On the elastoviscoplasticity of ferromagnetic crystals

Abstract

Based on a semi-phenomenological approach, a theory of finitely deformable elastoviscoplastic ferromagnetic crystals is constructed with the ultimate purpose to study the influence of dislocations on the dynamical properties of ferromagnets. The initial reference configuration of the body is a so-called one-domain ferromagnetic fundamental phase. Thermomagnetoelastic and viscoplastic parts of the finite strain are obtained by means of a multiplicative decomposition and the introduction of a “natural” local configuration (which corresponds to a relaxation of both elastic and ferromagnetic processes). The viscoplastic processes are accounted for through evolution equations (for internal variables) and are related to the microdynamics of dislocations. It is thus shown that a generalized notion of resolved shear stress can be introduced which involves both the Cauchy stress and ferromagnetic exchange effects. The evolution equation of dislocations densities in different glide systems is established on account of the activation criterion for dislocations. The model thus obtained is complete once the energy densities and the initial material symmetry of the material are specified.