Influence of electrode configuration on impact damage evaluation of self-sensing hierarchical composites

A technique based on the electrical resistance change of a network of carbon nanotubes within a polymer composite was implemented to assess damage caused by low-velocity impact in multiscale hierarchical composites. The influence of the electrode configuration in 100 mm x 100 mm x 1.7 mm plates is addressed. Three electrode configurations are evaluated, namely, a grid on the impacted surface, a grid on the opposite (non-impacted) surface, and through the thickness of the plate. Upon impact, matrix cracking, delamination, and fiber rupture cause disruption and redistribution of the electrical network of carbon nanotubes, whose electrical resistance changes can be correlated with such damage. It is found that the non-impacted surface exhibits a higher fractional change of electrical resistance and hence higher sensitivity to damage. The results obtained using the electrical technique showed a good correlation with damage detected by independent measurements by digital holographic interferometry and ultrasonic inspections.