INTERNAL SYMMETRY IN BILINEAR ELASTOPLASTICITY

Internal symmetry of a constitutive model of bilinear elastoplasticity (i.e. linear elasticity combined with linear kinematic hardening-soft ening plasticity) is investigated. First the model is analyzed and syn thesized so that a two-phase two-stage linear representation of the co nstitutive model is obtained. The underlying structure of the represen tation is found to be Minkowski spacetime, in which the augmented acti ve states admit of a Lorentz group of transformations in the on phase. The kinematic rule of the model renders the transformation group inho mogeneous, resulting in a larger group-the proper orthochronous Poinca re group. (C) 1998 Elsevier Science Ltd. All rights reserved.