EFFECT OF WELD-TOE GRINDING ON FATIGUE LIFE BASED ON THEORY OF CRITICAL DISTANCE

Abstract

This thesis aims to investigate the improved fatigue strength on three distinct types of welded joints: longitudinal attachment joints, cruciform joints, and butt joints through the numerical results of current research and statistical analysis of experimental datasets based on literature. This study introduces the critical distance approach for predicting the fatigue strength in welded structures, considering the influence of local geometries and notches to evaluate the fatigue stresses in real welded components. With the adoption of the theory of critical distance, the calculated stress is closer to the maximum principal stress of the weld toe determined by the finite element analysis, compared with the nominal stress and hot-spot stress methods. Ultimately, this study introduces two types of effective S-N curves to predict the fatigue behaviors of the three investigated welded joints based on the best-fit critical distance of 0.2 mm and 0.3 mm from statistical assessment.