title: An omnidirectional shear-horizontal guided wave EMAT for a metallic plate.
abstract: We propose a new electromagnetic acoustic transducer (EMAT) for generation and measurement of omnidirectional shear-horizontal (SH) guided waves in metallic plates. The proposed EMAT requires a magnetic circuit configuration that allows omnidirectional SH wave transduction. It consists of a pair of ring-type permanent magnets that supply static magnetic fluxes and a specially wound coil that induces eddy currents. The Lorentz force acting along the circumferential direction is induced by the vertical static magnetic flux and the radial eddy current in a plate, resulting in omnidirectional SH wave generation. To maximize the transducer output at given excitation frequencies, optimal EMAT configurations are determined by numerical simulations and validated by experiments. The omnidirectivity of the proposed EMAT is also confirmed by the simulations and experiments.
authors.affiliation: Center for Safety Measurement, Division of Metrology for Quality of Life, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong-gu, Daejeon 34113, South Korea.
authors.forename: Hong Min
authors.initials: HM
authors.lastname: Seung
authors.affiliation: School of Mechanical and Aerospace Engineering and Institute of Advanced Machines and Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea.
authors.forename: Chung Il
authors.initials: CI
authors.lastname: Park
authors.affiliation: School of Mechanical and Aerospace Engineering and Institute of Advanced Machines and Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea. Electronic address: yykim@snu.ac.kr.
authors.forename: Yoon Young
authors.initials: YY
authors.lastname: Kim
keywords: Electromagnetic acoustic transducer; Guided wave; Omnidirectional transducer; Shear-horizontal wave