A multiaxial criterion for notch fatigue using a critical-distance method.

In the present paper, a high-cycle critical plane-based multaxial fatigue criterion, recently proposed by the authors to determine the fatigue strength of smooth components, is extended to notched components by using the so-called point method. Accordingly, once the location of the ‘hot spot’ on the notch surface is determined, the orientation of the critical plane (material 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 round bars with a surface circular notch (an artificially drilled surface hole) submitted to cyclic loading are compared with the theoretical predictions of the proposed extension. The comparison, which is instrumental in highlighting the notch size-effect (as the hole diameter varies) under uniaxial and biaxial far-field stress conditions, appears to be quite satisfactory.