Electrical self-sensing of impact damage in multiscale hierarchical composites with tailored location of carbon nanotube networks

Low-velocity impact damage in multiscale hierarchical composites comprising glass fiber weaves reinforcing a vinyl ester matrix with tailored location of multiwall carbon nanotubes is assessed through the changes of electrical resistance before and after impact. The location of the multiwall carbon nanotubes within the multiscale composite is controlled from manufacturing, rendering two hierarchical architectures. In the first one, as-received glass fiber weaves are used and the multiwall carbon nanotubes are only dispersed within the matrix, while in the second one the multiwall carbon nanotubes are dispersed within the matrix and also bonded to the glass fibers. Spatial electrical resistance maps are able to track the damage progression and growth of damage extension under consecutive impacts and the results are correlated to stresses determined by finite element analysis and ultrasonic C-scanning. The correlation between the electrical mapping and finite element analysis showed that the panels containing multiwall carbon nanotubes on the fiber are more sensitive to delamination and interfacial damage than the ones containing multiwall carbon nanotubes only dispersed within the polymer matrix.