Stress Intensity Factors K_Ⅰ and K_Ⅱ of Oblique Through Thickness Cracks in a Semi-Infinite Body Under Fretting Fatigue Conditions

摘要

In this paper the formulas for calculating K_Ⅰ and K_Ⅱ of an oblique crack under fretting fatigue loading conditions have been derived. The scheme of the formulation is based on a method using Green's functions and the principle of superposition, i.e. the Green's functions have been obtained through boundary element analysis for normal and tangential localized forces on oblique crack faces and superimposed their results to calculate two components of mode Ⅰ and Ⅱ. The formulas for K_Ⅰ and K_Ⅱ were expressed as functions of crack angle, crack length and applied loading conditions, such as bulk fatigue stress, contact pressure distribution and friction stress distribution. A user-friendly program based on these formulas, then, has been developed to compute the values of stress intensity factors K_Ⅰ and K_Ⅱ under arbitrary fretting fatigue conditions. The values of stress intensity factors for both normal and oblique cracks have been illustrated as examples to understand the effects of crack angle and pad load distribution.