Crack sizing of deep cracks in eddy current testing using 3D electromagnetic field analysis

A computer-aided approach of the eddy current testing (ECT) is described to detect and to size up deep cracks in thick metal structures. A 3D eddy current field analysis based on the finite elements performs designing ECT probes and evaluating the size of crack depth quantitatively. An exhaustive study on the ECT probe specification gives the optimal design of coil elements and their combination. The experimental verification shows that the developed ECT probe employing double exciting coils is capable of detecting crack depth over 10mm from the inspection surfaces. The depth of cracks is quantitatively evaluated from the measured ECT signals with the help of numerical calculation. The results of evaluation profile the crack shapes with fairly high accuracy, supporting our approach.