Coil positioning for defect reconstruction in a steel plate

When a steel plate in an army ground vehicle is found to be defective, usually by eddy current testing (ECT), it is taken out of service for repairing without determining if the defect warrants withdrawal or not, whereas the defect might be minor and withdrawal wasteful. In building on our previous work we detect the optimal position to place the ECT coil, and investigate and establish a procedure for defect identification and characterization. We characterize defects by parametrically describing them and then optimizing the parameters to match computed fields to measurements. The pancake exciting coil is moved till the sensing coil reads maximum voltage and at that point compute the fields. We compare working with voltage versus impedance.