Design of and fabrication improvements to the cymbal transducer aided by finite element analysis

A miniature flextensional transducer, the "cymbal," is an emerging underwater transducer technology for large area and restricted volume transmit and receive arrays. The performance of the device is being evaluated for a number of applications requiring a large number of elements. Simple design, low cost and the ability to tailor performance to the desired application are attractive features of the cymbal. Analysis of the fabrication and performance of the cymbal has revealed that the benefits of the cymbal's flexible design also present production concerns. Asymmetry in the cavity depth or epoxy layer can result in unwanted resonances that can detract from the in-water performance. To avoid these spurious resonances, tolerances in cavity depth could be as low as 5 μm, resulting in low production yields. These and other fabrication concerns have been analyzed through experiment and finite element modeling software using the ATILA code. We were able to identify ways of improving manufacturing yields and minimizing variances to accommodate large array production. The origins of the spurious resonances are discussed along with the performance of a prototype array.