2 August 2004 Study of mode shapes and measurement of vibrations in square plates using DSPI and wavelet transform
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In this paper the study of out-of-plane or transverse vibrations in a square plate using digital speckle pattern interferometry (DSPI) is presented. To improve the accuracy of measurement, earlier we have suggested filtering scheme based on proper use of average/median filters followed by Symlet wavelet filter. In this paper we present a different filtering scheme to reduce the speckle noise and improve the accuracy of measurement of DSPI fringes by proper choice of average filter, sampling and thresholding followed by Symlet/Biorthogonal wavelet filter. The speckle index of filtered pattern is calculated and compared with speckle index of unfiltered fringe pattern. It is observed that speckle index is significantly reduced after filtering the DSPI fringe pattern. Experimentally obtained resonance frequencies for the square plate for the boundary condition fixed at all edges were compared with that of classical theory for thin plates. The resonance frequencies obtained from DSPI show good agreement with that of obtained from the classical theory.
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Chandra Shakher, Chandra Shakher, Saba Mirza, Saba Mirza, Rajesh Kumar, Rajesh Kumar, } "Study of mode shapes and measurement of vibrations in square plates using DSPI and wavelet transform", Proc. SPIE 5532, Interferometry XII: Applications, (2 August 2004); doi: 10.1117/12.560375; https://doi.org/10.1117/12.560375

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