ANALYSIS OF CRACK INITIATION AND PROPAGATION IN POLYCRYSTALLINE MESO- AND MICROSTRUCTURES OF METAL MATERIALS

Abstract. Meso- and microscale analysis are promising disciplines to cover the crack initiation as well as the various crack propagation phenomena in engineering structures. On mesoscale it is observed that the crack propagation in polycrystalline metal materials occurs mainly along grain boundaries. Following this observation we present a two dimensional polycrystal meso model consisting of grains with an elastic orthotropic material law and cohesive interfaces along crystal boundaries, which is able to reproduce crack initiation and propagation in metallic materials. As an extension to classical Voronoi cell diagrams we apply an advanced algorithm to generate polycrystal material structures based on arbitrary distribution functions of grain size. Therewith we are more flexible to represent realistic grain size distributions. The polycrystal model is applied to analyze the crack initiation and propagation in statically loaded representative volume elements of aluminum on the mesoscale without the necessity of initial damage definition. Future research work is focused on the determination of constitutive relations for the cohesive interface law from mixed continuum atomistic simulations performed on a representative volume element on the microscale and homogenized to the mesoscale