Gradient plasticity - A thermodynamic formulation

A thermodynamic background allowing for nonlocality is envisaged as a basis for consistent formulation of gradient plasticity. Concepts as ''regularization operator'' and ''reciprocity relation'' turn out to have a central role in a possible unified formulation of either gradient and nonlocal plasticity, with only the provision that this operator is of differential nature in the former case, of integral nature in the latter. The constitutive equations for (associative) gradient plasticity include held equations, as well as (Neumann) boundary conditions, which all describe a diffuse plastic mechanism occurring within a particles finite domain not smaller than some limit related to the material internal length scale. A pertinent form of the maximum intrinsic dissipation theorem is also envisaged. The particles domain response to a given total strain rate field is shown to be governed by a minimum principle.