Quantification of the Influence of Residual Stresses on Fatigue Strength of Al-Alloy Welded Joints by Means of the Local Strain Energy Density Approach

Depending on boundary conditions, welding parameters and plate thickness, high residual tresses may arise near the weld toe of a welded joint. Compressive or tensile residual stresses significantly influence the fatigue strength of the joints in the high-cycle regime. If the weld toe is modelled as a sharp, zero-radius V-shaped notch, the residual stress fields can be expressed in terms of residual notch stress intensity factors (R–NSIFs) calculated in the elastic or elastic-plastic fields. The possibility to quantify the intensity of the residual singular stress field by means of the R–NSIFs allows the designer to estimate the influence of residual stresses on the fatigue life of welded joints. In this work, the influence of residual stresses on the fatigue resistance of Al-alloy butt-welded joints is estimated by using the local stain energy density approach. Values predicted by the proposed method show a good agreement with experimental data taken from literature.