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Abstract

In order to model the mechanical performance of heterogeneous (multiphase) materials on the microstructural length scale we need to know the mechanical properties of all individual phases and their interfaces. However, micromechanical experiments have revealed that the material properties are not scale invariant, which means that the measurement of mechanical properties of individual phases with micromechanical devices does not yield unique values. Furthermore, this means that within micromechanical models, the intrinsic length scales of heterogeneous materials need to be taken into account. Recently, significant progress in this direction has been made by a combination of advanced experimentation and sophisticated modeling. Such combinations have provided new insight into and understanding of the fundamental mechanisms of deformation and failure of materials. This is demonstrated in two examples:

A first example will be given on how simulations on several length scales help us to understand material behavior during nanoindentation and to derive engineering material constants from nanoindentation results. In a second example, deformation and fracture of polycrystals is studied on different length scales, from two-dimensional dislocation dynamics and diffusion kinetics simulations to completely continuum mechanical approaches. The aim of this work is to provide a virtual material-testing lab that allows us to predict mechanical properties of materials based on their microstructure.