• Title, Summary, Keyword: 음향방출기법

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Experimental Evaluation Study on the Integrity of Plastic Shell Structure using Acoustic Emission Technique (음향방출기법을 응용한 플라스틱 쉘 구조물의 건전성 평가 연구)

  • Shul, Chang-Won;Lee, Kee-Bhum
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.12
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    • pp.39-47
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    • 2005
  • An acoustic emission technique is applied to the tensile tests of the plastic specimen under the different test speeds and the structural integrity evaluation of the plastic shell structure. Several AE characteristics are acquired from the tensile tests and they are proven to be useful parameters in evaluating its structural integrity. The results shows that tensile strength has almost constant value over some higher speed region while revealing some increasing tendency in strength as the test speeds up in lower speed region. The crack initiation loads and locations are accurately evaluated during the static compression testing of the plastic shell structures by using acoustic emission technique.

Real-Time Source Classification with an Waveform Parameter Filtering of Acoustic Emission Signals (음향방출 파형 파라미터 필터링 기법을 이용한 실시간 음원 분류)

  • Cho, Seung-Hyun;Park, Jae-Ha;Ahn, Bong-Young
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.2
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    • pp.165-173
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    • 2011
  • The acoustic emission(AE) technique is a well established method to carry out structural health monitoring(SHM) of large structures. However, the real-time monitoring of the crack growth in the roller coaster support structures is not easy since the vehicle operation produces very large noise as well as crack growth. In this investigation, we present the waveform parameter filtering method to classify acoustic sources in real-time. This method filtrates only the AE hits by the target acoustic source as passing hits in a specific parameter band. According to various acoustic sources, the waveform parameters were measured and analyzed to verify the present filtering method. Also, the AE system employing the waveform parameter filter was manufactured and applied to the roller coaster support structure in an actual amusement park.

Application of Acoustic Emission Technique for Bridge Cable Monitoring (교량 케이블 적용 강연선 모니터링을 위한 음향방출 기법 검토)

  • Kim, Ga-Young;Seo, Dong-Woo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.121-125
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    • 2018
  • This paper presents the assessment of 7-wire strand monitoring using acoustic emission technique for bridges. 7-wire strand is widely used construction materials to provide additional tensile force to bridges. PSC (PreStressed Concrete) bridge and cable-stayed bridge are representatives for such cases. However, as the bridge aging progresses recently, corrosion problems of strand are emerging. For this reason, various NDT (Non-Destructive Test) methods for cable inspection are being studied and applied to the field. One of the NDT methods, acoustic emission technique, is known as an effective technique to detect cable damage and breakage. In this study, to evaluate the applicability of acoustic emission technique to bridges, acoustic emission signals according to damage of the strand were acquired and analyzed by tensile test. Moreover, The optimal AE sensor type was selected for field application. As a result, it is considered that the acoustic emission technique will be able to detect corrosion breakage and signs of rupture.

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.

A Pattern Recognition Method of Fatigue Crack Growth on Metal using Acoustic Emission (음향방출을 이용한 금속의 피로 균열성장 패턴인식 기법)

  • Lee, Soo-Ill;Lee, Jong-Seok;Min, Hwang-Ki;Park, Cheol-Hoon
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.46 no.3
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    • pp.125-137
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    • 2009
  • Acoustic emission-based techniques are being used for the nondestructive inspection of mechanical systems used in service. For reliable fault monitoring related to the crack growth, it is important to identify the dynamical characteristics as well as transient crack-related signals. Widely used methods which are based on physical phenomena of the three damage stages for detecting the crack growth have a problem that crack-related acoustic emission activities overlap in time, therefore it is insufficient to estimate the exact crack growth time. The proposed pattern recognition method uses the dynamical characteristics of acoustic emission as inputs for minimizing false alarms and miss alarms and performs the temporal clustering to estimate the crack growth time accurately. Experimental results show that the proposed method is effective for practical use because of its robustness to changes of acoustic emission caused by changes of pressure levels.

