Computational modelling of brittle failure in polycrystalline materials using cohesive-frictional grain-boundary elements

A 3D grain-level formulation for the study of brittle failure in polycrystallinemicrostructures is presented. The microstructure is represented as a Voronoi tessellation and theboundary element method is used to model each crystal of the aggregate. The continuity of theaggregate is enforced through suitable conditions at the intergranular interfaces. The grain-boundarymodel takes into account the onset and evolution of damage by means of an irreversible linearcohesive law, able to address mixed-mode failure conditions. Upon interface failure, a non-linearfrictional contact analysis is introduced for addressing the contact between micro-crack surfaces. Anincremental-iterative algorithm is used for tracking the micro-degradation and cracking evolution. Anumerical test shows the capability of the formulation.