Sound absorption characteristics of a thin plate with PZT shunted with passive electrical circuit I. Theoretical analysis

The possibility of sound absorbing by a vibrating plate with piezoelectric material shunted with passive electrical circuit was theoretically investigated. Basing on an equivalent compliance of piezoelectric wafer shunted with RL circuits, the governing equations for the flexural vibration of the plate with piezoelectric wafer shunted with RL circuits were derived using Lagrange's approach. The equations take into account not only the mass, stiffness and structural damping for the plate and the wafer, but also the electrical resistance and electrical inductance of the RL circuits. Based on the governing equations derived, the surface impedance and sound absorption coefficient of the plate backed with a cavity were given. Numerical results showed that the sound absorption coefficient of the plate near its first mode can be significantly improved by adjusting the RL parameters.