James P. Carneal
Chris R. Fuller
Vib. and Acoust. Labs., Dept. of Mech. Eng., Virginia Polytech. Inst. and State Univ., Blacksburg, VA 24061
This work is concerned with an experimental investigation of active control of sound transmission through double panel systems. The technique used is the active structural acoustic control (ASAC) approach where control inputs, in the form of piezoelectric actuators, were applied to the structure while the radiated pressure field was minimized. The double panel system was mounted in a common wall between two reverberant chambers comprising a transmission loss test facility at VPI and SU. Two different panel systems were tested; the first in which both panels were of similar dynamic response and a second in which the radiating panel (of sandwich construction) was much stiffer and had higher resonant frequencies. Excitation of the source panel was induced by reverberant and plane-wave harmonic sound fields. Configurations in which the piezoelectric actuators were bonded to either the source or radiating side panel were tested. A multichannel filtered-X LMS algorithm was used as the controller. Error signals were taken from microphones in the radiated field. Results indicate that a 12-dB attenuation of acoustic radiated power could be typically achieved. The influence of excitation frequency and noise field, radiating plate stiffness, and control system configuration was studied. In particular, the results demonstrate that it is possible to take advantage of the double panel behavior to enhance control performance. In general, this investigation demonstrates the validity of ASAC of noise transmission through double panel systems. [Work supported by NASA LaRC.]