Micromechanical modeling of plastic anisotropy and strain induced phase transformation in dual-elastoplastic phase materials

A micromechanical model for dual phase elastoplastic materials is developed using the equivalent inclusion theory and a mean field approach. The model is written in the framework of the J(2) deformation theory for ellipsoYdal inclusions. Two applications have been addressed in this paper: i) the shape induced anisotropy has been investigated by calculating the anisotropy factor for geometrical configurations and loading conditions corresponding to rolled plates containing elongated or penny-shape grains or inclusions; particular attention has been paid to the strong dependence of the composite response on the coupling effect between the shape of the inclusions and the stress state, ii) the model has been extended to account for the transformation of the reinforcing phase during straining and applied to the case of a TRIP-assisted multiphase steel. A first validation of the model is proposed by comparison with experimental measurements of overall stress-strain curves and transformation rate.