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Active Vibration and Noise Control using Smart Foam

A new class of smart foam is developed and attached to a flexible aluminum plate coupled with a rigid acoustic cavity in an attempt to evaluate its effectiveness in controlling the structural acoustics of the plate/cavity system. The proposed foam consists of a passive foam layer bonded to one surface of an active piezoelectric composite whose other surface is bonded to the surface of the vibrating plate. In this manner, the active piezoelectric composite can control from one side the porosity and the acoustic absorption characteristics of the foam and from the other side can suppress the vibration of the flexible plate. With such capabilities, the proposed smart foam can simultaneously control structural and acoustic cavity modes over a broad frequency range. A finite element model is presented for the behavior of the smart foam when coupled with a plate/cavity system. The predictions of the model are validated experimentally using vibration and/or sound pressure level feedback control strategies. The obtained experimental results are found to be in good agreement with the predictions of the finite element model. Furthermore, it is found that vibration and noise attenuations of about 90% are obtained with control voltages of less than 180 volts for both vibration and sound pressure feedback.