ON THE INITIATION OF FRETTING FATIGUE CRACKS

This paper discusses macroscopic and microscopic approaches for predic tion of the initiation of fretting fatigue cracks. A novel series of f retting fatigue tests is described, involving the cycling of fretting force and specimen load at different frequencies. This technique attem pts to determine the proportions of specimen life consumed in initiati on and propagation. The experimental contact configuration is analysed and the variation of subsurface stresses calculated. The use of shear stress amplitude as a parameter for characterising the initiation of fretting cracks is discussed.