三角波加载下金属铝动态破坏现象的微观模拟

摘要

Employing an embedded-atom-method potential and molecular dynamics simulations, we have simulated the microscopic process and dynamical properties of the dynamic failure of metal Al specimens under triangular wave loading. The microstructure evolution of the sample is analyzed using the central symmetry parameter, while the difference of morphology between non molten and molten states is also explained. The pressure profiles were calculated based on the virial theorem, and the results show that the tensile strength of the material is decreased considerably in its molten state. Using the simulation results for different impact velocities, we discuss the variation of morphology and density distribution, from which the change of damage depth in the process from non molten to molten states is obtained. Our simulations also suggest that: the tensile strength of material derived from acoustic approximation is distinctively higher than the peak of internal stress from virial theorem for the melted state.%　　采用嵌入原子势模型和分子动力学方法，模拟研究了三角波加载下金属铝动态破坏的微观过程和动力学性质。根据原子中心对称参数变化给出了样品微结构演化过程，解读了熔化前后破坏过程的形态差异；基于Virial定理统计了样品中压力和温度等力学量波形，分析了熔化前后材料的强度变化。通过不同碰撞速度的模拟，讨论了破碎区内物质形态和密度分布的变化，给出了材料破坏深度的变化规律。研究还发现，熔化后材料的动态拉伸强度已显著降低，而此时由声学近似推算的材料拉伸强度已明显高于内部应力直接计算结果。