Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Bulk Shear-Wave Transduction Experiments Using Magnetostrictive Transducers with a Thin Fe-Co Alloy Patch

철-코발트 합금 패치로 구성된 자기변형 트랜스듀서를 이용한 체적 전단파 발생 및 측정

  • Park, Jae-Ha (Center for Safety Measurement, Korea Research Institute of Standards and Science) ;
  • Cho, Seung-Hyun (Center for Safety Measurement, Korea Research Institute of Standards and Science) ;
  • Ahn, Bong-Young (Center for Safety Measurement, Korea Research Institute of Standards and Science) ;
  • Kwon, Hyu-Sang (Center for Fluid Flow and Acoustics, Korea Research Institute of Standards and Science)
  • 박재하 (한국표준과학연구원 안전측정센터) ;
  • 조승현 (한국표준과학연구원 안전측정센터) ;
  • 안봉영 (한국표준과학연구원 안전측정센터) ;
  • 권휴상 (한국표준과학연구원 유동음향센터)
  • Received : 2010.03.16
  • Accepted : 2010.07.02
  • Published : 2010.08.01
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Abstract

Recently, the results of many studies have clarified the successful performance of magnetostrictive transducers in which a ferromagnetic patch is used for the transduction of guided shear waves; this is because a thin ferromagnetic patch with strong magnetostriction is very useful for generating and detecting shear wave. This investigation deals with bulk shear wave transduction by means of magnetostriction; on the other hand, the existing studies have been focused on guided shear waves. A modular transducer was developed; this transducer comprised a coil, magnets, and a thin ferromagnetic patch that was made of Fe-Co alloy. Some experiments were conducted to verify the performance of the developed transducer. Radiation directivity pattern of the developed transducer was obtained, and a test to detect the damage on a side drill hole of a steel block specimen was carried out. From the results of these tests, the good performance of the transducer for nondestructive testing was verified on the basis of the signal-to-noise ratio and narrow beam directivity.

최근 가공성이 우수하고 강한 자기변형성을 가진 강자성 패치가 소개되면서, 이를 이용한 탄성초음파 변환 연구가 활발하다. 이러한 자기변형 패치 트랜스듀서는 SH 파와 비틀림파 등 전단파 변환 성능이 우수하여 비파괴평가 분야에서 많은 주목을 받고 있지만, 지금까지 관련 연구가 유도초음파 변환에 집중된 반면 체적초음파에는 아직 적용이 된 예가 없다. 본 연구에서는, 자기변형성이 큰 재질 중 하나인 철-코발트 합금을 이용한 체적전단파 트랜스듀서를 제안하고자 한다. 제안한 트랜스듀서는 강자성 패치, 코일, 영구자석, 요크를 포함하여 모듈형으로 설계되었고, 실험을 통해서 파형 및 방사 패턴 등을 측정하였다. 결과적으로, 제안한 트랜스듀서는 신호대잡음비 및 방사패턴 면에서 상당히 우수한 성능을 보임을 확인하였다.

Keywords

References

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