Abstract:

A shift in US Navy emphasis from blue water to littoral regions has resultled in a need for improved acoustic devices. Wide aperture arrays will be hull-mounted, thereby making device weight critical. The Naval Research Laboratory has developed a unique, low-weight composite, transducer design, Piezogran[sup TM], to address this need. Piezograns consist of discrete, polycrystalline piezoelectric-ceramic elements dispersed in an epoxy matrix between two pressure plates. These plates make a direct mechanical as well as electrical contact to the piezoelectric elements. This design approach uses a 1-3 composite structure for high-gain operation with the flexibility of variable element spacing and ceramic volume fraction while achieving both low tooling and fabrication costs. Independent tests of 3.8-cm diameter Piezogran[sup TM] prototypes have yielded high hydrostatic response (d[inf h]>150 pC/N) and capacitance of 1.18 nF. Ten-centimeter-square array panels have also been assembled and are currently undergoing testing. This presentation will focus on fabrication and assembly of the Piezogran[sup TM] transducers as well as material properties.