内压对电场下晶内微裂纹演化的影响

摘要

Based on the theory of surface diffusion and its weak statement,a finite element method was de- veloped 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 When χ〈χc, the microcrack will evolve into a cylinder directly. W vided into two right-and-left or lower-and-upper microcracks. The split into two parts with the internal pressure increasing. There is when lncrea hen χ〉 χc, the a given aspect ratioβ. microcrack will be di- microcrack is easy and accelerative to a critical value of pressure qc for β〉1 bothβ and χ are given. If q〉qc ,the microcrack propagation firstly appears at its right side with the sing of2χ and q.%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。