Showing papers in "Journal of Tribology-transactions of The Asme in 1987"

Relating Profile Instrument Measurements to the Functional Performance of Rough Surfaces

Abstract: Relations entre mesure de profilometrie et performances fonctionnelles des surfaces rugueuses

A Reynolds-Eyring Equation for Elastohydrodynamic Lubrication in Line Contacts

Abstract: Equation de Reynolds-Eyring appliquee a la lubrification elastohydrodynamique d'un contact lineaire

Multigrid, an Alternative Method of Solution for Two-Dimensional Elastohydrodynamically Lubricated Point Contact Calculations

Abstract: Utilisation d'un maillage multiple pour le calcul d'un contact ponctuel elastohydrodynamique bidimensionnel

Wear Reduction and Surface Layer Formation by a ZDDP Additive

Abstract: Reduction de l'usure et formation d'une couche de surface dans le cas de l'additif dialkyldithiophosphate de zinc

Temperatures at Interfacial Contact Spots: Dependence on Velocity and on Role Reversal of Two Materials in Sliding Contact

Abstract: Cas d'un contact glissant. Temperature des asperites en contact. Effets de la vitesse et de l'inversion des roles des deux materiaux

Parallel Sliding Load Support in the Mixed Friction Regime. Part 2—Evaluation of the Mechanisms

Abstract: Capacite de charge de deux plaques paralleles glissant l'une sur l'autre en regime de frottement mixte. Etude des mecanismes mis en jeu

Calculating Rotordynamic Coefficients of Seals by Finite-Difference Techniques

Abstract: For modelling the turbulent flow in a seal the Navier-Stokes equations in connection with a turbulence (kappa-epsilon) model are solved by a finite-difference method. A motion of the shaft round the centered position is assumed. After calculating the corresponding flow field and the pressure distribution, the rotor-dynamic coefficients of the seal can be determined. These coefficients are compared with results obtained by using the bulk flow theory of Childs and with experimental results.

Influence of Surface Waviness and Roughness on the Normal Pressure Distribution in the Hertzian Contact

Abstract: Influence de la rugosite et de l'ondulation de surface sur la distribution des pressions normales dans un contact hertzien

Analysis of the Rolling Contact Residual Stresses and Cyclic Plastic Deformation of SAE 52100 Steel Ball Bearings

Abstract: Analyse des contraintes residuelles dans les contacts roulants et des deformations plastiques cycliques dans des roulements a billes en acier SAE 52100 (Society of automotive engineers)

Parallel Sliding Load Support in the Mixed Friction Regime. Part 1—The Experimental Data

Abstract: Capacite de charge de deux plaques paralleles glissant l'une sur l'autre en regime de frottement mixte. Donnees experimentales

The Influence of Pad Flexibility on the Dynamic Coefficients of a Tilting Pad Journal Bearing

Abstract: Influence de la flexibilite des patins sur les coefficients dynamiques d'un palier a patins oscillants

A New Running Torque Formula for Tapered Roller Bearings Under Axial Load

Abstract: Nouvelle formule pour calculer le couple en cours de fonctionnement d'un roulement a rouleaux coniques soumis a une charge axiale

A Model for the Influence of Pressure on the Bulk Modulus and the Influence of Temperature on the Solidification Pressure for Liquid Lubricants

Abstract: Two pressure chambers, for compression experiments with liquids from zero to 2.2 GPa pressure, are described. The experimentally measured compressions are then compared to theoretical values given by an isothermal model of equation of state recently introduced for solids. The model describes the pressure and bulk modulus as a function of compression for different types of lubricants with a very high accuracy up to the pressure limit of the high pressure chamber used (2.2 GPa). In addition the influence of temperature on static solidification pressure was found to be a simple function of the thermal expansion of the fluid.

Comparison of Hirs’ Equation With Moody’s Equation for Determining Rotordynamic Coefficients of Annular Pressure Seals

Abstract: The rotordynamic coefficients of an incompressible-flow annular pressure seal were determined using a bulk-flow model in conjunction with two different friction factor relationships. The first, Hirs' equation, assumes the friction factor is a function of Reynolds number only. The second, Moody's equation, approximates Moody's diagram and assumes the friction factor is a function of both Reynolds number and relative roughness. For each value of relative roughness, Hirs' constants were determined so that both equations gave the same magnitude and slope of the friction factor. For smooth seals, both relationships give the same results. For rough seals (e/2 H sub 0 = 0.05) Moody's equation predicts 44% greater direct stiffness, 35% greater cross-coupled stiffness, 19% smaller cross-coupled damping, 59% smaller cross-coupled inertia, and nominally the same direct damping and direct inertia.

A pressure-shear plate impact experiment for studying the rheology of lubricants at high pressures and high shearing rates

Abstract: Etude de la rheologie des lubrifiants a de hautes pressions et de forts taux de cisaillement

Sliding Friction and Boundary Lubrication of Snow

Abstract: Etude de la tribologie de la neige, mecanismes, effets et modeles pour des temperatures chaudes et froides en considerant l'humidite neigeuse et la lubrification humide

The Reynolds Centennial: A Brief History of the Theory of Hydrodynamic Lubrication

Abstract: Historique rapide de la theorie de la lubrification hydrodynamique a l'occasion du centenaire de l'article de Reynolds (1886)

A Study of the Effect of Fluid Inertia and End Leakage in the Finite Squeeze Film Damper

Abstract: Etude des effets de l'inertie du fluide et des fuites aux extremites dans un amortisseur a film comprime de longueur finie

A Model for Run-In and Other Transitions in Sliding Friction

Abstract: The mathematical framework for a sliding friction model for run-in and other tribological transitions is presented The semiempirical model was developed to portray the commonly observed shapes, durations, and variations in kinetic friction coefficient versus sliding time curves Terms in the model involve material properties and physical interface conditions such as transfer, debris accumulation, and surface roughness The forms of individual terms are adjustable through the use of systemspecific scaling parameters in order to provide enough modeling flexibility to treat a variety of possible tribological conditions Effects of such conditions as lubrication efficiency loss over time, and temperature build-up can be incorporated by modification of appropriate terms Illustrative plots using the framework with several combined contributions are compared with experimental data from previous work The basic framework of the model can be further developed to incorporate sub-models for specific sliding friction contributions and, in so doing, reduce the number of empirical system parameters required to model actual tribosystem behavior

Combined Effects of Thermal and Non-Newtonian Character of Lubricant on Pressure, Film Profile, Temperature Rise, and Shear Stress in E.H.L.

Abstract: A derivation of the lubrication equation suitable for nonlinear rheological model is presented. Full numerical solutions coupling the lubrication equation with film shape equation and energy equation are obtained to reveal the combined influence of thermal and non-Newtonian character of lubricant on elasto-hydrodynamic lubrication. Results show that the minimum film thickness is influenced only slightly in general. Nevertheless, the spikes of pressure and temperature rise, and the coefficient of friction are strongly affected by the rheological character of lubricant. It is concluded that both the temperature rise and non-Newtonian character of the oil film should be considered in E.H.L. analysis in order to obtain reliable results.