Role of Anisotropic Strength and Stiffness in Governing the Initiation and Propagation of Yielding in Polycrystalline Solids

The ratio of directional strength-to-stiffness is important in governing the relative order in which individual crystals within a polycrystalline aggregate will yield as the aggregate is loaded. In this paper, a strength-to-stiffness parameter is formulated for multiaxial loading that extends a similar parameter developed specifically for uniaxial loading. Building on the principle of strength-to-stiffness, a methodology for predicting the macroscopic stresses at which elements in a finite element mesh yield is developed. This analysis uses elastic strain data from one increment of a purely elastic finite element simulation to make the prediction, given knowledge of the single-crystal yield surface. Simulations of austenitic stainless steel AL6XN are used to demonstrate the effectiveness of the strength-to-stiffness parameter and yield prediction methodology.