Lamb wave generation and analysis in a non-ferromagnetic plate using an orientation-adjustable patch-type magnetostrictive transducer

조향 자기변형 트랜스듀서(OPMT)를 이용한 비자성체 판구조물에서 램파 발생 및 신호해석

This paper is concerned wi th the generation of the Lamb waves in a non­ferromagnetic plate by a recently-developed orientation-adjustable patch-type magnetostrictive transducer (OPMT) and the dispersion analysis from the measured Lamb waves. OPMT is capable of adjusting wave-propagation orientation only with a single installation on a plate. The mechanics behind the wave generation and measurement by the magnetostrictive phenomenon, the working principle of OPMT is explained and the actual generation and measurement of the Lamb waves were conducted in a 3 mm-thick aluminum plate. For the accurate analysis of the dispersion characteristics of the measured Lamb waves, a modified version of the short-time Fourier transform, known as the dispersion-based short-time Fourier transform, was employed. The results presented in this work would serve as the underlying research for an advanced non-destructive evaluation based on ultrasonic waves.