Fretting fatigue: recent developments

Fretting Fatigue (FF) is one of the most di¢cult areas of fatigue, and require a multidisciplinary e¤ort in the areas of contact mechanics, tribol-ogy, fatigue and fracture mechanics. It is clear that two aspects contribute to the fatigue detrimental e¤ect, and these are stress concentration and fric-tional surface damage due to microslip, which result in the typical fretting scars, but it is not clear what the in‡uence of the combined presence is. FF is presently receiving a large e¤ort from many academic and industrial groups in Europe and USA. Attacks to FF over the years have been various and conceptually very di¤erent, and all of them signi…cantly oversimpli…ed and/or highly empirical. However, most of them have recognized the pres-ence of pronounced and distinct “thresholds ” and “regimes”. We attempt here to collect few ideas on connecting the two concepts with the obvious conterparts of fatigue (endurance) limit and crack propagation thresholds, trying to elucidate what would most likely happen in limiting conditions