APPLICATION OF THE TAYLOR POLYCRYSTAL PLASTICITY MODEL TO COMPLEX DEFORMATION EXPERIMENTS

The extended Taylor assumption of uniform deformation gradient among g rains was applied in 3-D polycrystal plasticity simulations for comple x loading paths at finite strain for OFHC Cu using the Los Alamos poly crystal plasticity (LApp) code (Kocks et al., 1994). Comparisons of bo th stress-strain behavior and texture evolution, with and without the inclusion of latent hardening effects, show that the theory overpredic ts the rate of development of texture in both torsion and compression. Compression stress-strain behavior was accurately predicted but the e ffect of the prestrain, either compressive Or torsional, on subsequent nonproportional deformation response was inadequately modeled. Some p ossible sources of the discrepancies are discussed, including the low order nature of the extended Taylor model for intergranular interactio ns as compared to self-consistent models, low order formulation of sli p system hardening, lack of accounting for formation of dislocation su bstructure within grains, and the possible role of anisotropic elastic ity. Deformation-induced anisotropy and accommodation of intergranular constraint afforded by geometrically necessary dislocation substructu re formation is viewed as the key neglected element of the formulation .