内压对电场下晶内微裂纹演化的影响

基于表面扩散的经典理论及其弱解描述,建立曲率、内压和电场共同作用下的有限单元法,分析了金属材料内部晶内微裂纹的演化过程。对于形态比为β的微裂纹,存在一临界电场值χc,当χ<χc时,微裂纹逐渐圆柱化;当χ>χc时,微裂纹分节为上下或左右两个较小的微裂纹。内压加速有助于微裂纹分节。对于β>1的微裂纹,当β和χ一定时存在一临界内压值qc,当q>qc时,随着电场和内压的增大会率先在裂纹的右端发生裂纹扩展。

The effects of the internal pressure on the evolution of intra-granular microcracks under electric field

Based on the theory of surface diffusion and its weak statement,a finite element method was developed to simulate shape evolutions of intra-granular microcracks due to the internal pressure,electric field and curvature of surface.The results show that there is a critical value χc for a given aspect ratio β.When χ<χc,the microcrack will evolve into a cylinder directly.When χ>χc,the microcrack will be divided into two right-and-left or lower-and-upper microcracks.The microcrack is easy and accelerative to split into two parts with the internal pressure increasing.There is a critical value of pressure qc for β>1 when both β and χ are given.If q>qc,the microcrack propagation firstly appears at its right side with the increasing of χ and q.