Fatigue Performance of Cracked Tubular T Joints under Combined Loads. II: Numerical

In practice, tubular joints are always subjected to a combination of axial loading (AX), in-plane bending (IPB), and out-of-plane bending (OPB), and the initiation of surface cracks does not always start at the saddle or the crown position on the joints. A systematic finite element modeling of tubular Y joints with any surface crack and located at any position along the brace-chord intersection is developed and proposed in this paper. The weld details in the model conform to the American Welding Society codes. The contact surfaces have been defined carefully between the two crack surfaces that may arise due to some loading cases. Along the crack tip, a well-graded finite element mesh is generated to get the stress intensity factors. This modeling method is then used to analyze three tubular T joint specimens which were tested to failure earlier, and they were subjected to IPB only, combination of IPB and OPB, and a combination of AX, IPB, and OPB, respectively. The numerical results compared favorably with the experimental results based on the Paris' law, and all of these results demonstrate that the proposed model is consistent and reliable.