Inhomogeneous deformation growth of a metal under cyclic loading and its influence on fatigue

Abstract

In this paper, the effects of inhomogeneous material deformation and fatigue caused by meso-mechanical inhomogeneity are investigated. A representative volume element is constructed for pure copper as a material model which features a polycrystalline Voronoi aggregation consisting of a number of crystal grains. The Chaboche model with random parameters is adopted to reflect inhomogeneous cyclic plastic behavior of grains. Key simulations are performed to model the experimental cyclic evolution of strain fatigue under symmetrical tensile–compressive loading. The simulation results show that, although the macroscopic material hysteresis curve keeps stable, the mesoscopic deformations become increasingly inhomogeneous and the statistic differences keep growing. Accordingly, further research on the underlying relation between inhomogeneous deformation and fatigue is conducted, and a systematic methodology to predict the low-cycle fatigue life is revealed.