Parametric formulae for stress concentration factor and clamping-induced stress of butt-welded joints under fatigue test condition

Parametric study for the stress concentration factor (SCF) and clamping-induced stress of butt-welded joints under fatigue test condition has been carried out with the finite element method. The effect of angular and axial misalignments on the SCF and clamping-induced stress are investigated in wide application ranges. Corresponding parametric formulae are proposed with considerable parameters taken into account, which have been proved to be accurate. As an application of these parametric formulae, fatigue test data of butt-welded joints has been collected and re-analyzed with the effective notch stress approach. The results reveal that the FAT225 ( m = 3 ) notch S–N curve recommended by IIW is slightly non-conservative for butt-welded joints. FAT200 ( m = 3 ) line is recommended by this paper for higher reliability. For the fatigue data with different plate thickness ( t_s = 3 - 40mm ) and material yield strength ( f_y = 247.4 - 1100MPa ), no significant difference is found in the notch S–N diagram.