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Lubricants 2018, 6(3), 80;

Analytical Formula for the Ratio of Central to Minimum Film Thickness in a Circular EHL Contact

Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2896/2, 616 69 Brno, Czech Republic
Author to whom correspondence should be addressed.
Received: 23 July 2018 / Revised: 28 August 2018 / Accepted: 31 August 2018 / Published: 7 September 2018
(This article belongs to the Special Issue Fluid-Film Lubrication)
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Prediction of minimum film thickness is often used in practice for calculation of film parameter to design machine operation in full film regime. It was reported several times that majority of prediction formulas cannot match experimental data in terms of minimum film thickness. These standard prediction formulas give almost constant ratio between central and minimum film thickness while numerical calculations show ratio which spans from 1 to more than 3 depending on M and L parameters. In this paper, an analytical formula of this ratio is presented for lubricants with various pressure–viscosity coefficients. The analytical formula is compared with optical interferometry measurements and differences are discussed. It allows better prediction, compared to standard formulas, of minimum film thickness for wide range of M and L parameters. View Full-Text
Keywords: point contact lubrication; minimum film thickness; prediction formula point contact lubrication; minimum film thickness; prediction formula

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Sperka, P.; Krupka, I.; Hartl, M. Analytical Formula for the Ratio of Central to Minimum Film Thickness in a Circular EHL Contact. Lubricants 2018, 6, 80.

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