Results of high resolution slip measurements in a fretting experiment

An optical method of slip measurement in a fretting experiment has been developed which allows the measurement of slip amplitude to ±0.95 μm. Average sliding velocities of fretting interfaces during each 1.9 μm of relative motion can be calculated from the slip measurement data. Results on 4130 steel indicate that previously reported temperature variations of the fretting interface closely follow the pattern of the instantaneous sliding velocity of the interface, as is expected for frictional heating. The pattern of sliding velocity versus time is very regular from one fretting cycle to the next. It is concluded that any welding or adhesion which occurs at the interface is either on such a small scale that it does not disrupt the regular motion of sliding parts or is so infrequent in occurrence that it was not observed in any of the present experiments.