A modified conductive network used to characterize the conductivity of carbon fibre reinforced polymers in eddy current testing

• Published in: Composite structures 2023-06, Vol.314, p.116948, Article 116948
• Main Authors: Wang, Teng, Wu, Dehui
• Format: Article
• Language: English
• Subjects: Carbon fibre reinforced polymers; Eddy current testing; Electrical properties; High frequency
• ISSN: 0263-8223
• DOI: 10.1016/j.compstruct.2023.116948

Carbon fibre reinforced polymers (CFRPs) are prone to various defects during production and service due to their special composite structures. These defects alter the electrical properties of CFRPs, so they are often be analyzed by eddy current testing (ECT). However, owing to the low conductivity of CFRPs, ECT must operate at high frequencies. And the conductivity mechanism of CFRPs at high frequencies is more complex than that at low frequencies, which makes the electrical properties of CFRPs difficult to be determined. Based on the conductivity characteristics of unidirectional CFRP laminates under high-frequency excitation, a modified conductive network model and a unique non-destructive calibration method are proposed in this paper. By introducing density characteristic parameters of equivalent impedance element, the analytical relationship between characteristic parameters and transverse conductivity of CFRPs is established in the proposed model. And the impedance parameters of CFRPs specimens are calibrated by eddy-current induction experiment and Monte Carlo method. The experimental results show that the proposed model is more accurate than the traditional tensor conductivity model in determining the conductivity characteristics of CFRPs at high frequencies. In addition, the proposed method can effectively determine the internal conductive elements of unidirectional CFRP laminates with different fabrication processes.