Tailoring Fiber Volume Fraction of Vacuum-assisted Resin Transfer Molding

Report No. ARL-TN-0510
Authors: Zachary J. Larimore* and Larry R. Holmes, Jr.
Date/Pages: November 2012; 16 pages
Abstract: Classical composite laminated plate theory (LPT) shows that high fiber volume fraction (fvf) composites in the range of 0.60 to 0.65 can optimize the strength to weight ratio of composite structure. Current processing methods capable of achieving idealized fvf use a high-pressure autoclave and require pre-impregnated fibers with specialized resin volume. Autoclave processing is extremely high cost due to inherently long cycle time, specialized non-portable equipment, and high-cost molds. Structural requirements of aerospace applications serve as justification for the high cost of autoclave processes. The Vacuum- Assisted Resin Transfer Molding (VARTM) process is an alternative, out-of-autoclave, method which is attractive due to its low cost, simplicity, and portability. However, a limitation to current VARTM processing methods is the ability to tailor, or increase, the fvf of the composite laminate. Reducing resin volume available to the optimum resin volume, calculated using LPT, can yield increased fvf in the composite laminate while preserving complete wet-out of the fiber plies. Pre-measured volumes of resin placed in a bladder bag within the consolidation vacuum bag allow for the fvf of the composite to be controlled by limiting the resin volume available to flow into the fiber. This processing technique also has potential as a small scale field repair option.
Distribution: Approved for public release
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Last Update / Reviewed: November 1, 2012