Fatigue assessment of notched specimens by means of a critical plane-based criterion and energy concepts

A strain-based multiaxial fatigue criterion previously proposed for fatigue assessment of unnotched specimens is here extended to the case of notched ones. Such a criterion is a reformulation of the stress-based multiaxial High-Cycle Fatigue (HCF) criterion by Carpinteri and Spagnoli. The extension herein presented considers as the critical point, where to perform the fatigue assessment, the material point located at a certain distance from the notch tip, depending such a distance on both the biaxiality ratio (defined as the ratio between the applied shear stress amplitude and the normal stress amplitude) and the control volume radii R-1 (related to Mode I) and R-3 (related to Mode III). Some multiaxial fatigue data related to specimens made of titanium grade 5 alloy (Ti-6Al-4V) and weakened by sharp notches are examined to validate the extended criterion. (C) 2016 Elsevier Ltd. All rights reserved.