Study on the nonlinear characteristic of a longitudinal piezoelectric ultrasound transducer with stepped horn

Longitudinal vibration sandwich piezoelectric transducers with a stepped horn are widely used in high-intensity ultrasonic applications such as ultrasonic welding, ultrasonic machining, and ultrasonic cleaning. In these applications, due to the increased losses, transducers exhibit nonlinear phenomena such as heating, resonance frequency drift, and amplitude saturation. Consequently, existing linear theoretical models are no longer suitable for analyzing the nonlinear characteristics of such transducers. In this paper, we develop a nonlinear equivalent circuit model for a longitudinal vibration piezoelectric transducer with a stepped horn, considering elastic loss, composite loss (the total loss resulting from the combination of elastic, dielectric, and piezoelectric losses) and structural damping loss. Through theoretical analysis, finite element simulation, and experimental testing, we investigate the effects of each type of loss on the key electromechanical performance parameters of the transducer. The research results provide accurate theoretical guidance and reference data for the application of such transducers in high-intensity ultrasonic scenarios.