• 제목/요약/키워드: acoustic emission parameters

검색결과 158건 처리시간 0.034초

트리잉 열화에 따른 $\phi$-AE 분포특성에 관한 연구 (A Study on $\phi$-AE Distribution Patterns Characteristics due to Treeing Deterioration)

  • 박재준;강태오;김재환
    • 대한전기학회논문지
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    • 제41권9호
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    • pp.1060-1070
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    • 1992
  • In this paper, characteristics of Acoustic Emission in Low Density Polyethylene were studied from tree initiation to breakdown under long-term inhomogeneous alternative electrical field. The voltage levels used were 9, 11 and 14[kV]. Especially, a newly developed automatic measuring system was used to measure time variations of AE average amplitude, AE pulse number, AE pulse distribution patterns due to polarities. The patterns wer specially the variated patterns, when tree propagated. Also, parameters for dielectric breakdown prediction, which were suggested by Okamoto, were calculated. The result was analysed by tree shapes and partial discharge activities in tree due to tree initiation and propagation.

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Comparison of Different Techniques for Measurement of Cold Work in Mild Steel

  • Badgujar, B.P.;Jha, S.K.;Goswami, G.L.
    • 비파괴검사학회지
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    • 제23권6호
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    • pp.616-621
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    • 2003
  • There are various Non-Destructive Evaluation (NDE) techniques used for measurement of residual stresses in material, such as magnetic methods, X-ray diffraction, Ultrasonic velocity measurement etc. The capabilities, applications and limitations of these techniques for evaluation of cold work/plastic deformation were studied and compared. Mild steel plates were subjected to different degree of cold deformation and were analyzed by Magneto-mechanical Acoustic Emission (MAE), Barkhausen Noise (BN) and magnetic properties (hysteresis loop parameters analysis). Further, these specimens were analyzed by X-ray diffraction and ultrasonic velocity measurements. The microhardness measurement and microstructure studies of these cold worked plates were also carried out. The results of all these studies and comparison of different techniques are discussed in this paper.

절삭조건과 AE 신호들과의 관계에 관한 실험적 연구 (Experimental Study on the Relationship between Cutting Conditions and AE Signals)

  • 원종식
    • 한국생산제조학회지
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    • 제7권6호
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    • pp.64-71
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    • 1998
  • This paper investigates the relationship between cutting conditions and Acoustic Emission(AE) signals; $AE_{avg}$, $AE_{rms}$, $AE_{mode}$$AE_{avg}$ and $AE_{rms}$ are increased as the increasing of cutting velocity and depth of cut respectively. The new parameters, derived from $AE_{avg}$ and $AE_{rms}$, which may be used for the in-process detection of tool wear is discussed. It is also known that $AE_{mode}$

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자기추진 로타리 공구를 사용한 절삭에서 천이칩 형성에 관한 연구 - 실험에 의한 증명 (A Study on Transient Chip Formation in Cutting with Self-Propelled Rotary Tools-Experimental Verification)

  • 최기흥;최기상;김정수
    • 대한기계학회논문집
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    • 제17권8호
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    • pp.1910-1920
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    • 1993
  • An experimental study to investigate the unconventional chip formation called triangulation of chip in cutting with a SPRT (self-propelled rotary tool) is performed using acoustic emission (AE) signal analysis. In doing that, a quantitative model of the AE RMS signal in triangulation with a SPRT is first developed. The predicted results from this model show good correlation between the AE RMS signal and the general characteristics of triangular chip formation. Then, effects of various process parameters such as cutting conditions (cutting speed, depth of cut, oblique angle and normal rake angle) and the work material properties on the chip formation in cutting with a SPRT are explored. Special attention is paid to the work material properties which are found to have significant effects on triangulation.

Fault Detection of the Cylindrical Plunge Grinding Process by Using the Parameters of AE Signals

  • Kwak, Jae-Seob;Song, Ji-Bok
    • Journal of Mechanical Science and Technology
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    • 제14권7호
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    • pp.773-781
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    • 2000
  • The focus of this study is the development of a credible fault detection system of the cylindrical plunge grinding process. The acoustic emission (AE) signals generated during machining were analyzed to determine the relationship between grinding-related faults and characteristics of changes in signals. Furthermore, a neural network, which has excellent ability in pattern classification, was applied to the diagnosis system. The neural network was optimized with a momentum coefficient, a learning rate, and a structure of the hidden layer in the iterative learning process. The success rates of fault detection were verified.

