• 제목/요약/키워드: AE Signal

검색결과 498건 처리시간 0.029초

회전기 진단을 위한 무선식 AE 측정장치 개발 (Development of a Wireless Acoustic Emission System for the Monitoring of Rotating Structures)

  • 권오양;김영환;윤동진
    • 비파괴검사학회지
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    • 제11권2호
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    • pp.15-21
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    • 1991
  • A wireless acoustic emission (AE) system has been developed for continuous monitoring of rotating structures such as turbine rotors. The cable between preamplifier and signal processing unit of a conventional AE system was replaced by the frequency modulated telemetry. The detected signals were modulated and transmitted as an RF signals by the transmitting module, then received and demodulated by the receiving module. The distance between the transmitting and the receiving antennas could be separated up to 10cm within a reasonable signal-to-noise ratio. The simulated AE signals generated by pencil lead breaks from rotating structures were successfully detected using the developed wireless AE monitoring system.

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SUS 강판 용접부의 AE 방법에 의한 피로파괴전파 특성에 대한 연구 (A Study on the characteristics of crack propagation in stainless steel wellding zone by AE Method)

  • 신근하;김용수
    • 한국안전학회지
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    • 제6권3호
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    • pp.50-55
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    • 1991
  • It is well known that mechanisms of fracture and crack growth depend upon material characteristics such as fracture toughness, environmental condition, cracd geometry and mechanical properties. It seems to be very important to investihate the effects of the above factors on the behavior of structural components which contain flaws for the detailed evaluation of their intehrity. In this experimental research, fracture behaviors of moterials were investigated by using Acoustic Emission(AE) technique. The fracturing processes of materials were estimated through both the tension specimens. For the detrmlnatlon of yied strength or fracture toughness, the critical applied load at the crack initiation and propagation is thought to be very important. The critical applied load(PQ) was determined through AE signal. The source of AE signal was estimated by fractography analysis. These experimental results may contribute to the safety analyses and the evaluation of strength of structures.

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퍼지 클러스터링을 이용한 금형강에 미세 그루브 가공시 가공상태 모니터링 (Machining condition monitoring for micro-grooving on mold steel using fuzzy clustering method)

  • 이은상;곽철훈;김남훈
    • 한국정밀공학회지
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    • 제20권11호
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    • pp.47-54
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    • 2003
  • Research during the past several years has established the effectiveness of acoustic emission (AE)-based sensing methodologies for machine condition analysis and process. AE has been proposed and evaluated for a variety of sensing tasks as well as for use as a technique for quantitative studies of manufacturing process. STD11 has been known as difficult-to-cut materials. The micro-grooving machine was developed for this study and the experiments were performed using CBN blade for machining STD11. Evaluating the machining conditions, frequency spectrum analysis of acoustic emission (AE) signals according to each conditions were applied. Fuzzy clustering method for associating the preprocessor outputs with the appropriate decisions was followed by frequency spectrum analysis. FFT is used to decompose AE signal into different frequency bands in time domain, the root mean square (RMS) values extracted from the decomposed signal of each frequency band were used as features.

AE(acoustic emission)센서를 이용한 공구파손검출에 관한 연구 (A Study of Tool Breakage Dection Using AE Sensor)

  • 이재종;송준엽;박화영
    • 한국기계연구소 소보
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    • 통권19호
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    • pp.61-68
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    • 1989
  • As the system monitoring technology become required in order to improve the system performance and the productivity, we’ve studied to the detection for the tool wear and the tool breakage using AE sensors that is able to detection of generated high frequency stress pulse at cutting. The detection system is consist of a sensing part, a amplifier part, a signal processing part, and a analysis & output part. The moment (a rms and a kurtosis) of statistical method is used for analysis of AE singnal. The experiment are carried out in a CNC lathe. In this study, we achieved that the amplitude level of the AE signal and statistical moments was largely changed as the tool failure. The change rate of Kurtosis was especially large, but the change rate of the rms was small.

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CFRP 적층 형태에 따른 파괴시 음향방출 신호특성 (AE Signals Characteristics from Fracture by Type of CFRP Stacking Structure)

  • 남기우;문창권
    • 한국해양공학회지
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    • 제16권2호
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    • pp.67-71
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    • 2002
  • Damage process of CFRP laminates was characterized by Acoustic Emission (AE). The main objective of this study is to determine if the sources of AE in CERP laminates could be identified from the characteristics of the waveform signals recorded during monotonic tensile test. The time history and power spectrum of each individual wave signal recorded during test were examined and classified according to their special characteristics. The wave from and frequency of AE signal from a specimens is an aid to the determination of the extent of the different fracture mechanism such as matrix crack, debonding, fiber pull-out and fiber fracture as load is increased. Four distinct types of signals were observed regardless of specimen condition. The result showed that the AE method could be effectively used for analysis of fracture mechanism in CFRP laminates.

지상탱크 저판부의 부식손상 평가를 위한 음향방출 신호의 분석 (Characteristics of Corrosion Damages in Bottom Plate of Above Ground Tank by Acoustic Emission Signal)

  • 김승대;정우광;이종오
    • 한국가스학회지
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    • 제11권4호
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    • pp.64-72
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    • 2007
  • 충수된 지상 탱크 저판부에서 발생하는 AE 신호 특성을 관찰하여 누수 등 손상에 대한 신호를 분석, 평가하였다. EMI 잡음신호를 에너지, 카운트. 지속시간 등과 누적진폭 분포상의 기울기를 비교 분석하여 제거하였다. EMI 신호는 높은 에너지 카운트, 지속시간을 나타내며, 누적 분포상에서 큰 기울기를 갖는 특성을 보였다. 남은 AE 신호의 위치표정과 클러스터 분석을 통해 부식손상의 가능성을 추정할 수 있었으며 총 20개의 클러스터로 에너지는 최대 11,990에서 8,565까지 이벤트는 최대 8에서 5까지 나타났다. 개방에 의한 손상확인을 하지 못했으나 보다 높은 고감도의 센서와 문턱값을 60dB 이상 높여서 평가한 다면 보다 정확한 발생위치 추정이 가능하리라 본다.

