Advanced time domain wave-number sensing for structural acoustic systems. Part III. Experiments on active broadband radiation control of a simply supported plate
The present work gives further developments and experimental testing of a new time domain structural sensing technique for predicting wave-number information and acoustic radiation from vibrating structures. Most structure-borne active sound control approaches now tend to eliminate the use of microphones located in the far field by developing sensors directly mounted on the structure. In order to reduce the control authority and complexity required to minimize sound radiation, these sensors should be designed to provide error information that is solely related to the radiating part of the structural vibrations, e.g., the supersonic wave-number components in the case of planar radiators. The approach discussed in this paper is based on estimating supersonic wave-number components coupled to acoustic radiation in prescribed directions. The spatial wave-number transform is performed in real time using a set of point structural sensors with an array of filters and associated signal processing. The use of the sensing approach is experimentally demonstrated in the time domain LMS active control of broadband sound radiated from a vibrating plate. Comparisons of the control performances obtained with the wave-number sensor and error microphones in the far field show that only a few point sensors are required to provide accurate radiation information over a broad frequency range. The approach demonstrates good broadband global control of sound radiation. (C) 1995 Acoustical Society of America.