The Effects of Modal Coupling on the Acoustic Power Radiation From Panels

Abstract

The effects of modal coupling on the acoustic power radiated from line forced panels of unit width with s-s (simply supported-simply supported) and c-c (clamped-clamped) end conditions have been studied. The expressions for the power radiated by the total square terms and by the coupling terms in these two one-dimensional problems were derived using Heckl’s power integral. A qualitative and quantitative discussion regarding the properties of Pmn (the power radiation coefficient of the m- and nth modes) and Dmn (the wavenumber cross-spectrum of modal velocities) for the s-s panel are presented. Numerical calculations (for both s-s and c-c cases) were carried out to investigate the relative importance of the modal coupling in the acoustic radiation. The results show that if the panel is under resonant excitation or if the driving force is at high frequency, then the effects due to modal coupling are negligible. At low frequency, however, or if the panel is under off-resonant excitation, then the contributions due to the modal coupling may be important.

Vibro-acoustic analysis of a rectangular-like cavity with a tilted wall

“…Therefore, an accurate characterization of the sound-structural interaction is essential for the prediction of acoustic field. Since conventional modal-based methods heavily rely on the availability of the acoustic modes, which are not analytically known in the presence of geometry irregularity, most of previous investigations focused on systems with perfect geometry and homogeneous structural properties [7][8][9][10]. In practice, imperfections (geometrical distortion or structural parameter uncertainty) always exist to a certain extent, which may lead to significant discrepancy from results obtained using idealized models, in terms of both eigen-frequencies and responses of the system.…”

“…Early researches in this field were presented by Junger and Feit [1] and Dowell et al [2,3], who developed a comprehensive modal-based theoretical framework for interior sound field prediction. Since then, a large amount of efforts has been devoted to investigating the vibro-acoustic behavior of such systems, such as analysis of structural-acoustic modal interaction [4][5][6][7] and sound radiation prediction [8][9][10][11].…”

The effect of different combinations of boundary conditions on the average radiation efficiency of rectangular plates

“…The importance of the cross-modal coupling on the radiation from a panel was pointed out by Keltie and Peng in [11]; it was noted that, particularly at low frequencies and under off-resonant excitation, this contribution should not be neglected. [12] demonstrated that the cross-modal contributions are only non-zero for pairs of modes that are either both odd or both even in a given direction.…”

Determination of the Mutual Radiation Resistances of a Rectangular Plate and Their Impact on the Radiated Sound Power

“…Although the potential problem of only considering the self-powers generated independently by each mode has long been recognized [14], there are few publications in the literature about the characteristics of the mutual-radiation resistances and their impact to the radiated sound power. Keltie and Peng [15] investigated the e!ects of the cross-modal coupling on acoustic radiation from one-dimensional (1-D) panels by varying force locations. It was demonstrated that the contributions due to the cross-terms could be important in a low-frequency range or for a non-resonant response.…”