G.A.U.S. Mech. Eng. Dept., Univ. de Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada
The radiated sound power of a planar structure is related to the velocity distribution over the surface of that structure. The well-radiating velocity distributions have in general a nonzero volume velocity. A PVDF sensor design strategy is presented for applications in active structural acoustic control (ASAC). It is based on the modal representation of the response of the studied finite simply supported plate. It consists in designing a PVDF sensor composed of several PVDF strips bonded to the surface of the structure in such a way that the output signal of the sensor is directly proportional to the volume velocity of the vibrating simply supported finite plate. This sensor detects only contributions from the odd--odd modes, being the only ones with a nonzero volume velocity as well as being the most effective radiators. Experimental implementation of such a PVDF volume velocity sensor will be discussed. The efficiency of this type of sensor in ASAC will be analytically evaluated as the far-field radiated acoustic power, the quadratic velocity as well as the radiation efficiency before and after control will be extensively studied. The advantage of this active control approach (minimization of volume velocity) is that only one error sensor is used in the control process.