The Role of Wear in the Initiation of Thermoelastic Instabilities of Rubbing Contact

Thermoelastic instability of rubbing contact results from the interaction of thermal expansion, frictional heating, and conduction of heat away from the contact zone. These interactions are modified by wear, which is shown to damp the growth of disturbances in contact pressure from a nominal uniform value. In some cases the presence of wear is found to give rise to oscillatory behavior where portions of the rubbing surfaces alternately rise and drop in temperature. These effects are analyzed for the case of a two-dimensional scraper or blade moving normal to its edge, which presses against the surface of a stationary semi-infinite body. The roles of material properties and operating variables are delineated in terms of dimensionless parameters appropriate to the system.