Analysis of real contact area between an elasto-plastic rough body and an elasto-plastic flat body

Abstract

A three-dimensional model of an elasto-plastic rough surface featured by fractal geometry sliding over an elasto-plastic flat body is developed. The three-dimensional model considers the thermo-mechanical coupling and the heat flux coupling between the sliding surfaces. To obtain the transient real contact area, the problem under this three-dimensional model is solved by the finite element method. The results show that the real contact area is a small fraction of the nominal contact area during the loading and sliding process, and increases with the increase in the applied normal load. In the initial stage of friction sliding, the real contact area increases and fluctuates noticeably for the abrupt change of sliding speed, and then varies in a small range under the constant normal load and sliding velocity. It is also shown that frictional heating increases the real contact area, the instantaneous maximum contact pressure by comparing the results with those obtained from the same model, however, in which the thermal effect of frictional heat is not considered. That is to say, the real contact area is larger when the thermo-mechanical coupling is considered. It is crucial to take the thermo-mechanical coupling effect into account especially for the micro frictional sliding analysis.