Foam-PVDF smart skin for aircraft interior sound control

The development and testing of foam-PVDF smart skin designed for aircraft interior noise control are discussed. The smart skin is designed to reduce sound by the action of the passive absorption of the foam (which is effective at higher frequencies) and the active input of a PVDF element driven by an oscillating electrical input (which is effective at lower frequencies). The device consists of cylindrically curved PVDF piezoelectric film embedded in partially reticulated polyurethane acoustic foam, For performance testing, the foam-PVDF smart skin is mounted in the cockpit of a Cessna Citation III fuselage. Each smart foam element controls the effective acoustic source of individual fuselage panels. The fuselage crown panels are excited with a speaker located on the outside of the cockpit. A MIMO feedforward LMS controller is implemented to minimize the error sensor signals provided by microphones in the close proximity of the active elements under band-limited random excitation. The use of two different reference signals, i.e. the voltage sent to the speaker (disturbance) and the signal from an accelerometer directly mounted on the fuselage (more realistic in practice), are compared in terms of the interior noise attenuation achieved. The potential of the smart foam-PVDF skin for reducing interior noise is demonstrated.