Active control of sound radiation from a vibrating structure

The active control of sound radiation from a vibrating structure is of importance in the mitigation of machinery and vehicle noise. With piezoelectric sensors and actuators, along with effective feedback methods, the structural vibrations which are responsible for the sound/noise radiation can be actively controlled. A prototype two-dimensional structure of a square thin metal plate with all edges clamped is chosen as a study model for the vibration and radiation noise control. The radiation efficiencies are studied for each mode of a clamped vibrating steel plate. A series of active vibration/noise control experiments has been performed for several lower modes with different types of control algorithms. The idea for a combined unidisc-type collocated sensor/actuator has been proposed to implement actual collocation of sensors/actuators and to minimize the numbers of transducers used. Experimental results are presented for the radiated sound level in the air from the plate with and without control. The concept of optimization with respect to minimum total radiating from modes will be introduced in the feedback control algorithm