Affiliations: [a] State Key of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, China | [b] Durham University, Durham, Department of Engineering, United Kingdom
Correspondence:
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Corresponding author: Songling Huang, State Key of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 10084, China. E-mail: huangsling@tsinghua.edu.cn
Abstract: Electromagnetic ultrasonic testing, based on the propagation characteristics of the ultrasonic wave in the medium, is an effective technique for defect detection. The structural of the electromagnetic acoustic transducer (EMAT) determines the detection effect, which should be reasonably designed. We propose an improved unilateral point-focusing EMAT structure with curved coils in this manuscript. The 3D model of the designed EMAT is numerically simulated utilizing the finite element method, and the bilateral point-focusing EMAT is also studied for comparison. The simulation results of the magnetic field intensity and the distributions of the displacement are shown in the manuscript, which prove the effectiveness of the improved unilateral point-focusing EMAT. Five impact parameters such as aperture angle, focal position, excitation current, lift-off distance, and coil winding number are investigated in detail. We verify the calculation results of the aperture angle and excitation current by the experiments. The conclusion shows that the focusing intensity of the improved unilateral point-focusing EMAT is relatively higher, and other factors also have a significant effect on the focal intensity.
