Radiation Efficiency of Rectangular Orthotropic Plates

Author： Anderson J. S. Bratos-Anderson M.

ISSN： 1610-1928

Source： Acta Acustica united with Acustica, Vol.91, Iss.1, 2005-01, pp. : 61-76

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Abstract

The sound radiation efficiency of specially orthotropic, baffled rectangular plates is analysed for plates with dimensions much greater than the structural wavelength. A unidirectional carbon laminate is chosen as the main example. The numerically-obtained, averaged sound radiation efficiency as a function of frequency for the carbon laminate is compared with experimental data. The modal sound radiation efficiency is derived either directly from Rayleigh's integral or by an asymptotic approach based on Leppington et al. The resonant modes and their sound radiation properties are discussed in the context of the distribution of the different classes of resonant modes in wavenumber space. In particular the influence of the orthotropy on the distribution of the different types of the resonant modes is considered. The average sound radiation efficiency of resonant modes within a frequency band, obtained with the assumption of a continuous distribution of resonant modes within the frequency band, is compared with radiation efficiency averaged over an ensemble of resonant modes within the frequency band (discrete model) and its dependence on the parameters associated with the material properties and geometry of the plate is discussed.