Document Type

Article

Publication Date

3-2012

Abstract

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 finiteelement model (FEM) for a specific 16-tine case. The spectrum consists of a sequence of families of modes lying on saturation curves and so is 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 Pattern Interferometry (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.

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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 Robert Perrin, Luke Chalmers, Daniel P. Elford, Gerry M. Swallowe and Thomas R. Moore, Journal of the Acoustical Society of America 131, 2288-2294 (2012) and may be found at http://scitation.aip.org/content/asa/journal/jasa/131/3/10.1121/1.3681924.

Publication Title

Journal of the Acoustical Society of America

ISSN

0001-4966

DOI

10.1121/1.3681924

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