• Title, Summary, Keyword: 음향방출 파라미터

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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.

A New Method of Health Monitoring for Press Processing Using AE Sensor (음향방출센서를 이용한 프레스공정에서의 새로운 건전성 평가 연구)

  • Jeong, Soeng-Min;Kim, JunYoung;Jeon, Kyung Ho;Hong, SeokMoo;Oh, Jong-Seok
    • Journal of the Korea Convergence Society
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    • v.11 no.11
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    • pp.249-255
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    • 2020
  • This study developed the health monitoring method of press process using the acoustic emission (AE) sensor and high-pass filter. Also, the AE parameters such as ring-down count and peak amplitude are used. Based on this AE signal, the AE parameters were acquired and was utilized to detect the crack of the specimen. Since the defect detection is difficult due to noise and low magnitude of signal, the signal noise and press operation frequency were checked through the Short Time Fourier Transform(STFT) and damped. High-pass Filtering data was applied to AE parameters to select effective parameters. By using this signal processing techniques, the proposed AE parameters could improve the performance of defect detection in the press process.

Fracture Behavior Analysis in CFRP Specimens by Acoustic Emission and Ultrasonic Test (음향방출 및 초음파시험을 이용한 CFRP 시험편의 파괴 거동 해석)

  • Ahn, Seok-Hwan;Nam, Ki-Woo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.3
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    • pp.251-260
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    • 2001
  • Damage Profess of CFRP laminates under monotonic tensile test was characterized by the correlation between Acoustic Emission(AE) and Ultrasonic Test(UT). The amplitude distribution 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 pullout and fiber fracture as load is increased. In addtion, the characteristics of ultrasonic amplitude attenuation are useful lot analysis of the different type of fracture mechanism. Different orientation of carbon fiber reinforced plastic specimens were used to investigate the AE amplitude range and ultrasonic amplitude attenuation. Finally, loading-unloading tests were carried out to check Felicity effect. During the tests, ultrasonic amplitude attenuation was investigated at the same time and compared with AE parameters. The result showed that two parameters of both AE and UT could be effectively used for analysis of fracture mechanism in CFRP laminates.

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Early Shell Crack Detection Technique Using Acoustic Emission Energy Parameter Blast Furnaces (음향방출 에너지 파라미터를 이용한 고로 철피균열의 조기 결함탐지 기술)

  • Kim, Dong-Hyun;Lee, Sang-Bum;Bae, Dong-Myung;Yang, Bo-Suk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.1
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    • pp.45-52
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    • 2016
  • Blast furnaces are crucial equipment for steel production. A typical furnace risks unexpected accidents caused by contraction and expansion of the walls under an environment of high temperature and pressure. In this study, an acoustic emission (AE) monitoring system was tested for evaluating the large-scale structural health of a blast furnace. Based on the growth of shell cracks with the emission of high energy levels, severe damage can be detected by monitoring increases in the AE energy parameter. Using this monitoring system, steel mill operators can establish a maintenance period, in which actual shell cracks can be verified by cross-checking the UT. From this study, we expect that AE systems permit early fault detection for structural health monitoring by establishing evaluation criteria based on the severity of shell cracking.

Application of Acoustic Emission Technique and Friction Welding for Excavator Hose Nipple (굴삭기용 호스 니플의 마찰용접과 음향방출기법의 적용)

  • Kong, Yu-Sik;Lee, Jin-Kyung
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.5
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    • pp.436-442
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    • 2013
  • Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, the feasibility of industry application was determined by analyzing the mechanical properties of weld region for a specimen of tube-to-tube shape for excavator hose nipple with friction welding, and optimized welding variables were suggested. In order to accomplish this object, friction heating pressure and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. An acoustic emission(AE) technique was applied to evaluate the optimal friction welding conditions nondestructively. AE parameters of accumulative count and event were analyzed in terms of generating trend of AE signals across the full range of friction weld. The typical waveform and frequency spectrum of AE signals which is generated by friction weld were discussed. From this study the optimal welding variables could be suggested as rotating speed of 1300 rpm, friction heating pressure of 15 MPa, and friction heating time of 10 sec. AE event was a useful parameter to estimate the tensile strength of tube-to tube specimen with friction weld.

A Study on the characteristics of the Signals of AE according to Fracture mode of CFRP under Tensile load (탄소섬유강화플라스틱(CFRP)의 인장하중하에서의 파괴거동에 따른 음향방출신호 특성에 관한 연구)

  • Lee, Kyung-Won;Lee, Sang-Yun;Nam, Jun-Young;Lee, Jong-Oh;Lee, Sang-Yul;Lee, Bo-Young
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.18 no.4
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    • pp.51-58
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    • 2010
  • Recently, aerospace structures have lightweight trend in order to reduce the cost of fuel and system, Carbon Fiber Reinforced Plastic (CFRP) can give the ability to reduce weight at 20~50% as the substitution of metal alloy, and there are advantages such as high Non-rigid, specific strength and anti-corrosion, but it is difficult to prove its destruction properties due to heterogeneous structure and anisotropy. In this study we designed specimen, inducing distinguishing destructions of material (for example, matrix crack, fiber breakage, and delamination) by using the Carbon Fiber Reinforced Plastic (CFRP) which is used in a real aircraft, to apply acoustic emission technique to aerospace structures. And we gained data via tensile testing and acoustic emission technique, from which each fault signal was classified respectively by using AE parameters and waveform.

