Unidirectional focusing Rayleigh waves EMAT for plate surface defect Inspection
Tao Chen, Tingyu Lou, Chen Lv, Xiaochun Song, Jun Tu, Qiao Wu, Xu Zhang
Abstract
Electromagnetic ultrasonic Rayleigh waves are commonly used for detecting surface or near-surface defects, but they still exhibit the drawback of low energy conversion efficiency. In this study, based on the Huygens principle and the discrete point source method, a double curving meander line coils EMAT (DC-MLCs EMAT) which generate unidirectional focusing Rayleigh waves is designed. Firstly, a simulation model of the transducer is established using COMSOL Multiphysics. Then, the impacts of magnet and coise defect detection efficiency is validated by numerical simulation method. Finally, a physical transducer is made, an experimental system is built, and the defect specimens are tested using this experimental system. The simulation and experimental results show that the optimised DC-MLCs EMAT significantly improves ultrasound focusing effect. Compared with the existing single constant length meander line coil（SCL-MLC）EMAT, the signal strength increases by 164.36%. This DC-MLCs EMAT shows good application prospects in the field of fixed focal length measurement.