Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 100-109). / The relatively high mass-specific strength and stiffness of carbon fibers (CFs) has established CF reinforced plastics (CFRPs) as the benchmark material for next-generation aerospace structures. While CFRPs with radially-grown aligned carbon nanotubes (CNTs), termed fuzzy fiber reinforced plastics (FFRPs), have exhibited enhanced inter- and intralaminar mechanical properties on model FRP systems, these results have not been replicated for aerospace-grade CFRP due to challenges in manufacturing. This thesis reports a scaled (weave- vs. tow-level) manufacturing method of fuzzy woven CFRPs designed to yield dense and aligned CNT coverage on the fibers, and retain the fiber tensile and interface properties. These challenges were explored through mechanical testing, in addition to numerical reactive computational fluid dynamics (CFD) CNT growth models. Single fiber tensile tests for fuzzy fibers from aerospace-grade CF weaves showed no reduction in tensile strength compared to baseline (as received) fibers. Continuously monitored single fiber composite fragmentation testing revealed a 34% decrease in fiber-matrix interfacial shear strength (IFSS) for sized (polymer coating on fibers) fuzzy fibers, attributed to thermally induced sizing transformations during CNT growth, whereas the fuzzy de-sized fibers exhibited no reduction in IFSS. The CFD model demonstrated gas depletion trends correlated to the areas of substandard growth and a high sensitivity to the surface-to-volume ratio of the porous woven substrate. Retained CF properties supports this facile, scaled manufacturing method's ability to disperse CNTs uniformly on CF weaves to create a laminate-level fuzzy CFRP towards enhanced mechanical and multifunctional properties. With continued CNT growth modeling efforts, further scaling of this fuzzy CFRP architecture could be integrated into commercial manufacturing processes. / by Hayden K. Cornwell. / S.M.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/112417 |
| Date | January 2017 |
| Creators | Cornwell, Hayden K |
| Contributors | Brian L. Wardle., Massachusetts Institute of Technology. Department of Aeronautics and Astronautics., Massachusetts Institute of Technology. Department of Aeronautics and Astronautics. |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 109 pages, application/pdf |
| Rights | MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission., http://dspace.mit.edu/handle/1721.1/7582 |
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