Exploring the High-Cycle Fatigue Behaviour of Metals from the Mesoscopic Scale

Abstract

The aim of this paper is to present a high-cycle fatigue theory of metals. In particular, this work is confined to the study of the problem of the fatigue limit under multiaxial stress conditions. Knowledge of the fatigue limit of a metal component allows the distinction of a damaging cyclic loading from a non damaging one. The latter can be sustained by the component for a very high number of load cycles (theoretically infinite) without the development of a macroscopic fatigue crack. The fatigue behaviour is explored from the mesoscopic scale. Within the framework of the mesoscopic approach, the local stresses and strains acting at the scale of the metal grain are evaluated with the help of the Lin-Taylor assumption. The fatigue limit is interpreted as a restraint applied on the plastic strain accumulated by a cyclic loading in some plastically deforming crystals of the metallic aggregate. Comparison of the predictions of this theory against experimental results obtained under non-proportional multiaxial loading, shows very good agreement.