Assessing the fatigue life of butt-welded joints under oblique loading by using local approaches

The fatigue life of butt-welded joint specimens under oblique loading was experimentally investigated. Five types of specimens with different oblique butt-welding angles were used for the fatigue tests and subjected to the fixed-directional loading to study the effect of oblique loading on fatigue strength of butt-welded structures. The finite element method was employed to obtain the local stress states at weld toes. Based on the finite element-simulated local stresses, four multiaxial fatigue prediction models – von Mises equivalent stress model, modified von Mises equivalent stress model, the Sines’ model and the Findley’s critical plane model – were utilized to evaluate the fatigue life of studied specimens. Mean stress effect was also considered by the prediction models. The prediction results show that Findley’s parameter provides better prediction than the other three parameters. Furthermore, the observed critical locations are identical to those experiencing the maximum stress identified by the finite element analysis.