Fatigue crack initiation point of load carrying cruciform joints in low and high cycle fatigue regions

Load carrying cruciform joints with incomplete penetration generally have two fatigue cracking points which are the weld root and toe. The crack initiation point in high cycle fatigue region depends mainly on weld leg size and incomplete penetration ratio, while the material mismatching between the base and weld metal becomes significant in the low cycle fatigue region. Elasto-plastic analysis was performed on load carrying cruciform joints with difference in size of weld leg, incomplete penetration and material mismatching. The effective notch was assigned at the weld root and toe, and the strains around both notches were compared. It was demonstrated that the cracking points estimated from the analysis agreed with the experimental results.