On the anisotropic behavior of electrodes for electrical‐based monitoring of CFRP laminated composites

Electrical impedance tomography (EIT) is a promising structural health monitoring technique for carbon fiber‐reinforced polymer (CFRP) composites. EIT technique has been specifically adopted as a non‐destructive testing method along with the electrical characterization methods. Electrodes are the primary component in any EIT system because they act as an interface connecting the instrument/hardware to the structure under inspection. Simulation of electrical inspection of CFRP usually assumes the electrodes to be electrically isotropic interfaces. We show here that such isotropic assumption is a very poor approximation. We experimentally investigated the electrodes contact impedance behavior on CFRP‐laminated composite specimens for different surface processing (sanding, CO₂ laser, and Yb‐fiber laser). The effective electrical responses of electrodes are characterized in‐depth, so an accurate description can be proposed. Our findings emphasize that the electrodes contact impedance is strongly anisotropic, and varies largely between the on‐axis (along surface fibers) and the off‐axis (bias and perpendicular to the surface fibers) for all tested surface processing. POLYM. COMPOS., 2018. © 2018 Society of Plastics Engineers