Design and analysis of eddy current probe based on “八” shape excitation

In order to adapt to the complex curved surface structure detection, flexible eddy current probe has been used. However, due to the low energy of the flexible eddy current probe, further improve the detection capability of the flexible eddy current probe is always a problem. In this paper, a probe based on “八” shape excitation coil was proposed, and its detection principle and performance were studied theoretically and experimentally. Through the simulation analysis of the probe using comsol simulation software, it was found that compared with the conventional probe, the probe structure based on the “八” shape excitation can be used for reducing the directly coupled magnetic field,and it was only sensitive to the eddy current disturbance, so the signal-to-noise ratio can be effectively improved. In addition, through the experimental analysis, it was found that when the angle between the two excitation coils was 60°, its detection ability for the carbon steel specimen used in this paper was the strongest. At the same time, it can distinguish the crack defects of different depths, and can detect the crack defects of 0. 5 mm wide and 5 mm deep under the 10 mm lift-off.