• Title/Summary/Keyword: Electronic Speckle Pattern Interferometry

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The Study on Measurement of In-Plane Displacement in Mechanical Structure applied to Washing Machine using ESPI (ESPI를 이용한 세탁기 적용 기계 구조물의 면내변위 측정에 관한 연구)

  • Lee, Hac-Ju;Kim, Sang-Tea;Choi, Eun-Oh;Chang, Seog-Weon
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.108-113
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    • 2001
  • Recently, the mechanical structures applied to many industrial products, especially in electronic products, appear to be miniaturized and complicated. This trend makes it difficult to analyze the stress distribution of those mechanical structures and generates new challenges for precise measurement of strain. Therefore, generally most of those cases largely depend on the finite element analysis. But the development of optical metrology which has the capability of non-contact, full-field and precise measurement makes it possible to solve these measuring problems. Among the optical measurement techniques, the electronic speckle pattern interferometry (ESPI) has been developed and considered as one of the most useful tools for measuring displacement and deformation. But the shortage of recognition and difficulties of measurement have limited its industrial applications in spite of its excellent capabilities. Therefore in this study, in order to enhance the industrial application of ESPI, the measurement of in-plane displacement of mechanical structure with ESPI, which is applied to washing machine and cannot be measured by strain gauges, was performed. And the verification of validity of FEA results was also done.

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A Study on the Rotating Displacement Measurement of Rigid Body by ESPI Method (ESPI법에 의한 강체 회전 변위 측정에 관한 연구)

  • 김경석;홍명석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.1 no.2
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    • pp.125-133
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    • 1993
  • Electronic Speckle Pattern Interferometry(ESPI) using a CW laser, a video system and image processor was applied to the rotating displacement of rigid body. ESPI require no special surface preparation or attachments and displacements between any two arbitrary points on the surface can be measured. The characteristic speckle pattern formed when imaging a scattering surface illuminated by laser light retains phase information, which can be used for interferometric measurement of surface displacement. The application of this principle to measuring in-plane displacement resolved in one direction is described, together with the novel use of television equipment to detect and process the information contained in the speckle pattern. This is faster, and more convenient and versatile than customary photographic methods.

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The Development of In-Plane Displacement Measurement System on Laser Speckle Interferometry (레이저 스페클 간섭법을 이용한 면내변위 측정시스템 개발)

  • Yoon H.S.;Kim K.S.;Park C.J.;Choi T.H.;Choi J.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.556-560
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    • 2005
  • The measurement method by Laser Speckle Interferometry which uses the interference law which will grow precedes and with it explains a resolution measurement ability and together the change of place arrowhead and general measurement, at real-time measurement sensitivity it has application boat song from candle precise measurement field it is increasing. But, currently the domestic application technique to sleeps and optical science military merit by optical science interferometer and directness it composes purchases to the level which it applies the expensive commercial business equipment the outside and in spite of the technical ripple effect is deficient even in many strong point. The hazard which complements like this problem point form technical development it leads from the research which it sees and an application degree and to sleep as the measurement equipment which tries to develop the small-sized optical science interference sensor and an interpretation program it raises it does.

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Thermal Expansion Coefficient Measurement of STS430 by Laser Speckle Interferometry (레이저 스페클간섭법에 의한 STS430의 열팽창계수 측정)

  • 김경석;이항서;정현철;양승필
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.29-33
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    • 2004
  • This paper presents ESPI system for the measurement of thermal expansion coefficient of STS430 up to 1,000$^{\circ}C$. Existing methods, strain gauge and moire have the limitation of contact to object and do not supply the coefficient up to 800$^{\circ}C$. There needs to measure the data up to 800$^{\circ}C$, because heat resistant materials have high melting temperature up to 1,000$^{\circ}C$. In previous studies related to thermal strain analysis, the quantitative results are not reported by ESPI at high temperature, yet. In-plane ESPI and vacuum chamber for the reduction of air turbulence and oxidation are designed for the measurement of the coefficient up to 1,000$^{\circ}C$and speckle correlation fringe pattern images are processed by commercial image filtering tool-smoothing, thinning and enhancement- to obtain quantitative results, which is compared with references data. The comparison shows two data are agreed within 4.1% blow 600$^{\circ}C$ however, there is some difference up to 600$^{\circ}C$. Also, the incremental ratio of the coefficient is changed up to 800$^{\circ}C$. The reason is the phase transformation of STS430 probably begins at 800$^{\circ}C$.

