Stress intensity factors for semi-elliptical surface cracks in plate-to-plate butt welds with parallel misalignment of same thickness

A set of fatigue and fracture assessment equations had been incorporated into British Standard 7910:2013 (BS 7910:2013) to estimate the effect of misalignment for various geometric configurations containing a surface crack. In this study, extensive 3-D finite element (FE) analyses are carried out to determine the dimensionless stress intensity factors (Y) at the crack deepest point and crack ends of plate-to-plate butt welds with parallel misalignment of same thickness. In comparison to BS 7910:2013, it is observed that the assessment equations underestimate the Y values for shallow cracks and overestimate the corresponding values for deeper cracks with percentage differences in values being as high as 82% and 12%, respectively. New Y equations for misaligned butt welds are proposed using multiple regression analyses.