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Normal modes of the Indian elephant bell

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journal contribution
posted on 2014-06-17, 10:25 authored by R. Perrin, Luke Chalmers, Daniel Elford, Gerry Swallowe, Thomas R. Moore
The geometrical structure of the Indian elephant bell is presented and the requirements on its normal modes from group representation theory are described. These are in good agreement with the results of a finite-element model (FEM) for a specific 16-tine case. The spectrum consists of a sequence of families of modes lying on saturation curves, completely different from those of conventional bells. Physical explanations for the occurrence of these families are presented in terms of the tines behaving as a closed loop of coupled cantilevers with constraints from the dome. Each family is found to consist of modes in one of two specific sequences of symmetry types. Experimental measurements of the modes of this same 16-tine bell, using electronic speckle patterninterferometry (ESPI), have been made and are compared with the FEM predictions. Although the interpretation of the interferograms is difficult in all but the simpler cases, agreement in terms of frequencies is surprisingly good for the first few family sequences. The ESPI study also showed up numerous harmonics and subharmonics of true normal modes, showing the system to be rather non-linear and making comparisons with the FEM results tricky.

History

School

  • Science

Department

  • Physics

Published in

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA

Volume

131

Issue

3

Pages

2288 - 2294 (7)

Citation

PERRIN, R. ... et al, 2012. Normal modes of the Indian elephant bell. Journal of the Acoustical Society of America, 131 (3), pp. 2288 - 2294.

Publisher

© Acoustical Society of America

Version

  • VoR (Version of Record)

Publication date

2012

Notes

Copyright 2012 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America. The following article appeared in Journal of the Acoustical Society of America, 2012, 131 (3), pp. 2288 - 2294 and may be found at http://dx.doi.org/10.1121/1.3681924

ISSN

0001-4966

Language

  • en

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