N101-021 TITLE: Innovative Structures for Sonobuoy Applications

TECHNOLOGY AREAS: Materials/Processes, Sensors

ACQUISITION PROGRAM: PMA-264; AIR ASW Systems

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted." The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: Develop lightweight, deployable and adaptable (smart) structures for "A" size sonobuoy components.

DESCRIPTION: The "A" size sonobuoy is a unique Anti-Submarine Warfare (ASW) sensor system: It is required to deliver acoustic detection and localization performance on a par with larger fixed and surface vessel mounted systems while being constrained by an expendable sensor budget. The "A" size sonobuoy volume and weight are limited by aircraft payload limitations and sonobuoys operate autonomously upon deployment from ASW aircraft. Because of these constraints great emphasis is placed on sonobuoy packaging efficiency and reliable deployment. This is particularly true when large planar or volumetric arrays need to be deployed to exploit performance gains achieved through array gain and beamforming techniques. These gains are further enhanced if the array geometry is adaptable to environmental or tactical conditions, i.e., the array can autonomously change shape in response to ASW operator commands or networked environmental sensor data.

Sonobuoy designers devote a great deal of effort to the design of acoustic sensor suspension systems. These systems attempt to isolate the sensors from in-situ ocean forces such as surface waves, internal waves and ocean currents. These forces can generate sensor motion modes which corrupt acoustic data and greatly limit sensor effectiveness. Research over the past 40 years has resulted in the use of suspension components like mass-damper systems of elastic spring-like elements, large fabric surfaces designed to capture the hydrodynamic mass of the water in the vertical direction (damper disks) and large drogues in the horizontal direction. Despite the best efforts of sonobuoy designers, suspension components cannot be tuned to optimum performance in all conditions. A deployable drogue or damper disk that is capable of adapting its shape to changing conditions could greatly enhance the performance of sonobuoy systems.

PHASE I: Develop and demonstrate a design concept within the constraints of an "A" size sonobuoy by evaluating design feasibility and performance. Construct a detailed design of the "A" size package and deployed structure. Develop modeling and simulation of the structure including deployment and operational dynamics, shape control and structural loading. Determine performance gains associated with the use of this technology over existing systems.

PHASE II: Refine and develop Phase I candidate structure / concept. Fabricate an "A" size prototype of most promising concept and conduct laboratory testing of candidate hardware. Demonstrate system in an operationally relevant environment. Assemble Phase III plan for sonobuoy integration, air drop testing and certification.

PHASE III: Finalize a production design of Phase II prototype and apply the design to a specific sonobuoy suspension system. Integrate prototype system with sonobuoy hardware. Obtain air drop certification.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Technology developed in this SBIR could be leveraged for other marine or space based systems that require adaptable, lightweight, strong, deployable systems. This could include satellite vehicle antenna or solar panel structures; oceanographic drifter buoy drogues or portable shelters that would adapt to the terrain or weather.

REFERENCES:
1. Sherman, C.H., Butler, J.L. 2006. Transducers and Arrays for Underwater Sound. Springer Science+Business Media, LLC, New York.

2. Furuya, H., 1992. Concept of deployable tensegrity structures in space application. International Journal of Space Structures 7, pp. 143–151.

3. Pugh, A., 1976. An Introduction to Tensegrity, University of California Press, Berkeley, CA.

4. Skelton, R.E., Sultan, C., 1997. Controllable tensegrity, a new class of smart structures. SPIE, San Diego, pp. 12.

KEYWORDS: sonobuoy; tensegrity; array structure; damper; adaptable structure; shape control

** TOPIC AUTHOR (TPOC) **

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