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 P mn (the power radiation coefficient of the m - and n th modes) and D mn (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.