In this paper, a rate-type constitutive framework in micropolar plasticity is presented. In order to describe the plastic dissipation in the deformation process, a set of internal variables is introduced, thus the Helmholtz free energy can be expressed as a function of the non-symmetric strain, rotation and internal variables. By the introduction of the loading (yield) surfaces both in the non-symmetric strain and rotation space, and in the work conjugate non-symmetric stress and couple stress space, a loading-unloading criterion for a micropolar plastic material is suggested, and three types of material response, namely hardening, softening and perfectly plastic behaviors are discussed. Based on a mechanical postulate of non-negative work proposed by the present authors, the normality condition and the corresponding incremental constitutive relations are derived. The present results can be applied for the description of path-dependent mechanical behaviors of micropolar elastic-plastic materials.
展开▼
