Fatigue life assessment of load-carrying fillet-welded cruciform joints inclined to uniaxial cyclic loading

This study examines, the relationship between the direction of an applied stress cycle and the fatigue behaviour of load-carrying fillet-welded cruciform joints with weld root cracks, and presents the fatigue life assessment of the joints. Fatigue tests were performed on four sets of cruciform joints inclined at an angle of 0, 15, 30, or 45° to the normal direction of the uniaxial cyclic loading. Fatigue cracks propagated perpendicularly to the stress direction, and formed a flat plane or multiple propagation planes according to the inclination angles. The fatigue crack propagation rate may be estimated by only the mode I stress intensity factor of an inclined through crack assumed in this study. The fatigue life can be evaluated by the stress range at the weld throat in the normal direction to the inclined crack propagation, irrespective of difference in the inclination angle.