Stresses numerical analysis of oscillating laser welding in aluminum alloys based on the equivalent fluid–structure interactions model

Abstract

Residual stress constitutes an essential parameter for evaluating the operational reliability of welded components. While oscillating laser welding demonstrates notable benefits, including superior weld morphology, diminished porosity, optimized grain refinement, and augmented mechanical characteristics, its influence on residual stress distribution remains insufficiently characterized. This study develops a stress numerical model specifically for oscillating laser welding processes, demonstrating a coefficient of fitting degree greater than 90 %. Additionally, an equivalent fluid–structure interactions model is introduced, accounting for the convective heat transfer of the molten material caused by the laser beam’s stirring effect. This model improves the fusion depth fitting to 97.1 %. Using this model, the evolution and distribution of residual stresses in oscillating laser welding are analyzed. The findings reveal that residual stresses are primarily concentrated at the top of the weld, with transverse and longitudinal residual stresses being predominant. Transverse stresses are mostly tensile, while longitudinal stresses are mainly compressive. Furthermore, the oscillating laser beam was found to be effective in reducing the area of high residual tensile stress distribution in the centre of the weld, where the longitudinal area of distribution was reduced by 3.3 %, and the transverse area of distribution was reduced by 7.3 %.