加载速率和点缺陷对裂纹扩展影响的原子级模拟

Molecular-dynamics simulation of influence of loading rate and defects on crack growth

为了研究纳米尺度下材料裂纹扩展的微观机理及加载速率和点缺陷对裂纹扩展的影响,以金属银为研究对象,用分子动力学方法对具有初始裂纹的银在I型加载下的裂纹扩展进行了模拟研究.对模拟结果的研究分析表明,裂纹扩展的断裂应力随着加载速率的增大而增大;对某一固定速率的加载,裂纹尖端原子的更新速率逐渐增大;带点缺陷的材料在I-型加载下会导致空位和微孔洞的出现,结果使裂纹的扩展出现了非连续的跃变现象.

In order to understanding the atomistic details of crack growth in nanophase materials and the effects of loading speed and point defects for it,the simulation of molecular dynamics(MD) of the crack growth in metal Ag which undergoing I type loading and having initial crack have been performed.It is showed that the critical value of external force for crack growth increased as the loading speed increasing.For a constant loading speed,the refresh rates of the crack tip atoms gradually augment.In this loading process,vacancy will produced when point defects exist in metal samples,this mechanics leads to the jump of the original continual crack expanse.