Accurate evaluation of fracture parameters for a surface-cracked tubular T-joint taking welding residual stress into account

An efficient numerical analysis procedure based on FEM was implemented for evaluating the effect of welding residual stress (WRS) on mixed-mode stress intensity factors (MM-SIFs) for a non-planar surface-cracked tubular T-joint with a rounded weld toe. A multi-pass welding simulation was carried out using real welding conditions by means of an effective in-house welding simulation code. A fully compatible 3D finite element mesh generation system was implemented to model non-planar perpendicular surface-cracked tubular T-joints with rounded weld toes. The adequacy of the mesh generation system was verified with the reference solutions. A fully automated mapping code was developed to assign the six components of the simulated WRS to each element face over the crack surface. A developed fracture approach was employed to accurately compute MM-SIFs resulting from WRS in which normal and shear components of WRS were considered. MM-SIFs were calculated carefully for several surface cracks with different shapes under different loading conditions. The behavior of MM-SIF solutions resulting from the combination of external load and WRS was influenced significantly by the behavior of those produced due to WRS only. In addition, the value of the computed SIFs resulting from the combination of external load and WRS was almost doubled for mode-I SIF compared to those obtained by external load only and WRS only especially near the crack end locations. The behavior of the calculated fracture parameters was also discussed.