Abstract: Fatigue strength of aluminum 5083 welded joint with longitudinal fillet welded gusset by TIG is studied, hot spot stress is computed by the FEM and measured by strain gauges, the test data is statistical treated with the method recommended by IIW, the nominal stress S-N curves and the hot spot stress S-N curves are obtained respectively. The test analysis shows that the fitted slope of test data to nominal stress and hot spot stress S-N curves for aluminum 5083 welded joint with longitudinal fillet welded gusset is 5.62, higher than 3.0 recommended by IIW. The fatigue limit tested for nominal stress and hot spot stress is 54.0 Mpa and 64.8 Mpa respectively. There is greater safety factor in welded structures design if 3.0 applied. Moreover, it is safer to design aluminum alloy welded joint with longitudinal fillet welded gusset with the nominal stress FAT28 and the hot spot stress FAT40.

Key words: Aluminum alloy, Hot spot stress, Nominal stress