Control of sound radiation from panels using multiple globally detuned vibration absorbers

Abstract

In this paper, the results of an investigation on using multiple globally detuned vibration absorbers to minimize sound radiation from vibrating elastic panels will be presented. The vibration absorbers consist of lumped mass–spring systems whose characteristics (i.e., resonance frequency) can be electronically varied. A fully coupled multiple-channel control algorithm, implemented on a DSP, is used to adapt the characteristics of the multiple absorbers so as to minimize the radiated sound at selected positions in the far field. Both theoretical and experimental results are presented and are compared to those obtained using tuned (i.e., to the disturbance frequency) vibration absorbers. Improved sound attenuation is shown to be obtained using the globally detuned vibration absorbers. The results are very similar in characteristics to those obtained previously using active structural acoustic control implemented with electrodynamic shakers or piezoelectric actuators. The results thus suggest a combined active–passive method to minimize structural sound radiation which requires lighter, smaller actuators and much lower control electrical power. [Work supported by ONR and NASA LaRC.]