• Title/Summary/Keyword: AE Signal

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A study on the improvement of polishing surface using Oscillation-type tool and AE sensor (요동형 공구와 AE센서를 이용한 연마면 향상에 관한 연구)

  • 김정욱;김성렬;안중환
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1682-1687
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    • 2003
  • Die polishing technology is very critical to determine quality and performance of the final products. Generally, the rotation-type tool is used most widely in the polishing process. However it is difficult to make the mirror surface, because the method using the rotation-type tool causes a lot of tiny scratch on the polished surface. This paper proposes a new method using the oscillation-type tool that reduces the scratch and improves the surface roughness. As result. the mirror surface was able to obtain by using the oscillation-type tool. AE is known to be closely related to material removal rate(MRR). As the surface is rougher, MRR gets larger and AE increase. The surface roughness can be indirectly estimated using the AE signal measured during automatic die polishing process. In this study. an AE sensor based monitoring system was developed to investigate the relation the level of AE RMS with the surface roughness during polishing process.

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On-Line Monitoring of Microscopic Fracture Behavior of Concrete Using Acoustic Emission (음향방출을 이용한 콘크리트 부재의 미시적 파괴특성의 온라인 모니터링)

  • Lee, Joon-Hyun;Lee, Jin-Kyung;Yoon, Dong-Jin
    • Journal of the Korean Society for Nondestructive Testing
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    • v.19 no.1
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    • pp.25-33
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    • 1999
  • Since concrete is an inhomogeneous material consisting of larger aggregates and sand embedded in a cement paste matrix, it relatively shows a complex failure mechanism. In order to assure the reliability of concrete structure. microscopic fracture behavior and internal damage progress of concrete under the loading should be fully understood. In this study, an acoustic emission(AE) technique has been used to clarify microscopic failure mechanism and their corresponding AE signal characteristics of concrete under three-point bending test. In addition 2-dimensional AE source location has been performed to monitor the progress of an internal damage and the successive crack growth behavior during the loading. The relationship between AE signal characteristics and microscopic fracture mechanism is discussed.

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Evaluation of SHCC on Direct Tensile Load using Acoustic Emission Technique (음향방출기법을 이용한 혼입되는 섬유의 종류에 따른 SHCC의 직접인장거동특성 평가)

  • Kim, Yun-Su;Yun, Hyun-Do;Jeon, Esther;Park, Wan-Shin
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.177-180
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    • 2008
  • SHCC shows the high energy tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For effective material design and application of SHCC, it is needed to investigate the damage process and micro-fracture mechanism of cement matrix reinforced with different types of fibers. The objective of this paper is to investigate the direct tensile response of cement composites reinforced with single and hybrid fibers using acoustic emission(AE) technique. In this study, the correlations between AE signal and result of the direct tensile response of SHCC. For these purposes, three kinds of fibers were used: PET1.5%, PET1.0+PE0.5%, PET1.0%+PVA0.5%. The result of the direct tensile response of SHCC, for the same volume fraction of fibers, ultimate strength of PET-PE specimen was 2.7 times higher than specimens with PET fibers. And from AE signal value, AE event numbers and cumulative energy were different according to kind of fiber because of the different material properties of reinforced fiber.

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A Study of the Development of PC-Based Source Location System using Acoustic Emission Technique (음향방출기법을 이용한 PC기반 위치표정시스템 개발에 관한 연구)

  • Lee, M.R.;Lee, J.H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.3
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    • pp.205-211
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    • 2003
  • Acoustic emission (AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the el)tire structure or a limit zone only. Although several AE devices have already been developed for the on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, wc developed a specially designed PC-based source location system using the A/D board. The source location technique is very important to identify the source, such as crack, leak detection. However, since the AE waveforms obtained from transducers are very difficult to distinguish the defect signals, therefore, it is necessary to consider the signal analyses of the transient waveform. Wavelet Transform (WT) is a powerful tool for processing transient signals with temporally varying spectra that helps to resolve high and low frequency transients components effectively In this study, the analyses of the AE signals are presented by employing the WT analyses. AE results are compared the PC-based source location system using A/D board with the commercial AE system.

Determination of acoustic emission signal attenuation coefficient of concrete according to dry, saturation, and temperature condition (포화유무 및 온도조건에 따른 콘크리트 음향방출 신호 감쇠계수 결정)

  • Lee, Hang-Lo;Hong, Chang-Ho;Kim, Jin-Seop;Kim, Ji-Won
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.24 no.1
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    • pp.39-55
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    • 2022
  • This study carried out the laboratory tests for AE signal attenuation to determine the attenuation coefficient (α) of silo concrete in Gyeongju low and intermediate-level disposal environments. The concrete samples were prepared by satisfying the concrete mixing ratio used in the Gyeongju disposal silo, and these samples were additionally exposed depending on the temperature conditions and saturation and, dry condition. As a result of attenuation tests according to the transmission distance on three concrete specimens for each disposal condition, the AE amplitude and absolute energy measured on the saturated concrete were higher than that of the dry concrete in the initial range of the signal transmission distance, but the α of the saturated concrete was higher than that of the dry concrete. Regardless of the saturation and dry conditions, the α tended to decrease as the temperature increases. The α had a more major influence on the saturation and dry condition than the temperature condition, which means that the saturation and dry condition is the main consideration in measuring the signal attenuation of a concrete disposal structure. The α of concrete in the disposal environment expect to be used to predict the integrity of silos concrete in Gyeongju low and intermediate-level disposal environments by estimating the actual AE parameter values at the location of cracks and to determine the optimum location of sensors.

