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UBC Theses and Dissertations

Visualization of nodes, antinodes and lateral displacements in vibrating plates Niven, Robert D.


The use of optical techniques for the study of vibrating surfaces has thus far been limited to measuring small amplitudes on the order of a few hundred microinches. To extend the measuring range to much larger amplitudes a completely new technique is sought. In this thesis optical vibration methods are presented that allow amplitudes of .001" and up to be investigated, the upper limit being determined solely by the prohibitive size and cost of the equipment. The study is based on a combination of the shadow moire deflection measuring method and the Salet-Ikeda slope measuring method which, as far as the author knows, have been applied only to the study of static situations. It is shown how these two methods may be applied to the dynamic case to permit the direct visualization of nodal and antinodal locations and displacements in vibrating plates. Three specimens are studied: a cantilever beam, a square cantilever plate and a circular free plate. Complete photographic results along with theoretical or experimental solutions are given for each specimen.

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