Notch-Stress S-N Curves for Welded Aluminum-Alloy Components Subjected to Bending

Fatigue analysis of aluminum-alloy welded joints based on the linear elastic notch-stress approach is presented in this paper. The International Institute of Welding proposes two variants of the approach, one for thick joints, i.e., joints with a plate thickness of 5 mm or more, with a reference radius r(ref) = 1 mm, using the FAT71 notch-stress design curve, and one for thin joints, i.e., joints with a plate thickness of less than 5 mm, with a reference radius r(ref) = 0.05 mm, using the FAT180 notch-stress design curve. In this work, the feasibility of the proposed S-N curves, obtained mainly by fatigue tests on axially loaded joints, was investigated for 4 mm thick joints subjected to bending. The fatigue analysis was performed for two types of joints: a joint with longitudinal fillet-welded attachment and a joint with round sheet fillet-welded attachment. It was shown that a more accurate estimation of the fatigue life of 4 mm thick aluminum joints loaded in bending can be obtained using the FAT71 notch-stress design curve.