Simulation of Fatigue Crack Propagation Process after Overload Based on Cohesive Zone Model

Abstract

Fatigue failure due to varying load is one of the main failure modes in engineering. A large plastic deformation due to accidental tensile overload around the crack tip has a significant effect on the fatigue crack propagation. In order to simulate the crack propagation process, the Cohesive Zone Model (CZM) based on elastoplastic mechanics was studied to take into account the plastic deformation. Based on the bilinear cohesive constitutive model and experimental data, two parameters including cohesive fracture energy and material strength were determined. By comparing Digital Image Correlation (DIC) experiment results with simulation results, it was concluded that both the normal quasi-static model and the cohesion model had a good coincidence with the test data when the plastic area around the tip of crack was small. For a larger plastic zone around the crack tip, the cohesive model method was obviously better than the quasi-static model.