Inspection of defects in CFRP by improved magnetic induction tomography

Magnetic induction tomography (MIT), a relatively new method of non-destructive testing, is applied to monitor the structural health of carbon fiber reinforced plastics (CFRP). MIT utilizes inductive coils to map the properties of an object. A 3D finite element model of the sensor operation with defects in different CFRP layers is developed to obtain the sensitivity profile and solve the MIT forward problem. Moreover, a linear back projection algorithm was performed to reconstruct images for on-line detection. The results showed that the voltage values induced in the detection coil increase significantly at the defect positions within the related layer. Moreover, the average voltage of the layer with the defect is always higher than at the other layers. This indicates that MIT can easily detect not only surface defects of CFRP but also internal defects successfully and localize them accurately in depth as well.