PREDICTION OF TRACTION IN ELASTOHYDRODYNAMIC LUBRICATION

The prediction of traction (friction) in lubricated rolling-sliding co ntacts remains a challenging problem despite the development of the re alistic Maxwell-Eyring-limiting shear stress model by Johnson and co-w orkers in the 1980s. This is largely because there is a strong couplin g between the elastohydrodynamic traction and the film temperature. An added complication is that the heat conducted into the rubbing surfac es, as well as influencing traction directly, also determines the temp erature in the inlet to the contact and hence the thickness of the ela stohydrodynamic film. In the present paper, the traction model of John son et al. is combined with a heat transfer analysis of the contacting bodies as well as the film thickness regression equation. In addition , the variations in the lubricant's rheological properties with temper ature and pressure based upon the measurements of Muraki et al. have b een included. The traction equation is expressed in dimensionless form and is solved using a simple iterative scheme, which in many cases al lows estimation of the traction without the use of a computer. Closed- form equations for the friction are given for each of the traction reg imes.