Hybrid, Multiscale Numerical Simulations of the Equal Channel Angular Pressing (ECAP) using the Crystal Plasticity Theory

Abstract

The FEM simulations of the EcAP including real conditions of the process – the friction between the metal extruded and the die walls, as well as, the channels rounding, were done here in two scales – macro-and micro-. The macroscopic analyses were done for isotopic material with a non-linear hardening using the UMAT user material procedure. The pure Lagrangian approach was applied here. The stress, strains and their increments, as well as, the deformation gradient tensor were recorded for selected finite elements in each calculation step. The displacements obtained in the macroscopic FEM analysis are then used as the kinematic input for the polycrystalline structure. The dislocation slip was included as the source of the plastic deformation here for the face-centered cubic structure. The results obtained with the use of the crystal plasticity show the heterogeneous distribution of stress and strain within the material associated with the grains anisotropy. The results in both micro-and macro-scales are coincident. The FEM analyses show the potential of the application of the crystal plasticity approach for solving elastic-plastic problems including the material forming processes.