Effect of Carbon Nanotube Embedding on the Mechanical Properties of Delaminated Carbon Fiber Reinforced Polymer Composite Plates

DOI https://doi.org/10.15407/pmach2026.01.016
Journal Journal of Mechanical Engineering – Problemy Mashynobuduvannia
Publisher Anatolii Pidhornyi Institute of Power Machines and Systems
of National Academy of Science of Ukraine
ISSN  2709-2984 (Print), 2709-2992 (Online)
Issue Vol. 29, no. 1, 2026 (March)
Pages 16-27
Cited by J. of Mech. Eng., 2026, vol. 29, no. 1, pp. 16-27

 

Author

Muhammad Imran, International Islamic University (Islamabad 44000, Pakistan), e-mail: muhammad.imran@iiu.edu.pk, ORCID: 0000-0002-2704-6813

 

Abstract

Carbon fiber reinforced polymer (CFRP) composites are widely employed in aerospace, automotive, and civil infrastructure applications owing to their exceptional specific stiffness and strength. Delamination is one of the critical parameter in composite materials. However, interlaminar delamination remains the predominant failure mode critically undermining structural integrity. The present study investigates the influence of multi-walled carbon nanotube (MWCNT) reinforcement, introduced via matrix-level dispersion, on the mechanical response of CFRP laminates with pre-existing circular delaminations of varying diameters (10, 20, and 30 mm) at the mid-plane. Quasi-isotropic [0/45/−90/−45]ₛ laminates (nominal thickness 4 mm) were fabricated by vacuum-assisted resin infusion. Three MWCNT weight fractions (0, 0.3, and 0.5 wt.%) were examined. Specimens were characterised by tensile, compressive, short-beam shear, mode-I double-cantilever beam fracture, and compression-after-impact tests. Digital image correlation was employed to map full-field strain distributions. Incorporation of 0.3 wt.% MWCNTs increased ILSS by 18.3%, mode-I Gᴵc by 34.4%, and compression-after-impact strength by 22.0% relative to neat CFRP with equivalent delamination. At 0.5 wt.%, agglomeration effects partially offset these gains. Fractographic SEM revealed carbon nanotube pull-out, crack bridging, and matrix micro-crack deflection as operative toughening mechanisms. These findings demonstrate that low-concentration MWCNT doping constitutes an effective strategy for mitigating delamination-induced degradation in CFRP structural panels.

 

Keywords: carbon nanotube, сarbon fiber reinforced polymer, delamination, interlaminar fracture toughness, short-beam shear, compression-after-impact, digital image correlation, toughening mechanism, epoxy nanocomposite.

 

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Received 18 February 2026
Accepted 03 March 2026
Published 30 March 2026