A Study on the Wear of Milling Tool and Relativity of Acoustic Emission in Cutting Process (절삭중 밀링공구의 마멸과 음향방출의 관련성에 관한 연구)

  • 윤종학;김동성
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.4 no.2
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    • pp.31-37
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    • 1995
  • This study is focused on the prediction of appropriate tool life by clarifying the correlation between progressive tool wear and AE signal. when rcutting SM45C by End mill in machining center. First of all, end mill have a problem that position of sensor sticking because it is revolution tool, but I think that it can be bained specific character according to sticking Sensor in the Vise. Consequently, the following results have been obtained; 1. Each cutting speed of feed rate over 0.1mm had a tendency to increase linearly according to the RMSAE 2. The level of AE signal at the same cutting area was more sensitive to depth of cut tharn the variation of feed rate 3. In the range of cutting duringqr about 75minqr atqr cutting speed 27m/min flankqr wear turns up aboutqr 0.21mm, aboutqr 0.29mm in the caseqr of about 65minqr at 33/min, qr hereby RMSAE increased rapidly at 0.2mm flank wear, also AE-HIT and CUM-CNTS.

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A Study on Machining Characteristics of Single-insert and Multi-insert Face Milling (단인과 다인 정면밀리의 가공특성에 관한 연구)

  • Kim, S.I.;Lee, W.R.;Kim, T.Y.
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.4
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    • pp.19-27
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    • 1995
  • Face milling is required to study cutting process with a view of multipoint cutter. This experimental study mainly deals with the single and multi-insert cutting characteristics using coated tool. Because metal cutting of the single and multi-insert has a large relation to the improvement of productivity, the economic cutting process can be achieved by the analysis of proper metal cutting mechanism. Therefore, machining characteristics of face molling in this paper has been studied by investigating the role of different insert number which is concerned with mean cutting force, the RMS values of AE(acoustic emission) signal, tool life and surface roughness in milling SS 41 and SUS 304. The cutting force and AE signal are monitored to make an analysis of cutting process. The surface roughness of the specimens machined by inserts of different numbers is measured at different speeds, feeds and depth of cut. The width of flank wear is also observed.

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Femto Slider Head/Disk Interaction Detection by Acoustic Emission and Natural Frequency Analysis

  • Hwang, Pyung;Galina Pan;Xuan Wu
    • KSTLE International Journal
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    • v.6 no.1
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    • pp.17-20
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    • 2005
  • The object of the present work is the natural lre%uency analysis of femto slider, HeaHdisk interaction during starustop and constant speed were detected by using the acoustic emission (AE) test system. The frequency spectrum analysis wasperformed using the AE signal obtained during the head/disk interaction. The FFT (Fast Fourier Transform) analysis of the AEsignals is used to understand the interaction between the AE signal and the state of contact. Natural frequency analysis wasperformed using the ANSYS program. The results indicate acceptable accordance of finite element calculation results with theexperimental results.

Application of AE Sensor for Calibration of Depth of Cut in Micro-machining (마이크로 가공에서 절삭깊이 보정을 위한 AE 센서의 적용)

  • Kang, Ik-Soo;Kim, Jeong-Suk;Kim, Jeon-Ha
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.9
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    • pp.53-57
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    • 2009
  • There are technical requirements to manufacture large size functional parts with not only simple geometries like a flat or spherical surface but also sculptured geometries. In addition, the required machining accuracy for these parts is becoming more severe. In general, the form accuracy of machined parts is determined by the relative position between workpiece and tool during machining process. To improve machining accuracy the relative position errors should be maintained within the required accuracy. This study deals with the estimation and calibration of depth of cut using the AE signal in micro-machining. Also, this sensing technique can be applied to detect the initial contact between workpiece and tool.

AE Characteristics for Fracture Mechanism of Al 7075/CFRP Hybrid Composite (Al 7075/CFRP Hybrid 복합재료의 파손특성에 대한 AE 특성 연구)

  • 이진경;이준현;송상헌;윤한기
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.268-271
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    • 2001
  • When compared to other composite materials such as FRP and MMC, hybrid composite material is more attractive one due to the high specific strength and the resistance to fatigue. However, the fracture mechanism of hybrid composite material is extremely complicated because of the bonding structure of metals and FRP. Recently, nondestructive technique has been used to evaluate the fracture mechanism of these composite materials. In this study, AE technique has been used to clarify the fracture mechanism and the degree of damage for Al 7075/CFRP hybrid composite material. It was found that AE event, energy and amplitude among AE parameters were effective to evaluate fracture process of Al 7075/CFRP composite material. In addition, the relationship between the AE signal and the characteristics of failure surface using optical microscope was discussed.

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