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Research Papers: Elastohydrodynamic Lubrication

A Numerical Study of Friction in Isothermal EHD Rolling-Sliding Sphere-Plane Contacts With Spinning

[+] Author and Article Information
H. Dormois, N. Fillot, G. Dalmaz, P. Vergne

CNRS INSA-Lyon, LaMCoS, Université de Lyon, UMR5259, F-69621 Villeurbanne, France

W. Habchi

Department of Industrial and Mechanical Engineering, Lebanese American University (LAU), P.O. Box 36, Byblos, Lebanon

G. E. Morales-Espejel

 SKF Engineering and Research Center, 3430 DT Nieuwegein, The Netherlands; CNRS INSA-Lyon, LaMCoS, Université de Lyon, UMR5259, F-69621 Villeurbanne, France

E. Ioannides

 SKF Engineering and Research Center, 3430 DT Nieuwegein, The Netherlands; Imperial College, SW7 2BX, London, UK

J. Tribol 132(2), 021501 (Mar 24, 2010) (10 pages) doi:10.1115/1.4001104 History: Received March 17, 2009; Revised January 12, 2010; Published March 24, 2010; Online March 24, 2010

This paper presents a study of the spinning influence on film thickness and friction in EHL circular contacts under isothermal and fully flooded conditions. Pressure and film thickness profiles are computed with an original full-system finite element approach. Friction was thereafter investigated with the help of a classical Ree–Eyring model to calculate the longitudinal and transverse shear stresses. An analysis of both the velocity and shear stress distributions at every point of the contact surfaces has allowed explaining the fall of the longitudinal friction coefficient due to the occurrence of opposite shear stresses over the contact area. Moreover in the transverse direction spinning favors large shear stresses of opposite signs, decreasing the fluid viscosity by non-Newtonian effects. These effects have direct and coupled consequences on the friction reduction that is observed in the presence of spinning. They are expected to further decrease friction in real situations due to shear heating.

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Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematic geometrical representation of the analyzed contact, showing the two elements: an upper spinning spherical-end pin (solid B) and a lower rotating flat disk (solid D)

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Figure 2

Schematic representation of the different speed components onto the spherical-end specimen surface (solid B)

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Figure 3

Three-dimensional cube representation of the elastic media analyzed by the model (length at each edge=60a). Over the contact area, the two-dimensional representation of the Reynolds equation domain with dimensions 6a×6a. Notice the two different scales for the sake of clarity.

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Figure 8

Transverse friction coefficient versus slide-to-roll ratio for varying tilting angles

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Figure 9

Velocity maps on the spherical-end specimen surface: without spin (Case 1) and with spin (Case 2). The circle represents the Hertzian contact area.

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Figure 10

Longitudinal shear stress τyx distributions (top part) and profiles along x=0 for λ=90 deg (Case 1, left) and λ=2 deg (Case 2, right), Ue=3 m/s, and SRR=5%

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Figure 11

Transverse shear stress τyz distributions (top part) and profiles along z=−0.12×10−3 m for λ=90 deg (Case 1, left) and λ=2 deg (Case 2, right), Ue=3 m/s, and SRR=5%

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Figure 12

Schematic to explain the interaction between spin local effects and their global consequences on the friction coefficient

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Figure 4

Central and minimum film thickness versus tilting angle

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Figure 5

Tilting angle influence on hλ/h90, the rolling+spinning over rolling film thickness ratio

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Figure 6

Film thickness profiles (×10−5 m) on the line x=0 for two entrainment velocities and varying tilting angles from 90 deg down to 0.5 deg

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Figure 7

Longitudinal friction coefficient versus slide-to-roll ratio for varying tilting angles

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