Bimorph-based piezoelectric air acoustic transducer: Model

A new type of bimorph-based piezoelectric air transducer with the working frequency range of 200-1000 Hz has recently been developed [B. Xu, Q. Zhang, V.D. Kugel, L.E. Cross, Piezoelectric air transducer for active noise control, Proc. SPIE, 2717 (1996) 388-398]. In the present work, basic acoustic characteristics of this device and its piezoelectric elements are analyzed. To model the vibration spectrum of the transducer, a one-dimensional approach is developed where inertia, elastic and damping forces are included. Analytical equations describing mechanical vibrations and electrical impedance of piezoelectric bimorph cantilevers under external forces are derived. In order to describe various losses in the transducer, complex piezoelectric, dielectric, and elastic constants are used. Results of the modeling are in good accord with experimental data. The suggested model can be used for device optimization.