Vibroacoustic Modes and Active Control of Both Vibration and Sound

摘要

Vibration reduction and sound reduction are not necessarily compatible. The sum of the structural kinetic energy and acoustic power in free space (acoustic potential energy in an enclosed space) is an error criterion to control both vibration and sound. The orthogonal contributors with respect to the sum, "vibroacoustic modes" and the frequency dependent spatial filters, which can estimate the amplitudes of the vibroacoustic modes, "vibroacoustic modal filters," are formulated. Vibroacoustic modal filters allow a controller to coordinate both vibration and sound reduction and achieve order reduction. However, the implementation is not very easy because of the frequency dependence. The frequency independent vibroacoustic modal filters are formulated by omitting the frequency dependence. The omission of the frequency dependence mathematically proves to be valid for baffled structures in free space. Moreover, the developed theories are applied to baffled rectangular plates in free space, and the simulation results, for example, the contributions of the vibroacoustic modes to the sum of the structural kinetic energy and acoustic power, the shapes of the vibroacoustic modes, and the performance of the feedforward control using the frequency independent vibroacoustic modal filters, are presented.