• Title/Summary/Keyword: ESPI(Electronic speckle pattern interferometry)

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Vibration measurement with stroboscopic ESPI (스트로보스코픽 ESPI를 이용한 진동측정)

  • Ung, Gang-Jeon;Yeong, Yun-Hae;Jun, Jeong-Seung;Gi, Hong-Jeong
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.02a
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    • pp.20-21
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    • 2003
  • Electronic speckle pattern interferometry has many applications in science and engineering. Among these, vibration measurement is the area where ESPI has many advantages over other techniques. We developed a stroboscopic ESPI system to measure the harmonic vibration of a piece of copper tape attached to a circular hole structure. Figure 1 shows the schematic diagram of the stroboscopic ESPI system. (omitted)

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Residual Stress Measurement of Flat Welded Specimen by Electronic Speckle Pattern Interferometry (전자처리스페클패턴 간섭법을 이용한 평판 용접시험편의 잔류응력 측정)

  • Chang, Ho-Seob;Kim, Dong-Soo;Jung, Hyun-Chul;Kim, Kyung-Suk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.32 no.2
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    • pp.149-154
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    • 2012
  • The size and distribution of welding residual stress and welding deformation in welding structures have an effect on various sorts of damage like brittle failure, fatigue failure and stress corrosion cracking. So, research for this problem is necessary continuously. In this study, non-destructive technique using laser electronic speckle pattern interferometry, plate of welding specimen according to the external load on the entire behavior of residual stress are presented measurement techniques. Once, welding specimen force tensile loading, using electronic speckle pattern interferometry is measured. welding specimen of base metal and weld zone measure strain from measured result, this using measure elastic modulus. In this study, electronic speckle pattern interferometry use weld zone and base metal parts of the strain differences using were presented in residual stress calculated value, This residual stress value were calculated by numerical calculation. Consequently, weld zone of modulus high approximately 3.7 fold beside base metal and this measured approximately 8.46 MPa.

Measurement of Out-of-plane Displacement in a Spot Welded Canti-levered Plate using Laser Speckle Interferometry with 4-step Phase Shifting Technique (레이저스펙클 간섭법과 4단계 위상이동법에 의한 외팔보점용접부의 면외 변위측정)

  • 백태현;김명수;차병석;조성호
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.226-230
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    • 2001
  • Electronic Speckle Pattern Interferometry (ESPI) has been recently developed and widely used because it has advantage to be able to measure surface deformations of engineering components and materials in industrial areas with non-contact. The spekle patterns to be formed with interference phenomena of scattering phenomena measure the out-of-plane deformations, together with the use of digital image equipment to process the informations included in the speckle patterns and the display consequent interferogram on a computer monitor. In this study, the experimental results of a canti-levered plate using ESPI were compared with those obtained from the simple beam theory. The ESPI results of the canti-levered plate analyzed by 4-step phase shifting method are close to the theoretical expectation. Also, out-0of-plane displacements of a spot welded canti-levered plate were measured by ESPI with 4-step phase shifting technique. The phase map of the spot welded canti-levered plate is quite different from that of the canti-levered plate without spot welding.

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Development of ESPI System Using a Modulating LASER (모듈레이팅 레이저를 이용한 ESPI 시스템 개발)

  • Lee, Kun-Young;Kang, Young-June;Park, Nak-Kyu;Lee, Dong-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.3
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    • pp.93-100
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    • 2008
  • Laser interferometry is widely used as a measuring system in many fields because of its high resolution and ability to measure a broad area in real-time all at once. In conventional LASER interferometry, for example Out-of-plane ESPI(Electronic Speckle Pattern Interferometry), In plane ESPI, Shearography and Holography, it uses PZT or other components as a phase shift instrumentation to extract 3D deformation data, vibration mode and others. However, in most cases PZT has some disadvantages, which include nonlinear errors and limited time of use. In the present study, a new type of LASER interferometry using a laser diode is proposed. Using LASER Diode Sinusoidal Phase Modulating (LD-SPM) interferometry, the phase modulation can be directly modulated by controlling the LASER Diode injection current thereby eliminating the need for PZT and its components. This makes the interferometry more compact. This paper reports on a new approach to the LD Modulating interferometry that involves four-buckets phase shift method. This study proposes a four-bucket phase mapping algorithm, which was developed to have a guaranteed application, to stabilize the system in the field and to be a user-friendly GUI. In this paper, the theory for LD wavelength modulation and sinusoidal phase modulation of LD modulating interferometry is shown. Four-bucket phase mapping algorithm is then introduced.

Evaluation of Young's Modulus of a Cantilever Beam by TA-ESPI (TA-ESPI에 의한 외팔보의 탄성계수 측정)

  • Lee H.S.;Kim K.S.;Kang K.S.;Jung H.C.;Yang S.P.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1115-1119
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    • 2005
  • The paper proposes the elastic modulus evaluation technique of a cantilever beam by vibration analysis based on time-average electronic speckle pattern interferometry (TA-ESPI) with non-contact and nondestructive and Euler-Bernoulli equation. General approaches for the measurement of elastic modulus of thin film are Nano indentation test, Bulge test and Micro-tensile test and so on. They each have strength and weakness in the preparation of test specimen and the analysis of experimental result. ESPI has been developed as a common measurement method for vibration mode visualization and surface displacement. Whole-field vibration mode shape (surface displacement distribution) at a resonance frequency can be visualized by ESPI. And the maximum surface displacement distribution from ESPI is a clue to find the resonance frequency at each vibration mode shape. And the elastic modules of test material can be easily estimated from the measured resonance frequency and Euler-Bernoulli equation. The TA-ESPI vibration analysis technique is able to give the elastic modulus of materials through the simple processing of preparation and analysis.

