Structural health monitoring offers a high potential to increase safety, reliability, and cost efficiency of fiber reinforced structures. Electrical conductivity of carbon fibers and carbon nanotubes provides the possibility of in situ strain monitoring and damage detection of composite structures by electrical resistance measurement. To exploit this property and use the material itself as a sensor in a structural health-monitoring system a reliable contacting of the material is needed to enable electrical resistance measurement during operation. Due to its high potential for industrial automation and its excellent reproducibility, ink-jet printing is a promising technology to place conducting paths and realize contacting on the monitored material.
The study deals with a new online monitoring approach using silver nanoparticle based ink. Impact damages are introduced into both, adhesively bonded glass fiber reinforced polymer specimens and carbon fiber reinforced polymer specimens. A modification of the epoxy based adhesive films allows for electrical resistance measurements through the bonding. The introduced impacts are investigated using non-destructive testing methods and light microscopy. Electrical resistance measurements show the possibility of accurate damage detection and damage localization in one or two dimensions, depending on the conducting path designs. The applicability of the presented method as a structural health monitoring system is demonstrated.