Evaluating the fatigue strength of aluminium fillet-welded joints under multiaxial variable amplitude loading using the Peak Stress Method

This study investigates the fatigue strength of arc-welded joints made of aluminium alloys and subjected to multiaxial variable amplitude loadings through the application of the Peak Stress Method (PSM). The PSM is an engineering approach that exploits the Strain Energy Density criterion to efficiently estimate the fatigue resistance of welded joints by using FE analyses with relatively coarse mesh. In its more recent formulation, the PSM has been extended to variable amplitude (VA) loading conditions through the integration of the linear damage rule. This study further advances the method by exploring, for the first time, its application to aluminium welded joints subjected to multiaxial VA loading. Specifically, the proposed approach is successfully validated against experimental data taken from the literature and relevant to tube-to-flange arc-welded joints made from extruded and peak aged AlSi1MgMn alloy tested under constant and variable amplitude in-phase and out-of-phase combined bending and torsion loadings.