A technique for the analysis of propagating multimode signals is presented. The method involves a two-dimensional Fourier transformation of the time history of the waves received at a series of equally spaced positions along the propagation path. The technique has been used to measure the amplitudes and velocities of the Lamb waves propagating in a plate, the output of the transform being presented using an isometric projection which gives a three-dimensional view of the wave-number dispersion curves. The results of numerical and experimental studies to measure the dispersion curves of Lamb waves propagating in 0.5-, 2.0-, and 3.0-mm-thick steel plates are presented. The results are in good agreement with analytical predictions and show the effectiveness of using the two-dimensional Fourier transform (2-D FFT) method to identify and measure the amplitudes of individual Lamb modes.
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March 01 1991
A two-dimensional Fourier transform method for the measurement of propagating multimode signals
D. Alleyne, P. Cawley; A two-dimensional Fourier transform method for the measurement of propagating multimode signals. J. Acoust. Soc. Am. 1 March 1991; 89 (3): 1159–1168. https://doi.org/10.1121/1.400530
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