金属薄膜裂纹扩展的分子动力学研究

研究了冲击载荷作用下金属薄膜表面裂纹扩展的微观机制，采用分子动力学方法对Cu薄膜进行模拟计算，求得冲击载荷作用下带有表面裂纹模型的系统动能、应力、应变及微观结构变化图.当系统从压应力转变为拉应力状态时，裂纹上的原子获得较大动能，裂纹尖端原子开始发生溅射，继而晶格内部出现空位.当拉应力达到364385MPa时，空位扩大形成裂尖钝劈现象，裂纹发生扩展.结果表明:在高速冲击载荷作用下，金属薄膜裂纹扩展主要原因是系统能量和应力的变化使得微裂纹尖端出现钝劈损伤.

Molecular Dynamics Study of Crack Extension of Metal Film

The microscopic mechanism of metal film crack extension under impact loading was investigated. Molecular dynamics method was adopted to simulate Cu metal film， and the system kinetic energy， stress， strain and microstructure charts were obtained with surface cracks under impact loading. When the system stress shifted from compressive stress to tensile stress， the atoms on the crack got large kinetic energy， and atoms on crack tips began to sputter， then vacancies appeared in the crystal lattice. When tensile stress reached 364385MPa， lattice vacancies extended to blunt cuts， and the crack grew. The results show that the change of the system energy and stress causes blunt cut damage to the micro crack tips， which is the main reason of metal film crack extension under high speed impact loading.