Design of 1-3 piezocomposite hydrophones using finite element analysis

The 1-3 piezocomposite material was originally developed because of its perceived good performance under hydrostatic operating conditions. Several constrained-dimensional models for piezocomposite hydrophones have been proposed but were found to lack accuracy when compared with experimental data. In addition, they could not be easily extended to include the effect of ancillary components such as cover plates, on the transducer behavior. In this work a finite element model is used for modelling of 1-3 piezocomposite hydrophones to help overcome these two shortfalls. A finite element model initially developed for modelling of thickness mode operation has been extended to include lateral pressures typical of the hydrostatic environment. The response of the new model has been compared with experiment with satisfactory results, allowing an extensive set of simulations to be presented for comprehensive evaluation of 1-3 piezocomposite design as an actuator or a hydrophone. The best hydrostatic performance was obtained by using a low volume fraction composite of PZT-5H and a soft compressible polymer, with potential enhancements by the incorporation of stiff cover plates covering the ceramic pillars. It is shown that the aspect ratio of the ceramic pillars should be minimized to maximize stress transfer. Additionally, ceramic pillar shape and distribution do not exert a major influence on the hydrostatic behavior.