Abstract: A radial cascaded composite ultrasonic transducer is analyzed. The transducer consists of three short metal tubes and two radially polarized piezoelectric ceramic short tubes arranged alternately along the radial direction. The short metal tubes and the piezoelectric ceramic short tubes are connected in parallel electrically and in series mechanically, which can multiply the input sound power and sound intensity. Based on the theory of plane stress, the electro-mechanical equivalent circuit of radial vibration of the transducer is derived firstly. The resonance/anti-resonance frequency equation and the expression of the effective electromechanical coupling coefficient are obtained. Excellent electromechanical characteristics are determined by changing the radial geometric dimensions. Two prototypes of the transducers are designed and manufactured to support the analytical theory. It is concluded that the theoretical resonance/anti-resonance frequencies are consistent with the numerical and experimental results. When R₂ is at certain values, both the anti-resonance frequency and effective electromechanical coupling coefficient corresponding to the second mode have maximal values. The radial cascaded composite ultrasonic transducer is expected to be used in the fields of ultrasonic water treatment and underwater acoustics.

Key words: radial cascaded transducer, radial vibration, equivalent circuit, effective electromechanical coupling coefficient