Eddy Current Magneto-Optical Imaging Based on Phase Change for CFRP Defects

The realization of nondestructive testing (NDT) of weak conductive materials is a key research area of eddy current magneto-optical (ECMO) imaging, such as carbon fiber reinforced polymer (CFRP) materials widely used in aerospace field. In this article, magnetic field phase is used for ECMO imaging NDT of CFRP defects, different from magnetic field amplitude imaging for conductive materials. Finite element analysis (FEA) and magnetic field distribution simulation are used to analyze the characteristics of ECMO imaging detection with different excitation source frequencies. The results show that the CFRP defects are more sensitive to the magnetic field phase other than amplitudes and exhibit frequency dependent. Furthermore, an ECMO imaging NDT system based on magnetic field phase is established for CFRP defects detection, which includes an efficient specimen scanning platform. The experimental results show that the proposed NDT system with optimal excitation frequency can detect the CFRP defects effectively, both surface crack and impact damage defects. In a word, the ECMO imaging NDT system based on magnetic field phase can be successfully implemented in fast and efficient NDT of weak conductive materials defects.