Noise and vibration reduction technology in aircraft cabins

This study investigates how to reduce noise and vibration in aircraft cabins with Pb(TiZr)O-3 (PZT), using a semi-monocoque structure 1.5 m in diameter and 3.0 m long with a 2.3 mm skin, which simulates an aircraft body. We utilized 480 pieces of PZT bonded on the inner surface of the structure as sensors and actuators. We applied random noise in the low frequency range from 0 to 500 Hz to the test model. By controlling the PZTs, we tried to reduce the vibration level of the structure and the internal air due to the external load. Two control methods, gain control and feed-forward control, were tried. We measured internal sound pressure at 150 points and compared the overall values of sound pressure with gain control to those without control and evaluated the reduction capabilities. The tests demonstrated a maximum 4.0 dB O.A. reduction with gain control and a maximum 3.5 dB O.A. reduction with feed-forward control.