APPLICATION OF FRACTURE-MECHANICS TO WEAR

Theoretical considerations are presented which show that in general there may be two crack growth mechanisms proceeding simultaneously under wear conditions. Each pass of a rider over a particular subsurface flaw causes it to experience two distinct growth periods, separated by a period when there is no tendency for relative motion between the crack faces. Furthermore, one growth period, just before the rider arrives at the flaw, consists of mode II stress intensification with a light clamping force between the crack faces. The other growth period, following behind the rider, consists of both mode I and II openings. In the first growth period, because there will be some small relative motion between the crack faces under loading, a fretting type of degradation may occur. © 1979.