A simplified approach for predicting plain and notch fatigue resistance of shot peened Al-7075-T651

A simplified approach aimed at predicting plain and notch fatigue resistance of shot peened Al-7075-T651 is presented. For this purpose, different shot peening treatments were carried out on plain and notched samples. Reverse bending Wöhler curves were determined for both notched and unnotched condition. Initial and stabilized residual stresses were measured by X-ray diffraction (XRD) on plain specimens. An evolution to stabilised values of the surface stresses, depending on the applied loads, was observed. Residual stresses measured on plain specimens were used for predicting, by means of a finite element modelling, respectively the residual stress distributions in the notched specimens and the residual stress relaxation in the vicinity of the notch due to the application of different fatigue loads. The results of the numerical analysis were used to validate a simplified analytical approach developed for computing residual stress relaxation and surface residual stress field both in plain and notched specimens. The predicted residual stress distribution was finally incorporated into a multiaxial fatigue criterion. Specifically, the critical distance theory was successfully used to predict the fatigue resistance of bodies carrying stress concentrations in the presence of a compressive residual stress field. © 2011 Published by Elsevier Ltd.