Effect of initial temperature on impact-induced spalling behavior in single-crystal aluminum studied by molecular dynamics simulations

Abstract

Spallation is a typical dynamic fracture mode under shock loading and has attracted the attention of most researchers. However, due to the difficulty in measuring temperature in dynamic experiments, the effect of initial temperature on spalling response has been rarely investigated. Molecular dynamics simulation perfectly corresponds to the short duration and high strain rate of the spalling process. Therefore, in this work, molecular dynamics simulations are used to study the spalling reaction of single-crystal aluminum at different initial temperatures. The research has shown that the evolution of spallation is related to dislocation and hole nucleation. First, the spall strength of the material decreases as initial temperature increases, while the dislocation density gradually increases. However, when the initial temperature increases to 750 K, the dislocation density decreases. Then, the number of holes and the degree of damage change as initial temperature increases. However, at the low impact strength (v < 2.0 km/s), the changes in the number of holes and the degree of damage are highly dependent on the initial temperature. In the case of high impact strength, the opposite is true. Finally, the thermodynamic path of the material during impact compression is studied. It is found that melting may occur during compression, release or tension, and damage stages, depending on the initial temperature and impact strength. The discovery and research of these systems have laid a solid foundation for subsequent studies.

Molecular dynamics study of temperature effects on shock response and plastic deformation mechanism of CoCrFeMnNi high-entropy alloys

“…利 用多面体模板匹配(polyhedral template matching, PTM)方法 [40] 进行结构识别, 均方根偏差(root-mean-square deviation)选取为0.1 [24] . 使用OVITO [41] 进行后处理及可视化显示. [24] 也发现了类似的 在较强冲击下高熵合金内部剪切应力P sh 出现负 值的现象.…”