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Thin-Ply Composite Technology and Applications

Description:

The use of thin-ply composites is one area of composites technology that has not yet been fully explored or exploited. Thin-ply composites are those with cured ply thicknesses below 0.0025 in., and commercially available prepregs are now available with ply thicknesses as thin as 0.00075 in. By comparison, a standard-ply-thickness composite would have a cured ply thickness of approximately 0.0055 in. or greater. Thin-ply composites hold the potential for reducing structural mass and increasing performance due to their unique structural characteristics, which include (when compared to standard-ply-thickness composites):
 

  • Improved damage tolerance.
  • Resistance to microcracking (including cryogenic-effects).
  • Improved aging and fatigue resistance.
  • Reduced minimum-gage thickness.
  • Thinner sections capable of sustaining large deformations without damage.
  • Increased scalability of structures.


Thin-ply composites are attractive for a number of applications in both aeronautics and space as they have the potential for significant weight savings over the current state-or-the-art standard-ply materials due to improved performance. For example, preliminary analyses show that the notched strength of a hybrid of thin and standard ply layers can increase the notched tensile strength of composite laminates by 30%. Thus, selective incorporation of thin plies into composite aircraft structures may significantly reduce their mass. There are numerous possibilities for space applications. The resistance to microcracking and fatigue makes thin-ply composites an excellent candidate for a deep-space habitation structure where hermeticity is critical. Since the designs of these types of pressurized structures are typically constrained by minimum gage considerations, the ability to reduce that minimum gage thickness also offers the potential for significant mass reductions. For other space applications, the reduction in thickness enables: thin-walled, deployable structural concepts only a few plies thick that can be folded/rolled under high strains for launch (and thus have high packaging efficiencies) and deployed in orbit; and greater freedom in designing lightweight structures for satellite buses, landers, rovers, solar arrays, and antennas. For these reasons, NASA is interested in exploring the use of thin-ply composites for aeronautics applications requiring very high structural efficiency, for pressurized structures (such as habitation systems and tanks), for lightweight deep-space exploration systems, and for low-mass high stiffness deployable space structures (such as rollable booms or foldable panels, hinges or reflectors). There are many needs in development, qualification and deployment of composite structures incorporating thin-ply materials – either alone or as a hybrid system with standard ply composite materials. In particular, there is substantial interest in proposals that address manufacturability and production of composite structures utilizing thin-ply composites that at minimum develop the process and plan for the production of one prototype in Phase I and demonstrate reproducibility of prototype manufacturing and key parameter validation of repeated samples in Phase II. Another area requiring development is in new testing methods adapted for thin-ply, high strain composites for folded and rolled structures.  The Phase II deliverables will depend on the aspect addressed, but in general will be documentation of the analytical foundation and process, maturing the necessary design/analysis codes, and to validate the approach though design, build, and test of an article representative of the component/application of interest to NASA.

 

Relevance to NASA

 

The most applicable ARMD program is AAVP, and within that is Advanced Air Transport Tech. (AATT). Additional projects within AAVP that could leverage this technology Commercial Supersonic Tech. (CST), Hypersonic Technology (HT), and Revolutionary Vertical Lift Tech. (RVLT). Projects within TACP could also benefit. That is, any project in need of lightweight structures can benefit from the thin-ply technology development.  Within STMD, projects with deployable composite booms, landing struts, and other very lightweight structures can benefit from the thin-ply technology.

 

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