A Micropillar Compression Simulation by a Multiscale Plastic Model Based on 3-D Discrete Dislocation Dynamics

作者：Liu Z L; Liu X M; Zhuang Z^*; Gao Y; You X C

来源：International Journal for Multiscale Computational Engineering, 2009, 7(3): 217-225.

DOI：10.1615/intjmultcompeng.v7.i3.50

• multiscale
• discrete dislocation plasticity
• finite element method
• micropillar compression
• dislocation starvation

In this article, a microcompression test for the Cu single-crystal micropillar containing an initial dislocation network is simulated by a multiscale computational model. This model combines a 3-D discrete dislocation dynamics (DDD) approach and a finite element method (FEM). The DDD code calculates the plastic strain induced by the slip of dislocation lines in a finite single crystal, which serves as a substitute for the constitutive relationship used in the conventional continuum mechanics. On the other hand, the displacement and stress field in crystal are calculated by FEM. In our simulations, the compression stress-strain curve Of the micropillars can be divided into three distinct stages: a linear hardening stage, a normal plastic strain hardening stage, and a dislocation starvation hardening stage, accompanying a rather high stress level. The simulation results show that this atypical mechanical behavior is related with the effective "spiral dislocation sources" operation at the second stage and the dislocations escape from the free surfaces at the third stage. At last, the micropillar is almost dislocation-free, as observed in recent experiments.

• 出版日期2009
• 单位清华大学