Elastoplastic finite element analyses of metal deformations using polycrystal constitutive models

A finite element formulation using an elastoplastic polycrystal constitutiv e theory is presented. The crystal constitutive equations are expressed in an intermediate configuration obtained by unloading the deformed crystal wi thout rotation from the current configuration to a stress-free state throug h small elastic strains. These constitutive relations and an associated int egration procedure are implemented in a pressure-velocity (mixed) finite el ement formulation. Both small scale (finite element dimensions comparable t o crystal dimensions) and large scale (finite element dimensions much large r than the crystal size) problems are served to illustrate the formulation' s application to metal deformations, including the determination of the R-v alue in a tensile specimen and the prediction of residual stresses in a thi ck ring deformed in an upsetting operation. (C) 1998 Elsevier Science S.A. All rights reserved.