Master S-N curve analysis of 4R method using effective stress approach

Abstract

The current study is focused on the development of master S-N curve based on the fatigue assessment of welded joints using 4R method combined with the theory of critical distance. Literature data was used for the analysis consisting of different welded joints, steel grades including mild steel, high and ultra-high strength steel and post-weld treatments such as grinding and peening. The 4R method accounted the material strength, applied stress ratio, residual stresses and weld toe radius to predict the fatigue strength effectively. The fatigue notch factors were obtained from finite element analysis with critical distance of 0.1 mm from point method for all welded joints. Hence master S-N curve was obtained considering all weld joints and weld conditions and fatigue strength is calculated with slope parameter of m = 3.98 with least scattering range.