An analytical investigation on the resonances of surface bonded Piezoelectric wafer active transducers (PWaTs)

Piezoelectric wafer active transducers (PWaTs) play an important role for smart structures. Typically, they are bonded on the surface of structures to excite and sense mechanical vibrations or waves. The resonant characteristics of the surface bonded PWaT is very different from those of the free-standing PWaT. Since the resonances of the PWaTs strongly influence the transducer efficiency, it is important to understand their resonant behaviors. In this paper, an analytical model of the surface bonded PWaT is implemented to study the resonant characteristics of surface bonded PWaT in details. The study reveals that the PWaT supports two modes that have very different propagation constants below and above a cut-off frequency, leading to different resonance behaviors. These resonance behaviors can be explained with respect to the propagation of these two modes in the PWaT and the mode conversion at the edges of the PWaT. These fundamental understanding will benefit the design and optimization of the PWaTs.