N121-020 TITLE: Improved Resin Injection Repairs for Polymer Composite Materials

TECHNOLOGY AREAS: Air Platform, Materials/Processes

ACQUISITION PROGRAM: PMA 261

OBJECTIVE: Develop an innovative injection repair process that has improved rheological properties, chemical reactivity and mechanical properties for use in structural resin repairs.

DESCRIPTION: Injection of resin to repair voids, delaminations and disbonds present in composite laminates either from manufacturing flaws or operational damage is a common practice for naval aircraft. These repairs are only cosmetic for the most part, providing inadequate performance to restore the flawed laminate to full structural capability. Consequently, their permissible use within NAVAIR is limited.

Previous investigations have identified shortcomings in resin injection that limit their suitability for structural applications. First, the resin's rheological properties are such that it is difficult or impossible for the resin to fill the flaw completely, especially narrow and convoluted constrictions. Second, the reactivity between the injected resin and the internal surfaces of the flaw may be low, preventing an adequate bond from being established. This is particularly true on flaws created in manufacturing. Finally, the mechanical properties of the injection resin itself may not be sufficient for structural applications.

A solution through materials and processes suitable for structural resin injection repairs of manufacturing and operational flaws in naval aviation graphite/epoxy laminates is sought.

Innovative resins capable of restoring the structural integrity of flawed graphite/epoxy laminates, along with the development of the appropriate injection processes for these resins will be considered. Because it is generally considered in the technical literature to be the more challenging situation, the focus of the project should be on developing materials and processes for resin injection of manufacturing flaws. Consequently, the appropriate injection processes developed in this project should be targeted for use on a typical factory floor.

The injection repair resin and associated processes must be capable of restoring the repaired laminate for use in the conditions typically encountered by Navy and Marine Corps aircraft. These conditions include thermal exposures ranging from -65 to 200 F, global climate extremes, and chemical exposures encountered while operating aircraft aboard ships.

Although it is anticipated that the successful resin materials and processes will require improvements to rheological properties, chemical reactivity and mechanical properties, the topic is not limited to improvements in these characteristics only. The successful resin must be capable of being manufactured in sufficient quantities to support naval aviation requirements. Manufacturing processes for these resins must either be standard chemical industry processes or must be developed in this SBIR to at least a pilot-plant level of operation. The resins, injection repair processes and resin manufacturing processes must avoid, to the greatest extent possible, the use of environmentally restricted substances.

PHASE I: Develop a concept for an innovative resin injection repair process. Demonstrate feasibility of the approach by performing simple repairs and demonstrating improved performance.

PHASE II: Optimize the technology into a fully developed repair process that provides restoration of structural performance. Perform validation and verification testing, and demonstrate the repair technique through restoration and testing of structural components.

PHASE III: Transition the developed technology to military and commercial applications.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Successful innovative solutions for structural resin injection repair materials and processes would have potential commercial use in commercial aircraft, marine, automotive and wind turbine blade applications.

REFERENCES:
1. Baker, A., Dutton, S. & Kelly, D. (Eds.). (2004). Composite Materials for Aircraft Structures (2nd edition). pp 375 -376. Reston, VA: AIAA

2. Austrailian Government Department of Defence (2006). Progress Report on Activities in Support of Composite Repair Engineering Development Program Tasks AF, AH and AI. (Defence Science & Technology Organisation No. DSTD-TR-1932). Victoria, Austrailia: Rider, A. & Parslow, D. Retrieved from: http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA465919

3. Evaluation of bisphenol E cyanate ester for the resin-injection repair of advanced composites; Wilber Y. Lio; Iowa State University, 2009; http://www.osti.gov/bridge/servlets/purl/969023-WTBBj0/969023.pdf.

KEYWORDS: composites; composite repair; resin injection repair; structural repair; resin viscosity; resin reactivity

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 9 and December 11, 2011, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting December 12, 2011, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (12.1 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 12.1 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at (866) 724-7457 or email weblink.