crystal Cu under supported (square) and decaying (Taylor wave) shock wave loading with molecular dynamics simulations. Varying the target-to-flyer plate thickness ratio R (with target thickness fixed) as well as the impact velocity induces square and Taylor waves with different pulse shapes, durations and strengths, which are well correlated with prespall damage, spall strength, and spall damage. Taylor wave loading results in higher spall strength than the supported shock loading at the same impact velocities, and the spall strength can be similar for both loadings with the same peak free surface velocities, while Taylor wave loading induces less spall damage than square wave loading. Void nucleation is preceded by plasticity and solid-state disordering. Multiple spall events appear to be independent of each other at the early stage of spallation. In applying the acoustic method for deducing the spall strength from the free surface velocity histories, one should consider the proper sound speed and R. The method works better for large R (Taylor waves) than for small R (square waves). However, this method may significantly underestimate strain rate for both types of loading.