A fracture mechanics-based stress approach for fatigue life prediction of welded joints considering weld profile effect

Abstract

This paper presents a new method, based on fracture mechanics analysis of fatigue, to calculate the generalized stress proposed by Maddox. The generalized stress is computed from the currently existing structural stress definition and the stress intensity factor (SIF) calculation. With the structural stress term accounting for the effect of global weldment geometry, the stress intensity factor captures the local effect of the weld profile, characterized by the weld angle and weld toe radius. Weight function methods are used for the purpose of obtaining the generalized stress. Finally, the generalized stress is validated with fatigue test results of various specimen types and thickness combinations (up to 4.9 mm). It is found that the generalized stress is able to effectively predict the fatigue life of welded joints and can serve as a better fatigue damage parameter than the structural stress since the weld profile effect has been included.