Diffuse instability of anisotropic inelastic plates by J<inf>2</inf> and QRI models

Abstract

© 2019 Elsevier Ltd Elastic strain is covered by the effective medium homogenization method inside a representative volume element (RVE). Evolution equation formed by tensor representation is derived from very simple micro-evolution equation. It has an incremental quasi rate-independent (QRI) form obtained by the endochronic concept of thermodynamic time. The rate dependence takes place by means of stress rate dependent value of the initial yield stress. Free meso rotations and constrained micro rotations within a representative volume element (RVE) are assumed. The theory is applied to metal forming of orthotropic austenitic steel plates. A comparison between QRI and J2 diffuse instability equations is presented for transversely isotropic as well as for orthotropic materials.