WTC2005-63955 A PARAMETRIC ANALYSIS OF THE THERMAL SHEAR LOCALIZATION IN EHL FILMS

Abstract Experiments and computer simulations The Parameter and Results A number of assumptions are made so that the general EHL conditions may be determined under which the thermal shear localization develops. The film gap is assumed to be parallel and subjected to a uniform pressure. The uniform pressure also leads to a constant cross-film shear stress. The surface temperatures are assumed to be uniform and the temperature in the EHL film has reached a steady state, varying only across the film. Under these assumptions, a dimensionless group-parameter is identified that fully governs the degree of the thermal inhomogeneous shear if the lubricant is Newtonian obeying the Barus law of viscosity. It is given by where β is lubricant temperature-viscosity coefficient, op µ is lubricant isothermal viscosity, k is lubricant thermal conductivity and u ∆ is the sliding velocity of the EHL contact. γ& is the ratio of the average shear strain rate in the lower one quarter of the EHL film to the cross-film average strain rate. The results show that the inhomogeneous shear starts after 0