An approach to design a high power piezoelectric ultrasonic transducer

Application of ultrasonic waves has been considerably progressed during the last decade and piezoelectric ceramics have had a common use as the driving source of such waves. However, there is not enough documented information on design and technology of manufacturing a high power ultrasonic transducer. In this paper, an attempt has been made to analyze the stress produced along the oscillating PZT employed ultrasonic head by applying the principles of acoustic wave propagation. Then, based on such analysis, general principles of PZT transducer design, excited by a DC-biased alternating electrical source, has been derived and finally a typical such transducer has been designed, manufactured and tested. By employing finite element modal analysis, the resonance frequency of the transducer was determined and compared with the experimental results. It was concluded that, the constitutive piezoelectric equations referred to in most sources and books are not valid for analyzing the acoustical dynamic stress in ultrasonic transducers. Instead, the analysis should be done with considering the dynamic behavior (elastic, damping and Inertia factors) of the problem.