Observing the Fracture Behavior of a Center Crack via Electrical Impedance Tomography Using Inkjet-printed Carbon Nanotube Thin Films

Optimized lightweight design materials such as fiber-reinforced polymer composites (FRPs) allow aerospace and automotive industries to build robust structures with reduced self-weight, attaining improved fuel-efficiency with less strength loss. These structures require rigorous assessment to prevent catastrophic structural failure. Current development in tomographic methods offers opportunity to perform online damage assessment of a structure without installing heavy instrument over a target region. This paper demonstrates the spatial sensing capability of an inkjet-printed carbon nanotube (CNT) thin film upon a crack’s fracture behavior via electrical impedance tomography (EIT). A CNT-thin-film-printed coupon with a center crack was tensile loaded and evaluated under three loading cases. The printed thin film served as both a spatial damage sensor and a speckled pattern for digital image correlation (DIC) analysis. The EIT results, which were compared to the DIC measurements of the planar strain distribution developed over the thin film, showed that the sensor may identify crack severity and plastic zones formed at crack tips.