A new intermediate model for polycrystalline viscoplastic deformation and texture evolution

In this paper, we propose a model for large viscoplastic deformation of polycrystalline materials called phi-model. The proposed interaction law is based on a new non-linear intermediate approach. In this formulation, we propose to minimize an error function which combines the deviations of the local fields from the corresponding macroscopic ones. A scalar weight parameter was introduced to span the entire solution domain between the upper and lower bound approaches. We applied this approach to predict the stress-strain response and texture evolution in face-centered cubic metals under tension, compression and plane strain compression. We analyzed the effect of the weight parameter in terms of slip activity, stress-strain responses and texture transitions such as copper-type vs. brass-type textures. A comparison between the self-consistent model (VPSC code) and the phi-model is also performed in this paper. Some possible links between the phi parameter and microstructural features are also discussed. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.