Ultrasonic piezoceramic-polymer composite transducer-dynamic behavior and effects of heterogeneous structure

A dynamic theory is developed for piezocomposites with 2-2 connectivity. By solving the coupled dynamic equations in the piezoceramic plate and polymer region subjected to the boundary conditions at the ceramic-polymer interface, the distributions of the elastic and electric variables in a composite are obtained. The electromechanical coupling factor, the acoustic impedance, the resonant frequency, and the elastic coupling between the polymer and ceramic at the thickness resonance can be determined. The effects of mode coupling on the thickness resonance and lateral resonance are elucidated and the dependence of the frequency of these resonant modes on the composite thickness can be estimated. Theoretical results are compared with experimental observations.