Flextensional transducers are common underwater electro-acoustic transducers, which convert small longitudinal displacements of a driver into relatively large flexural displacements of a shell. Flextensional transducer works mainly at frequency near the resonance of the shell. There is usually only one resonant mode of the transducer.

PAN Yaozong, MO Xiping, CHAI Yong, LIU Yongping and CUI Zheng of Institute of Acoustics, Chinese Academy of Sciences carried out a series of studies and presented a broadband free-flooded transducer with three vibrating modes-the cavity, the longitudinal and the radial.

The new flextensional transducer presented is driven by a tube stacked by longitudinally polarized piezoelectric ceramic rings. The rings are compressed between two annulus steel end plates which are coupled by a dual convex aluminum shell with slotted gaps. The transducer is a free-flooded design with the interior of the tube open to the surrounding water. Three main vibrating modes including the cavity, the longitudinal and the radial can be utilized by appropriately coupling design to broaden the working bandwidth. A prototype is fabricated and measured. The results confirm the three vibrating modes mentioned above and the broad band of transmitting voltage response is gained successfully with difference less than 10 dB from 2200 Hz to 9000 Hz

This research result was published on the recently issued Applied Acoustics(2011,72(11):836-840)