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Quantitative Evaluation of Delamination Inside of Composite Materials by ESPI (ESPI를 이용한 복합재료 박리결함의 정량평가)

  • Kim, Koung-Suk;Yang, Kwang-Young;Kang, Ki-Soo;Ji, Chang-June
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.3
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    • pp.246-252
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    • 2004
  • Electronic speckle pattern interferometry (ESPI) for quantitative evaluation of delaminations inside of a composite material plate is described. Delaminations caused by the impact on composite materials are difficult to detect visual inspection and ultrasonic testing due to non-homeogenous structure. This paper proposes the quantitative evaluation technique of the defects made in the composite plates by impact load. Artificial defects are introduced inside of the composite plate for the development of a reliable ESPI inspection technique. Real defects produced by impact tester are inspected and compared with the results of visual inspection which shows a good agreement within 5% error.

A Study on the Vibration Characteristics of Symmetry, Asymmetry Laminated Composite Materials by using Time-Average ESPI (시간평균 ESPI를 이용한 대칭.비대칭 적층 복합재료의 진동 특성 비교에 관한 연구)

  • Hong Kyung-Min;Ryu Weon-Jae;Kang Young-Jung;Kang Shin-Jae
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.259-260
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    • 2006
  • The ESPI(Electronic Speckle Pattern Interferometry) is a real time, full-field, non-destructive optical measurement technique. In this study, ESPI is proposed for the purpose of vibration analysis for new material, composite material. Composite materials have various complicated characteristics according to the ply materials, ply orientations, ply stacking sequences and boundary conditions. Therefore, it is difficult to analysis composite materials. For efficient use of composite materials in engineering applications the dynamic behavior, that is, natural frequencies, nodal patterns should be informed. If use Time-Average ESPI, can analyze vibration characteristic of composite material by real time easily. This study manufactured laminated composite of symmetry, asymmetry two kinds that is consisted of CFRP(Carbon Fiber Reinforced Plastics) and shape of test piece is rectangular form.

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Study of Shearography Imaging for Quantity Evaluation Defects in Woven CFRP Composite Materials (직조 CFRP 복합재료 내부결함의 정량적 평가를 위한 Shearography 영상처리 기법 연구)

  • 최상우;이준현;이정호;변준형
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.211-214
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    • 2001
  • Electronic Speckle Pattern Interferometry(ESPI) is one of optical technique to measure displacement precisely, uses CCD camera to show result image in real time. General ESPI system measures in-plane or out-of-plane displacement. Shearography is one of electronic speckle pattern interferometric methods which allow full-field observation of surface displacement derivatives and it is robust in vibration. The shearography provides non-contacting technique of evaluating defects nondestructively. In this study, the shearography was used to evaluate defects in Carbon Fiber Reinforced Plastic(CFRP). Various sizes of artificial defects were embedded in various depths of woven CFRP plate. Effects due to the variation of size and depth of defects were evaluated in this study.

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Quantitative Evaluation of Impact Defects inside of Composite Material Plate by ESPI (ESPI를 이용한 충격손상을 받은 복합재료 내부결함의 정량평가)

  • 김경석;양광영;장호섭;지창준;윤홍석
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.10a
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    • pp.254-258
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    • 2003
  • Electronic Speckle Pattern for quantitative evaluation of a impact defect inside of composite material plate are described. The impact on composite material makes inside delamination which is difficult to detect visual inspection and ultrasonic testing due to non-homeogenous structure. This paper proposes the quantitative evaluation technique of defects under real impact. Artificial defects are designed inside of composite plate for development of inspection technique and real defects under impact are inspected and compared with results of visual inspection.

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Application of Shearography for Nondestructive Evaluation of Internal Defects in CFRP (CFRP에 내재된 결함의 비파괴 평가를 위한 Shearography기법 적용)

  • 최상우;이준현
    • Proceedings of the Korean Reliability Society Conference
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    • 2002.06a
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    • pp.245-251
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    • 2002
  • Electronic Speckle Pattern Interferometry(ESPI) is one of optical technique to measure displacement precisely, uses CCD camera to show result image in real time. General ESPI system measures in-plane or out-of-plane displacement. Shearography is one of electronic speckle pattern interferometric methods which allow full-field observation of surface displacement derivatives and it is robust in vibration. The shearography provides non-contacting technique of evaluating defects nondestructively In this study, the shearography was used to evaluate defects in Carbon Fiber Reinforced Plastic(CFRP). Various sizes of artificial defects were embedded in various depths of woven CFRP plate. Effects due to the variation of size and depth of defects were evaluated in this study.

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