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Research Papers: Elastohydrodynamic Lubrication

Starved Elastohydrodynamic Lubrication With Reflow in Elliptical Contacts

[+] Author and Article Information
Takashi Nogi

Japan Aerospace Exploration Agency,
7-44-1 Jindaiji-higashimachi,
Chofu, Tokyo 182-8522, Japan
e-mail: nogitak@gmail.com

Hiroshi Shiomi

Japan Aerospace Exploration Agency,
2-1-1 Sengen,
Tsukuba, Ibaraki 305-8505, Japan
e-mail: shiomi.hiroshi@jaxa.jp

Noriko Matsuoka

Japan Aerospace Exploration Agency,
7-44-1 Jindaiji-higashimachi, Chofu,
Tokyo 182-8522, Japan
e-mail: matsuoka.noriko@jaxa.jp

1Present address: Kyodo Yushi Co., Ltd., 2-2-30 Tsujido Kandai, Fujisawa, Kanagawa 251-8588, Japan.

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received April 4, 2017; final manuscript received May 25, 2017; published online August 22, 2017. Assoc. Editor: Wang-Long Li.

J. Tribol 140(1), 011501 (Aug 22, 2017) (9 pages) Paper No: TRIB-17-1123; doi: 10.1115/1.4037135 History: Received April 04, 2017; Revised May 25, 2017

Under repeated overrollings, the elastohydrodynamic lubrication (EHL) film thickness can be much less than the fully flooded value due to the ejection of the lubricant from the track. The ejection of the lubricant is caused by the pressure flow in the inlet, and under conditions of negligible reflow, the reduction rate is predicted by the numerical analysis with a uniform inlet film thickness. However, the degree of starvation is determined by the balance of the ejection and reflow. In the previous papers for circular contacts, the reflow is taken into account using a nonuniform inlet film thickness obtained based on the Coyne–Elrod boundary condition. In this paper, the model for circular contacts is extended to elliptical contacts, which are of more practical importance in rolling bearings. The model is verified for the inlet distance and the film thickness using a roller on disk optical test device. Numerical results are fitted to an inlet distance formula, which is a function of the initial film thickness, the fully flooded central film thickness, the capillary number, and the ellipticity ratio. The inlet distance formula can be applied to the Hamrock–Dowson formulas for the starved film thickness.

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References

Figures

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Fig. 1

Meniscus around the contact

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Fig. 2

Film thickness outside the meniscus

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Fig. 3

Coyne–Elrod boundary conditions

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Fig. 4

Dimensionless pressure, κ=0.35, C = 0.28 and Hi=9.1

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Fig. 5

Dimensionless film thickness, κ=0.35, C = 0.28 and Hi=9.1

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Fig. 6

Comparison between the numerical and experimental results for the meniscus, κκ=0.63, C = 0.38, Hi = 20: (a) meniscus and (b) Hertzian contact

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Fig. 7

Comparison between the numerical and experimental results for the meniscus, κ=0.63, C = 0.73, Hi = 20: (a) meniscus and (b) Hertzian contact

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Fig. 8

Comparison between the numerical and experimental results for the meniscus, κ=0.63, C = 1.0, Hi = 20: (a) meniscus and (b) Hertzian contact

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Fig. 9

Comparison between the numerical and experimental results for the meniscus, κ=0.35, C = 0.18, Hi=9.1: (a) meniscus and (b) Hertzian contact

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Fig. 10

Comparison between the numerical and experimental results for the meniscus, κ=0.35, C = 0.28, Hi=9.1: (a) meniscus and (b) Hertzian contact

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Fig. 11

Comparison between the numerical and experimental results for the meniscus, κ=0.22, C = 0.14, Hi=6.1: (a) meniscus and (b) Hertzian contact

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Fig. 12

Comparison between the numerical and experimental results for the meniscus, κ=0.22, C = 0.18, Hi=6.1: (a) meniscus and (b) Hertzian contact

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Fig. 13

Comparison between the numerical and experimental results for the dimensionless inlet distance (a) m as a function of C and Hi and (b) numerical versus experimental results

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Fig. 14

Comparison between the numerical and experimental results for the reduction factor of the central film thickness

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Fig. 15

Comparison between the numerical and experimental results for the reduction factor of the minimum film thickness

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Fig. 16

Dimensionless inlet distance in circular contacts as a function of the capillary number

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Fig. 17

Ratio of the dimensionless inlet distance in elliptical contacts to the dimensionless inlet distance in circular contacts as a function of the capillary number, κ=0.5

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Fig. 18

Ratio of the dimensionless inlet distance in elliptical contacts to the dimensionless inlet distance in circular contacts as a function of the capillary number, κ=0.2

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Fig. 19

Ratio of the dimensionless inlet distance in elliptical contacts to the dimensionless inlet distance in circular contacts as a function of the capillary number, κ=0.1

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Fig. 20

Reduction factor of the central film thickness as a function of the inlet boundary parameter

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Fig. 21

Reduction factor of the minimum film thickness as a function of the inlet boundary parameter

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Fig. 22

Reduction factor of the viscous rolling resistance as a function of the inlet boundary parameter

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