• 제목/요약/키워드: NDT (Non-destructive Testing)

검색결과 91건 처리시간 0.029초

Non-destructive evaluation of concrete quality using PZT transducers

  • Tawie, R.;Lee, H.K.;Park, S.H.
    • Smart Structures and Systems
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    • 제6권7호
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    • pp.851-866
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    • 2010
  • This paper presents a new concept of using PZT (lead zircornate titanate) transducers as a non-destructive testing (NDT) tool for evaluating quality of concrete. Detection of defects in concrete is very important in order to check the integrity of concrete structures. The electro-mechanical impedance (EMI) response of PZT transducers bonded onto a concrete specimen can be used for evaluating local condition of the specimen. Measurements are carried out by electrically exciting the bonded PZT transducers at high frequency range and taking response measurements of the transducers. In this study, the compression test results showed that concrete specimens without sufficient compaction are likely to fall below the desired strength. In addition, the strength of concrete was greatly reduced as the voids in concrete were increased. It was found that the root mean square deviation (RMSD) values yielded between the EMI signatures for concrete specimens in dry and saturated states showed good agreement with the specimens' compressive strength and permeable voids. A quality metric was introduced for predicting the quality of concrete based on the dry-saturated state of concrete specimens. The simplicity of the method and the current development towards low cost and portable impedance measuring system, offer an advantage over other NDE methods for evaluating concrete quality.

목조 건축물의 비파괴 검사를 위한 표면하부 탐사 레이더의 적용 가능성 검토 : FDTD 모의계산과 실험 측정 (A Feasibility Study on a Subsurface-Penetrating Radar for Nondestructive Testing of Wooden Architectures : FDTD Simulation and Laboratory Measurement)

  • 현승엽;김세윤
    • 한국전자파학회논문지
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    • 제13권8호
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    • pp.790-796
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    • 2002
  • 우리나라에는 역사적으로 아름답고 소중한 목조 건축물들이 문화재로 보존되고 있다. 그러나 목조 건축물들은 오랜 세월동안 풍화작용, 병충해 등과 같은 거친 환경조건에 노출되어 있다. 이러한 원인으로 인하여 건축물에 구조적 결함을 야기하기도 한다. 따라서 사전에 목조 건축물을 진단할 수 있는 방법이 필요하다. 본 논문에서는 목조 건축물의 비파괴 검사에 표면하부 탐사 레이더의 적용 가능성을 3차원 유한차분 시간영역 모의계산과 실제 측정을 통하여 조사하였다.

자기 누설 비파괴 탐상 시스템에서 PIG의 주행속도가 검출신호에 미치는 영향 (Effects of the PIG Draft Velocity on the Defect Signals in MFL NDT System)

  • 박상호;박관수
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제52권10호
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    • pp.475-483
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    • 2003
  • In this paper, dynamic characteristics of the magnetic flux leakage(MFL) type non-destructive testing(NDT) are analyzed. Effects of a sensor speed in MFL PIG system and remanent magnetization of the gas pipeline are analyzed by using 3 dimensional nonlinear finite element analysis including eddy current and hysteresis characteristics. Results show that the speed of the sensor reduces the magnitude of the sensing signals where as the hysteresis of the pipeline distorts the sensing signals.

홀로그래픽 간섭법을 이용한 미소변형 측정법 (The Measurment Method of Small Deformation by using Holographic Interferometry)

  • 강영준;문상준
    • 한국정밀공학회지
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    • 제12권9호
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    • pp.52-58
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    • 1995
  • Conventional measurement methods for non-destructive testing(NDT) in nuclear power plants and other industrial plants have been performed as the methods of contact with objects to be inspect, but those methods have been taken relatively much time to be inspected. Holographic interferometry which is a non-contact optical measurement method using a coherent light can overcome these demerit, and also has an advantage that the quantitative measurement of small deformation for large areas can be accomplished at a time with high precision. In this paper the comparisons of the experimental results form holographic interferometry with those from the finite element method(FEM) and the analytical solutions of the elastic equation are discussed.

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Theoretical Consideration of Nondestructive Testing by use of Vertical Magnetization and Magneto-Optical Sensor

  • Lee, Jinyi;Tetsuo Shoji;Dowon Seo
    • Journal of Mechanical Science and Technology
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    • 제18권4호
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    • pp.640-648
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    • 2004
  • This paper describes a new magnetization method for non-destructive testing with magneto-optical sensor (denoted as MO sensor) which have the following characteristic : high observation sensitivity, independence of the crack orientation, and precise imaging of a complex crack geometry such as multiple cracks. When a magnetic field is applied normally to the surface of a specimen which is significantly larger than its defects, approximately the same magnetic charge per unit area occurs on the surface of the specimen. If there is a crack in the specimen, magnetic charge per unit area has the same value at the bottom of the crack. The distribution of the vertical component of the magnetic flux density, B$\_$Z/, is almost uniform over the no-crack area (denoted as B$\_$Z,BASE/), while the magnetic flux density is smaller in the surroundings of the crack(denoted as B$\_$Z,CRACK/) If B$\_$Z, BASE/ is a bit larger than the saturated magnetic flux density of the MO sensor (B$\_$s/) , then small magnetic domains occur over the crack area and a large domain over the non-crack area because B$\_$Z,CRACK/ is smaller than B$\_$s/.

