| Summary: | Advanced structural fiber composite materials have lightweight, multi-directional, and tailorable properties which are vital for weight-critical applications such as aerospace vehicles. Nanoengineered aerospace-grade composites have been developed to have integrated multifunctionalities while ensuring maintained, or even enhanced, mechanical properties, without significant changes in the dimension or weight of the composite system. While integrating individual multifunctionalities into such composites has been demonstrated in a limited set of cases, integrating more than one multifunctionality has not yet been explored. This thesis focuses on the manufacturing and characterization of a nanoengineered integrated multifunctional composite (IMC), that would enable the inclusion of more than one multifunctional capability, while maintaining or enhancing structural function. To this end, a glass fiber reinforced polymer (GFRP) unidirectional-ply composite laminate was nanoengineered with carbon nanotubes (CNTs) in the composite’s interlaminar regions and surfaces, to produce the IMC. A preliminary study, focusing on the compatibility of CNTs in GFRP and on enhancing the laminate’s structural function, determined the preferred CNT architectures to reinforce the interlaminar regions and enable various multifunctionalities. The IMC integrated a commercial CNT film on the outer surfaces and two preferred architectures in the interlaminar region: a 10 µm aligned carbon nanotube (A-CNT) film (termed nanostitch) and a patterned and coherently buckled A-CNT film (termed nanostitch 2.0). The resulting IMCs had an equivalent quality (no detectable voids, insignificant difference in the laminate thickness and interlaminar thickness) to the baseline GFRP system, while demonstrating maintained or enhanced mechanical performance. Relative to the baseline, the IMCs have enhanced (∼5%) interlaminar shear strength (ILSS) and maintained notched tensile strength with equivalent damage progression as revealed through in situ testing using synchrotron radiation computed tomography (SRCT). The IMCs demonstrated here, with electrically and thermally conductive interlaminar regions and surfaces, support future demonstrations of multifunctionalities through a composite system designed to serve independent yet synergistic functionalities in life-cycle enhancement, energy savings during manufacturing, in situ cure (manufacturing) monitoring, Joule heating ice protection system (IPS) applications, and in-service damage sensing, among others.
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