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Ultrasonic oil-film thickness measurement: An angular spectrum approach to assess performance limits

Zhang, J., Drinkwater, B.W. and Dwyer-Joyce, R.S. (2007) Ultrasonic oil-film thickness measurement: An angular spectrum approach to assess performance limits. Journal of the Acoustical Society of America, 121 (5). pp. 2612-2620. ISSN 00014966

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The performance of ultrasonic oil-film thickness measurement in a ball bearing is quantified. A range of different viscosity oils (Shell T68, VG15, and VG5) are used to explore the lowest reflection coefficient and hence the thinnest oil-film thickness that the system can measure. The results show a minimum reflection coefficient of 0.07 for both oil VG15 and VG5 and 0.09 for oil T68 at 50 MHz. This corresponds to an oil-film thickness of 0.4 μm for T68 oil. An angular spectrum (or Fourier decomposition) approach is used to analyze the performance of this configuration. This models the interaction of component plane waves with the measurement system and quantifies the effect of the key parameters (transducer aperture, focal length, and center frequency). The simulation shows that for a focused transducer the reflection coefficient tends to a limiting value at small oil-film thickness. For the transducer used in this paper it is shown that the limiting reflection coefficient is 0.05 and the oil-film measurement errors increase as the reflection coefficient approaches this value. The implications for improved measurement systems are then discussed.

Item Type: Article
Copyright, Publisher and Additional Information: Copyright (c) 2007 Acoustical Society of America. This is an author produced version of a paper published in ' Journal- Acoustical Society of America '. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: Ball bearings Computer simulation Error analysis Film thickness Oils and fats Reflection Transducers Ultrasonic transmission Angular spectrum Oil-film thickness measurement Plane waves Thick films lubricating agent article film mathematical computing measurement performance measurement system priority journal simulation spectrum thickness transducer ultrasound viscosity
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Mechanical Engineering (Sheffield)
Depositing User: Mr Christopher Hardwick
Date Deposited: 18 Aug 2009 14:54
Last Modified: 08 Feb 2013 16:58
Published Version: http://dx.doi.org/10.1121/1.2713676
Status: Published
Publisher: Acoustical Society of America
Refereed: Yes
Identification Number: 10.1121/1.2713676
URI: http://eprints.whiterose.ac.uk/id/eprint/9167

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