Estimate of the radiated acoustical power using strain sensing

Abstract

In common active structural acoustic control systems, the acoustical feedback signal is obtained from error microphones placed in the far field of the vibrating structure. Using strain sensors on the surface, the need for far-field acoustic sensors is eliminated, which is advantageous in practical applications where no microphones can be used. An estimate of the radiated acoustic power from a vibrating plate by the use of on-plate PVDF sensors is discussed. Since the number and the location of the sensors directly affect the quality of the radiation information, the influence of various sensor arrangements is investigated. For this purpose, a clamped rectangular plate is considered which is excited at four discrete frequencies in such a way that four modes contribute effectively to sound radiation. Since the vibrational behavior is well known, the required number of PVDF sensors may be reduced, which speeds up the computation of the radiated acoustic power during the adaptation process. It will be shown that the analytical results agree well with experimental data.