Coupled crystal plasticity and micromechanics damage model based on viscoplastic self-consistent theory and X-ray computed tomography

Abstract

In recent years, coupled crystal plastic and micromechanics damage models have been applied to effectively deal with the complex interactions between the polycrystalline environments and void behaviors. The classical viscoplastic self-consistent (VPSC) model, as a widely used analytical model with excellent computational efficiency, has been extended to the dilatational-VPSC (DVPSC) model. However, as proposed by the model developers (Lebensohn et al., 2004), there are two main challenges hindering the further extension of the DVPSC model, including (1) the lack of the void nucleation and coalescence and (2) the effective experimental verification. Aiming at the above challenges, a modified-DVPSC model considering the void nucleation and coalescence was proposed and experimentally verified in this work. Accordingly, some improvements were made on the original DVPSC model including the linearization method, the self-consistent equations, and also the volume update equations. Then, with the support of the X-ray computed tomography (CT) technique, the void evolution and fracture mode were analyzed and revealed during the uniaxial tension deformation of 2055 aluminum alloy, through which the essential parameters of the modified model were calibrated. Compared to the previous VPSC and DVPSC models, this modified model accurately describes the stress-strain state, the porosity evolution, and fracture behaviors. Finally, the modified model was applied to investigate the effects of the different loading directions, exhibiting a substantial influence of texture on the void evolution. This research is thereby an innovative attempt for the improvement of the DVPSC model, which can provide inspirations for the future extensions of this theoretical system.