Fretting may be deŸned as a friction-driven contact phenomenon in which damage occurs in the vicinity of the contact of two nominally clamped surfaces. In the presence of cyclic tangential loads, the two contacting bodies undergo small-scale, oscillatory, relative tangential motions known as “microslip.” ˜is slipping motion may be localized so that the contacting surfaces do not exhibit global relative motion. Typical microslip amplitudes are on the order of 10-100 μm. ˜e physical mechanism of the damage involves a combination of wear, corrosion, and fatigue. ˜ese, in turn, are driven by high stress gradients near the contact and microslip. ˜e resulting nucleated fretting crack may grow in the presence of an external cyclic stress Ÿeld, ultimately resulting in failure of the component. While fretting damage is very localized, it can have a huge impact on the fatigue life of an engineering component, reducing it by as much as 40%–60% (Waterhouse, 1972).