An improved analytical model of the magnetostriction-based EMAT of SH0 mode guided wave in a ferromagnetic plate

Xiaodong Zhang; Xiucheng Liu; Bin Wu; Cunfu He; Tetsuya Uchimoto; Toshiyuki Takagi

doi:10.1016/j.ultras.2020.106213

An improved analytical model of the magnetostriction-based EMAT of SH₀ mode guided wave in a ferromagnetic plate

Ultrasonics. 2020 Dec:108:106213. doi: 10.1016/j.ultras.2020.106213. Epub 2020 Jun 26.

Authors

Xiaodong Zhang¹, Xiucheng Liu², Bin Wu³, Cunfu He³, Tetsuya Uchimoto⁴, Toshiyuki Takagi⁴

Affiliations

¹ College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China; Institute of Fluid Science, Tohoku University, Sendai 980-8577, Japan.
² College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China. Electronic address: xiuchliu@bjut.edu.cn.
³ College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China.
⁴ Institute of Fluid Science, Tohoku University, Sendai 980-8577, Japan.

PMID: 32615364
DOI: 10.1016/j.ultras.2020.106213

Abstract

The accuracy of electro-acoustic energy transfer efficiency (EAETE) model directly determines the optimization results of an electromagnetic acoustic transducer (EMAT). In this study, the EMAT model of SH₀ mode generation based on magnetostriction mechanism is re-examined. In the existing magnetostriction-based EMAT (MEMAT) analytical model, an approximate method of dynamic magnetic field was employed. Thus the effects of the tested ferromagnetic materials on the dynamic magnetic field in the air is ignored and the boundary condition between air and material is not exact. As a result, the calculated dynamic magnetic field inside the tested ferromagnetic materials is incorrect, thus leading to the calculation errors of magnetostriction body force and the final EAETE of MEMAT. The rigorous analytical solutions for calculating the dynamic magnetic field are derived based on Maxwell equations and boundary conditions in this study. The prediction results of improved analytical model were consistent with previously reported experimental results. Compared with existing analytical models, the improved model showed the higher prediction accuracy of several parameters, including dynamic magnetic field, magnetostriction force and the EAETE.

Keywords: Analytical model; Electro-acoustic energy transfer efficiency; Magnetostriction-based EMAT; SH(0) mode guided wave.