Feedforward piezoelectric structural control: An application to aircraft cabin noise reduction

The use of adaptive feedforward central within the active structural acoust ic control framework vies applied to the problem of propeller-induced noise and vibration reduction in the passenger cabin of the Bombardier (de Havil land) Dash-P aircraft. Piezoceramic elements mere used for structural actua tion, and either vibration or acoustic sensing was employed. Actuators comp rised of segmented piezoelectric elements were designed with the objective of reducing the noise and vibration levels at the propeller blade passage f requency (BPF) and the first harmonic. The actuator design objective was su ppression of the operating deflection shapes (ODS) of the fuselage at the v arious frequencies by the judicious placement of piezoelectric elements. Us ing an actuator and sensor design optimized for the BPF together with vibra tion error sensing, the controller was successful in reducing interior nois e in addition to vibration, Further improvement in noise reduction was obta ined when acoustic error sensing was employed. Similar optimized designs fo r actuator and sensors were also found to exist at other frequencies, provi ding good noise and vibration attenuation. Furthermore, this strategy was s uccessfully applied to noise reduction at two operating frequencies, where suppression of the ODSs at both the BPF and 2 X BPF was the objective.