Impact Damage Detection and Localization of Adhesively Bonded Fiber Reinforced Structures using Silver Nanoparticle Based Printed Circuits

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 serves as promising technology to print circuits and realize contacting on the monitored material. The study deals with a new structural health monitoring approach using inkjet printing of silver nanoparticle based ink directly onto the composites structure. Impact damages are introduced into adhesively bonded glass fiber reinforced polymer test specimens. A modification of the epoxy based adhesive films with carbon nanoparticles allows for electrical resistance measurements through the bonding. The introduced impacts are investigated using non-destructive testing methods, i.e. ultrasonic inspection, and light microscopy. Electrical resistance measurement shows the possibility of accurate damage detection and damage localization in one or two dimensions, depending on the conducting path designs.