Effect of residual stresses on fatigue crack initiation life for butt-welded joints

This investigation performs a thermal elasto-plastic analysis using finite element techniques to analyse thermomechanical behaviour and evaluate residual stresses in weldments, and develops an effective procedure by combining the finite element, strain-life methods and considerations of the residual stress effect to predict fatigue crack initiation (FCI) life in weldments. Herein, the FCI lives of butt-welded joints are forecast using the proposed procedure. The proposed procedure that followed the conventional strain-based method (Mason and Halford equation and SWT equation) to predict the fatigue life of the butt-welded joints was fairly sensitive to welding residual stress. Furthermore, the FCI life predictions made herein are compared to those of the BS 5400, AASHTO standard specifications, and the experimental results. Comparative results demonstrate that fatigue life estimates made using the novel procedure closely approximate experimental results.