MODAL SENSING OF EFFICIENT ACOUSTIC RADIATORS WITH POLYVINYLIDENE FLUORIDE DISTRIBUTED SENSORS IN ACTIVE STRUCTURAL ACOUSTIC CONTROL APPROACHES

An experimental investigation was performed to determine the feasibility of implementing polyvinylidene fluoride (PVDF) piezoelectric distributed sensors on the surface of a structure as error sensors in an adaptive least-mean-squares (lms) control approach to minimize acoustic radiation. While much research has been devoted to controlling vibration of structures with these sensors, they have yet to be implemented in structural acoustic control. To this end, two narrow strip PVDF sensors were positioned on a simply supported plate such that the dominant observed response was due to the odd-odd modes of the plate (i.e., the more efficient acoustic radiators). The error sensors in effect act as spatial wave-number filters and only observe those components that contribute significantly to far-field sound radiation. A variety of test cases were studied for controlling sound radiation due to a disturbance both on and off resonance. Results from these experiments indicate that PVDF sensors and piezoceramic actuators show much promise for controlling acoustic radiation from structures, to a large degree overcoming the need for error microphones in the far field.