Numerical assessment on fatigue damage evolution of materials at crack tip of CT specimen based on CPFEM

Abstract

Fatigue failure of metal parts is common in engineering, and the failure mechanisms remain to be studied. The crystal plastic finite element method (CPFEM) was used to study the damage evolution of materials at the crack tip of precracked compact tension (CT) specimen based on the established crystal plasticity constitutive relation which considered the grain size effect and cyclic hardening. The parameters used in polycrystal model were obtained through reverse optimization method combined with genetic algorithm, which are performed through the combination of commercial software ABAQUS and MATLAB. The stress–strain curve obtained by 2D polycrystal model finite element simulation is closed to the experimental curve of 304 stainless steel. Then, the 3D Voronoi-like polycrystalline model was established to investigate the effects of stress state, grain size and inclusion on the fatigue properties of materials at crack tip of precracked 304SS CT specimen by evaluating the evolution of plastic strain energy (PSE) and Von Mises stress under cyclic load. These factors will affect the fatigue damage evolution of materials from different aspects which were analyzed in detail. The proposed method and model are helpful to study the fatigue failure of metal materials at mesoscopic scale.