The initial stage of friction contact between brittle bodies

It is proposed to estimate the surface fatigue of brittle crystalline bodies using experimental data on the initial stage of friction and wear. The mean fatigue stress is estimated from the relation between the force of friction and the size of the section of the surface layer characterized by the mean debris size; the number of fatigue fracture cycles is determined by the relation between the time of damage accumulation on the surface asperities before their total fracture and the mean profilogram step. The calculation includes the asperities that correspond to the initial portion of the reference curve, while the damage accumulation time is determined from the measurement of acoustic emission. There are no published data on the ultimate fatigue of brittle materials, though such data are essential for proper choice of materials for ceramic artificial joints and thrust bearings in some modern tools and for devices intended to withstand long-term operation in any harsh environment.