Fatigue design of aluminium welded joints by the local stress concept with the fictitious notch radius of rf=1 mm

The investigations were carried out with three different types of MIG-welded joints of the two aluminium alloys AlMg4.5Mn (AW-5083) and AlMgSi1 T6 (AW-6082 T6) under fully reversed and pulsating axial loading. The evaluation of the results showed that the local stress concept using the fictitious notch radius of rf=1.0 mm can be applied to aluminium welded joints from plates with thickness t≥5 mm independently from the alloy and weld geometries (fully or partially penetrated butt welds, transversal stiffener). Master design curves are proposed for different stress ratios, i.e. R=−1, 0 and 0.5, which allow the consideration of residual stresses as well as load induced mean stresses. The results permit also the suggestion of Δσ=70 MPa as FAT-value for the IIW-fatigue design recommendations.