Effects of additional weld and grinding on fatigue life extension of non-load-carrying cruciform joints

Abstract

Welded joints are often characterized by fatigue failure due to a series of factors such as stress concentration caused by bead geometry, changes in material properties by weld heat, and the effect of residual stresses. Grinding, TIG treatment, peening, etc., are available to improve the fatigue strength of weld joints. Also, the application of additional welding has been reported as one of the methods for reducing the stress concentration at the weld toe, with the consequential extension of fatigue life. A previous work reported that an additional weld could improve fatigue life of non-load-carrying fillet joints. The benefits of additional weld are also confirmed for the pre-fatigue damaged joints. Besides, grinding treatment achieves further improvement of fatigue life. However, additional weld and grinding treatments introduce geometrical and material changes such as the modification of the bead shape, angular distortions and welding residual stresses. In this study, the fatigue performance, in terms of crack initiation and propagation life, was numerically evaluated and compared with experimental results. Fatigue crack initiation and propagation life are evaluated based on cyclic elastoplastic FE and X-FE analyses.