Preliminary Study on Characteristics of Sound Radiation from Beam-Stiffened Plates

Abstract

Beam structures attached on the surface of a panel has been commonly used in practice to increase stiffness of the panel. This paper studies the sound radiation from a vibrating beam-stiffened plate. To investigate the effect, a mathematical model which comprises of a semi-analytical model from a discrete Rayleigh formula and numerical calculation from Finite Element (FE) model is used to calculate the radiation efficiency of the structure. The latter is utilized to obtain the surface velocity of the panel. Acoustic power and radiation efficiency of beam-stiffened plates for different number of beams, arrangement of the beams and geometries of the beam are presented. It is found that beam-stiffening significantly reduces the acoustic power at the monopole region at very low frequency and at high frequency in edge mode region and above the critical frequency. Increasing the number of beam stiffener increases the radiation efficiency of the panel at the corner mode region due to reduction of the panel velocity. Similarly, the two-dimensional stiffening provides greater effect in reducing vibration velocity of the panel, but not necessarily reducing the acoustic power. Hence this increases the radiation efficiency at certain frequency range compared to the one-dimensional stiffening. Increasing the thickness of the beam reduces both velocity and acoustic power consistently and therefore results in no significant change in radiation efficiency.
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