Experimental characterization and numerical study on the interlaminar fracture toughness of carbon fibre reinforced polymer laminates reinforced with carbon nanotubes

The present study is focused on the nanoreinforcement of carbon fiber reinforced polymer laminates to evaluate its effect on delamination growth in double cantilever beam specimen. Multi-walled carbon nanotubes were sprayed on the laminate interface using air-brush spraying technique. Three nanofiller contents of 0.05 wt.%, 0.1 wt.%, and 0.5 wt.% were examined to evaluate the mode I fracture toughness (GIC) in a double cantilever beam specimen and the results were compared with the base laminate (0.0 % carbon nanotubes). The average mode I fracture toughness of composite laminates increased from 180.6 J/m2 to 270.92 J/m(2) due to the addition of 0.05 wt.% multi-walled carbon nanotubes, and to 268.27 J/m(2) for 0.1 wt.% multi-walled carbon nanotubes. Mechanisms for the increase in GIC of the nanofiller reinforced laminates are discussed based on the experimental results and microscopic study of fractured specimen surfaces from scanning electron microscopy. Energy dissipation from carbon nanotube bridging ahead of the crack front is the major toughening mechanism resulting in improved fracture toughness. Numerical simulations of delamination growth were performed as well by using virtual crack closure technique analysis in Abaqus. The R-curve behaviour from the experiments is implemented in the finite element modeling of delamination growth to validate the effect of nanoreinforcements.