Caustic investigation of dynamic interactions between propagating matrix crack and modified fibre bundles

The dynamic interactions between a propagating crack in a matrix and fibre bundles coated with multi-wall carbon nanotubes (MWCNTs) are investigated. First, the dynamic stress intensity factor at the propagating crack tip in front of the fibre bundles was derived. Second, dynamic caustic experiments were performed to characterise the dynamic interactions for three different modified fibre/epoxy specimens with MWCNTs. Finally, important fracture parameters of these specimens are evaluated. The modified MWCNT fibre bundles perform better than untreated fibre/epoxy specimens in reducing the dynamic stress intensity factor and the crack propagation velocity at the propagating crack tip in front of the fibre bundles. The modified MWCNT-coated fibre bundles can also realise equilibrium partitioning of the fibre fracture energy and interfacial bonding energy, thus preventing massive interfacial debonding and matrix failure. These results can be used to evaluate the toughening effect of carbon nanotubes on polymer composites.