The energy method for analyzing piezoelectric ceramic transducers [
B. S. Aronov, J. Acoust. Soc. Am. 117, 210–220 (2005)
] is applied to the treatment of transducers with mechanical systems that can be considered as two-dimensional. Analysis is made following the general outline of the theory of coupled vibration in two degrees-of-freedom systems and its extension in calculating the resonance frequencies of elastic bodies, as suggested by Giebe and Blechschmidt [
Ann. Physik, Ser. 5 18, 417–485 (1933)
]. The approach to the problem is illustrated with examples of piezoceramic rectangular thickness poled plates. The resonance frequencies and effective coupling coefficients are presented as functions of the plates’ aspect ratio.