Modelling ductile fracture in an Al alloy with crystal plasticity models

Abstract

Crystal plasticity models enhanced with coupled or uncoupled damage and fracture criteria give an opportunity to account for the role of microstructure in ductile fracture, most directly representing the local variations of stress and strain fields inside and between the grains, voids and particles. Some computationally efficient crystal plasticity, damage and fracture models have recently been developed and applied to some cases of polycrystalline fracture. Such models allow to investigate in a direct way the effects of, e.g., shear bands, larger voids, particles, free surfaces and load direction on the development of damage and fracture. The cast and homogenized Al1.2Mn alloy investigated previously is used here as a basis for simulations. The alloy has an equiaxed grain structure with no texture and contains a population of larger particles and a population of dispersoids. The grain structure and the large particles are modelled directly in the finite element model, while the effect of dispersoids is represented by the damage and fracture part of the single crystal plasticity model. The study investigates the effect of different model parameters and features on the global and local behaviour of the material during localization and fracture, in light of available experimental data.