Health monitoring of scarfed CFRP joints under cyclic loading via electrical resistance measurements using carbon nanotube modified adhesive films

This study deals with a structural health monitoring approach for adhesively bonded carbon fiber reinforced polymer joints. A modification of an epoxy based adhesive film with single wall carbon nanotubes allows for electrical resistance measurements through the joint. Cyclic fatigue tests of adhesively bonded scarf joints with simultaneous electrical resistance measurements are conducted to investigate the damage detection and localization of repaired composite parts during operation. The measured electrical resistance changes are compared to results from digital image correlation. Crack initiation and growth can be detected by an increase of electrical resistance. Furthermore, it is possible with parallel oriented ink-jet printed circuits to localize the damages occurred.