Experimental identification and validation of models in micro and macro plasticity

Abstract

For micro-macro approaches to finite plasticity, one needs experimental results on both scales, the engineering scale (macro scale) and the crystal scale (micro scale). Since we know that a monocrystal behaves different from a crystallite embedded in a polycrystal, one is also interested in data obtained on the micro scale of a polycrystal. Such data is needed not only for the identification of the material parameters like hardening variables, but also for the validation of these models. In this paper, experiments on both scales and, in parallel, FEM-simulations are presented, in order to compare the results of both approaches. The specimens stem from a rolled sheet of the deep-drawing steel DC04. On the micro scale indenter tests have been performed and the orientation changes in the volume below the indent have been measured using micron-resolution 3D x-ray microscopy (Larson et al., 2004, 2008). On the macro scale the usual tension tests and additional shear tests in different directions (Bouvier etal.,2006) have been performed. In corresponding simulations, the micro-macro transition is performed by a full constrained Taylor-model and, in order to overcome the drawbacks of the Taylor-model, the RVE technique has been applied.