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회전기계 결함신호 진단을 위한 신호처리 기술 개발 (Signal Processing Technology for Rotating Machinery Fault Signal Diagnosis)

  • 최병근;안병현;김용휘;이종명;이정훈
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2013년도 추계학술대회 논문집
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    • pp.331-337
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    • 2013
  • Acoustic Emission technique is widely applied to develop the early fault detection system, and the problem about a signal processing method for AE signal is mainly focused on. In the signal processing method, envelope analysis is a useful method to evaluate the bearing problems and Wavelet transform is a powerful method to detect faults occurred on rotating machinery. However, exact method for AE signal is not developed yet. Therefore, in this paper two methods which are Hilbert transform and DET for feature extraction. In addition, we evaluate the classification performance with varying the parameter from 2 to 15 for feature selection DET, 0.01 to 1.0 for the RBF kernel function of SVR, and the proposed algorithm achieved 94% classification accuracy with the parameter of the RBF 0.08, 12 feature selection.

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SHPB 시험과 음향방출법을 이용한 알루미늄 합금의 압축 변형거동 분석 (Analysis of Compressive Deformation Behaviors of Aluminum Alloy Using a Split Hopkinson Pressure Bar Test with an Acoustic Emission Technique)

  • 김종탁;우성충;사공재;김진영;김태원
    • 대한기계학회논문집A
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    • 제37권7호
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    • pp.891-897
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    • 2013
  • 본 논문에서는, 고 변형률 속도에서의 알루미늄 합금의 압축 변형거동을 홉킨슨 압력봉 시험, SHPB 방법을 통해 연구하였다. 이와 함께 음향방출기법이 사용되었고, 웨이브 가이드선을 통해 시편에 연결된 AE 센서를 이용하여 충격 변형시 검출되는 AE 신호를 실시간으로 검출하였다. 검출된 AE 신호를 통해 진폭, 에너지 및 최대 주파수 특성을 분석하였다. 또한 손상 기구에 따른 음향방출신호의 특성을 분석하기 위하여 시험 수행 후 충돌 시험편 표면과 측면을 관찰하였다. 변형률이 높아질수록 AE 진폭과 AE 누적에너지는 증가하였고, AE 최대 주파수는 감소하였다. 각 신호의 특성은 재료의 손상 기구와 밀접한 관련이 있는 것으로 확인되었다.

음향방출법을 이용한 Glass Fiber/PET 복합재료의 손상평가 (Damage Evaluation of Glass Fiber/PET Composite Using Acoustic Emission Method)

  • 김상태;김덕윤
    • Composites Research
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    • 제14권1호
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    • pp.1-7
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    • 2001
  • 본 연구에서는 유리 섬유 강화 열가소성 복합재료의 손상평가를 음향방출법을 이용하여 관찰하였다. 시편은 PET와 유리섬유를 7겹으로 적층시켜 만들었으며 두께는 1.7mm이다. 노치 시험편과 풍격 시험편을 제작하여 단순인장 시험과 부하-제하 시험을 수행하였다. AE 신호의 파라미터와 파괴모드간의 관계를 찾아내기 위해 충격 에너지와 노치비의 함수로 AE신호를 측정하였다. 실험견과 모재의 미소균열과 성장 때문에 저진폭 AE 신호가 나타났고, 중진폭 신호는 섬유와 모재간의 층간분리와 계면분리에 대응됐다. 또한 90dB의 고진폭 영역에서는 유리섬유의 파단과 대응되었다 층간분리와 모재의 균열과 음력집중의 영향 때문에 노치비와 충격 에너지가 증가할수록 인장강도는 감소했다. 손상영역의 비율에 따라 AE 신호는 넓은 영역의 주파수가 나타날 뿐만 아니라 신호도 증가하였다.

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AE기법을 이용한 자기애자의 손상 분석 (Analysis on Damage of Porcelain Insulators Using AE Technique)

  • 최인혁;신구용;임윤석;구자빈;손주암;임대연;오태근;윤영근
    • 한국전기전자재료학회논문지
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    • 제33권3호
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    • pp.231-238
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    • 2020
  • This paper investigates the soundness of porcelain insulators associated with the acoustic emission (AE) technique. The AE technique is a popular non-destructive method that measures and analyzes the burst energy that occurs mainly when a crack occurs in a high-frequency region. Typical AE methods require continuous monitoring with frequent sensor calibration. However, in this study, the AE technique excites a porcelain insulator using only an impact hammer, and it applies a high-pass filter to the signal frequency range measured only in the AE sensor by comparing the AE and the acceleration sensors. Next, the extracted time-domain signal is analyzed for the damage assessment. In normal signals, the duration is about 2ms, the area of the envelope is about 1,000, and the number of counts is about 20. In the damage signal, the duration exceeds 5ms, the area of the envelope is about 2,000, and the number of counts exceeds 40. In addition, various characteristics in the time and frequency domain for normal and damage cases are analyzed using the short-time Fourier transform (STFT). Based on the results of the STFT analysis, the maximum energy of a normal specimen is less than 0.02, while in the case of the damage specimen, it exceeds 0.02. The extracted high-frequency components can present dynamic behavior of crack regions and eigenmodes of the isolated insulator parts, but the presence, size, and distribution of cracks can be predicted indirectly. In this regard, the characteristics of the surface crack region were derived in this study.