• Title/Summary/Keyword: AE monitoring

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Application of Acoustic Emission Technique for On-Line Monitoring of Quench in Racetrack Superconducting Coil at Cryogenic Environment (음향방출기법을 이용한 극저온 환경하에서 초전도 계자코일의 퀀칭탐지 적용에 관한 연구)

  • Lee, Min-Rae;Gwon, Yeong-Gil;Lee, Jun-Hyeon;Son, Myeong-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4 s.175
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    • pp.858-865
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    • 2000
  • It is well recently recognized that quench is one of the serious problems for the integrity of superconducting magnets, which is mainly attribute to the rapid temperature rising in the magnet due to some extrinsic factors such as conductor motion, crack initiation etc. In order to apply acoustic emission(AE)echnique effectively to monitor and diagnose superconducting magnets, it is essential to identify the sources of acoustic emission. In this paper, an acoustic emission technique has been used to monitor and diagnose quenching phenomenon in racetrack shaped superconducting magnets at cryogenic environment of 4.2K. For these purposes special attention was paid to detect AE signals associated with the quench of superconducting magnets. The characteristics of AE parameters have been analyzed by correlating with quench number, winding tension of superconducting coil and charge rate by transport current. In addition, the source location of quench in superconducting magnet was also discussed on the basis of correlation between magnet voltage and AE energy.

A Study on Acoustic Emission Characteristics through the Cyclic Thermal Test of Thermal Barrier Coating by Plasma Spray Process (플라즈마 용사법에 의한 열차폐 코팅의 열피로에 따른 AE신호 특성 연구)

  • Park J.H.;Lee K.H.;Ye K.H.;Kim S.T.;Jeon C.H.;Kim J.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1349-1352
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    • 2005
  • This paper is to investigate a defect for thermal barrier coating layers by acoustic emission method in 4-point bending test. The two-layer thermal barrier coating is composed of $150\mu{m}\;CoNiCrAlY\;bond\;coating\;by\;vacuum\;plasma\;spray(VPS)\;process\;and\;250\mu{m}\;ZrO_2-8wt%Y_2O_3$ ceramic coating layer by air plasma spray(APS) process on Inconel-718. The specimen prepared by cyclic thermal test(500, 1000, 2000cycle) at $1050^{\circ}C$ The AE monitoring system is composed of PICO type sensor, a wide band pre-amplifier(40dB), PC and AE DSP(16/32 PAC) board. The AE event, amplitude, Cumulative energy and count of coating specimens is evaluated according to cyclic thermal test.

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Acoustic Emission Source Location and Material Characterization Evaluation of Fiberboards (목재 섬유판의 음향방출 위치표정과 재료 특성 평가)

  • Ro Sing-Nam;Park Ik-Keum;Sen Seong-Won;Kim Yong-Kwon
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.3
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    • pp.96-102
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    • 2005
  • Acoustic Emission(AE) technique has been applied to not only material characterization evaluation but also on-line monitoring of the structural integrity. The AE source location technique is very important to identify the source, such as crack, leak detection. Since the AE waveforms obtained from sensors are very difficult to distinguish the defect signals, therefore, it is necessary to consider the signal analysis of the transient wave-form. In this study, we have divided the region of interest into a set finite elements, and calculated the arrival time differences between sensors by using the velocities at every degree from 0 to 90. A new technique for the source location of acoustic emission in fiberboard plates has been studied by introducing Wavelet Transform(WT) do-noising technique. WT is a powerful tool for processing transient signals with temporally varying spectra. If the WT de-noising was employed, we could successfully filter out the errors of source location in fiberboard plates by arrival time difference method. The accuracy of source location appeared to be significantly improved.

