SIMULATIONS OF EARING IN ALUMINUM SINGLE-CRYSTALS AND POLYCRYSTALS

Simulations of earing during the deep drawing of single crystals and of polycrystalline sheets have been performed. The anisotropic constitutive properties responsible for the earing phenomenon are derived from crystal plasticity models. These models account for the evolution of anisotropy at finite strains. The behavior of the polycrystalline materials was specified by ascribing part of the behavior to the dominant crystal orientations. The remaining volume fraction was characterized by isotropic plasticity. A detailed finite-element model and a simplified model of the deforming flange adequately capture the behavior of the single-crystal cups. Calculations depicting the drawing of polycrystalline sheets give earing predictions which are in reasonable agreement with the experiments. Less satisfactory agreement is obtained from solutions using a phenomenological yield surface description. Simplified geometric models, which approximate the stress and the strain state in the cup, do not generally result in good agreement with the experiments.