Influence of welding residual stresses on fatigue life of Al2024 plate

Sequential coupled thermo-mechanical model and fracture mechanical model based on finite element method and J-integral method are established to calculate the residual stress and the stress intensity factor for friction stir welding, TIG and laser welding process, respectively. The commerical code NASGRO is used to predict the fatigue crack growth rate. This method is validated by comparing with the experimental data and results of the virtual crack closure technique method. The distribution of the residual stress intensity factor is similar with the residual stress profile and the residual stress has a significant impact on the effective stress ratio R. The influence decreases as the increase of the stress ratio. The residual stresses severely shorten the fatigue life of the plate, and the fatigue life of the plate welded with TIG technology is shorter than the ones of the plates welded with friction stir welding and laser welding.