Traveling Wave Controllers on beams and plates using piezoelectric actuators

Uncontrolled beams and plates often perform poorly as sound radiating structures because of their resonant modes, creating a frequency response with sharp peaks and nulls as well as rapid changes in acoustic directionality. An active control technique known as Traveling Wave Control (TWC) has been previously demonstrated to perform well at forcing beams and plates to vibrate without modes, as though they were infinitely large, producing an improved acoustic response. This paper is specifically concerned with evaluating the interaction of piezoelectric actuators with simulated TWC systems and comparing the vibratory and acoustic responses as well as the derived filters to those of ideal point source actuators. Simulations demonstrate that piezoelectric actuators act in a very similar manner to point source actuators on simulated beams and plates, and that the bandwidth of control is proportional to the inverse distance between secondary actuators and edges. An experiment demonstrates that the TWC system implemented on a beam with both moving-coil and piezoelectric actuators is able to mitigate the modal response considerably.