A Numerical Simulation Method for High-Frequency Eddy Current Testing Considering Displacement Current Effect

Eddy current testing (ECT) is an efficient nondestructive testing (NDT) technique for the inspection of defect in conductive structural components. The eddy current field problem of ECT is usually treated as a quasi-static field by ignoring the displacement current term in the Maxwell equations, as the metallic inspection target usually has a large electric conductivity but a small dielectric constant close to the air one. Recently, high-frequency ECT (HF ECT) is adopted to the NDT of structures of the carbon fiber reinforced plastics (CFRPs) and shows good performance in some applications. However, the numerical method for simulating conventional ECT problem, which is indispensable for the probe optimization and defect sizing, is not suitable to calculate HF ECT signals because the effect of the displacement current was not taken it into account. In this article, a numerical method for HF ECT problem considering the displacement current effect is proposed and implemented based on an FEM-BEM hybrid code for conventional ECT. The validity and efficiency of the numerical method and code are demonstrated through simulating HF ECT signals of benchmark problems and compared with a full FEM software. The mechanism of ECT for CFRP was also studied using the developed code.