Effect of asperity interaction on scuffing.

Pairs of polished and ground rollers were run together in a geared roller tester at three combinations of rolling and sliding velocities, under progressively increasing normal load, until scuffing took place. Each test was repeated until the load reached half the scuffing load. The microgeometry at test termination was used as input to the ASPERSIM microcontact model, to predict, at test termination conditions (load and temperature), the average asperity force and area and the density of contacts and plastic contacts. The polished specimens exhibited a higher scuffing load at each velocity condition and had correspondingly lower predicted average asperity forces. Final predicted contact and plastic contact density at test termination conditions did not differ significantly with specimen finish or scuffing status. Using the microgeometry of the unrun specimens, the predicted asperity force and contact density at the most severe velocity condition were lower by a factor of 3 for the polished specimens. The plastic contact density was lower by a factor of five and thus appears to be the best single numerical quantity computable from a microcontact model to distinguish relative scuffing performance. Discussion of this paper is included on p.158. (A)