Mechanical characterization and impact damage assessment of a woven carbon fiber reinforced carbon nanotube–epoxy composite

Carbon nanotubes carry the promise of enhancing the poor out-of-plane mechanical performance of fiber reinforced polymer composites (FRPs). The present study is aimed to investigate the effect of adding multi-walled carbon nanotubes (MWCNTs) to the epoxy matrix of a carbon fiber reinforced composite (CFRP) on the composites’ damping performance, impact resistance and impact damage progression. Two sets of CFRPs with their matrices comprising MWCNTs–epoxy and neat epoxy, respectively, were fabricated and mechanically tested under tensile, Quasi-static punch test, vibration and intermediate velocity impact (IVI) environments. While the tensile failure strain of the carbon fiber reinforced epoxy–MWCNT composite increased, its tensile modulus and strength remained almost unaffected. Dynamic mechanical analysis (DMA) was employed to measure the damping performance of the two composite systems. The composite samples containing MWCNTs retained higher damping indicating their greater capability to attenuate impact shocks generated during an impact phenomenon. The samples were subjected to out-of-plane impact (at ∼100 ms−1) from which the energy dissipation capacity of the composites was evaluated. Incorporating MWCNTs into the CFRP increased the absorbed impact energy by 21%. The punch test provided valuable information on the damage mechanics of the ballistic impact of the composite panels. It also contrasted the effect of high-stain-rate on the impact test. The consequences of adding MWCNTs to the matrix of CFRPs on the impact progressive damage and energy absorption were discussed in terms of the damage mechanisms and the dynamic damping behavior of the composites. To better comprehend the effect of adding CNTs on the impact damage mechanisms, X-ray radiography was carried out on the impacted panels. It was shown that the addition of MWCNTs to the matrix of a CFRP improves its inter- and intra-laminar mechanical performance yielding a better impact resistance. It was confirmed that the impact failure behavior of the studied composite systems could be predicted from the quasi-static and dynamic mechanical tests.