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Additionally, manufacturability was a large driver in the final shell design. Given the twomonth production target and the constraint on available autoclave systems, an out-ofautoclave process was utilized. To yield a high quality part with low void fractions and high mechanical properties, we employed a closed mold composite manufacturing technique called “vacuum assisted resin infusion.” In contrast to a typical wet layup, dry woven carbon fabrics were draped onto a female mold along with peel ply and porous distribution flow media before vacuum bagged. Vacuum was connected to one end of the mold, and a resin valve was slowly opened from the other end, thus cleanly introducing resin onto the MIT’s Hyperloop concept for high-speed ground transportation would feature a carbon fiber carbon preform. Once the resin flow front had reinforced plastic shell with a lightweight foam core. (MIT Hyperloop Team illustration) reached through the full length of the part, we closed off the resin source, and held the part under vacuum to cure at room temperatures. As we anticipate the shell to be exposed to the sun for extended durations on competition day, the glass transition temperature of the composite was elevated by post-curing the part. Designing and fabricating the composite mold also presented many key challenges in manufacturing. Due to cost and surface finishing constraints, a direct female medium density fiberboard (MDF) mold was designed and routed, thus requiring efficient tool path programming. After the MDF plies were assembled and glued, the tool surface had to be sealed, polished, and waxed to create a mirror surface, while also ensuring part release. In the end, we were successful in manufacturing two stiff, yet lightweight, CFRP shells within two months and they are now ready for competition.

SPECIAL SECTION

Student Projects: tiny rocket drones, hyper-speed transport, a composite rocket, and a lunar orbit competitor

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MIT AeroAstro annual magazine 2015-2016Aeroastro 2015 16  

Annual magazine review of MIT Aeronautics and Astronautics Department research and educational initiatives.

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