Determination of concrete quality with destructive and non-destructive methods

  • Kibar, Hakan;Ozturk, Turgut
    • Computers and Concrete
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    • 제15권3호
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    • pp.473-484
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    • 2015
  • In this study, the availability of Schmidt hammer has been investigated as a reliable method to determine the quality of concrete in irrigation networks. For this purpose, the 28-day compressive strength of concrete material used in the construction irrigation channel of Bafra lowland, which is one of the most fertile plains in Turkey was examined by means of concrete compression and as well as concrete Schmidt hammer in laboratory conditions. This study was carried out on cylindrical samples to represent the everyday concrete party ($150m^3$) produced by contractor firm as 3 replications. The statistical analysis of experimental data showed that the correlations between the values of 28-day compressive strength of Schmidt hammer and the rebound number was found to be 0.98. Differences of the compressive strength between compression testing and Schmidt hammer were statistically significant at P<0.01. In this context, it was found that the reliability of compressive strength of the concrete compression test are excellent, also the reliability of compressive strength of Schmidt hammer are fair in assessing the quality of concrete irrigation channels.

누설자속센서를 탑재시킨 이동로봇을 이용한 사장교 케이블 비파괴검사 시스템의 현장 적용 (Field Application of a Cable NDT System for Cable-Stayed Bridge Using MFL Sensors Integrated Climbing Robot)

  • 김주원;최준성;이은찬;박승희
    • 비파괴검사학회지
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    • 제34권1호
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    • pp.60-67
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    • 2014
  • 본 연구에서는 사장교의 핵심부재인 케이블 점검을 위한 자동화 검사 시스템을 개발하였다. 강자성체로 이뤄진 연속체 구조물인 케이블의 내외부 검사에 적합한 비파괴검사법으로는 선행연구를 통해 검증된 누설자속탐상법이 적용되었고, 홀센서와 영구자석을 이용하여 다채널의 누설자속 측정용 자기센서헤드를 제작하였다. 또한 케이블 검사의 자동화로 접근성을 높이기 위해 사장교 케이블을 따라 이동할 수 있는 바퀴굴림 방식의 케이블 등반 로봇을 설계 및 제작하였고, 로봇을 다양한 디바이스에서 모니터링 및 제어하기 위한 컨트롤 프로그램을 제작하였다. WLAN 방식의 무선통신기술을 적용하여 원격으로 계측 데이터 전송 및 로봇제어를 가능하게 하였다. 최종적으로 본 연구를 통해 개발된 세부 기술들이 연동된 누설자속탐상법 기반 케이블 이동형 진단 시스템을 이용하여 실제 운용중인 서해대교의 케이블을 대상으로 현장 시험을 수행함으로써 본 시스템의 현장 적용성을 검증해보았다.

마모 단계의 볼 베어링에 대한 적외선 열화상 비파괴 결함 진단 연구 (Study on NDT Fault Diagnosis of the Ball Bearing under Stage of Abrasion by Infrared Thermography)

  • 서진주;홍동표;김원태
    • 비파괴검사학회지
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    • 제32권1호
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    • pp.7-11
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    • 2012
  • 기존 진단법과 달리 동적 하중조건하 회전체의 마모 단계에 따른 결함 진단을 위해 비접촉, 비파괴의 적외선 열화상 기법이 제안된다. 본 연구에서는 시험시편인 단열 깊은 홈의 볼 베어링을 설정하여 기존의 스펙트럼 분석과 같은 고장탐지법에 대한 대안으로써 수동형 열화상시험이 수행되었다. 본 연구로부터, 적외선 열화상시험은 신뢰성을 평가하기 위해 기존 진동 스펙트럼 분석시험과 비교, 분석되었다. 연구의 비파괴시험의 결과로써, 마모 단계에 따른 볼 베어링의 온도 특성이 분석되었다.

An Experimental Study on Evaluation of Compressive Strength in Cement Mortar Using Averaged Electromagnetic Properties

  • Kwon, Seung-Jun;Maria, Q. Feng;Park, Tae-Won;Na, Ung-Jin
    • International Journal of Concrete Structures and Materials
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    • 제3권1호
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    • pp.25-32
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    • 2009
  • A non-destructive testing (NDT) method for evaluating physical properties of concrete including the compressive strength is highly desirable. This paper presents such an NDT method based on measurement of electromagnetic (EM) properties of the material. Experiments are carried out on cement mortar with different water/cement (W/C) ratios. Their EM properties including the conductivity and the dielectric constant are measured at different exposure conditions and curing periods over a wide frequency range of the EM wave. The compressive strength of these specimens is also tested. It is found that both the conductivity and the dielectric constant increase as the W/C ratio decreases and the curing period increases, which lead strength development in the specimens. A linear correlation is observed between the averaged EM properties over the 5 to 20 GHz frequency range and the measured compressive strength, demonstrating the effectiveness of the EM property-based NDT method in evaluating strength of OPC mortar.

DEFECT EVALUATION IN RAILWAY WHEELSETS

  • Kwon, Seok-Jin;Lee, Dong-Hyong;Seo, Jung-Won;You, Won-Hee
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2007년도 추계학술대회 논문집
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    • pp.1940-1945
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    • 2007
  • The wheelsets are one of most important component: damages in wheel tread and press fitted axle are a significant cost for railway industry. Since failure in railway wheelset can cause a disaster, regular inspection of defects in wheels and axles are mandatory. Ultrasonic testing, acoustic emission and eddy current testing method and so on regularly check railway wheelset in service. However, it is difficult to use this method because of its high viscosity and because its sensitivity is affected by temperature. Also, due to noise echoes it is difficult to detect defects initiation clearly with ultrasonic testing. It is necessary to develop a non-destructive technique that is superior to conventional NDT techniques in order to ensure the safety of railway wheelset. In the present paper, the new NDT technique is applied to the detection of surface defects for railway wheelset. To detect the defects for railway wheelset, the sensor for defect detection is optimized and the tests are carried out with respect to surface and internal defects each other. The results show that the surface crack depth of 1.5 mm in press fitted axle and internal crack in wheel could be detected by using the new method. The ICFPD method is useful to detect the defect that initiated in the tread of railway wheelset.

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