Low cycle fatigue life prediction in shot-peened components of different geometries - part Ⅱ: life prediction

摘要

This study investigates the effects of shot peening on the low-cycle fatigue performance of a low-pressure steam turbine blade material. The finite element model incorporating shot-peening effects, which has been introduced in part Ⅰ, has been used to predict the stabilised stress/strain state in shot-peened samples during fatigue loading. The application of this model has been extended to different notched geometries in this study. Based on the modelling results, both the Smith-Watson-Topper and Fatemi-Socie critical plane fatigue criteria have been used to predict the fatigue life of shot-peened samples (treated with two different peening intensities) with varying notched geometries. A good agreement between experiments and predictions was obtained. The application of a critical distance method considering the stress and strain hardening gradients near the shot-peened surface has been found to improve the life prediction results. The effects of surface defects on the accuracy of life predictions using the proposed method were also discussed.