Noise and vibration reduction technology in aircraft internal cabin

Abstract

The study to reduce noise and vibration in aircraft cabin through PZT was implemented, using a semi-monocoque structure, 1.5m in diameter and 3.Om long with 2.3mm skin, which simulates an aircraft body. We utilized PZT of 480 pieces bonded on inner surface of the structure as sensor and actuator. We applied random noise of low frequency range between 0-500Hz to the test model. We tried to reduce the vibration level of structure and internal air due to the external load by controlling the PZTs.Two control methods, gain control and feed-forward control, were tried. We measured internal sound pressure on 150 spots and compared overall values of sound pressure with gain control to them without control and evaluated its reduction capability. The tests showed 4.0dB O.A. reduction at maximum in gain control and 3.5dB O.A. reduction at maximum in feed forward control.

Active Suppression of Plate Vibration Excited by Acoustic Pressure in a Chamber: Cluster-mode Approach

“…More specifically, noise reduction in an airplane cabin was experimentally and analytically studied, for example, by Takahashi et al (2003), Herdic et al (2005), etc. The sum of the numbers of both structural vibration modes of an actual fuselage and acoustic modes in its cabin is very large, so that mechanical interactions among the structural and acoustic modes observed under active control of noise reduction are quite complicated.…”

“…The sum of the numbers of both structural vibration modes of an actual fuselage and acoustic modes in its cabin is very large, so that mechanical interactions among the structural and acoustic modes observed under active control of noise reduction are quite complicated. For instance, Takahashi et al (2003), including the second author of the present study, performed an analysis and experiment using a CFRP cylindrical shell of 2.3 mm thickness, 1.5 m diameter, and 3.0 m length with bulkheads at both ends, which represented a one-third scale model of an airplane fuselage. There were 301 cylindrical vibration modes and 105 acoustic modes inside the shell between 0 and 500 Hz.…”