Composite Terfenol-D Transducers for Underwater Arrays

Oriented composites of PZT and polymer can have properties superior to ordinary PZT as drivers for sonar transducers and hydrophones because they have a lower Poisson ratio, and a lower dielectric constant. Terfenol-D is superior to ordinary PZT because it has larger maximum strains and higher energy density, and is not subject to fatigue or depoling. For these reasons, composite Terfenol-D should be superior to both composite PZT and ordinary Terfenol-D. This is especially true at high frequencies, since the brittleness of ordinary Terfenol-D makes laminating it expensive and does not allow very thin laminations. SatCon proposes to investigate the hydrostatic magnetostrictie properities of an improved composite Terfenol-D recently developed by Prof. G. Carman's group at UCLA. It is the hydrostatic properties that are relevant for underwater sonar transducers with dimensions that are small compared to a wavelength, as would be true of a small transducer used in an array. In collaboration with the UCLA group, we will develop Terfenol composites that are optimized for sonar and hydrophone use (e.g., reducing the Poisson ration). A small composite Terfenol-D transducer, operating in the 1kHz to 20kHz range, will be designed and built in Phase I, and a full array will be built and demonstrated in Phase II.