Fracture toughness and fatigue behavior of nanoreinforced carbon/epoxy composites

Joel S. Fenner*, Isaac M. Daniel

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In this study, the objective was to develop, manufacture, and test hybrid nano/microcomposites with a nanoparticle reinforced matrix and demonstrate enhancements to damage tolerance properties in the form of fracture toughness and fatigue life. The material employed was a woven carbon fiber/epoxy composite, with multi-wall carbon nanotubes (CNT) as a nano-scale reinforcement to the epoxy matrix. A direct-mixing process, aided by a block copolymer dispersant and sonication, was employed to produce the nanoparticle-filled epoxy matrix. Initial tests were performed on cast epoxy sheets (neat and with nanotubes) to determine effects of nanotubes on the matrix alone. Specimens were tested in Mode I three point bend, showing a 20% increase in critical stress intensity factor K for nanotube-filled epoxy over neat resin. Woven carbon fiber performs were then infused with epoxy (neat and with nanotubes) by a wet layup process to produce flat composite plates. Composite specimens cut from these plates were subjected to Mode I double cantilever beam (DCB) tests (straight and tapered) showing nearly a 200% increase in Mode-I fracture toughness G for nano-reinforced composite over reference composite. Fatigue tests were then performed on the woven carbon fiber composite in the form of cyclic short-beam three point bend to produce interlaminar shear fatigue. Stress-life curves obtained from cyclic short-bearm three point bend showed an increase of more than an order of magnitude in cyclic life at a given cyclic load between reference and nano-reinforced composite. Fatigue-fracture tests were performed on interlaminar Mode-I tapered double cantilever beams to produce Mode-I interlaminar fatigue-crack growth. The results of cyclic interlaminar Mode-I testing showed a much lower crack growth rate for nano-reinforced composite than for reference material. SEM micrographs of failed specimens also showed significant differences in fracture surface morphology between nano-reinforced and reference composite.

Original languageEnglish (US)
Title of host publicationExperimental Mechanics of Composite, Hybrid, and Multifunctional Materials - Proceedings of the 2013 Annual Conference on Experimental and Applied Mechanics
Number of pages9
StatePublished - 2014
Event2013 Annual Conference on Experimental and Applied Mechanics - Lombard, IL, United States
Duration: Jun 3 2013Jun 5 2013

Publication series

NameConference Proceedings of the Society for Experimental Mechanics Series
ISSN (Print)2191-5644
ISSN (Electronic)2191-5652


Other2013 Annual Conference on Experimental and Applied Mechanics
Country/TerritoryUnited States
CityLombard, IL

ASJC Scopus subject areas

  • Engineering(all)
  • Computational Mechanics
  • Mechanical Engineering


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