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Proceedings Paper

Modal testing using impact excitation and a scanning LDV
Author(s): Anthony B. Stanbridge; A. Z. Khan; David J. Ewins
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Paper Abstract

If a laser doppler vibrometer is used in a continuously- scanning mode, its output spectrum contains side-bands from which the response mode shape, as defined along the scan line, may be obtained. With impact excitation, the response is the summation of a set of exponentially-decaying sinusoids which, in the frequency domain, has peaks at the natural frequencies and at 'sideband' pseudo-natural frequencies, spaced at multiples of the scan frequency. Techniques are described for deriving natural mode shapes from these, using standard modal analysis procedures. Some limitations as to the types of mode which can be analyzed are described. The process is simple and speedy, even when compared with a normal point-by-point impact test survey. Information may also be derived, using a circular scan, on the direction of vibration, and angular vibration, at individual points.

Paper Details

Date Published: 1 June 1998
PDF: 9 pages
Proc. SPIE 3411, Third International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, (1 June 1998); doi: 10.1117/12.307718
Show Author Affiliations
Anthony B. Stanbridge, Imperial College of Science, Technology and Medicine (United Kingdom)
A. Z. Khan, Imperial College of Science, Technology and Medicine (United Kingdom)
David J. Ewins, Imperial College of Science, Technology and Medicine (United Kingdom)


Published in SPIE Proceedings Vol. 3411:
Third International Conference on Vibration Measurements by Laser Techniques: Advances and Applications
Enrico Primo Tomasini, Editor(s)

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