Evaluation of Static Structural Integrity for Composites Wing Structure by Acoustic Emission Technique (음향방출법을 응용한 복합재 날개 구조물의 정적구조 건전성 평가)

  • Jun, Joon-Tak;Lee, Young-Shin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.8
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    • pp.780-788
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    • 2009
  • AE technique was applied to the static structural test of the composite wing structure to evaluate the structural integrity and damage. During the test, strain and displacements measurement technique were used to figure out for static structural strength. AE parameter analysis and source location technique were used to evaluate the internal damage and find out damage source location. Design limit load test, the 1st and 2nd design ultimate load tests and fracture test were performed. Main AE source was detected by an sensor attached on skin near by front lug. Especially, at the 1st design ultimate test, strain and displacements results didn't show internal damage but AE signal presented a phenomenon that the internal damage was formed. At the fracture test, AE activities were very lively, and strain and displacements results showed a tendency that the load path was changed by severe damage. The internal damage initiation load and location were accurately evaluated during the static structural test using AE technique. It is certified from this paper that AE technique is useful technique for evaluation of internal damage at static structural strength test.

Interpretation of AE Signals from Rocket Motor Case Assembly (로켓 연소관 조립체의 음향방출 신호해석)

  • Rhee, Sang-Ho;Hwang, Tae-Kyong;Mun, Sun-Il
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.5
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    • pp.488-496
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    • 2003
  • To establish nondestructive test method for rocket motor assembly with rubber and aerospace composite materials, practicable quality control acoustic emission test method is presented. Structural analysis for motor assembly is performed by ABAQUS code and analysis output result is confirmed by strain gage and AE data. Various specimens were tested and analyzed using strain gage and acoustic emission data. The hit rate of acoustic emission was closely related with case/rubber debonding. This report also describes practicable acoustic emission nondestructive method for evaluating motor case assembly quality assurance in the industrial field.

Acoustic Emission Application for Aerospace Composite Materials (항공용 복합재료에 대한 음향방출의 활용)

  • Lee, Sang-Ho
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.3
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    • pp.313-318
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    • 2001
  • To establish nondestructive test method for aerospace composite materials, various composite specimens were tested and analyzed using acoutic emission. The hit rate of acoustic emission closely was rotated with crack initiation and propagation. This report also presents defection capability of crack initiation pressure, initial crack active location, and crack propagation using acoustic emission.

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Nondestructive Testing and Applications for Electric Power Plant Equipments by Acoustic Emissin Technology (음향방출기술에 의한 발전설비 비파괴검사 및 응용)

  • Lee, Sang-Guk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.4
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    • pp.396-409
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    • 2004
  • Diagnosis f structural integrity is the basis for correct treatment of and countermeasures against progressive structural abnormalities. An exact diagnosis is at present the most reliable means for determining the soundness of structures during power plant operations. Acoustic emission(AE) technology has recently strengthened its application base, and practitioners' understanding of the technique's fundamentals. This paper presents the results of a survey and assessment on AE monitoring applications in nuclear, fossil and hydraulic power plant. The main objective of this paper was to obtain information on various applications of AE technology in electric power plant.

Three Dimensional FE Analysis of Acoustic Emission of Composite Plate (복합재료 파손 시 발생하는 음향방출의 3차원 유한요소 해석)

  • Paik, Seung-Hoon;Park, Si-Hyong;Kim, Seung Jo
    • Composites Research
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    • v.18 no.5
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    • pp.15-20
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    • 2005
  • In this paper, damage induced acoustic emission in the composite plate in numerically simulated by using the three dimensional finite element method and explicit time integration. Acoustic source is modeled by equivalent volume source. To verify the proposed method, dynamic displacements due to the elastic wave are compared with the experiment when the fiber is broken in the single fiber embedded isotropic plate. For the laminated composite plates, the results are compared between homogenized model and DNS approach which models fibers and matrix separately. To capture high frequencies in the elastic wave, small time step size and a large number of meshes are required. The parallel computing technology is introduced to solve a large scale problem efficiently.