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Full-Text Articles in Physics
A Simple And Inexpensive Optical Technique To Help Students Visualize Mode Shapes, Thomas R. Moore, Ashley E. Cannaday, Sarah A. Zietlow
A Simple And Inexpensive Optical Technique To Help Students Visualize Mode Shapes, Thomas R. Moore, Ashley E. Cannaday, Sarah A. Zietlow
Student-Faculty Collaborative Research Publications
An imaging technique is introduced that is suitable for visualizing the mode shapes of vibrating structures in an educational setting. The method produces images similar to those obtained using electronic speckle pattern interferometry (ESPI) but it can be implemented for less than 1=10 the cost of a commercial ESPI system, and the apparatus is simple enough that it can be constructed by undergraduate students. This technique allows for real-time visualization of the normal modes and detection shapes of harmonically vibrating structures, including those with shapes that make generating Chladni patterns with sand or powder impossible. The theory of operation and …
Normal Modes Of The Indian Elephant Bell, Robert Perrin, Luke Chalmers, Daniel Elford, Gerry M. Swallowe, Thomas R. Moore
Normal Modes Of The Indian Elephant Bell, Robert Perrin, Luke Chalmers, Daniel Elford, Gerry M. Swallowe, Thomas R. Moore
Faculty Publications
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 …
The Limitations On Applying Classical Thin Plate Theory To Thin Annular Plates Clamped On The Inner Boundary, Daniel W. Zietlow, Donald C. Griffin, Thomas R. Moore
The Limitations On Applying Classical Thin Plate Theory To Thin Annular Plates Clamped On The Inner Boundary, Daniel W. Zietlow, Donald C. Griffin, Thomas R. Moore
Student-Faculty Collaborative Research Publications
The experimentally measured resonance frequencies of a thin annular plate with a small ratio of inner to outer radii and clamped on the inner boundary are compared to the predictions of classical thin-plate (CTP) theory and a finite-element (FE) model. The results indicate that, contrary to the conclusions presented in a number of publications, CTP theory does not accurately predict the frequencies of a relatively small number of resonant modes at lower frequencies. It is shown that these inaccuracies are attributable to shear deformations, which are thought to be negligible in thin plates and are neglected in CTP theory. Of …