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In this paper a singular integral equation method is applied to calculate the variation of stress intensity factors along the crack front of a 3 D oblique semi-elliptical surface crack when the whole of the crack surfaces are in contact each other. The body force method is used to formulate the problem as a system of singular integral equations. In the numerical solutions unknown body force densities are approximated using fundamental density functions and polynomials. The calculation shows that the present method yields rapidly converging numerical results and smooth variation of stress intensity factors along crack front even when the inclination angle between the crack and the free surface is small. The mode II and mode III stress intensity factors are shown when an inclined edge crack is subjected to compressive residual stresses or Hertzian contact loads with varying the inclination crack angle and friction coefficient.

In a previous paper, the present authors clarified that COD is a suitable parameter to interpret the fatigue damage on the basis of the fatigue crack growth in low-cycle random fatigue. Especially the COD parameter correlated well the fatigue damage counted using the rainflow method (RFM) with the crack growth life in LCF. To extend this idea to high-cycle random fatigue the present study has been done. The result showed that although the RFM is valid to evaluate total fatigue life, it is invalid to predict the crack growth life. This is due to the fact that the crack growth life is strongly affected by the effect of crack closure, which is more amplified in high-cycle fatigue than low-cycle fatigue.