The support effect approach for fatigue resistance prevision of Ti-6Al-4V alloy, with and without surface treatment

The subject of this paper is to investigate the capability of the relative stress gradient (RSG) to properly represent the beneficial effect of residual stress states on the fatigue life of Ti-6Al-4V specimens, with notches of different severity. The research was developed, considering notched and un-notched specimens with different geometries and different shot-peening (SP) treatments. The results were determined by running a fatigue experimentation and by developing a novel predictive model based on the relationship between local fatigue limit and RSG. The proposed tool for fatigue limit estimation was completed by a stochastic analysis, which considered the variability of the involved parameters, in particular the residual stress entity. It made it possible to finally determine the component failure probability in a general, simple, and accurate way.