Size effect in fatigue modelling of defective materials: Application of the calibrated weakest-link theory

Abstract

Fatigue life prediction is critical for the design of engineering components made from defective materials. Not only do these imperfections show a detrimental effect on the fatigue performances, but they also contribute to a considerable scatter of fatigue properties. In this work, a probabilistic fatigue life prediction model under size effect was proposed based on the calibrated weakest-link theory (WLT) considering the defect location and the size sensitivity. Specifically, a surface factor was defined to consider the superiority of the surface-defect. In addition, a size sensitivity factor was developed to capture the sensitivity of fatigue strength to the volume/size change. Model validation and comparison using two types of metallic materials indicated that the developed surface factor and size sensitivity factor improve the predictive ability of the traditional WLT.