title: Review of magnetostrictive patch transducers and applications in ultrasonic nondestructive testing of waveguides.
abstract: A magnetostrictive patch transducer (MPT) is a transducer that exploits the magnetostrictive phenomena representing interactions between mechanical and magnetic fields in ferromagnetic materials. Since MPT technology was mainly developed and applied for nondestructive ultrasonic testing in waveguides such as pipes and plates, this paper will accordingly review advances of this technology in such a context. An MPT consists of a magnetic circuit composed of permanent magnets and coils, and a thin magnetostrictive patch that works as a sensing and actuating element which is bonded onto or coupled with a test waveguide. The configurations of the circuit and magnetostrictive patch therefore critically affect the performance of an MPT as well as the excited and measured wave modes in a waveguide. In this paper, a variety of state-of-the-art MPT configurations and their applications will be reviewed along with the working principle of this transducer type. The use of MPTs in wave experiments involving phononic crystals and elastic metamaterials is also briefly introduced.
authors.affiliation: School of Mechanical and Aerospace Engineering and Institute of Advanced Machines and Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea. Electronic address: yykim@snu.ac.kr.
authors.forename: Yoon Young
authors.initials: YY
authors.lastname: Kim
authors.affiliation: School of Mechanical and Aerospace Engineering and Institute of Advanced Machines and Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: Young Eui
authors.initials: YE
authors.lastname: Kwon
keywords: Magnetostrictive patch transducer; Ultrasonic non-destructive testing; Waveguides