On the Dead Zone of Eddy Current Heating of Lock-in Thermography for Unidirectional Carbon Fiber Reinforced Plastic

The unidirectional carbon fiber composite materials (UD CFRP) was taken as the research object and the lock-in eddy current thermography was utilized to heat the specimen, the high SNR of amplitude and phase diagram were calculated. Finite element model of the eddy current heating was established. Experimental results show that the UD CFRP will lead to dead zone of induction heating. Simulation and experimental results have a higher consistency and reveal that components of the eddy current vector which is perpendicular to direction of carbon fiber directly lead to non-uniformity of induction heating. This will also benefit NDT for CFRP avoiding inspection dead zone.