Chapter 9: A Cohesive-frictional Grain-boundary Technique for Microstructural Analysis of Polycrystalline Materials

The development of a 3D microstructural model for the analysis of degradation and failure in polycrystalline materials is reviewed in the present chapter. The material is explicitly modelled at the grain level, using integral equations in conjunction with a phenomenological crystal plasticity framework for the bulk grains, and with cohesive-frictional laws to represent inter-granular micro-cracking processes. The method allows to capture the initiation, development and coalescence of damage or plasticity at the aggregate scale. The formulation’s key feature is the representation of the mechanical problem in terms of inter-granular variables only, which allows to reduce the computational cost of the analysis. In the present chapter, the building blocks of the technique are described and emphasis is given to the description of the adopted cohesive-frictional laws, which are the fundamental ingredient for the study of inter-granular degradation processes. The potential of the framework is illustrated through micro-cracking and crystal plasticity simulations. The effect of inter-granular friction on the macroscopic material properties is highlighted through micro-cracking simulations under compressive loading.