微尺度金属单晶应变突变现象的理论模型

Theoretical Models of Strain Burst in Single Crystalline Micropillars

介绍了近期基于特定物理变形机理相继发展的一些应变突变理论模型,重点讲述了微米尺度金属单晶柱体应变突变现象的晶体塑性理论模型.该模型考虑了应变突变幅值的随机性,提出了间歇性塑性流动的边界条件,建立了应变突变发生的判定准则,引入了应变突变持续时间参数,获得了间歇性变形行为的应力-应变关系.有限元计算表明,模型预测结果能够较为合理、准确地描述特征尺寸处于数微米以上的微柱体间歇性塑性流动现象.

Some advances in the theoretical models of strain bursts in micropillar plasticity,especially the crystal plasticity model,were introduced.This model incorporated the observed power-law distribution of strain bursts by the displacement boundary conditions;and the occurrence of strain bursts were judged through the load serrations.By introducing a new parameter of burst time duration in the model,the stress-strain relationship for intermittent plastic flow was derived.Finite element analysis of the crystal plasticity showed that the simulation results could reasonably and accurately describe the intermittent plastic deformation of single crystalline micropillars with sizes larger than several micrometers.