TECHNOLOGY AREAS: Air Platform, Materials/Processes, Weapons

ACQUISITION PROGRAM: Joint Strike Fighter Program Office, Airframe IPT, ACAT I D Program

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Develop a cost-effective curing system (hardware) for a very rapid curing resin pre preg system for galvanic barrier ply restoration on complex pre-cured and machined carbon composite parts. The complete system is to be based on proven epoxy chemistry resins for barrier ply applications with type "E" 108 style fiberglass cloth.

DESCRIPTION: New developments in rapid cure resin systems have overcome limitations of legacy properties associated with these novel resin systems including, but not limited to brittleness, aircraft fluid and environment sensitivity, unpredictable cure, and low glass transition temperature. A rapid cure epoxy based resin has been identified as a prime candidate for the specific application of restoring galvanic barrier ply corrosion protection on pre-cured machined carbon composite surfaces. An objective of this effort will be to develop a very rapid cure system (hardware) that can cost-effectively cure aerospace quality galvanic barrier pre-preg on complex composite parts. The proposed rapid cure system equipment for the co-developed rapid cure epoxy resin pre-preg must demonstrate a minimum glass transition temperature of 375F and resistance to standard DoD aircraft fluids and environments. Curing optimization of surrogate materials will not be acceptable. The cure system equipment should provide the required energy necessary to activate the rapid cure epoxy resin, while curing through the 108 fiberglass cloth for all parts with no detriment to the host pre-cured composite part. Cure may take place on a vacuum bagged part to maintain specific cure ply thickness. The cure system equipment must be able to maintain adequate cure on the complex geometries and sizes of composite parts for DoD fighter aircraft. The system should be either a moving lamp assembly or a fixed lamp system with a conveyer belt for moving the composite parts. A potential for field deployablity should be considered along with the ability to support equipment logistically should upgrades or replacement parts be required. The system should be a fully enclosed assembly with adequate personnel protection for workers in the immediate area of the production environment and comply with applicable Occupational Safety and Health regulations and/or requirements. There are approximately 175+ parts that are available on DoD fighter aircraft.

A cost-effective, low power/energy efficient, robust, portable, upgradeable, reconfigurable, user friendly, cutting edge, safe, etc. system should be considered that does not require any special support equipment beyond that which may be available within a typical aerospace composite manufacturing center. An example may be a LED UV curing system chosen over a traditional bulb-type UV curing mechanism. Damage/degradation should not be incurred by host pre-cured composite part undergoing galvanic barrier ply restoration.

PHASE I: Demonstrate cure system (hardware equipment) proof-of-concept to deliver sufficient and consistent energy or specific activator over the surface geometry of complex composite parts. It is intended that this cure system will provide all that is required to fully cure the very rapid cure resin pre-preg system. Work with the chemistry formulators to optimize the cure effectiveness to reduce total system costs and significantly reduce cure cycle times.

PHASE II: Design, fabricate, and test a prototype enclosed cure system for composite parts to demonstrate the ability to fully cure the pre-preg. Evaluate staged cures and methods if required for satisfactory composite surface finish and properties. Scaleable consideration may be desired given required focal lengths as well as part size and geometry. No pre- or post-processing of parts should be required beyond this device or apparatus for final finish or material properties.

PHASE III: Modify the system to work with complex geometry surfaces of actual composite parts that have varied size, complexity and base composite resin systems. The system must have the final production environment and limitations in mind during this phase of the program. Provide adequate system description and specifications to effectively transition the technology to the DoD aerospace composite manufacturing facilities.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The commercial aircraft manufacturers and automotive and marine vehicle repair shops will benefit form the technology developed under this effort.

REFERENCES:
1. SAE-AMS 3824C - Glass Cloth.

2. Shi, W and Ranby, B., "UV Curing of Composites Based on Modified Unsaturated Polyester," Journal of Applied Polymer Science. Vol 51, 1129-1139, 1994.

3. Zahouily, K. and Decker, C., "High-Performance UV-cured Composite and Nanocomposite Materials," JEC Composites Magazine. Vol 32, 75-79 May 2007.

4. Allred, R. E.; Hoyt, A. E.; Harrah, L.A.; McElroy, P.M.; Scarborough, S.; Cadogan, D. and Pahle, J.W., "Light Curing Rigidizable Inflatable Wing," 45th AIAA/ASME/ASCE/AHS/ASC Structures, Structures Dynmaics and Materials Conference; Palm Springs, CA Apr. 19-22, 2004.

5. Allred, R.E.; Hoyt, A. E.; Harrah, L.A.; Scaraborough, S.; Mackusick, M. B. and Smith, T.,"Light Rigidizable Inflatable Wings for UAVs: Resin and Manufacturing Development," 46th AIAA/ASME/ASCE/AHS/ASC Structures, Structures Dynamacs and Materials Conference; Austin, TX Apr 18-21, 2005.

6. Mirle, S. K. and Kumpfmiller, R. J., US Patent 5,418,112, (1995)
"New Sandia UV LEDs emit short-wavelength, high-power output," Sandia National Laboratories Press Release, November 18, 2003.

7. "UV LEDs Have Multiple Uses," Sandia National Laboratories Press Release, November 18, 2003.

8. Ryan, A. J.; Valdya, U. R.;Mormann, W. and Macosko, C. W.," Networks by Fast Polymerization" Polymer Bulletin. Vol 24, 521-527, 1990.

9. Hoyt, A. E.; Harrah, L. A.; Allred, R. E. and McElroy, P. M.,"Rigidization on Command (ROC) Resin Development for Lightweight Isogrid Booms with MLI, " 33rd Intl Conf on Environmental Systems, Vancouver, BC, July 2003, technical paper series 2003-01-2342.

10. Jansen, J. F. G. A.; Dias, A. A.; Dorschu, M. and Coussens, B., "Fast Monomers: Factors Affecting the Inherent Reactivity of Acrylate Monomers in Photoinitiated Acrylate Polymerization," Macromolecues, Vol 36, 3861-3873, 2003.

11. Rix, B. A. and Bulluck, J. W., "Ultraviolet Radiation Cured Acrylate for Aircraft Composite Field Repairs," www.radtech.org, Radtech Report Nov/Dec 2004.

12. Black, S., "Technologies for UV Curing of Composite Laminates Demonstrated," www.compositesworld.com, April 2004.

KEYWORDS: Resin Cure Equipment; Galvanic Barrier Ply Restoration; Robotic Cure System; Manufacturing; Optimized Cure; Quality Assurance.

** TOPIC AUTHOR (TPOC) **

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