A Method of Shear-Horizontal EMAT Based on Dual-Reception Magnetic Encoded Spatial Pulse Compression for Multiple Cracks Identification and Location

The lowest order mode of a shear-horizontal electromagnetic acoustic transducer (EMAT) typically exhibits a low signal-to-noise ratio and poor spatial resolution in defect detection. To solve this issue, this letter presents a crack identification and location method based on dual-reception magnetic encoded spatial pulse compression technology. On the one hand, the method implements spatial pulse compression technology by adjusting the spatial distribution of the magnetic field to obtain a high amplitude and narrow pulse detection signal. On the other hand, this method multiplexes the excitation EMAT as a receiver through signal processing technology, so that the position of cracks can be more accurately judged by analyzing the signals of the dual EMATs. Most importantly, this method does not require additional EMAT and complex excitation equipment. Finally, a simulation model was built to verify the method. The simulation results show, that compared with the detection signal of the traditional method, the SNR is improved by over 1.1 dB, and the spatial resolution is improved by over 18%. Additionally, the method can effectively distinguish the crack defects on both sides of EMATs, and the localization accuracy exceeds 95%.