A 3-DIMENSIONAL MODEL FOR THE PROBABILISTIC INTERGRANULAR FAILURE OF POLYCRYSTALLINE ARRAYS

A three-dimensional grain model, in which the grains are represented b y regular truncated octahedra, has been developed to study probabilist ic time-dependent intergranular failure in polycrystalline arrays. In this model, grain boundary facets are assumed to fail randomly in time , as a function of the facet normal stress. A simple approximate metho d for calculating the load shed by failed facets and a reasonable choi ce of failure criterion complete the model. This leads to a conceptual ly simple, but computationally complex, model capable of handling asse mblages consisting of relatively large numbers (> 5000) of grains. The predicted scatter in the times-to-failure and the variation in number of failed facets with time are in quite reasonable agreement with ava ilable experimental data.