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Measurement of Tensile Properties of Copper Foil using Micro-ESPI Technique (마이크로 ESPI기법을 이용한 동 박막의 인장 특성 측정)

  • 김동일;허용학;기창두
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.8
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    • pp.89-96
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    • 2004
  • Micro-tensile testing system, consisting of a micro tensile loading system and micro-ESPI(Electronic Speckle Pattern Interferometry) system, has been developed for measurement of micro-tensile properties of thin micro-materials. Micro-tensile loading system had a load cell with the maximum capacity of 50N and micro actuator with resolution of 4.5nm in stroke. The system was used to apply a tensile load to the micro-sized specimen. During tensile loading, the micro-ESPI system acquired interferornetric speckle patterns in the deformed specimen and measured the in-plane tensile strain. The ESPI system consisted of a CCD-camera with a lens and the window-based program developed for this experiment. Using this system, stress-strain curves for 4 kinds of electrolytic copper foil 18$\square$m thick were obtained. From these curves, tensile properties, including the elastic modulus. yielding strength and tensile strength, were determined and also values of the plastic exponent and coefficient based on Ramberg-Osgood relationship were evaluated.

Deformation Characteristics Analysis of 3-Unit Fixed Partial Dentures by Using Electronic Speckle Pattern Interferometry (전자처리 스페클 패턴 간섭법(ESPI)을 이용한 3-유닛 고정성 국소의치의 변형특성 분석)

  • Kang, Hoo-Won;Lee, Chul-Min;Yang, Seung-Pil;Kim, Hee-Jin
    • Journal of Technologic Dentistry
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    • v.35 no.1
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    • pp.49-56
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    • 2013
  • Purpose: The deformation characteristics induced by non-destructive stresses using piezoelectric transducer(PZT) were analyzed for 3-unit fixed partial dentures manufactured PFM, Everest(CAD/CAM) and Zirkonzahn(copy milling, MAD/MAM) by electron speckle pattern interferometery(ESPI). Methods: The ESPI analysis after loading the restoration with PZT by applying electric voltage of 900mV at the points of 10 mm above the base of the prostheses. Results: PFM and All-Ceramic Everest prostheses showed about 0.1 ${\mu}m$ while that of All- Ceramic Zirkonzahn prostheses showed 0.085 ${\mu}m$, demonstrating that Zirkonzahn displaced less. For PFM and All-Ceramic Zirkonzahn prostheses, the displacements were large at just below the loading point, while generalize displacement was shown over the loading point and weak connector areas for All-Ceramic Everest prostheses. Conclusion: We could find that the deformation characteristics induced by non-destructive stresses using PZT analyzed by ESPI were similar to the fracture strengths evaluated using universal testing machine.

A study on the measurement of two-dimensional in-plane displacements of the plate with a circular hole by ESPI method (ESPI에 의한 원공판의 2차원 면내변위 측정에 관한 연구)

  • Kim, Kyoung Suk;Choi, Hyoung Chol;Yang, Seung Pil;Kim, Hyoung Soo;Hong, M.S.;Jung, W.K.
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.5
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    • pp.161-170
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    • 1994
  • This paper presents the performance and problems in analysis method and testing system of Electronic Speckle Pattern Interfermetry(ESPI) method, in measuring two-dimensional in- plane displacement. The analysis result of measurement by ESPI is quite comparable to that of measurement by strain gauge method. This implieds that the method of ESPI is a very effective tool in non-contact two-dimensional in-plane strain analysis. But there is a controversial point, measurement error. This error is discussed to be affected not by ESPI method itself, but by its analysis scheme of the interference fringe, where the first-order interpolation has been applied to the points of strain measured. Further development of advanced first-order interpolation method is being undertaken for the more precise in-plane strain measurement.

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Measurement of Dynamic Elastic Modulus of Foil Material by ESPI and Sonic Resonance Testing (ESPI와 음향공진법을 이용한 Foil 재료의 동적탄성계수 측정)

  • Lee H.S.;Kim K.S.;Kang K.S.;Ahmad Akhlaq
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.914-917
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    • 2005
  • The paper proposes a new sonic resonance test for a dynamic elastic constant measurement which is based on time-average electronic speckle pattern interferometry(TA-ESPI)and Euler-Bernoulli equation. Previous measurement technique of dynamic elastic constant has the limitation of application for thin film or polymer material because contact to specimen affects the result. TA-ESPI has been developed as a non-contact optical measurement technique which can visualize resonance vibration mode shapes with whole-field. The maximum vibration amplitude at each vibration mode shape is a clue to find the resonance frequencies. The dynamic elastic constant of test material can be easily estimated from Euler-Bernoulli equation using the measured resonance frequencies. The TA-ESPI dynamic elastic constant measurement technique is able to give high accurate elastic modulus of materials through a simple experiment and analysis.

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