| Double-Vacuum-Bag Process for Making Resin-Matrix Composites |
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| Langley Research Center, Hampton, Virginia | |
| Dec 31 2006 | |
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Figure 2 depicts the double-vacuum-bag assembly used in this process. Fiber-reinforced, reactive-resin-matrix prepregs are laid up between a steel caul plate and a steel tool plate. This subassembly is then enclosed by a vacuum bag, designated the inner bag, which is sealed around its edges onto the tool plate. Through a port built into the tool plate, the interior of the inner bag is connected to a vacuum pump. A tool that amounts to a perforated inverted bowl is placed on the tool plate outside the perimeter of the inner bag. Another vacuum bag, denoted the outer bag, is installed over the perforated inverted bowl, sealed to the tool plate, and connected to a vacuum pump in the same manner as that of the inner bag. The perforated inverted bowl must be rigid enough to withstand atmospheric pressure when the outer bag is evacuated.
 Figure 2. This Double-Vacuum-Bag Assembly makes it possible to maintain vacuum (for removal of volatiles) during the B stage, and then to apply consolidation pressure during the high-temperature curing stage. At the end of the B stage, the atmosphere is admitted to the interior of the outer bag, and full vacuum is applied in the inner bag. Therefore, the outer bag becomes loose from the perforated inverted bowl and the inner bag collapses onto the caul plate at atmospheric pressure, which now serves as the compaction pressure. The vacuum in the inner bag, and thus the compaction pressure, is maintained during the high-temperature ramp-and-hold period of the curing cycle. This work was done by Tan-Hung Hou and Brian J. Jensen of Langley Research Center. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Manufacturing & Prototyping category. This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, Langley Research Center, at (757) 864-3521. Refer to LAR-16877. This Brief includes a Technical Support Package (TSP).
Double-Vacuum-Bag Process for Making Resin-Matrix Composites (reference LAR-16877) is currently available for download from the TSP library. Login first to download.
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