Quasi-static evolution for the Armstrong-Frederick hardening-plasticity model

The Armstrong-Frederick model for nonlinear kinematic hardening is regarded as a benchmark model in contemporary elastoplasticity. This work presents an existence result to an appropriately time-rescaled evolution for that model. To do so, we have to resort to a regularization of the dependence of the convex of plasticity upon the back stress. Such a regularization process seems to be the unfortunate price one has to pay for a successful mathematical analysis.