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복합신호 검출에 의한 압축기 부품의 상태 진단 (The Abnormal Condition Diagnosis of Compressor Parts using Multi-signal Sensing)

  • 이감규;김전하;강익수;강명창;김정석
    • 한국기계가공학회지
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    • 제3권3호
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    • pp.11-16
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    • 2004
  • In this study, the characteristics of signals such as acoustic emission, vibration amplitude and noise level which are derived from the abnormal condition of compressor are investigated. The normal condition, vane stick sound and roller defect condition are chosen to analyze the signal in each cases. From the feature extraction of each signals, the dominant parameters of each signals which can identify the abnormal condition are suggested.

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연삭가공의 이상상태 진단 기법 (Trouble Diagnostic Method in Grinding Process)

  • 곽재섭
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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    • pp.20-27
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    • 2000
  • A chatter vibration and a workpiece burn are the main phenomena to be monitored in modern grinding processes. This study describes a trouble diagnosis of the cylindrical plunge grinding process using the power and acoustic emission (AE) signals. The raw signals of the power and the AE occurred during the grinding operation were sampled and analyzed to determine the relationship between each fault and change of signals. A neural network that has a high success rate of the fault detection was used. Furthermore, an analysis on the influence of parameters to the chatter vibration and the grinding burn was conducted.

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평면연삭시 AE 신호에 의한 표면거칠기 예측 (An Estimation of Surface Roughness from the AE Signal in Surface Grinding)

  • 송지복;이재경;곽재섭;이종렬
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1996년도 추계학술대회 논문집
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    • pp.115-119
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    • 1996
  • An estimation of surface roughness value is a very important and difficult issue in grinding process. The definition of the D.A.R.F(Dimensionless Average Roughness Factor) has been made including the absolute average and tile standard deviation that are the parameters of the AE(Acoustic Emission) sign. The theoretical equation of the surface roughness applying the D.A.R.F has been derived from the regressive analysis and specified with respect to the availability through the experimental approach on the machine.

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연마가공감시를 위한 AE와 연마파라미터의 관계 (Relation of AE and Polishing Parameters for Polishing Process Monitoring)

  • 김화영;김정욱;윤항묵;안중환;김성렬
    • 한국정밀공학회지
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    • 제22권10호
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    • pp.90-98
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    • 2005
  • A monitoring system is necessary to make the polishing process more reliable in order to ensure the high quality and performance of the final products. Generally, AE (Acoustic Emission) is known to be closely related to the material removal rate (MRR). As the surface becomes rougher, the MRR and AE increase. Therefore, the surface roughness can be indirectly estimated using the AE signal measured during the polishing. In this study, an AE sensor-based monitoring system was fabricated to detect the very small AE signal resulting from the friction between a tool and a workpiece during polishing. The performance of this monitoring system was estimated according to polishing conditions, the relation between the level of the AE RMS and the surface roughness during the polishing was investigated.

음향방출기법을 이용한 순환굵은골재 콘크리트의 타설방향에 따른 철근의 부착메커니즘에 관한 연구 (Study on the Bond Mechanism of the Reinforcing Bars by Casting Direction of Recycled Coarse Aggregate Concrete using Acoustic Emission Method)

  • 전수만;윤현도;유영찬
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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    • pp.245-248
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    • 2006
  • The objective of this study is to take the first step in creating a user-friendly health monitoring system for recycled aggregate concrete structure using acoustic emission(AE). Each specimen was a cube, the edge of which was 150mm. For pull-out tests, a steel rebar, 13mm in diameter, was embedded in the center of each specimen and casting directions(i.e., vertical and horizontal) were considered in this paper. The AE parameters were analyzed for damage levels(i.e. internal cracking stage, pull-out stage) of all specimens. Results from this study show that event, duration versus amplitude of a signal, showed a clear difference for different loading stages depending upon the concrete casting directions.

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