Investigation of the equivalent circuit and performance of an ultrasonic transducer under a force load

In ultrasonic processing technology applications, the force load can cause a drift in the resonance frequency of the ultrasonic transducer and significantly reduce its mechanical quality factor. The traditional equivalent circuit of an ultrasonic transducer can only be used to calculate performance parameters without a force load but not with a force load. Based on Mason’s equivalent circuit, a new equivalent circuit for ultrasonic transducers under a force load is derived while considering the effects of the force load on the material parameters and various types of losses in piezoelectric ceramics. Furthermore, performance parameters are analyzed, such as the resonance frequency, effective electromechanical coupling coefficient, and mechanical quality factor. The ultrasonic transducer sample is produced and the experimental platform is constructed for applying force loads on the ultrasonic transducer. The theoretical model is verified by static loading on the ultrasonic transducer. The proposed equivalent circuit provides theoretical guidance for tracking the exact resonance frequency and performance parameters of force-loading ultrasonic transducers.