Experimental study on acoustic emission characteristics of reinforced concrete components

  • Gu, Aijun;Luo, Ying;Xu, Baiqiang
    • Smart Structures and Systems
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    • v.16 no.1
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    • pp.67-79
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    • 2015
  • Acoustic emission analysis is an effective technique for monitoring the evolution of damage in a structure. An experimental analysis on a set of reinforced concrete beams under flexural loading was carried out. A mixed AE analysis method which used both parameter-based and signal-based techniques was presented to characterize and identify different failure mechanisms of damage, where the signal-based analysis was performed by using the Hilbert-Huang transform. The maximum instantaneous energy of typical damage events and the corresponding frequency characteristics were established, which provided a quantitative assessment of reinforced concrete beam using AE technique. In the bending tests, a "pitch-catch" system was mounted on a steel bar to assess bonding state of the steel bar in concrete. To better understand the AE behavior of bond-slip damage between steel bar and concrete, a special bond-slip test called pullout test was also performed. The results provided the basis of quantitative AE to identify both failure mechanisms and level of damages of civil engineering structures.

A Study on the Detection of the Drilled Hole State In Drilling (드릴 가공된 구멍의 상태 검출에 관한 연구)

  • 신형곤;김태영
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.3
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    • pp.8-16
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    • 2003
  • Monitoring of the drill wear :md hole quality change is conducted during the drilling process. Cutting force measured by tool dynamometer is a evident feature estimating abnormal state of drilling. One major difficulty in using tool dynamometer is that the work-piece must be mounted on the dynamometer, and thus the machining process is disturbed and discontinuous. Acoustic transducer do not disturb the normal machining process and provide a relatively easy way to monitor a machining process for industrial application. for this advantage, AE signal is used to estimate the abnormal fate. In this study vision system is used to detect flank wear tendency and hole quality, there are many formal factors in hole quality decision circularity, cylindricity, straightness, and so of but these are difficult to measure in on-line monitoring. The movement of hole center and increasement of hole diameter is presented to determine hole quality. As the results of this experiment AE RMS signal and measurements by vision system are shorn the similar tendency as abnormal state of drilling.

A Study on The On-line Detection of the Abnormal State in Drilling. (드릴링시 가공이상상태의 온라인 검출에 관한 연구)

  • 신형곤;박문수;김민호;김태영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.1038-1042
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    • 2002
  • Monitoring of the drill wear and hole quality change is conducted during the drilling process. Cutting force measured by tool dynamometer is a evident feature estimating abnormal state of drilling. One major difficulty in using tool dynamometer is that the work piece must be mounted on the dynamometer, and thus the machining process is disturbed and discontinuous. Acoustic transducer do not disturb the normal machining process, and provide a relatively easy way to monitor a machining process for industrial application. For this advantage, AE signal is used to estimate the abnormal state. In this study vision system is used to detect flank wear tendency and hole quality, there are many formal factors in hole quality decision circularity, cylindricity, straightness, and so on, but these are difficult to measure in on-line monitoring. The movement of hole center and increasement of hole diameter is presented to determine hole quality As the results of this experiment, AE RMS signal and measurements by vision system are shown the similar tendency as abnormal state of drilling. And detection of the abnormal states using BPNs was achieved 96.4% reliability.

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A Study on the Detection of the Abnormal Tool State for Neural Network in Drilling (신경망에 의한 공구 이상상태 검출에 관한 연구)

  • Shin, Hyung-Gon;Kim, Tae-Young
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.821-826
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    • 2001
  • Out of all metal-cutting processes, the hole-making process is the most widely used. It is estimated to be more than 30% of the total metal-cutting process. It is therefore desirable to monitor and detect drill wear during the hole-drilling process. One important aspect in controlling the drilling process is monitoring drill wear status. Accordingly, this paper deals with Basic system and Online system. Basic system comprised of spindle rotational speed, feed rates, thrust, torque and flank wear measured tool microscope. Online system comprised of spindle rotational speed, feed rates, AE signal, flank wear area measured computer vision. On-line monitoring system does not need to stop the process to inspect drill wear. Backpropagation neural networks (BPNs) were used for on-line detection of drill wear. This paper deals with an on-line drill wear monitoring system to fit the detection of the abnormal tool state.

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