Pressure Viscosity Relationship Research Articles

An Application of the Finite Element Method to EHD Lubrication

This paper is the literary property of the American Society of Lubrication Engineers. The Press may summarize freely from this manuscript after presentation, citing source; however, publication of material constituting more than 20 percent of the manuscript shall be construed as a violation of the Society's rights and subject to appropriate legal action. Manuscripts not to be published by the Society will be released in writing for publication by other sources. Statements and opinions advanced in papers are understood to be individual expressions of the author(s) and not those of the American Society of Lubrication Engineers. A design solution of the isothermal EHD problem for rollers is developed, in which the elasticity relationships are introduced using the Finite Element Method. An iterative technique is used to obtain the simultaneous solutions of the two-dimensional Reynolds Equation with the elasticity equations, for a lubricant modeled by an exponential pressure viscosity relationship. The problem...

Relationship between calculated film thickness and wear in elastohydrodynamic contacts of gears

Gear oils are important design elements and it is necessary to establish data relating their performance to operating conditions and gear design. Due to a combination of elastic distortion and increased viscosity due to high pressure, a hydrodynamic film is generated in gear tooth contacts. In this paper the authors consider the use of the Dawson and Higginson equation to relate film thickness to the performance of gears with respect to wear rate and present experimental data obtained using the FZG gear test procedure. Initial results of an experimental programme to determine actual pressure viscosity characteristics within highly loaded contacts are also presented, since the authors consider that it is errors in the pressure viscosity relationship that cause the lack of correlation between theoretical film thickness and experimental data on scuffing.

Film Thickness Between Gear Teeth: A Graphical Solution of Karlson’s Problem

Abstract This investigation completes a solution, undertaken by K. G. Karlson in his little-known Swedish paper of 1926, for the oil-film thickness between gear teeth. Karlson’s problem is characterized by the use of a parabolic curve for the viscosity-pressure relation. The numerical results here obtained are comparable with those previously published by Gatcombe, who used a more conventional viscosity-pressure formula. It is hoped that the present analysis will help to clarify the assumptions and calculations required in the hydrodynamic theory of gear-tooth lubrication. As an aid to its practical application, the relative film thicknesses found for geometrically similar pairs of gears are here shown by a chart constructed in terms of the appropriate dimensionless variables, and extending from zero to 10 microinches per in. of pitch diameter of the pinion. The limiting case of a lubricant whose viscosity is unaffected by pressure, for which an analytical solution had been given by Karlson, is represented by a straight line on this chart.