Tunable phononic structures using Lamb waves in a piezoceramic plate

Phononic crystals made of piezoceramic materials allow for frequency band structure tunability due to the ease of electric command use. In this paper, we develop a full elastodynamic model, taking into account piezoelectric coupling effects for the band-structure calculation of Lamb eigenmodes of a phononic crystal consisting of a piezoceramic plate with a one-dimensional periodic array of electrodes set on both sides. The dispersion-relation characteristics of these eigenmodes are nondestructively tuned via external circuit impedance loads coupled to the phononic plate, e.g., through inductance loads inducing tunable resonant flat bands that hybridize with the Lamb modes of the elastic plate, thus opening up hybridization gaps. It is shown that additional control of the shape of these resonant bands can be achieved by incorporating an impedance interconnecting two adjacent electrodes of the same side, the whole structure forming an electric quadripole. This behavior can be easily predicted with the help of our formalism combined with a simplified electric line model of the phononic crystal plate.