Investigation to the vibration characteristics of ultrasonic transducer based on the number of piezoelectric ceramics

As the vibration actuator source, PZT applied on the ultrasonic transducers (UTs) plays a crucial role in the vibration characteristics of UTs. Most conventional research focus on the overall size and positional relationship of PZT stack, while the influence of PZT numbers on vibration characteristics of UTs is seldom reported. In this article, we present a comprehensive investigation between the PZT numbers and vibration characteristics of UTs with identical geometric configurations, specifically UTs with 2 (UT2), 4 (UT4) and 6 (UT6) PZT. The electromechanical equivalent circuit and finite element analysis (FEM) based on PZT numbers are established to investigate the impedance and resonant frequency. Furthermore, the dynamic displacement model of the UTs is proposed to study the influence of PZT numbers on amplitude, and the calculation results are consistent with harmonic response analysis. Finally, the experimental platform is established to test the vibration characteristics of the three types UTs. The results show that the resonant frequency of the transducer is not affected by the numbers of PZT, while the impedance and impedance stability can be improved by the increased PZT numbers. Moreover, the amplitude of UTs is negatively correlated with the numbers of PZT. Through experiments, it is verified that UT2 is suitable for the conditions as the load less than 1000 g and amplitude less than 2.2 µm, and UT4 is applicable to the other conditions. Although the UT6 exhibits excellent impedance stability, its output power is relatively high and is not suitable for the structure used in this article. The findings suggest that the number of PZTs should be designed based on the operational conditions to improve amplitude output and minimize the loss of power. The presented methods can effectively improve energy consumption and working life, making the UTs greener and more efficient.