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RESEARCH PAPERS

Occurrence of a Noncentral Dimple in Squeezing EHL Contacts

[+] Author and Article Information
F. Guo1

Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu, Fukuoka, 804-8550, Japan and School of Mechanical Engineering, Qingdao Technological University, 11 Fushun Road, Qingdao 266033, P. R. Chinameguof@yahoo.com.cn

M. Kaneta, J. Wang, H. Nishikawa

Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu, Fukuoka, 804-8550, Japan

P. Yang

School of Mechanical Engineering, Qingdao Technological University, 11 Fushun Road, Qingdao 266033, P. R. China

1

Corresponding author.

J. Tribol 128(3), 632-640 (Mar 19, 2006) (9 pages) doi:10.1115/1.2194919 History: Received July 04, 2005; Revised March 19, 2006

Previous studies about pure squeeze elastohydrodynamic lubrication (EHL) have disclosed a film profile with a central dimple. Two problems about pure squeeze EHL are numerically solved in this paper. One is for a very small initial impact gap, and the other is the response of a squeezed EHL conjunction under stepwise loads. None of them result in the familiar film with a central dimple, which can be attributed to the local squeeze effect generated in the periphery region. In the first problem, it has been found that when there is adequate oil present on the plate, with a decrease in the initial impact gap, a shallow circumferential dimple occurs at the periphery of the conjunction instead of the primary central dimple presented in previous studies. Correspondingly the minimum film thickness occurs at the central region. The effect of the initial impact velocity on the periphery dimple is also investigated. In the second problem, the response of a conjunction subjected to a prescribed stepwise load is studied. When the first step load is applied, a central dimple film is produced. When the applied load is increased with a second step load, a periphery dimple appears, similar to that in the first problem. The local squeeze effect for the present numerical periphery dimple has been observed in previous experiments under similar conditions.

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Copyright © 2006 by American Society of Mechanical Engineers
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Figures

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Figure 1

Mathematical model

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Figure 2

Pressure distributions and film profiles in an approach-separation process for WA=1.41×10−6, Hoil=3.94(hoil=5.0μm), Hini=0.394(hini=0.5μm), Shell Turbo 33, Vini=0, and steel-steel contact: (a) variations of the central pressure, the central film thickness, and the minimum film thickness with time; (b) pressure distributions along the radius during approach; (c) film profiles along the radius during approach; (d) pressure distributions along the radius during separation; (e) film profiles along the radius during separation

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Figure 3

Influences of the initial central impact gap on the film pressure and film profile, WA=1.41×10−6, Hoil=6.30(hoil=8.0μm), Shell Turbo 33, Vini=0 and steel-steel contact: (a) variations of the central film pressure with time; (b) variations of the central film thickness with time; (c) pressure distributions along the radius at t=0;(d) film profiles along the radius at t=0; (e) variations of Hcen, Hmin,and Pcen at t=0 with initial impact gaps

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Figure 4

Influences of the oil layer thickness on the film pressure and film profile, WA=1.41×10−6, Hini=0.394(hini=0.5μm), Shell Turbo 33, Vini=0 and steel-steel contact: (a) variations of the central film pressure with time; (b) variations of the central film thickness with time; (c) pressure distributions along the radius at t=0; (d) film profiles along the radius at t=0; (e) variations of the central film thickness, the minimum film thickness and the central pressure at t=0 under different oil layer thickness

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Figure 5

Pressure distributions and film profiles at different time steps in the approach process for WA=1.41×10−6, Hoil=Hini=0.394, Shell Turbo 33, Vini=0 and steel-steel contact: (a) pressure distributions along the radius; (b) film profiles along the radius

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Figure 6

Influences of the initial impact velocities on the pressure distribution and film profile, WA=1.4×10−6, Hini=1.18, Hoil=6.3, Shell Turbo 33 and steel-steel contact: (a) variations of the central film pressure with time; (b) variations of the central film thickness with time; (c) pressure distributions along the radius at t=0; (d) film profiles along the radius at t=0

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Figure 7

Response of the conjunction under a stepwise loading scheme, Hoil=23.6, BS oil, Vini=0 and steel-glass contact: (a) the central pressure and the central film thickness versus time; (b) the rigid velocity versus time; (c) the squeeze coefficient versus time; (d) the rigid separation versus time

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Figure 8

Variations of pressure and film thickness within the contact at different time instants in Fig. 7: (a) pressure distributions along the radius; (b) film profiles along the radius

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Figure 9

Influence of t0 on the film profile along the radius when solid contact occurs, the dashed line in each plot is the film profile at t=t0 just before the step load is applied, and the solid line stands for the film profile when the solid contact occurs (hmin<1nm) after subject to the 60N step load: (a)t0=5ms; (b)t0=10ms; (c)t0=20ms; (d)t0=40ms; (e)t0=70ms

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