Nondestructive evaluation of carbon fiber reinforced polymer (CFRP)-steel interfacial debonding using eddy current thermography

The paper studies the characteristics of eddy current (EC) distribution in carbon fiber reinforced polymer (CFRP) laminates so as to guide the research and operation of eddy current testing of CFRP. To this end, an electromagnetic field computation model of EC response to CFRP based on the finite element method is developed. Quantitative analysis of EC distribution in plies of unidirectional CFRP reveals that EC changes slowly along the fiber direction due to the strong electrical anisotropy of the material. Variation of EC in plies of multidirectional CFRP is fast in both directions. The attenuation of EC in the normal direction in unidirectional CFRP is faster than that in isotropic material due to faster diffusion of EC. In multidirectional CFRP, EC increases near the interfaces of plies having different fiber orientations. The simulation results are beneficial to optimizing sensor design and testing parameters, as well as damage detection and evaluation.