Effet de surface libre dans les agrégats polycristallins en fatigue à grand nombre de cycles.

Abstract

An analysis of high cycle fatigue behavior is done via the numerical simulation of polycrystalline aggregates. Different metallic materials with a FCC crystalline structure, but different cubic elastic coefficients, are investigated. Several statistical elementary volumes (SEV), consisting of 300 grains with isotropic texture and equiaxed geometries, are loaded at the median macroscopic fatigue limit for 107 cycles. Three different models are studied: 2D generalized plane strain, 3D periodic and 3D periodic with a free surface. Different mesoscopic variables are analyzed using extreme value statistics. The results show a detrimental e ect on the fatigue strength of the modeled aggregates with a free surface, if the crystalline elastic anisotropy is sufficient.