Modeling the Low Cycle Fatigue in Copper Single Crystal: Multiscale Dislocation Dynamics Simulations

Abstract

ABSTRACTMultiscale dislocation dynamics plasticity (MDDP) model is used to investigate the evolution of dislocation microstructure in copper single crystals subjected to low cycle fatigue loading. Half cycle total plastic strain simulations are carried out at strain amplitudes ranging from 1×10-3 to 8×10-3. The initial hardening is investigated and the micro-structural cause behind it is presented. In addition, the loading history is presented and the effect of the initial micro-structure and dislocation distribution on the hardening behavior is studied. In addition, the evolution of the microstructures is examined. In depth analyses of the dislocation microstructures show that: 1) dislocation planes that are parallel and very close to each other are formed, 2) these walls contain dipoles that keep on zipping and unzipping during the first few cycles until they reach some stable zipping configuration. We can see that the hardening rate decreases with the increase of the number of cycles where we have large hardening rate in the first cycles then we reach to somehow constant stress. Our results are qualitatively in good agreement with recent experimental results of low cycle fatigue deformation.