Higher-Order Continuum Theory Applied to Fracture Simulation of Nano-scale Intergranular Glassy Film

Complex grain-boundary structures, such as the 1-2 nm thick intergranular glassy films (IGF), play a prominent role in the failure behavior of nano-phased ceramics. The IGF plays the role of an imperfection and serves as the location of strain localization and failure. We have recently performed “theoretical” mechanical loading experiments on very large atomic models of IGF in silicon nitride using ab initio simulation to obtain their failure behavior. The ab initio simulations yield characteristic post-peak softening accompanied by strain localization zone. In this paper a micro-structural granular mechanics based higher-order continuum theory is applied to model the failure behavior of these types of material systems. The results obtained from the ab initio simulations are compared with those predicted by the higher order continuum theory.