Fatigue assessment on butt welded splices in plates of different thicknesses

Fatigue performance of butt welded splices in plates of different thicknesses (hereafter referred to as BWSPDT) was investigated in this paper. Fatigue tests were conducted on 26 specimens. Experimental S-N curve of 95% survival probability for BWSPDT was established based on 21 effective fatigue test data involving 7 stress levels. Both analytical and numerical fatigue crack propagation analysis were fulfilled. It was found that the numerical approach would provide a lower stress intensity factor (SIF) level than that obtained through the analytical approach, as the numerical approach can better reflect the relationship between the local crack development and the variation of the stress distribution of the whole structural details. The influences on fatigue life due to the variation of the size, shape and location of the initial crack were investigated. The calculation formula for the fatigue crack propagation life in terms of arbitrary initial crack between 0.075 mm and 0.4 mm was derived. For the fatigue crack propagation analysis for BWSPDT, a semi-circular crack with 0.075 mm initial depth locating at the center of the specimen was recommended to be adopted as the initial crack input when no detailed inspection information on initial flaws available.