Fatigue life assessment of welded joints in a crane boom using different structural stress approaches

Abstract

This article presents a study of the fatigue strength of welded parts in a crane boom. A finite element analysis was carried out over the whole structure. Two critical welded zones were identified and a detailed analysis was carried out on them, in the form of sub-models. Three different approaches for estimating the structural stress in welded zones, were presented and applied to each sub-model (surface extrapolation, Xiao-Yamada, and Dong's method). Results were compared and discussed. The evaluation of fatigue resistance by the use of appropriate S-N curves for each method was also carried out and discussed. The use of these approaches on a complex industrial structure, and on tubular joints with hollow sections required to perform many adaptations and to solve several difficulties. The results obtained show a relatively good correlation between the surface extrapolation and Xiao-Yamada methods. However, the method of Dong shows more conservative results. Analysis and discussion of the results are presented in the conclusion.