Comparison of low-frequency piezoelectric switching shunt techniques for structural damping

In this paper, the performances of two novel low-frequency piezoelectric switching shunt techniques for structural damping are compared to the traditional passive tuned resonant shunt circuit technique. The first novel technique, state switching, is a semi-active variable stiffness technique in which bonded piezoelectric elements are switched from the short circuit to open circuit states. This technique changes the stiffness of the structure for two quarters of its vibration period, thus dissipating energy. The second novel technique, pulse switching, is a semi-active continuous switching technique in which a resistor/inductor shunt circuit is periodically connected to the bonded piezoelectric elements. This technique applies charges to the piezoelectric elements in a manner similar to the direct velocity feedback and bang-bang time optimal control techniques. A brief description of each of the damping techniques is given. Numerical simulations of the switching techniques are shown and compared to the resonant shunt damping technique. Finally, preliminary experimental results are presented for the resonant shunt, state switching, and pulse switching techniques on a simply supported beam.