Study of Defects in Carbon Fiber Reinforced Composites Visualized by Magnetic Induction Tomography

ABSTRACT This study proposed a new magnetic induction tomography (MIT) sensor-based electromagnetic induction to reconstruct the conductivity distribution of target conductors and ultimately visualize carbon fiber reinforced plastic (CFRP) plates to measure their defects. This unique MIT sensor was designed for all coil centers located in one line, whereas perpendicular center lines of excitation and detection coils were simulated in a 3D finite element model. The parameters of frequencies, turns, excitation currents, and liftoffs were optimized to further improve sensitivity. Four broken wire defects at different depths were also inspected in an experiment and imaged by the Landweber algorithm. The new probe effectively identified the 4 mm × 4 mm × 0.5 mm defect buried at 1.5 mm. The different depths of defects were also established by the voltage amplitude of the detection coil. The concavity of the reconstructed images effectively represented the depths of the defects. Hence, this MIT probe is highly useful in quantitatively measuring the defects of CFRP plates and visually displaying.