A Study on the Optimal Conditions of friction Welding for JLF & STS304 Using AE Technique (AE기법을 이용한 JLF/STS304이종재료의 최적 마찰용접조건에 관한 연구)

  • Yoon, Han-Ki;Lee, Sang-Pill;Kong, Yu-Sik;Lee, Jin-Kyung
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.2
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    • pp.148-155
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    • 2003
  • Japanese low activation terrific steel(JLF) is a good material for the parts of heat exchanger such as blanket and diverter. At first, JLF was developed as a candidate for structural materials in nuclear fusion applications. However, the development of the jointing technique of JLF steel to other materials is important for wide applications of this material to the industry fields. Recently the jointing technologies including diffusion bonding, brazing, roll bonding, explosive bonding and hot iso-static pressing have been studied for the heterogeneous materials of JLF-1 steel(Fe-9Cr-2W-V-Ta) and stainless steel(STS304). Friction welding is one of the most popular welding methods for two different kinds of materials. In this paper, the JLF-1 steel was jointed to SIS304 by friction welding method and the optimal conditions of the friction welding discussed. Acoustic emission was used as a nondestructive technique to evaluate the weld quality in processing.

Evaluation on Corrosion of A106 Carbon Steel using AE Technique (음향방출기법을 이용한 A106 탄소강의 부식평가)

  • Lee, Jin-Kyung;Lee, Sang-Pill
    • Journal of Ocean Engineering and Technology
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    • v.22 no.5
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    • pp.100-105
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    • 2008
  • A106 Carbon Steel has recently been used as the material for pipes, nozzles, and tank shells in nuclear power plants. Its corrosion resistance gives the steel many advantages for use in structures under high temperature and high pressure. This steel is also expected to be used as a structural material in the shipbuilding industry for applications involving severe conditions, such as high temperature and pressure. In this study, the mechanical properties of A106 carbon steel were evaluated in regard to its corrosion times. The tensile and yielding strengths decreased as the corrosion time increased. In particular, the tensile strength was influenced by corrosion. In addition, an acoustic emission (AE) technique was used to clarify the microscopic damage to specimens that had undergone corrosion for a certain period. It was found that AE parameters, such as events, energy, duration time, and amplitude were useful for evaluating the degree of damage and remaining life of the corroded specimen. Various properties of the waveform and frequency range were also seen, based on the degree of damage to the specimen from the corrosion time.

A Study on the characteristics of the Signals of AE according to Fracture mode of CFRP (Carbon Fiber Reinforced Plastic(CFRP)복합재의 파괴 거동에 따른 Acoustic Emission(AE)신호 특성에 관한 연구)

  • Lee, Kyung-Won;Kim, Jong-Hyun;Kim, Jae-Seong;Lee, Bo-Young
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.17 no.4
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    • pp.42-47
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    • 2009
  • Recently, the wide range of the composite materials is used for the making airplanes, trains and automobiles body for the lightweight. Despite having complex structures, composite materials usually have well defined mechanical characteristics. However, composite materials are difficult to understand the fracture mechanism clearly by simple mechanical test. Nondestructive evaluation (NDE) combined with mechanical testing can play a more important role and especially Acoustic Emission Testing (AET) would become known to be a useful tool to assess damage and fracture behavior of composites. In this study The experiment was performed to acquire the acoustic emission signal during tensile test using unidirectional CFRP specimen and the data was analyzed the acoustic emission parameters with the waveform.

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Interfacial fracture analysis of human tooth/composite resin restoration using acoustic emission (음향방출법을 이용한 치아/복합레진 수복재의 계면부 파괴해석)

  • Gu, Ja-Uk;Choi, Nak-Sam;Arakawa, Kazuo
    • Composites Research
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    • v.22 no.6
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    • pp.45-51
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    • 2009
  • The marginal integrity at the composite resin-tooth interface has been analyzed in real time through acoustic emission (AE) monitoring during the polymerization shrinkage of composite resin subjected to the light exposure. It was found that AE signals were generated by the polymerization shrinkage. Most AE hit events showed a blast type signal having the principal frequency band of 100-200kHz. Bad bonding states were indicated by many hit events in the initial curing period of 1 minute with high contraction rate. The quantity of hit events for the human molar dentin specimen was much less than that for the steel ring specimen but more than that for the PMMA ring specimen. The better the bonding state, the less the AE hit events. The AE characteristics were related with the tensile crack propagation occurring in the adhesive region between the composite resin and the ring substrate as well as the compressive behavior of the ring substrate, which could be used for a nondestructive characterization of the marginal disintegrative fracture of the dental restoration.