• 제목/요약/키워드: Electronic speckle pattern interferometry

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ESPI 기법을 이용한 미소 인장 특성 추정 (Measurement of Micro-Tensile Properties using ESPI technique)

  • 허용학;김동일;윤경진;김경석;오충석
    • 한국정밀공학회지
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    • 제18권5호
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    • pp.90-97
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    • 2001
  • An electronic speckle pattern interferometry (ESPI) system for measuring tensile properties under micro-tensile testing has been developed. The system consists of an optical system and an image processing system. In the optical system, optical components for measurement of in-plane deformation are arranged on the path of He-Ne laser. In the image processing system, the window-based program for acquiring speckle pattern interferometric image was developed and deformation in a small specimen is continuously evaluated during the test. Using this system, tensile strain of copper foil was measured during tensile testing. Tensile specimen had the thickness and width of 22 and 500 ${\mu}{\textrm}{m}$, respectively. Tensile properties, including the elastic modulus, yielding strength and tensile strength, of the copper were evaluated and also plastic exponent and coefficient in the Ramberg-Osgood relationship were evaluated from the stress-strain curve.

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In-plane ESPI를 이용한 고온에서 STS430의 열팽창계수 측정 (Thermal Expansion Coefficient Measurement of STS430 at High Temperature by In-plane ESPI)

  • 김경석;강기수;장호섭
    • 한국정밀공학회지
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    • 제21권11호
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    • pp.69-74
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    • 2004
  • This paper presents ESPI system for the measurement of thermal expansion coefficient of STS430 up to 1,00$0^{\circ}C$ . Existing methods, strain gauge and moire have the limitation of contact to object and do not supply the coefficient up to 80$0^{\circ}C$ . There needs to measure the data up to 80$0^{\circ}C$, because heat resistant materials have high melting temperature up to 1,000'E In previous studies related to thermal strain analysis, the quantitative results have 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 1,00$0^{\circ}C$ 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 80$0^{\circ}C$ . The reason is the phase transformation of STS430 probably begins at 80$0^{\circ}C$

ESPI를 이용한 엔지니어링 플라스틱 열 변형 분석

  • 함선일;최동준;박상득
    • 한국신뢰성학회:학술대회논문집
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    • 한국신뢰성학회 2005년도 학술발표대회 논문집
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    • pp.303-305
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    • 2005
  • Recently, various plastics are used for improvement of reliability and thermal stability of electronic goods. But, it is difficult to choose suitable balance of grade resin to each other product property. Selection of high efficiency resin is becoming inescapable circumstance according to change of reflow temperature of product and development of product following to lead free. Using a inexpensive and reasonable resin, that sustain a uniform performance of product quality. It is make a robust product and increase a company's competitive power. Hereupon, I introduce example that use ESPI methods of thermal deformation analysis of product using in our company product. I try to refer to a structural weak point detection of real time measurement of electronic parts instead of mechanical and chemical measurement of specimen type.

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무잔류 응력상태 결정을 통한 표면 잔류응력장 평가에의 레이저 간섭계 적용 (Application of Laser Interferometry for Assessment of Surface Residual Stress by Determination of Stress-free State)

  • 김동원;이낙규;최태훈;나경환;권동일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.25-30
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    • 2003
  • The total relaxed stress in annealing and the thermal strain/stress were obtained from the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI). The residual stress fields in case of both single and film/substrate systems were modeled using the thermo-elastic theory and the relationship between relaxed stresses and displacements. We mapped the surface residual stress fields on the indented bulk Cu and the 0.5 ${\mu}m$ Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -1.7 GPa to 700 MPa and -800 GPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the x-ray diffractometer (XRD) for the verification of above residual stress results by ESPI.

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레이저 간섭계를 이용한 배관 용접부 잔류응력 평가 (Evaluation of Residual Stress on Pipe Welded Joints Using Laser Interferometry)

  • 장호섭;나만균;김경석
    • 비파괴검사학회지
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    • 제34권1호
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    • pp.18-22
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    • 2014
  • 용접 잔류응력은 용접공정에서 발생하는 하는데, 용접 구조물의 결함 유발 및 파괴의 주요 원인이 된다. 본 논문에서는 전자 처리 레이저 스페클 간섭법을 이용하여 원전 배관의 용접부 잔류응력을 측정하였다. 인장시험기를 이용하여 용접된 배관에 압축 하중을 가하였으며, 면내 변형 측정 간섭계를 이용하여 용접부와 모재부의 변형을 측정하였고, 제안된 수식에 의하여 탄성계수를 측정하였다. 용접 배관에 가해지는 하중에 따라 변형이 일정하게 증가하며, 용접 배관의 모재부와 용접부에 발생한 변형을 비교하였을 때, 모재부의 변형이 더 크게 나타남을 확인할 수 있었다. 용접 배관 모재부의 탄성계수는 202.46 GPa, 용접부의 탄성 계수는 212.14 GPa, 잔류응력은 6.29 MPa로 측정되었다.

