Effect of weld geometry and residual stresses on fatigue in butt-welded joints

Abstract

This paper describes a mathematical model to predict the effects of important butt weld geometry parameters (such as weld toe radius, weld bead flank angle, preparation angle, and plate thickness), and residual stresses on the fatigue crack initiation (FCI) life of butt-welded joints. An effective procedure is also developed by combining the thermal elasto-plastic theory, finite element and strain-life methods, while simultaneously considering the effect of stress concentration at the critical location (weld toe) and tensile residual stress distribution to predict FCI life in the weldments. The procedure proposed is compared to those of the standard specifications of BS 5400, AASHTO, and experimental results. It is demonstrated that fatigue life estimates made using the novel procedure closely approximate the experimental results. Furthermore, the fatigue life of butt-welded joints subjected to simulated residual stress fields, induced by preheating temperature conditions, is calculated using the proposed procedure.