Fatigue Life Assessment of Full-Penetration Cruciform Welded Joints under Tensile Shear Cyclic Stress

To investigate the fatigue performance and fatigue life assessment method of full-penetration welded joints in tensile shear cyclic stress, fatigue tests and finite element analyses were carried out. With different inclined angles of weld lines of 0°, 15°, 30°, and 45°, full-penetration cruciform welded joints were designed at different tensile shear stress ratios. Using the ANSYS finite element program, three-dimensional (3D) finite element models of cruciform welded joints were developed and the stress distributions and stress concentration factors were investigated. Four groups of fatigue tests (12 specimens) were conducted under proportional loading over the same stress range as that on the end of the steel plates. Based on the nominal stresses, the fatigue lives of full penetration cruciform welded joints were evaluated by using effective stress, interaction equations, and bi-parametrical critical plane approaches. The accuracy and reliability of the assessment methods were checked against the experimental results of the fatigue testing. The research results showed that the fatigue life calculated using the approach of the International Institute of Welding (ⅡW) and Eurocode is longer than the test result, whereas the fatigue life based on the principal-tensile-stress method is shorter than the test result. Furthermore, fatigue life given by the effective stress and bi-parametrical critical plane approaches are in good agreement with the test results.