MODELING OF PLASTICITY AND DAMAGE IN A POLYCRYSTALLINE MICROSTRUCTURE

The mesomechanical behavior of a polycrystalline microstructure subjec ted to monotonic and cyclic loadings is investigated. The analysis is based on a Voronoi polygonization strategy for generation of grains em bedded in a contiguous matrix. The main emphasis is to investigate the interaction between the microconstituents and the failure processes a long grain boundaries. A rational interface theory based on damage dev elopment coupled to inelastic slip and dilatation is developed. The th eory uses the interface width as a constitutive parameter, which regul arizes the theory of LEMAITRE [1992], that is restricted to perfect bo nd between grain and matrix. In a series of FE-analyses parameter vari ations were performed: The unit cell size (as compared to the average grain diameter), the grain-matrix area ratio, the interface width and constitutive parameters. It appears that the composite behavior can be designed as brittle or ductile solely depending on the strength and r ate of damage development in the interfaces. A localization band was d etected, and its orientation is in the range that is predicted within continuum theory.