LARGE ELASTOPLASTIC DEFORMATIONS OF MATERIALS WITH RELAXED CONFIGURATIONS .1. CONSTITUTIVE ASSUMPTIONS

In the first part of the paper, we propose an axiomatic characterization of the thermoelastoviscoplastic behaviour of materials, experimentally motivated and based on the concept of local current relaxed configuration (l.c.r.c.). We formalize the common assumptions concerning the elasto-plastic behaviour of crystalline or polycrystalline materials. The elastic and plastic deformations are defined as local deformations (in the Noll's sense), but they are introduced at the same time with the material laws. The plastic deformation and the internal variables in l.c.r.c. are defined by means of the evolution equations in stress-temperature space (standard procedure). Within the constitutive framework considered here, we have obtained that such materials behave like a solid as a consequence of the relaxation axiom (A.4). The restrictions imposed by the objectivity requirements are also given. On the basis of the causality assumption the complementary plastic factor can be introduced, and, in this way the thermodynamic restrictions are obtained in a consistent way. © 1990.