Per Fredriksson

Competition between interface and bulk dominated plastic deformation in strain gradient plasticity

In the present report, the competition between dissipative plastic strain gradient effects in the bulk and in an interface is investigated within a strain gradient plasticity framework. The model of the interface is analysed in terms of hardening behaviour and strength for the case of a thin film with an elastic–plastic interface. It is found that the yield strength of the film is increased by length scale effects both in the bulk material and the interface. The effect is governed by quite a simple rule, namely the weakest link of bulk and interface. In addition, if the interface is allowed to harden, three regions are observed for the bulk (interior) and interface of the film during an increasing load: (i) elastic bulk and rigid interface, (ii) both bulk and interface plastic and (iii) plastic bulk and rigid interface. The properties of the model are illustrated with numerical results from a parametric study.