Residual Stress Release and Its Effects on the Fatigue Strength of Typical Welded Joints in Cone-Cylinder Pressure Structures

Abstract

Submergence and buoyancy may cause fatigue damage to cone-cylinder pressure structures (CCPSs). High-strength steel structures are prone to generating larger welding residual stress, which affects their fatigue strength and safety assessment. Therefore, it is necessary to investigate the effects of residual stress and its release on the fatigue strength of typical CCPS welded joints. In this study, typical CCPS welded joints were taken as the research object. First, the welding residual stress was investigated via non-destructive testing and numerical simulations. Then, a tensile test device was designed to investigate the release of welding residual stress and numerical simulations were carried out. The numerically obtained residual stresses coincide with those obtained by the tensile test. On this basis, the effects of residual stress on the fatigue life of typical CCPS welded joints was investigated with the tensile device and fatigue testing machine. The results show that the residual stress near the welding seam would be greatly released under an external load. The fatigue life of the structures is clearly decreased considering the welding residual stress. Therefore, it is determined that welding residual stress plays an important role in the analysis of the fatigue life of typical ship welded joints.