A framework to simulate the crack initiation and propagation in very-high-cycle fatigue of an additively manufactured AlSi10Mg alloy

Abstract

Currently, no systematic approach exists to simulate the crack initiation and propagation process in very-high-cycle fatigue including the microstructure sensitivity. A combined crystal plasticity and cohesive zone model based computational framework is developed to simulate the defect-induced short crack growth of an additively manufactured AlSi10Mg alloy. The crystal plasticity formulation is used to model the anisotropic deformation in the grains. The accumulated plastic shear strain obtained by the crystal plasticity is introduced into the cohesive zone model as the crack initiation damage evolution criteria. The total damage is suggested to be divided into static damage, fatigue initiation damage and fatigue propagation damage. The framework can control the crack growth rate and the proportion of crack initiation damage in the total damage. Besides, an acceleration strategy is proposed to accelerate the computational efficiency for the very-high-cycle fatigue (VHCF). It provides an equivalence of loading cycles and the computational efficiency and accuracy are controlled by the acceleration factor. The internal defect induced short crack initiation and propagation of VHCF are investigated experimentally and simulated by the proposed framework. Experimental observations of tortuous crack paths and fine grain regions are reasonably well captured by the simulation.