| Analytical and computational formulations have been developed for the investigation of microstructurally induced failure mechanisms in crystalline materials with coincident site-lattice (CSL) high angle grain-boundaries (GBs). A multiple-slip rate-dependent crystalline constitutive formulation that is coupled to the evolution of mobile and immobile dislocation densities and specialized computational schemes have been developed to obtain a detailed understanding of the interrelated physical mechanisms that result in material failure in crystalline materials. A transmission scalar has also been introduced to investigate slip-rate transmission, blockage, and incompatibility at the GB. The combined effects of high angle GB misorientation, mobile and immobile dislocation densities, strain hardening, geometrical softening, localized plastic strains, and slip-rate transmission and blockage on failure evolution have been studied. In a first part of this study, criteria have been developed to characterize the initiation and propagation of intergranular and transgranular failure modes in void-free face centered cubic (f.c.c.) materials with ;Results from the present study for void-free crystalline materials with CSL GBs are consistent with experimental observations that single dislocation pile-ups result in transgranular failure modes for ;The present study underscores the importance of using dislocation-based multiple-slip crystalline constitutive formulations that are consistent with experimental observations and results to accurately characterize the microstructural evolution of deformation and failure modes on a length scale that is commensurate with the material competition between the inherent strengthening and softening mechanisms of crystalline materials with high angle GBs. |