Phase Map Unwrapping 향상에 관한 연구 (A Study on the Improvement of phase Unwrapping in Discontinuous Fringe Pattern)

  • 조영학;김경석;장호섭;정승택
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 춘계학술대회 논문집
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    • pp.330-333
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    • 2002
  • This study Presents improvement of Precision in the non-contacted laser application measuring techniques. The phase map of deformation obtained by phase shifting method in Electronic Speckle Pattern Interferometry displays the wrapped image by the arctangent function, which is a characteristic of 4-step phase shifting method. To obtain deformation distribution from the results, the wrapped phase map is processed by an unwrapping method. But a previous method cannot apply discontinuous object as like plate with a circular hole to obtain precious deformation distribution To solve this problem, new algorithm is developed and the result is compared with previous method.

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ESPI 법에 의한 복합재 평판의 인장 및 진동 거동에 관한 연구 (A Study under behavior of tensile and vibration in composite plate by ESPI method)

  • 김경석
    • 한국생산제조학회지
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    • 제8권4호
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    • pp.106-111
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    • 1999
  • This study discusses a non-contact optical technique electronic, electronic speckle pattern interferometry(ESPI) that is well suited for in-plane and out-of-plane deformation measurement Used as specimen which has the boundary condition of two clamped parallel edges composite material AS4/PEEK[30/-30/90]s was analyzed by ESPI to determined the characteristics of tensile and vibration. These are quantitativly compared with the result of FEM analysis. Finally the results of this study are briefly summarized as follows : (1) In the in-plane strain analysis by comparison of theoretical results with experimental results qualitatively we confirmed that measurement errors are within 3 % in case of accuracy (2) From comparison of experimental vibration modes with numerical vibration mode shapes by the FEM analysis quantitatively we confirmed that vibration mode measurement by the ESPI has high accuacy.

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ESPI를 이용한 전자제품 패키지 열변형 신뢰성 평가에 관한 연구 (A Study on the Reliability Evaluation of Thermal Deformation of Electronic Product Package by ESPI)

  • 조지현;이재혁;박상영;장중순;김광섭
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제5권4호
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    • pp.439-450
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    • 2005
  • Thermal deformation of Digital Television effect friction noise directly. However there was no methods to find and to solve the thermal friction noise which is huge problem in Digital Television In this study, to figure out occurrence cause of friction noise of the product, we measured thermal deformation of the product to organize a triggering device united with Laser Doppler Vibrometer(LDV) which turned occurrence moment of thermal friction noise into a possibility to measure. In conclusion, we could offer an effective information of design, and ensured ESPI(Electronic Speckle Pattern Interferometry) measure technique which is more detailed than the past way.

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ESPI를 이용한 MEMS용 소재의 열팽창 계수 온도 의존성 평가 (Evaluation of Temperature-dependency of CTE of Materials for MEMS Using ESPI)

  • 김동원;김홍재;이낙규;최태훈;나경환;권동일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1315-1320
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    • 2003
  • The thermal expansion coefficient, which causes the micro failure at the interfacial state of thin films is necessary to consider for proper designing MEMS. The effect of temperature on the coefficient of thermal expansion(CTE) of $SiO_2$ and $Si_3N_4$ film was investigated. Thermal strain induced by mismatch of CTE between substrate and thin film continuously measured with resolution-improved electronic speckle pattern interferometry(ESPI). The thermal stress induced by mismatch of CTE derivate through thermal strain. The thermal expansion coefficients of thin film were calculated with the general equation of CTE and thermal stress in thin films, and it confirmed that CTE of $SiO_2$changed from $0.25{\times}10^{-6}/^{\circ}C$ to $1.4{\times}10^{-6}/^{\circ}C$ with temperature increasing from 50 to $600^{\circ}C$

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시간 평균 ESPI를 이용한 진동 물체의 모우드 형태의 계측 (Measurement of Vibration Mode Shapes Using Time Average ESPI)

  • 강영준;최장섭
    • 한국정밀공학회지
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    • 제13권2호
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    • pp.84-93
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    • 1996
  • Non-destructive inspection techniques using laser have been broading their application areas as well as growing their measurement skills together with the rapid development of circumferential technology like fiber optics, computer and image processing. The ESPI technique is already on the stage of on-line testing with commercial products in developed country nations. Especially, this technique is expected to be applied to the nuclear industry, automobile and aerospace because it is proper for the vibration measurement and it can be applied to objects of a high temperature. This paper describes the use of the ESPI system for measuring vibration patterns on the reflecting objects. Using this system, high-quality Jo fringes for identifying mode shapes are displayed. A bias vibration is introduced into the reference beam to shift the Jo fringes so that fringe shift algorithms can be used to determine vibration amplitude. Using this method, amplitude fields for vibrating objects were obtained directly from the time-average interferograms recorded by the ESPI system.

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