Application of electrical impedance tomography to an anisotropic carbon fiber-reinforced polymer composite laminate for damage localization

Electrical impedance tomography (EIT) is an emerging method for assessing the structural condition of composite structures. In this work, EIT's damage localization capability is investigated through its application upon a commercial laminated anisotropic carbon fiber reinforced polymer plate. Aluminum rivets were used as electrodes. EIT reconstructs the spatial conductivity within a defined space by using its boundary voltage response. The algorithm starts with a forward simulation of the voltage distributions within the boundary, hence the orthotropic conductivity of the CFRP plate was first characterized experimentally. It was found that the inhomogeneous fiber contacts through the thickness are influencing the reconstruction results. A detailed 3D finite element simulation was built to model the conductivity distribution. Different current injection patterns were attempted with their reconstruction results being evaluated via four criteria. It was found that the diagonal current injection and the difference evaluation lead to the best results.