TECHNOLOGY AREAS: Materials/Processes, Sensors

ACQUISITION PROGRAM: PMS 501, Littoral Combat Ship, ACAT 1

OBJECTIVE: To develop and demonstrate high-performance, light-weight, reliable sensor technology to enable the detection of corrosion in 5XXX-series aluminum onboard naval ships.

DESCRIPTION: Littoral Combat Ship (LCS), Joint High Speed Vessel (JHSV), and other newer ships are using new hull forms and structural materials such as 5XXX-series aluminum, whose physical properties and future degradation potential are not completely understood. While these material systems provide high strength-to-weight ratios while maintaining good as-welded strength and excellent corrosion resistance they are not completely immune from the possibility of corrosion over time especially once aluminum is combined with other materials to form aluminum alloys. Corrosion can be described as the formation and growth of pits due to a loss of material in the presence of a particular ion(s) on the surface of the material. In addition to corrosion on the outermost surface of a material, there is the potential for hidden corrosion between sandwiched or mechanically fused elements as well as within the ship�s internal structural components. As such, many preferable sensor locations for detecting and monitoring corrosion may not be assessable after construction is complete (e.g., interior of outer hull structure). The current state-of-the-art detection mechanisms include ultrasonic (including guided waves), eddy current, x-ray diffraction, and thermography. However, these mechanisms require external exciters that are not suitable for installation within hidden or inaccessible spaces and operation over long time periods or are destructive inspection methodologies.

This topic seeks to explore the development of non-traditional and innovative methodologies/approaches to provide the capability of detecting and monitoring corrosion (e.g., galvanic, dissimilar metal contact, salt water induced, fresh water induced, etc.) and its related physical property degradations for 5XXX-series aluminum. Since the physical properties of the material systems being measured change slowly over time, sampling rates of 1 per minute are acceptable. The goal is to be able to assess an area of material of at lease 20 cm2. Incorporation of "self powering" (e.g., energy harvesting methodologies) for system power would be most beneficial. The sensor(s) should also be capable of operating in stressful operating environments such as high humidity and/or flooding, high temperatures, electromagnetic interference, etc. with minimal degradation of performance and should be compliant with current American Bureau of Shipping (ABS) and Naval Vessel Rules (NVR) standards (www.eagle.org). It is intended that the proposed technologies will be able to be either permanently installed as part of the platform construction or back-fitable in areas of known concern. Proposers should address the ability of the proposed sensor technology solution(s) to exhibit sufficient performance robustness for the ship�s life which is expected to exceed 30 years. It is envisioned that information gathered from these sensors will provide real-world raw data to better understand the degradation of the physical properties over time, to validate the models used to determine and predict structural health, and to alert the platform operators of potentially disabling or platform damaging events as soon as possible. Technologies proposed need to be compliant with open architecture design protocols to able to interface with navy data acquisition systems such as, but not limited to, the Integrated Condition Assessment System (ICAS).

PHASE I: Demonstrate the feasibility of innovative methodologies/approaches and the associated senor technologies to provide the capability of detecting and monitoring corrosion (e.g., galvanic, dissimilar metal contact, salt water induced, fresh water induced, etc.) and its related physical property degradations for 5XXX-series aluminum. As applicable, the feasibility demonstration should include or address the ability to determine significant deviations from expected conditions on a laboratory test bed. Develop an initial conceptual design and establish performance goals and metrics to analyze the feasibility of the proposed solution. Develop a test and evaluation plan that contains discrete milestones for product development for verifying performance and suitability.

PHASE II: Develop and demonstrate the prototype(s) as identified in Phase I. Through laboratory testing, demonstrate and validate the performance goals as established in Phase I. Refine design and develop a detailed concept of operation and projected capabilities including, as applicable: prototype descriptions, production drawings, interface specifications, operating sequences, emergency procedures, logistics support plan, weight breakdown, system cost estimates (both acquisition and lifecycle), and manning/Human Systems Interface (H.S.I.) requirements. Develop a cost benefit analysis and a Phase III testing, qualification and validation plan.

PHASE III: The small business will work with the Navy and commercial industry to complete any remaining qualification testing, construct full-scale prototype(s) and install onboard a suitable naval platform. Conduct extended shipboard testing.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Any structural monitoring system developed for Navy ships will have direct commercial applications in ferries and cargo ships as well as possible applications in both military and civilian aviation.

REFERENCES:
1. H. Sohn. C.R. Farrar, F. M. Hemez, D. D. Shunk, S. W. Stinemates, B. R. Nadler and J. J. Czarnecki, "A Review of Structural Health Monitoring Literature from 1996-2001, "Los Alamos National Laboratory report LA-13976-MS (2004). http://www.lanl.gov/projects/ei/shm/publications.shtml

2. Dong, Saying, Liao, Yanbiao, and Tian, Qian, "Sensing of corrosion on aluminum surfaces by use of metallic optical fiber", Applied Optics, Vol. 44, Issue 30, pp. 6334-6337

3. McCafferty, E., "Sequence of steps in the pitting of aluminum by chloride ions", 2001 (http://www.sciencedirect.com), Corrosion Science, Volume 45, Issue 7, July 2003, Pages 1421-1438

4. ICAS Web site: https://icas.navsses.navy.mil/ (accessible without username/password)

KEYWORDS: structure; monitoring; sensors; collection; analysis; damage detection

** TOPIC AUTHOR (TPOC) **

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