Convenient and accurate formulas for stress intensity factor distribution of semi-elliptical surface crack

In this paper, the stress intensity factor (SIF) formula FISE along the crack front of a semi-elliptical surface crack is studied. The exact SIF solution FISE is used by solving the hypersingular integral equation of the body force method discussed in the previous paper. To obtain the accurate formula, the SIF ratio FISE/FIE is focused considering the exact solution FIE of an elliptical crack. By applying the least squares method to the ratio FISE/FIE, accurate and convenient formula is proposed. The proposed formulas may provide the accurate SIF distributions for the aspect ratio a/b=1–4 better than 0.2% accuracy.