Mechanics of surface damage in elastohydrodynamic contacts.

The first part of the grant was devoted to nearly pure rolling contacts and deals with an analysis of the rate of growth of a surface or a subsurface crack in a two-dimensional Hertzian contact with or without tangential force on the surface. This analysis is expected to be used as the basis on which a life prediction model can be formulated. Further analysis developed closed form solutions for problems of three-dimensional contact. Explicit expressions in closed form were developed for the subsurface stress field for normal and sliding elliptical contact. The second part of the grant was intended for contacts having a high slide to roll ratio. These contacts usually fail by an accelerated adhesive wear process commonly known as scuffing such as that occurring at the root or tip of gear teeth. Even though the detailed mechanisms of scuffing are yet to be uncovered, there is strong evidence indicating that scuffing failure is of a thermal origin. For this reason, the major part of the second part is focused on a detailed transient analysis of the growth of surface temperature at the asperity tips between two rough sliding EHL contacts. (A)