• A new implementation of an anisotropic Hill plasticity and GTN ductile damage model is presented. • Hill’s anisotropy material parameters inferred for AA6022-T4 based on crystal plasticity simulations. • GTN ductile damage model parameters identified for AA6022-T4. • Geometrical changes and damage during deep drawing and hole expansion of AA6022-T4 predicted. This paper adopts a 2D implementation of an anisotropic plasticity–ductile damage model coupling Hill yield and GTN failure criteria and extends it to a 3D implementation in a user material subroutine (UMAT) of Abaqus software. The implementation is first verified via comparisons with an isotropic model coupling von Mises yield and GTN failure criteria available in Abaqus. Next, a deep drawing of a cylindrical cup simulation from an aluminum alloy (AA) 6022-T4 orthotropic sheet is carried out using the developed anisotropic plasticity–ductile damage model to predict geometrical shape changes including the earing profile and sheet thinning/thickening as well as the structural punch force-displacement response. Parameters pertaining to the anisotropy are identified using simulations involving a polycrystal plasticity model calibrated for the alloy in prior works, while the flow curve was appropriately extrapolated to large strains to facilitate the simulation. Finally, an expansion of a circular hole at the bottom of a cylindrical cup simulation is performed from the same sheet alloy to predict anisotropy as well as the evolution of damage and failure during the expansion. Despite the axisymmetry of the hole expansion simulation set-up, non-uniform thinning is successfully predicted around the hole throughout the expansion owing to the anisotropy of the material in addition to the structural punch force-displacement behavior. The damage and void volume fraction evolution parameters are optimized to successfully predict the rate and spatial location of the failure during the expansion. The developed anisotropic plasticity – ductile damage simulation framework can be used to predict with acceptable accuracy phenomena pertaining to the material behavior, resulting geometrical changes, and damage important for the optimization of industrial metal forming processes. The practical significance of the model for industrial simulations is emphasized given its computational efficiency. Numerical aspects of the model implementation along with the simulation results are presented and discussed.
Sarkar et al. (Sun,) studied this question.