Showing papers in "Journal of Lubrication Technology in 1981"

Surface Temperatures in Sliding Systems—A Finite Element Analysis

Abstract: Finite element equations are developed for studying surface temperatures resulting from frictional heating in sliding systems. The equations include the effect of velocity of moving components, an effect which is found to be quite significant, even at low sliding velocities. A program was written using the equations and it was applied to the study of surface temperatures in two different sliding systems: dry or boundary lubricated sleeve bearings and a labyrinth gas path seal configuration. Very good agreement was achieved between analytical predictions using the program and experimental temperature measurements. The program was used to study the influence of various material parameters on surface temperatures in the two sliding systems.

The Behavior of Adhered Fragments Interposed Between Sliding Surfaces and the Formation Process of Wear Particles

Abstract: To study the behavior of adhered fragments on rubbing surfaces, the transverse movement of a slider is measured and recorded during the wear process The gap between the mating surfaces is enlarged gradually through the origin and growth of a transfer particle adhering to the slider and then closed suddenly by the removal of the particle The removal process of wear particles can be observed by an optical microscope Furthermore, an X-ray microanalysis is made on the cut section of the rubbing system just before the removal of the particle The particle is press-slide flattened in shape and has a hair line mixed structure containing metals of both mating surfaces The maximum lift of the slider is nearly equal to the size of the produced particle These observations show that the adhered fragments are piling up and are being press-slide flattened between the mating surfaces until their final removal as wear particles

Centrifugal Effects in Thrust Bearings and Seals Under Laminar Conditions

Abstract: An analysis is conducted and solutions are provided for the effect of centrifugal forces on the hydrodynamics of high-speed thrust bearings and seals. First, a scrutiny of the individual inertia terms of the Navier-Stokes equations delineates the circumstances under which the centrifugal term (u2 /r) becomes the dominant component. A Reynolds equation incorporating centrifugal forces is then derived for finite sectorial configurations operating under incompressible laminar conditions. Thermal effects are included. The equation is solved by finite difference methods. The results show that at the upper limits of laminar operation centrifugal forces reduce considerably the load capacity and alter the pattern of lubricant flow. As a result, at sufficiently high velocities the inflow of lubricant at the inner radius of a sectorial configuration may bring about the scavenging of lubricant from wide portions of the bearing surface, producing a form of thrust bearing cavitation. Design features which would reduce the negative consequences of centrifugal action are outlined, including the introduction of radial tapers.

An Experimental Evaluation of the Hamrock and Dowson Minimum Film Thickness Equation for Fully Flooded EHD Point Contacts

Abstract: Fifty-seven measurements of the minimum lubricant film separating the elastohydrodynamically lubricated point contact of a steel crowned roller and a flat sapphire disk were made by an optical interferometry technique The data collected were used to evaluate the Hamrock and Dowson minimum EHD film thickness model over a practical range of contact ellipticity ratio where the major axis of the contact ellipse is aligned both parallel and perpendicular to the direction of motion A statistical analysis of the measured film thickness data showed that on the average the experimental data averaged 30 percent greater film thickness than the Hamrock and Dowson model predicts

On the Traction Behavior of Several Lubricants

Abstract: A number of lubricants in the well known classes denoted by MIL-L-23699 and MIL-L-7808 specifications and a traction fluid are investigated for their traction behavior in rolling sliding contacts. The experimental traction data are reduced to simple rheological models and the appropriate coefficients are computed. The reduced models are presented in a form which is readily adaptable to the rolling bearing performance simulation computer programs.

Fluid-Film Journal Bearings Operating in a Hybrid Mode: Part II—Experimental Investigation

Abstract: An extensive experimental program was carried out to test the theoretical predictions discussed in Part I of this paper. The design of the bearing test rig is described. Line-source plain hybrid journal bearings have been investigated and results are presented for bearings at the optimum and higher speeds. Such parameters as load, eccentricity, oil-film pressure, speed, inlet and outlet temperatures, friction torque, oil flow-rate, and attitude angle have been measured. A description of the appropriate instrumentation is also included. Whereas close agreement was found between theory and experiment, there was a tendency for measured loads to be slightly higher than predicted, particularly as the eccentricity ratio approached a value of unity. It was also found that at high values of power ratio corresponding to higher temperature rise conditions, frictional torque was lower than predicted.