Enhancement of fretting fatigue strength through stress-relieving slot

Fretting is a complex phenomenon which enhances the stress/strain state in the contact region between two bodies due to micro-slip, and decreases the fatigue resistance of materials. Conventional fretting fatigue configurations generally involve the contact between cylindrical or flat with rounded edges pad and flat substrate (i.e., specimen) loaded by cyclic load. This study investigated the effects of stress-relieving slots, in a flat pad with rounded edge, on the fretting fatigue behavior of Ti-6Al-4V alloy using the finite element analysis. Several fretting fatigue crack initiation parameters were analyzed using the computed stress/strain state. All parameters decreased in the presence of the slots. Further, the analysis showed that the slot length has the most dominant effect on crack initiation parameters. An optimum size and location of the slots was obtained for the geometry considered in this study. In addition, the analysis was supplemented with experiments to verify the advantage of stress-relieving slots to improve the fretting fatigue strength/life.