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Torsional and bending vibration measurement on rotors using laser technology

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journal contribution
posted on 04.12.2015, 15:40 by Toby J. Miles, Margaret Lucas, Neil A. Halliwell, Steve RothbergSteve Rothberg
Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) was developed for non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. This paper describes comprehensive theory to account for the sensitivity of the LTV's measurements to shaft motion in all degrees of freedom. The optical geometry of the LTV offers inherent immunity to translational motion of the target shaft, either axial or radial. However, its measurements are sensitive to angular lateral vibration of the shaft. The significance of this sensitivity is compared with the instrument noise floor and typical torsional and lateral vibration levels. Optimum alignments of the instrument are then specified to ensure effective immunity to all lateral motion in typical applications. To overcome this problem more reliably, a new technique is proposed permitting unambiguous measurement of pure torsional vibration in situations where use of a single LTV demonstrates unacceptable sensitivity to angular lateral vibrations. Practical application of this technology is demonstrated with torsional vibration measurements from a diesel engine crankshaft. Simultaneously, previously unattained measurements of shaft bending vibration measurements are made. The first bending mode of the crankshaft was identified and its vibration amplitude and damping estimated. This application of laser vibrometry for non-contact measurements of shaft vibration represents a further step forward in the use of this technology for machinery diagnostics.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

JOURNAL OF SOUND AND VIBRATION

Volume

226

Issue

3

Pages

441 - 467 (27)

Citation

MILES, T.J. ... et al, 1999. Torsional and bending vibration measurement on rotors using laser technology. Journal of Sound and Vibration, 226 (3), pp. 441 - 467.

Publisher

Elsevier (© Academic Press Ltd)

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

1999

Notes

This article was accepted for publication in the Journal of Sound and Vibration [Elsevier © Academic Press]. The definitive version is available at: http://dx.doi.org/10.1006/jsvi.1999.2253

ISSN

0022-460X

Language

en

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