Model-Based Poling of Piezoelectric Monolithic Ring Elements for Ultrasonic Torsional Transducers

Today the designs and applications of ultrasonic torsional transducers are limited by the availability of suitable poled piezoelectric elements. The thesis aims at the poling of piezoelectric monolithic ring elements with polarization in circumferential direction to achieve an adequate torsional output. Both modeling and experimental investigations are performed: two poling patterns with fan-shape and parallel-shape electrode configurations are compared and optimized. Piezoelectric monolithic ring samples are poled based on the poling parameter study and then characterized by quasi-static and dynamic measurement methods. They show advantages on the mechanical quality factor and electrical admittance in comparison to conventional manufactured torsional elements. The assembled torsional transducer using the poled samples has been designed, assembled and tested. The results present promising perspectives for manufacturing compact and cost-efficient torsional transducers in future.