Aligned Carbon Nanotube Reinforcement of Aerospace Carbon Fiber Composites: Substructural Strength Evaluation for Aerostructure Applications

© 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Aligned carbon nanotube (A-CNT) arrays that were densified via patterning and mechanical instability are placed at the resin-rich ply-ply interface in aerospace-grade advanced composite laminates for z-direction reinforcement. The buckled A-CNT arrays display a wavelike folding shape and maintain such a shape after being transferred between the plies. The buckled A-CNT reinforced laminates were tested under short-beam shear (SBS) and double edge-notched tension (DENT) and are found to have a 7% increase in SBS strength and 25% increase in DENT strength, respectively. Both scanning electron microscope imaging and micro-computed tomography reveal that the buckled A-CNT arrays suppress delamination and force damage into the intralaminar region. Furthermore, they introduce multiscale and mixed mode reinforcement mechanisms. The findings demonstrate good potential for using mechanical instability in nanofiber arrays to densify them and tune their shapes, as well as the promising reinforcement effect from buckling-densified A-CNT arrays. Future work to change the pattern (e.g., patterning feature shape and interspacing between features), as well as synchrotron radiation computed tomography-based in situ testing is planned.National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (award DMR-0819762