Piezoelectric trapped energy resonators vibrating in thickness-twist modes

Abstract

In the present paper we investigate theoretically the phenomenon of energy trapping in piezoelectric devices, operating in thickness-twist modes. For a single resonator we have computed the input impedance as a function of both the frequency and the width of the electrode. In addition, we have obtained the fundamental resonant frequency of the device as a function of the width of the electrode and the mass-loading. This is achieved by employing the integral equation formulation of piezoelectric diffraction problems. For a resonator with massless electrodes, the resonant frequency of the fundamental lateral mode and the lowest two inharmonic overtones have been computed as a function of the width of the electrodes. Also the influence of the mass-loading on the resonant frequency of the fundamental lateral mode has been studied. When considering a coupled resonator system, the first resonator is connected with an electric generator, while the second is connected with a load impedance. For this configuration the transfer function has been computed. Next, the second resonator is short-circuited and the input impedance of the first resonator is determined. Finally, the resonant frequency of both the even and the odd lateral mode of the resonator assembly is computed as a function of the spacing between the two resonators. As piezoelectric material we have taken the piezoelectric ceramic PZT-4.