文献类型：期刊文献

英文题名：An Emat Design with Track Coil and Periodic Permanent Magnets for Enhanced Ultrasonic Lamb Wave Generation in Non-Ferromagnetic Plates

作者：Guo, Xinfeng[1]; Jiang, Ying[1]; Zhu, Wujun[1]; Xiang, Yanxun[1]; Xuan, Fu-Zhen[1]

机构：[1] Key Laboratory of Pressure Systems and Safety of MOE, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, 200237, China

年份：2022

外文期刊名：SSRN

收录：EI(收录号：20220120361)

语种：英文

外文关键词：Eddy current testing - Ferromagnetism - Magnetic fields - Permanent magnets - Plates (structural components) - Surface waves - Ultrasonic waves

摘要：As a typical non-destructive testing method, electromagnetic acoustic testing is often used to test metal materials and components. The main shortcoming in practical application is poor energy conversion efficiency, especially in the case of non-ferromagnetic materials. To solve this problem, this article proposed a Lamb electromagnetic acoustic transducer (EMAT) for ultrasonic testing of non-ferromagnetic plates. The new type of EMAT consists of a track coil and a group of periodic permanent magnets (PPMs). Conventional Lamb wave EMATs typically use meander coil and rectangular magnet to generate Lorentz forces with a periodic distribution. The track coil provides stronger eddy currents than meander coil, and the PPMs provide more even bias magnetic fields than rectangular magnet, which generates Lorentz forces with a similar periodic distribution and larger values, compared with the conventional Lamb wave EMAT. Then two-dimensional finite element (FE) simulation models of the conventional meander-line-coil (MLC) and TCPPM transducers were completed to compare the distribution of eddy currents, bias magnetic fields and Lorentz forces. Eventually, a series of transducers with coils of different sizes were manufactured and incorporated into the experimental study. The experimental results proved that the TCPPM transducers could generate and receive more powerful ultrasonic Lamb waves than the conventional MLC EMATs. Due to the dispersion characteristics, pure A0 or S0 mode of ultrasonic Lamb waves can be generated and received by selecting suitable frequencies. Compared with the MLC EMATs, the maximum amplitudes of the A0 and S0 modes were increased by 18.9 dB and 10.4 dB, respectively. The contribution of the direction of Lorentz forces to A0 and S0 mode Lamb waves was also verified by comparing the signals of three groups of TCPPM EMATs with different structures. ? 2022, The Authors. All rights reserved.