In situ sensing of impact damage in epoxy/glass fiber composites using percolating carbon nanotube networks

Carbon nanotubes have been dispersed in thick epoxy/plain woven glass fiber composites using a sizing agent. Electrically conductive networks that act as in situ impact damage sensors were provided by the well dispersed carbon nanotubes. Electrical resistance increases with repeated impact loading; elastic deformation and damage evolution can be identified from the resistance-change. Correlations between resistance-change, absorbed energy, accumulated acoustic emission counts, and damage area of the composite have been established.