Simple Flow Rules for Modeling the Behaviour of Inhomogeneous Viscoplastic Materials

The “Iso‐W” approach recently proposed to generate simple flow rules for two phase materials is extended to nonlinear viscoplastic constituents and generalized, which produces three families of models. Comparison with the Hashin‐Shtrikman bounds leads to select the variant assuming strain rate compatibility and stress equilibrium. The “Iso‐W” assumption is in fairly well agreement with the Mori‐Tanaka and self‐consistent models for mixtures of both linear and nonlinear materials.