Micromechanically-Based Modelling in Nonlocal Crystal Plasticty

Abstract

Within purely local descriptions inhomogeneous plastic deformations induce an incompatibility of the intermediate configuration introduced in connection with the multiplicative split of large strain crystal plasticity. Extending the local model by inclusion of higher order gradients of the inelastic deformation restores on the one hand the compatibility of the intermediate configuration and leads on the other hand to size effects in the material behavior in analogy to experimentally observed phenomena. The underlying physical interpretation is the storage of geometrically necessary dislocations (GNDs) for plastically inhomogeneous deformations. We briefly address the relation between deformation incompatibilities and the storage of GNDs. Furthermore we consider the corresponding numerical implementation, validate our approach by means of a benchmark problem and give a short comparison to other dislocation density based as well as rather phenomenological models. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)