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Operating Limits for Acoustic Measurement of Rolling Bearing Oil Film Thickness

Dwyer-Joyce, R.S., Reddyhoff, T. and Drinkwater, B. (2004) Operating Limits for Acoustic Measurement of Rolling Bearing Oil Film Thickness. Tribology Transactions, 47 (3). pp. 366-375. ISSN 1547-397X


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An ultrasonic pulse striking a thin layer of liquid trapped between solid bodies will be partially reflected. The proportion reflected is a function of the layer stiffness, which in turn depends on the film thickness and its bulk modulus. In this work, measurements of reflection have been used to determine the thickness of oil films in elastohydrodynamic lubricated (EHL) contacts. A very thin liquid layer behaves like a spring when struck by an ultrasonic pulse. A simple quasi-static spring model can be used to determine the proportion of the ultrasonic waves reflected. Experiments have been performed on a model EHL contact between a ball and a flat surface. A transducer is mounted above the contact such that the ultrasonic wave is focused onto the oil film. The reflected signals are captured and passed to a PC for processing. Fourier analysis gives the reflection spectrum that is then used to determine the stiffness of the liquid layer and hence its thickness. In further testing, an ultrasonic transducer has been mounted in the housing of a deep-groove ball bearing to measure the film generated at the outer raceway as each ball passes. Results from both the ball-flat and ball bearing measurements agree well with steady-state theoretical EHL predictions. The limits of the measuring technique, in terms of the measurable rolling bearing size and operating parameters, have been investigated.

Item Type: Article
Copyright, Publisher and Additional Information: Copyright © 2004 Society of Tribologists and Lubrication Engineers. Reproduced by permission of STLE and Taylor and Francis, Inc., http://www.taylorandfrancis.com
Keywords: Rolling Bearings, Oil-Film Measurement, Elastohydrodynamic Lubrication, Ultrasound
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Mechanical Engineering (Sheffield)
Depositing User: Repository Officer
Date Deposited: 17 Jan 2005
Last Modified: 06 Jun 2014 03:29
Published Version: http://journalsonline.tandf.co.uk/openurl.asp?genr...
Status: Published
Refereed: Yes
Identification Number: 10.1080/05698190490455410
URI: http://eprints.whiterose.ac.uk/id/eprint/215

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