• Title/Summary/Keyword: Shearography

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Phase Error Analysis in Shearography Using Wave Plates (파장판를 이용한 스펙클패턴 전단간섭법에 있어서의 위상오차 해석)

  • Kim, Soo-Gil
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.1
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    • pp.34-39
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    • 2005
  • We presented the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ by passive devices such as wave plate and polarizer, and calculate the phase at each point of the speckle pattern in shearography using Wollaston prism. And, we analyzed the phase error caused by wave plates used in the proposed method by Jones matrix.

Deformation Analysis of Wall Thinning Pipe by Using Laser Measurement (레이저 계측을 이용한 곡관 감육부의 변형 해석)

  • Kim K.S.;Jung H.C.;Jung S.W.;Kwag J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.27-28
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    • 2006
  • This study performs to investigate deformation of wall thinning pipe and to find out the position of the internal thinning defect by shearography. Shearography is one of optical methods those have applied to nondestructive testing (NDT) and the strain/stress analysis. This technique has the merit of the directly measuring the first derivative of displacement, sensitivity of which can be adjusted by the handling of optical component in interferometer. In this paper, we tested carbon steel pipe locally wall thinned and loaded internal pressure and developed the nondestructive out-of-plane deformation analysis technique fur internal thinning defect of elbow by shearography. From the results, it was confirmed that this technique is proper to the practical application on the pipe line system with internal defect.

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Quantitative Measurement of Out-of-plane Deformation Using Shearography (전단간섭계를 이용한 면외변형의 정량적 계측)

  • Chang, Ho-Seob;Jung, Sung-Wook;Kim, Kyoung-Suk;Jung, Hyun-Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.4 s.193
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    • pp.131-137
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    • 2007
  • Electronic Speckle Pattern Interferometry(ESPI) is a common method for measuring out-of-plane deformation and in-plane deformation and applied for vibration analysis and strain/stress analysis. However, ESPI is sensitive to environmental disturbance, which provide the limitation of industrial application. On the other hand, Shearography based on shearing interferometer which is insensitive to vibration disturbance can directly measure the first derivative of out-of-plane deformation. In this paper a technique that extract out-of-plane deformation from results of shearography by numerical processing is proposed and measurement results of ESPI and Shearoraphy are compared quantitatively.

Analysis of Phase Error Due to the Azimuth Angle of the Wave Plates in the Shearography Using Wollaston Prism (Wollaston prism을 이용한 스펙클패턴 전단간섭법에 있어서 파장판의 방위각에 의한 위상오차 해석)

  • Kim, Soo-Gil;Kim, Ki-Soo;Ko, Myung-Sook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.8
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    • pp.1-7
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    • 2005
  • We introduced the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ by the polarizing elements, and calculate the phase at each point of the speckle pattern in shearography using Wollaston prism and polarizing elements. Ant we analyzed the phase error caused by the azimuth angles of wave plates used in the proposed method by Jones matrix.

A Study on Radial Electronic Shearography for Measuring Amplitudes of Vibration of Symmetrical Objects (대칭형 물체의 진동 진폭 분포 측정을 위한 레이디얼 전단 간섭계에 대한 연구)

  • Kang, Young-June;Choi, Jang-Seob;Rho, Kyung-Wan
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.12
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    • pp.9-16
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    • 1997
  • In this paper, a newly radial electronic shearography system was developed in order to study vibration characteristics of symmetrical objects. We utilized the electro-optic holography theory for quantificational analysis and a porror prism for shearing two inages radially in this study. These image data obtained by this shearography give us various distributions of the gradient of vibration amplitude, and they are useful informations to study vibrational characteristics of symmetrical objects. Finally this developed system with phase stepping and modulation was applied to fans and disks to inspect characteristics of the vibration and the blance of symmetrical objects and obtained good results.

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Influence of Shearing Amount on Detection of Internal Defect of Pressure Pipeline by Shearography (Shearography 기법에 의한 압력 배관 내부 결함 검출에서 전단량의 영향)

  • Kim, Koung-Suk;Kang, Ki-Soo;Choi, Man-Yong;Kang, Young-June
    • Journal of the Korean Society for Nondestructive Testing
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    • v.26 no.2
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    • pp.122-129
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    • 2006
  • Shearography is one of optical methods that has been applied to nondestructive testing (NDT) and strain/stress analysis. The technique has the merit of the directly measuring relative displacement, which is insensitive to environmental vibration disturbance. Previous studies about the method have emphasized on extending its application to new fields and lack insufficient research on effective parameters for qualitative and quantitative evaluation of defects. In this paper, the influence of shearing amount on the detection of an internal defect is investigated. In experiment, slender defects along longitudinal direction of pipeline are artificially designed and detection results according to the change of shearing amount are analyzed. Based on the investigation, we propose the technique for the determination of defect size and accurate source location.