T.J. Wahl and J.S. Bolton, “The Use of the Discrete Fourier Transform to Calculate the Spatial Response of Damped Panels,” Proceedings of the Acoustics '90, 1990 Spring Conference of the Institute of Acoustics (U.K.), published in Proceedings of the Institute of Acoustics, Vol. 12 (1), pp. 945-952, 1990.


In this paper we present a technique for calculating the vibration response of damped panels when forced by a line input. The damping that will be considered here is provided either by radiation into an adjacent acoustic medium (including porous media) or by a damping treatment applied to the panel, or both. It is well-known that formal solutions to problems of this sort are easily obtained using wavenumber transform tehniques as outlined in recent books by Junger and Feit and by Fahy. However, the wavenumber domain solution must then be inverse transformed to obtain the spatial response. This inversion may be performed analytically in only the simplest of circumstances. In this paper it will be shown that for damped panels, the inversion may be evaluated efficiently and "exactly" by using the Fast Fourier Transform (FFT) algorithm to evaluate the Inverse Discrete Fourier Transform (IDFT). The use of this technique will be demonstrated by calculating the damping effect of finite depth layers of porous media when they are confined between a panel and a hard surface.


panel damping, porous media, spatial response


Acoustics and Noise Control

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