MODELING OF PLASTIC ANISOTROPY BASED ON TEXTURE AND DISLOCATION-STRUCTURE

Anisotropy and work hardening behaviour are the most significant mater ial properties in sheet metal forming. Beside the initial anisotropy d ue to crystallographic texture, anisotropic hardening due to the evolu tion of the dislocation structure is observed at large prestrains. The developed model is a mixed hardening model in which the shape of the yield locus is generated from the texture and the dislocation structur es are responsible for isotropic hardening and kinematic hardening. Th is microstructural evolution is modelled with three internal stare var iables and their evolution equations. Furthermore an elastoplastic tan gent modulus is derived from the plasticity model. The model is constr ucted in the framework of dual potentials bath in deviatoric stress sp ace and plastic strain rate space. Finally, the flow stress evolution is computed for several strain-path changes. (C) 1997 Elsevier Science B.V.