MICROMECHANICAL AND THERMODYNAMIC ASPECTS OF THE PLASTIC SPIN

Abstract--The paper focuses on the concept of plastic spin and its constitutive description i phenomenological theories for macroscopic large strain elastoplasticity. An overview is given of kinematic descriptions of the plastic spin and of constitutive r lationships which have been proposed in the literature. Two important classes are distinguished: one in which plastic spin constitutive laws are derived from application of tensor epresentation theorems, and thesec-ond where they are derived from normality rules. Both classes are critically examined from a micromechanical point of view as well as from the standpoint of deterministic irreversible ther-modynamics. The role of nonsymmetric state or structure variables in macroscopic plastic spin constitutive r lations i emphasized and their origin is identified within the framework of crys-tal plasticity. The plastic spin in simple shear deformation processes is studied using various ki-nematic hardening models as well as a simple analytical multiple slip model proposed here