Fatigue finite element analysis on the effect of welding joint type on fatigue life and crack location of a tubular member

The results of a fatigue finite element analysis (FEA) based on the continuum damage mechanics of welding tubular members are presented. The effects of welding joint type on fatigue life and crack location were investigated. The initial mechanical state of a welded tubular member was simulated to identify initial welding imperfections such as welding residual stress and welding deformation using three-dimensional (3D) thermal elasto-plastic large-deformation FEA. The temperature history, which was simulated by using a 3D nonsteady heat conduction FEA, was used in the thermal elasto-plastic analysis as the initial thermal load. The welding joint type effects on fatigue life and crack location of a tubular member were investigated using 3D fatigue FEA. The effect of welding joint type on fatigue strength was also observed. It clarified that fatigue life was different depending on the joint type. Moreover, crack initiation and crack propagating direction of welded T- and K-type tube members were investigated. It was found that crack initiation takes place at different positions depending on the welding joint type. The 3D fatigue FEA method presented here is helpful in identifying fatigue crack location and ascertaining fatigue life.