Impedance calculation for a plate with crack in eddy current NDT using 3D indirect BIEM

By using the 3-dimensional indirect boundary integral equation method (BIEM), the effective impedance calculation method for a plate with crack in eddy current nondestructive testing (NDT) is proposed. The procedure of the indirect BIEM makes it possible that only one LU decomposition processing of the system matrix is used for the full processing of the NDT analysis. The impedance signal of the pancake type absolute circular air-cored coil probe is used for the detection of the crack in the plate. The mesh is coarse far from the crack and the impedance signal can have some numerical error. By using the impedance subtraction method, the error is reduced and effective impedance signal is obtained. The effective impedance signal is compared with the experimental signal. The agreement of the signal pattern shows the validity of the proposed method.