Inter- to intra-laminar crack bifurcation in aerospace-grade carbon fiber reinforced polymer composites due to aligned carbon nanotube reinforcement
Name
neptune_share.pdf
Size
8.95 MB
Format
Adobe PDF
Checksum (MD5)
bd4fb3d53ab5b92595b094492c0a6776
Author(s)
Kwon, Christopher
Li, Carina
Gonuleri, Riza
Alicioglu, Batuhan
Euvrard, Nielsen
Powell, Talia
Blanco-Varela, Tamara
Guven, Ibrahim
Wardle, Brian
Date Issued
June 12, 2026
Journal
Composites Science and Technology
Publisher
Elsevier BV
Version
Author's final manuscript
Abstract
Here, we examine vertically aligned carbon nanotube (VA-CNT) interlaminar reinforcement of aerospace-grade epoxy carbon fiber reinforced polymer (CFRP) composite using short-beam shear (SBS) and Mode I&II fracture testing, together with peridynamics modeling, to elucidate inter- to intra-laminar crack bifurcation. SBS testing revealed clear evidence of more diffuse (intralaminar) cracks in postmortem imaging for CNT vs. baseline laminates, along with interlaminar shear strength (ILSS) retention. By contrast, Mode I and II fracture testing demonstrated pronounced interlaminar toughening with sustained crack bifurcation away from the interlaminar region and into the intralaminar region. Mode I and II cracks deflect from CNT-reinforced interlaminar regions into adjacent intralaminar plies, then propagate as sustained intralaminar Mode I cracks parallel to the interlaminar plane. The bifurcation distance into the adjacent ply from the midplane is ∼10 μm greater in this 190 gsm system than the ∼24 μm distance in the prior 130 gsm system. Peridynamics modeling at two scales in Mode I further elucidated bifurcation mechanisms: a global laminate model matching macroscopic results (load, deflection, toughness), and a microscale submodel predicting crack bifurcation consistent with experiments for bond strengths at least 2.5× higher in CNT-reinforced regions. This corresponds to ∼200% toughness increase due to the A-CNTs and shows the bifurcation distance into adjacent plies remains constant beyond a 2.5× bond strength threshold. With new mechanistic insights and a novel predictive capability for crack bifurcation and propagation, future work can extend to design studies and applying VA-CNT reinforcement to other interfaces, such as woven composites and composites with interlaminar microparticle tougheners.
MIT Department
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
Massachusetts Institute of Technology. Department of Mechanical Engineering
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivatives
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1016/j.compscitech.2026.111729
