Influences of Residual Stress on the Fatigue Strength of the Typical Welded Joint of the Underwater Pressure Structure

The Typical welded joint of the underwater pressure structure is often built with high strength steel that is sensitive to residual stress. Therefore, it is necessary to study the influences of residual stress on the fatigue strength of the typical welded joint. In this paper, numerical simulation on the welding residual stress of the typical welded joint is conducted based on the ANSYS APDL language. Then, using the local stress-strain method, the numerical analysis for the fatigue strength in both cases of ignoring and considering the residual stress is carried out. The results show that the maximum residual stress and the shortest life cycle of the joint both occur near the welding line of the concave cone. Specifically, the fatigue life cycles are 104, which belongs to the category of low-cycle fatigue. Meanwhile, the fatigue life decreases as the fatigue load increases, which indicates that the existence of the residual stress reduces the fatigue life of the typical welded joint significantly.