Abstract: From the motion equation of the bar which vibrates one-dimensionally and longitudinally, the model of mechanical four-terminal network and the transfer equations are set up, and the transfer parameters of tae four-terminal networks of some frequently used bars with variable cross-sections are given. The frequency equations arid the ratios of two terminal vibration velocities of ultrasonic transducers and horns are analysed, and the vibration mode and stress distributions of the vibration system of our ultrasonic surgical knife are calculated. It is very efficient to design all kinds of ultrasonic transducers, horns and any complicated vibration systems of their combinations.

Key words: Design model, Mechanical four-terminal network, Transfer parameters, Ultrasonic vibration system, Vibration characteristics