Non-local plasticity at microscale: A dislocation-based and a Cosserat model

An interpretation of intrinsic length seals in materials containing plastically soft and hard phases is proposed, based on the idea that dislocations gliding in the soft phase have to bow between thr hard phase. Accordingly, the self-energy (line-tension) of the bowing dislocations is introduced into the continuum mechanics description of the plastic deformation. A direct relation between a simple dislocation-based and a Cosserat model is established, allowing for identification of the Cosserat intrinsic length, rotation and curvature. Attention is also paid to the question whether the geometrically necessary dislocations contribute primarily to isotropic or to kinematic hardening.