SBIR-STTR Award

This SBIR Phase I Proposal addresses the need for a low-profile, broad-band, high- performance, shear-mode tonpilz transducer that can operate at deep depths. In one approach we add a special suspension system to the Van Tol/Meyer tonpilz that allows operation at submarine depth with only a small impact on the performance. Two other less conventional approaches which would allow operation at even greater depths are also presented. All three designs are discussed with emphasis placed on the first design using finite element modeling and analysis, including a comparison with the original tonpliz design in addition to a hydrostatic stress analysis. All three designs would be investigated during the Phase I Basic program and the best candidate for the goals of this program would be selected going forward. The finite element analysis program ANSYS will be our main tool allowing us to accurately model, evaluate and compare the various designs with each other.

Benefit:
The compact, light-weight, broad-band shear mode transducer will find applications in numerous civilian underwater applications: UUV and tethered ROV guidance, sea floor exploration/profiling, sea floor module mining, oil platform inspection/repair, and the like. The enhanced energy efficiency in untethered applications will dramatically decrease operating cost by extending effective utilization times per mission.

Keywords:
SONAR TRANSDUCER, SONAR TRANSDUCER, Energy-Efficient Transducer, Shear-Mode Transducer, Broad Bandwidth, Low-Profile Transducer, Lead-Magnesium-Niobate Lead Titanate Crystals

The main objective is to design, build and test a low-profile, high-power, low-frequency broadband, d36 shear-mode piezoelectric single crystal transducer capable of operating at submarine depths. Because of Phase I program constraints, we designed an initial modified shear mode transducer with a nylon cylinder head-suspension, that would be used in a d36 design capable of operating at submarine depths. This transducer was FEA modeled, fabricated and tested with PZT-5A d15 shear mode elements of the same size as the legacy single crystal d36 elements. A wide band response from below 2 kHz to over 9 kHz was measured and FEA results showed no significant stress in the single crystal material for a hydrostatic pressure of 1,000 psi. During the proposed Phase II a partial array of improved pressure tolerant d36 shear mode transducers will be developed. To this end, and before the array development, an optimized, improved, pressure-tolerant d36 single crystal version would be FEA modeled, fabricated and tested in-air and in-water under low and high pressures.

Benefit:
Because of the need to fulfill wide-band, low-frequency system requirements the effective coupling coefficient of earlier transducers can be low, requiring large amplifiers to drive the low power factor transducer array to source level. The pressure-tolerant shear-mode transducer is well suited for many applications, in part, because of its low-profile, wide-band, low-frequency performance and more so, because of its d36 mode high coupling coefficient and pressure tolerant design. The commercialization transition plan is to implement a wide band array of d36 single crystal shear mode transducer capable of replacing the current single crystal cymbal array or use these arrays in LDUUV vehicles or the MOCCA underwater vehicles that can operate at submarine depth. Our subcontractor, Ultra Ocean Systems is in a perfect position to help us accomplish this transition. Although we believe the above noted transitions to be exceptional opportunities, Image Acoustics and Ultra Ocean Systems, will continue to seek out other possible systems that would benefit from this shear mode transducer.

Keywords:
Shear-Mode Transducer, Broad Bandwidth Transducer, SONAR TRANSDUCER, Low-Profile Transducer