Predictions of polycrystalline yield surfaces for fcc metals using a new viscoplastic intermediate approach

In this paper, we propose the computation of polycrystalline yield surfaces using the viscoplastic ϕ-model. We also compare our results to those predicted by the viscoplastic self-consistent model. Results concerning fcc metals subjected to a plane strain compression test are presented. The influence of the strength of grain interactions effects in both approaches on yield surfaces evolution is studied. The analysis of the change of yield locus shape and size for different values of the parameters controlling the interaction strength show that the results depend strongly on these parameters but are more pronounced with the ϕ-model. The influence of the strain rate sensitivity coefficient on the predicted responses is also discussed and show that only the ϕ-model is able to reproduce the strain rate sensitivity effect on polycrystalline yield surfaces.