Multiaxial endurance limit estimation in notched structural components using a combined critical point-critical plane approach

A high-cycle multiaxial fatigue criterion, based on a combined critical point-critical plane approach, is used to estimate the multiaxial endurance limit in notched metal structural components. Accordingly, once the location of the hot spot on the notch surface is determined, the orientation of the critical plane (where fatigue strength assessment has to be performed) is assumed to be correlated with the principal stress directions in the hot spot itself. Some experimental results related to small hole-containing steel specimens subjected to out-of-phase axial and torsional loading are analysed. The comparison is instrumental in highlighting the notch size-effect (as the hole diameter varies) under uniaxial and biaxial far-field stress conditions as well as the effect of the loading phase.