Towards meso scale impedance-based monitoring of degradation in laminated composites

A practical way to track the evolution of damage in laminated composites is to monitor the change of its electrical resistance. Such measurements can be conveniently processed at the meso scale by using recently developed rigorous micro meso relations for electrical conductivity. Yet, pure resistive monitoring is limited due to small penetration without the material. Electrical impedance spectroscopy (EIS) of carbon fiber reinforced polymer (CFRP) has been conducted with ECG electrodes directly pasted on the CFRP samples without removing the resin layer. The impedance and phase angle variations obtained for a CFRP composite plate with delamination is compared to the data obtained from a sample without delamination. Results demonstrate that the impedance and phase angle profiles change for a CFRP plate with delamination from a sample without delamination. The delamination induced impedance variation in CFRP composites can be utilized for nondestructive damage evaluation.