Finite deformation Cosserat-type modelling of dissipative solids and its application to crystal plasticity

Recently, several proposals were made for the enlargement of the classical field equations in order to solve locally inhomogeneous deformation problems (e.g. at shear banding and damage localization or of composites). In the present paper basic issues of this topic will be treated : (i) the implicit dependence within the gradient plasticity theory, (ii) the more open micromorphic view-point of the gradient of internal variable approach, (iii) a derivation of an elastic-plastic decomposition of the Cosserat strain measures, (iv) its application to the description of lattice curvature in crystals. Finally, finite element simulations of strain localization in Cosserat single crystals are presented. (orig.)