Modeling of multi-layer thickness mode underwater acoustic transducers

This thesis develops distributed models for determining steady state and transient performance characteristics of multi-layered underwater acoustic transducers operating in thickness mode. This important class of transducers is usually modeled using lumped circuit or distributed models with only a couple of layers. Distributed models are preferred for design purposes since lumped circuit models are generally not defined by material parameters. Distributed models are developed and closed form expressions are obtained for key steady-state performance characteristics including, the electrical impedance/admittance, receive sensitivity, transmit sensitivity, and efficiency. The impedance/admittance and receive sensitivity models are verified using experimental measurements. Expressions for transient performance are determined using the Laplace transform and are validated using theoretical and experimental methods. A novel method is derived for outputting desired pressure waveforms by pre-shaping the input drive voltage. The distributed models developed in this thesis accurately predict the performance of existing transducers and are valuable for transducer design.