An efficient approach for computing residual stresses in welded joints

Abstract

Although the finite element method has emerged as one of the most attractive approaches for computing residual stresses in welded joints, its application to practical analysis and design problems has been hampered by computational difficulties. These difficulties do not arise in modeling the complex constitutive response of melting and solidifying metal; rather, they occur mostly because of the enormous computational size of any practical problem resulting primarily from the three-dimensional (3D) modeling of a welding process. Although two-dimensional (2D) modeling has been used widely in residual stress problems, current belief holds that 2D analysis cannot render accurate residual stresses that occur due to welding. This study investigates the residual stress fields in a welded T-joint, comparing those computed by 3D models with those computed by 2D models. The study shows that the temperature distribution in the central zone of the joint can be captured successfully by a 2D finite element model and a technique that takes into account the heat transfer balance and welding speed. The residual stresses in the plane of the 2D model computed by this method show fairly good agreement with those computed by the 3D model. More substantial differences are observed in the out-of-plane stresses, which are attributed primarily to the different mechanical boundary conditions in the out-of-plane direction of the 2D and the 3D models. All analyses in this investigation are performed with the finite element code ABAQUS.