At the beginning of this century very little information was available related to the phenomenon of fretting and fretting-fatigue. However, significant progress has been made in developing an understanding of the mechanisms of fretting-fatigue in this century. Progress toward developing a holistic view of the process of fretting fatigue is presented.

Contributions that have been made in understanding nucleation of fretting-fatigue damage are reviewed. As well, characterization of damage is discussed related to improving our understanding. Those parameters that are viewed as mechanism controlling, thus important to test methods development, are reviewed. The progress made in micromechanical modeling is also reviewed. The paper concludes with recommendations for the standards development group to consider in relation to test methods and some suggestions for future research and development.