Evaluation of welded cast steel joint fatigue data using structural stress methods

Understanding the weld-root-based fatigue failure of welded cast steel joints is critical, and the fatigue stress parameter corresponding to the S-N curve for the fatigue-derived design of welded cast steel joints still needs to be addressed. In this paper, we compared three widely used fatigue stress parameters, namely, the structural hot spot stress, the traction stress, and the 1-mm stress, for the analysis of different types of welded cast steel joints under various loading conditions. The results indicate that: (1) the structural hot spot stress calculated through linear extrapolation is close to the traction stress proposed by Dong (2001) but is easier to compute; (2) the 1-mm stress performs slightly better in correlating the fatigue data of different joint geometries and loading conditions, but its calculation requires more effort; and (3) finally, the equivalent hot spot stress parameter is proposed for fatigue design and data-based analysis of welded cast steel joints as it balances computational efficiency and data correction accuracy. Two S-N curves corresponding to the equivalent hot spot stress and the 1-mm stress are provided for the fatigue-based life evaluation of welded cast steel joints. • Equivalent hot spot stress is proposed to take account of thickness and loading mode effects. • The 1-mm stress parameter performs slightly better in terms of fatigue data correction of welded cast steel joints. • Two design S-N curves are proposed for the fatigue life evaluation of welded cast steel structures.