A critical analysis of electric shunt circuits employed in piezoelectric passive vibration damping

Vibration damping of an elastic structure can be obtained by bonding a piezoelectric actuator onto the vibrating structure, and by shunting the actuator to a suitable electric resonant circuit, tuned to the structural eigenmode to be damped. The achievable damping depends on the particular electric circuit used. In this paper three different electric shunt circuits are analyzed and their performances are compared. In particular, the optimal values of the electric components belonging to each shunt circuit and the corresponding exponential time decay rates of the free vibrations relevant to the controlled structural eigenmode are explicitly determined, also taking into account the inherent structural damping. Finally, some experimental results are reported, obtained by using two of the shunt circuits analyzed, which are in good agreement with the theoretical predictions.