A variational principle for hardening elastoplasticity

We present a variational principle governing the quasi-static evolution of a linearized elastoplastic material. In the case of linear hardening, the novel characterization allows us to recover and partly extend some known results and proves itself to be especially well suited for discussing general approximation and convergence issues. In particular, the variational principle is exploited in order to prove in a novel setting the convergence of time and space-time discretizations as well as to provide some possible a posteriori error control.