EVOLUTION-EQUATIONS FOR DISTORTIONAL PLASTIC HARDENING

In an earlier paper the authors proposed a geometrical description of distortional plastic hardening. The parameters of this model describe, in turn, all the elements of transformation of the initial yield surf ace, namely proportional expansion, translation, affine deformation, r otation, and distortion. The present paper is devoted to evolution equ ations for individual parameters: after a general discussion and analy sis of existing experimental data, some effective equations are propos ed. In particular, they are adjusted to describe Bui's experiment on s ubsequent yield surfaces under combined compression and torsion of a t hin-walled tube.