• Title/Summary/Keyword: AE counts

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Real-time evaluation of automatic production quality control for friction welding machine (摩擦熔接機械 의 自動생산品質制御 實時間 評價)

  • 오세규;임우조;김형자
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.6
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    • pp.757-766
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    • 1985
  • Both in-process quality control and high reliability of the weld is one of the major concerns in applying friction welding to the economical and qualified mass-production. No reliable nondestructive monitoring method is available at present to determine the real-time evaluation of automatic production quality control for friction welding machine. This paper, so that, presents the experimental examinations and statistical quantitative analysis of the correlation between the initial cumulative counts of acoustic emission(AE) occurring during plastic deformation period of the welding and the tensile strength of the welded joints as well as the various welding variables, as a new approach which attempts finally to develop an on-line (or real-time) quality monitoring system and a program for the process of real-time friction welding quality evaluation by initial AE cumulative counts. As one of the important results, it was well confirmed that the initial AE cumulative counts were quantitatively and cubically correlated with reliability of 95% confidence level to the joint strength of the welds, bar-to-bar (SCM4 to SUM31, SCM4 to SUM24L) and that an AE technique using initial AE counts can be reliably applied to real-time strength evaluation of the welded joints, and that such a program of the system was well developed resulting in practical possibility of real-time quality control more than 100% joint efficiency showing good weld with no micro-structural defects.

A Study on the Damage Estimation of CFRP using Acoustic Emission (음향방출을 이용한 탄소섬유강화 플라스틱의 손상 평가에 관한 연구)

  • 이장규;박성완;김봉각
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.10a
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    • pp.307-312
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    • 2003
  • The object of this study is to investigate a damage estimation of single edge cracked tensile specimens ($2_a$/W) as a function of acoustic emission (AE) according to the unidirectionally oriented carbon/epoxy composites, CFRP AE signals were analyzed and classified 3 regions by event counts, energy and amplitude for coressponding applied load. On tensile loading and using the results of the AE analysis, it was found that the event counts, cumulative counts or energy, and amplitude distributions useful for the prediction of damage failure.

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Study on Filtering Method of Acoustic Emission and Characteristic of Signals for the Deformation Process of Steel (강재 변형과정에서 음향방출잡음제거와 신호특성에 관한 연구)

  • Na, E.G.;Oh, S.H.;Lee, S.K.
    • Journal of Power System Engineering
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    • v.13 no.4
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    • pp.43-48
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    • 2009
  • The purpose of this study is to show how to eliminate the noises and to obtain the data related with the relationship between AE signal characteristics and mechanical behaviors for the pressure vessel steel. Various kinds of noises are introduced into the AE data in the course of experiments. Accordingly, real AE data have to be obtained after tests. AE test was carried out under four point bending load. Among AE signals, counts and signal strength are used to find out the differences of AE characteristics between the basemetal and weldment. After tests, this paper shows the procedures of filtering the noises against basemetal of the pressure vessel steel to obtain the real data around crack tip. Relationships between plastic zone size and cumulative AE counts are shown also. AE signals were absent within an elastic region, regardless of the specimens. Most of AE signals are produced in the process of plastic deformation. The deformation and fracture modes of basemetal and weldment are quiet different.

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Acoustic Emission Studies on the Structural Integrity Test of Welded High Strength Steel using Pattern Recognition (패턴인식을 이용한 고장력강의 용접 구조건전성 평가에 대한 음향방출 사례연구)

  • Kim, Gil-Dong;Rhee, Zhang-Kyu
    • Proceedings of the Safety Management and Science Conference
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    • 2008.04a
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    • pp.185-196
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    • 2008
  • The objective of this study is to evaluate the mechanical behaviors and structural integrity of the weldment of high strength steel by using an acoustic emission (AE) techniques. Simple tension and AE tests were conducted against the 3 kind of welding test specimens. In order to analysis the effectiveness of weldability, joinability and structural integrity, we used K-means clustering method as a unsupervised learning pattern recognition algorithm for obtained multivariate AE main data sets, such as AE counts, energy, amplitude, hits, risetime, duration, counts to peak and rms signals. Through the experimental results, the effectiveness of the proposed method is discussed.

