Array Electromagnetic Probe with Three-Phase Excitation for CFRP Inspection

This paper presents an array electromagnetic probe with three-phase excitation for carbon fiber reinforced polymer (CFRP) inspection. The probe can generate C-scan image of the magnetic field in a linear probe pass. Within the probe, two rows of circular excitation coils are located in a specified way that the centers of every three adjacent excitation coils form an equilateral triangle. The array of pickup coils are located at the centers of the equilateral triangles. The excitation currents of the coils are 120° apart in phase. The induced eddy currents in the conductive sample shift electrically eliminating the necessary of multiplexer. The background signal measured by the sensor is small if there is no defect in the sample. Therefore, in the presence of a defect, the output is mighty sensitive to the disturbing of the eddy current. A prototype probe has been developed and used to test a carbon fiber reinforced polymer (CFRP) sample with machined artificial defects. The experiment results demonstrate the feasibility of the proposed probe for CFRP inspection.