Electrically forced thickness-shear and flexural vibrations of rectangular piezoelectric plates of rotated Y-cut quartz and langasite

We perform a theoretical analysis on electrically forced, coupled thickness-shear and flexural vibrations of rectangular piezoelectric plates of monoclinic crystals. Mindlin´s first-order theory for piezoelectric plates is used. Two types of boundary conditions are considered. Trigonometric series solutions are obtained. The motional capacitance of the plates and its frequency dependence under a time-harmonic driving voltage, an important property when the plates are used as piezoelectric resonators, is calculated and examined from the series solutions for quartz and langasite plates.