A comparative study of multiaxial high-cycle fatigue criteria for metals

The aim of this paper is firstly, to provide a concise assessment of some commonly used high-cycle fatigue criteria and secondly, to check their predictive capabilities against synchronous sinusoidal out-of-phase bending and torsion experimental results (i.e. sinusoidal stress signals of the same frequency but with a phase difference). This bending-torsion stress system does not closely represent real load conditions undergone by a machine part. However, it is complex enough to differentiate the various fatigue criteria and to permit a first classification of the approaches examined, according to the accuracy of their predictions. A fatigue criterion recently formulated by the first of the authors is also included in this comparative study. According to this criterion the phase difference in out-of-phase bending and torsion does not affect the fatigue strength corresponding to a very high (theoretically infinite) fatigue life. It is pointed out that this theoretical finding is valid for the category of hard metals for which the ratio of the fully reversed torsion fatigue limit over the fully reversed bending fatigue limit lies in the interval from 1/root 3 to approx. 0.8. Experimental results collected from the relevant literature, concerning precisely hard metals, fully support this theoretical finding. Copyright (C) 1997 Elsevier Science Limited.