Equivalent circuit for unloaded triple-layer piezoelectric cantilevers

Triple-layer piezoelectric composite cantilevers possess good electromechanical conversion behavior with characteristics suitable for diverse applications, especially at low frequency. Thus, the use of such cantilevers has been extensively attempted in fabricating piezoelectric devices. This study reports on the accurate determination methods for the equivalent circuit parameters derived from the electrical admittance of triple-layer piezoelectric cantilevers. Analytical expressions of electrical admittance are presented. The lumped parameters available for the Van Dyke equivalent circuit model are also derived from expressions for the electrical admittance of piezoelectric sandwich structures with two piezoelectric layers. Finally, prototype devices based on the triple-layer piezoelectric cantilever are constructed and tested. Results from the experiments show good agreement with the analytical models.