A study on fatigue crack initiation point of load-carrying fillet welded cruciform joints

Load-carrying fillet welded cruciform joints have two fatigue crack initiating points. These are located at the weld toes and weld roots, where high stress concentrations occur. The location of the fatigue crack initiation depends on the weld size, plate thickness and weld penetration. These mechanisms are easily understood. Previous experimental results have indicated that the fatigue crack originating point is also influenced by the magnitude of the stress range, but the reason for this phenomenon is not yet clear. To better understand this phenomenon, fatigue tests on welded joint specimens were performed in this study. In addition, the welding residual stresses were analyzed with a thermo-elastic-plastic finite element method. Finally, a fatigue crack propagation analysis that considered the residual stresses was performed.