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Study on Friction Welding of SUS431 and SCM21 for External Shaft of Ship (선외기 샤프트용 재료의 마찰용접에 관한 연구)

  • 오세규;이종환;배명주;오명석
    • Journal of Advanced Marine Engineering and Technology
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    • v.17 no.4
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    • pp.38-48
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    • 1993
  • A study on friction welding of stainless steel bar(SUS431) to chrome molybdenum steel bar(SCM21) was accomplished experimentally through analysis for relations among friction welding conditions, tension test, hardness test, microstructure test and acoustic emission test. The results obtained are summarized as follows ; 1. Through friction welding of SUS431 bar to SCM21 bar, the optimum welding condition by considering on strength and toughness was found to be the range of heating time of 3-5 sec when the number of rotating speed of 2000rpm, heating pressure of 10kg/$mm^2$, and upsetting time of 4 sec. 2. Quantitative ralationship was identified between heating time($T_1$, sec) and tensile strength (${\sigma},\;kgf/mm^2$) of the friction welded joint and the relation equation is $\sigma$=52.62$T_1{^{0.06}}$. 3. Through AE test, quantitative relationship was confirmed between heating time($T_1$, sec) and total AE(N, counts) during welding, and the relation is computed as follows ; N=30413.6$e^{0.06T1}$. 4. It was confirmed that the quantitative ralationship exists between the tensile strength of the welded joints and AE cumulative counts. And the relation is computed as the following ; ${\sigma}$=16.37(ln N)- 116.4. 5. When ONZ=36500-41500 counts by $OT_1Z$=3~5sec, it was identified by experiment that the range of welded joint tensile strength is 55.6-57.7kgf/$mm^2$/ whose joint efficiency is more than 100%, and it was experimentally confirmed that the real-time nondestructive quality(strength) evaluation for the friction welded joints could be possible by acoustic emission technique.

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Dissimilar Friction Welding of Elevated Temperature Materials for Pressure Vessels and Its AE Evaluation (압력용기용 고온재의 이종재 마찰용접과 AE평가)

  • Kong, Y.S.;Lee, Y.T.;Yoo, I.J.;Oh, S.K.;Lim, M.B.
    • Journal of Power System Engineering
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    • v.6 no.1
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    • pp.68-73
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    • 2002
  • An opportunity to use the elevated temperature has been recently increasing in various elements of heat facilities or machines such as heat exchanger tubes, pressure vessels, engines of aircraft, boilers and turbines in power plants, and nuclear reactor components, etc. as machinery industry develops. Thus, the development of such elevated-temperature heat-resisting materials and the studies on their elevated-temperature materials friction welding, creep design and analysis have been considered as an important and needful fact. In this paper, friction welding optimization for 1Cr0.5Mo to STS304 and AE applications for the weld quality evaluation were investigated. The important results of this study are as follows : The techniques for dissimilar friction welding optimization of the elevated temperature materials 1Cr0.5Mo and STS304 and its real-time weld quality evaluation by AE were developed, considering on both strength and toughness. Quantitative relationship was identified among welding condition, weld quality and cumulative AE counts.

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Acoustic Emission Studies on the Structural Integrity Test of Welded High Strength Steel using Pattern Recognition: Focused on Tensile Test (패턴인식을 이용한 고장력강의 용접 구조건전성 평가에 대한 음향방출 사례연구: 인장시험을 중심으로)

  • Kim, Gil-Dong;Rhee, Zhang-Kyu
    • Journal of the Korea Safety Management & Science
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    • v.10 no.4
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    • pp.127-134
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    • 2008
  • The objective of this study is to evaluate the mechanical behaviors and structural integrity of the weldment of high strength steel by using an acoustic emission (AE) techniques. Monotonic simple tension and AE tests were conducted against the 3 kinds of welded specimen. In order to analysis the effectiveness of weldability, joinability and structural integrity, we used K-means clustering method as a unsupervised learning pattern recognition algorithm for obtained multi-variate AE main data sets, such as AE counts, energy, amplitude, hits, risetime, duration, counts to peak and rms signals. Through the experimental results, the effectiveness of the proposed method is discussed.

Signal Characteristics of Acoustic Emission from Angiosperm and Gymnosperm by the Water Stress (물 스트레스를 받는 속씨식물과 겉씨식물에서 검출된 음향방출의 신호특성)

  • Nam, Ki-Woo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.5
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    • pp.480-487
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    • 2003
  • To improve environmental control in various plants, signal characteristics of plants have been studied by a nondestructive technique. In this paper, the acoustic emission (AE) from plants was analyzed for water stress dependency. AE signals were taken from gymnosperm and angiosperm. AE sensor detected AE signals from the plant stem underneath the plant surface below the sensor. AE hit-event counts in daytime were more than those in night time, and it was found that the daily hit counts pattern was strongly affected by the water stress in the plant. frequency bands of AE signals from the angiosperm was different from those from the gymnosperm. Frequency bands of AE in outdoor condition were in accord with those in indoor having similar conditions.

Thermo-Acoustic Emission Behavior of Composites (복합재료의 열-음향방출거동)

  • 김영복;우성충;최낙삼
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.10a
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    • pp.111-115
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    • 2001
  • Thermo-acoustic emission (AE) from composite laminates under the repetitive thermal cyclic loads have been quantitatively analyzed in consideration of AE source mechanisms. The repetitive thermal load brought about a large reduction, i.e. an exponential decrease in AE total ringdown counts and AE amplitudes. It was thought that generation of thermo-AE during the first thermal cycle was not caused by crack propagation but by secondary microfracturing due to abrasive contact between crack surfaces.

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