• Title/Summary/Keyword: magnetostrictive

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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)

  • Lee, Ju-Seung;Sun, Kyung-Ho;Cho, Seung-Hyun;Hong, Jin-Chul;Kim, Yoon-Young
    • 한국신재생에너지학회:학술대회논문집
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    • 2005.06a
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    • pp.542-545
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    • 2005

  • 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.

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Pipe Wall Thinning Evaluation through the Arrival Time Delay of A0 Lamb Wave Using Magnetostrictive Patch Transducers

  • Cho, Seung-Hyun;Kwon, Hyu-Sang;Ahn, Bong-Young;Lee, Seung-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.6
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    • pp.512-518
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    • 2008

  • Guided wave technology is advantageous for fast inspection of pipe wall thinning since the guided wave propagates long distance. In this investigation, the method to evaluate gradual wall thinning in a pipe based on the arrival time delay with magnetostrictive patch transducers is presented. Low frequency A0 Lamb waves were generated and measured by the present transducer and it was applied to arrival time delay measurement experiments on a test pipe having gradual wall thinnings artificially manufactured. From experiments, consistent results that wall thinning increases the arrival time delay of A0 waves were obtained. Consequently, the feasibility of the magnetostrictive patch transducers to evaluate wall thinning was verified.

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