• 제목/요약/키워드: Fretting-Wear

검색결과 168건 처리시간 0.024초

프레팅 마멸계수 및 마찰계수 측정에 관한 연구 (Measurement of Wear and Friction Coefficients for the Prediction of Fretting Wear)

  • 조용주;김태완
    • Tribology and Lubricants
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    • 제28권3호
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    • pp.124-129
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    • 2012
  • The prediction of fretting wear is a significant issue for the design of contacting mechanical components such as flexible couplings and splines, jointed structures and so on. In our earlier study, we developed a numerical model to predict the fretting wear using boundary element method. The developed algorithm needs experimental fretting wear coefficients and friction coefficients between two moving materials to get more reliable results. In this study, therefore, we demonstrated the measurement method of the fretting wear coefficients and friction coefficients using disk on plate tribometer with piazo actuator and gap sensor. For four different material combinations, the fretting wear coefficients and friction coefficients are acquired through the fretting wear experiment and the analysis of the measured values. Thess results are useful to predict the quantative fretting wear rate in the developed algorithm.

THEORETICAL ANALYSIS FOR STUDYING THE FRETTING WEAR PROBLEM OF STEAM GENERATOR TUBES IN A NUCLEAR POWER PLANT

  • LEE CROON YEOL;CHAI YOUNG SUCK;BAE JOON WOO
    • Nuclear Engineering and Technology
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    • 제37권2호
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    • pp.201-206
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    • 2005
  • Fretting, which is a special type of wear, is defined as small amplitude relative motion along the contacting interface between two materials. The structural integrity of steam generators in nuclear power plants is very much dependent upon the fretting wear characteristics of Inconel 690 U-tubes. In this study, a finite element model that can simulate fretting wear on the secondary side of the steam generator was developed and used for a quantitative investigation of the fretting wear phenomenon. Finite element modeling of elastic contact wear problems was performed to demonstrate the feasibility of applying the finite element method to fretting wear problems. The elastic beam problem, with existing solutions, is treated as a numerical example. By introducing a control parameter s, which scaled up the wear constant and scaled down the cycle numbers, the algorithm was shown to greatly reduce the time required for the analysis. The work rate model was adopted in the wear model. In the three-dimensional finite element analysis, a quarterly symmetric model was used to simulate cross tubes contacting at right angles. The wear constant of Inconel 690 in the work rate model was taken as $K=26.7{\times}10^{-15}\;Pa^{-1}$ from experimental data obtained using a fretting wear test rig with a piezoelectric actuator. The analyses revealed donut-shaped wear along the contacting boundary, which is a typical feature of fretting wear.

스플라인 커플링의 프레팅 마멸 예측에 관한 연구 (A Study on Estimating of Fretting Wear of a Spline Coupling)

  • 김응진;이상돈;조용주
    • Tribology and Lubricants
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    • 제25권4호
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    • pp.256-260
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    • 2009
  • Fretting is a kind of wear which effects on reliability and durability. When machine parts are joined joint in parts such as a bolt or a rivet or a pin, fretting phenomenon is occurred by micro relative movement. When fretting occurs in joint parts, there is wear which is the cause of fatigue crack. Recently, although the ways of assessment of fatigue and damage tolerance are established, there is no way to evaluate fatigue crack initiation life by fretting phenomenon. Consequently, the prediction of life and prevention plan caused by fretting are needed to improve reliability. The objective of this paper is to predict fretting wear by using a experimental method and contact analysis considering wear process. For prediction of fretting wear volume, systematic and controlled experiments with a disc-plate contact under gross slip fretting conditions were carried out. A modified Archard equation is used to calculate wear depths from the contact pressure and stroke using wear coefficients obtained from the disc-plate fretting tests.

충격 프레팅에 의한 증기발생기 세관 마모손상 진행모델 (Wear Progress Model by Impact Fretting in Steam Generator Tube)

  • 이정근;박치용;김태룡;조선영
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회A
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    • pp.1684-1689
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    • 2007
  • Fretting wear is one of the important degradation mechanisms of steam generator tubes in the nuclear power plants. Especially, impact fretting wear occurred between steam generator tubes and tube support plates or anti-vibration bar. Various tests have been carried out to investigate the wear mechanisms and to report the wear coefficients. Those are fruitful to get insight for the wear damage of steam generator tubes; however, most wear researches have concentrated on sliding wear of the steam generator tubes, which may not represent the wear loading modes in real plants. In the present work, impact fretting tests of steam generator tube were carried out. A wear progression model for impact-fretting wear has been investigated and proposed. The proposed wear progression model of impact-fretting wear is as follows; oxide film breaking step at the initial stage, and layer formation step, energy accumulation step and finally particle torn out step which is followed by layer formation in the stable impact-fretting progress. The wear coefficient according to the work-rate model has been also compared with one between tube and support.

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충격 프레팅에 의한 증기발생기 세관 마모손상 진행모델 (Wear Progress Model by Impact Fretting in Steam Generator Tube)

  • 박치용;이정근;김태룡
    • 대한기계학회논문집A
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    • 제32권10호
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    • pp.817-822
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    • 2008
  • Fretting wear is one of the important degradation mechanisms of steam generator tubes in the nuclear power plants. Especially, impact fretting wear occurred between steam generator tubes and tube support plates or anti-vibration bar. Various tests have been carried out to investigate the wear mechanisms and to report the wear coefficients. Those are fruitful to get insight for the wear damage of steam generator tubes; however, most wear researches have concentrated on sliding wear of the steam generator tubes, which may not represent the wear loading modes in real plants. In the present work, impact fretting tests of steam generator tube were carried out. A wear progress model for impact-fretting wear has been investigated and proposed. The proposed wear progress model of impact-fretting wear is as follows; oxide film breaking step at the initial stage, and layer formation step, energy accumulation step and finally particle torn out step which is followed by layer formation in the stable impact-fretting progress. The wear coefficient according to the work-rate model has been also compared with one between tube and support.

프레팅 조건하에 있는 증기 발생기 세관재의 스틱-슬립 영역별 마멸 메커니즘 규명 (Investigation of Wear Mechanisms of Tube Materials for Nuclear Steam Generators due to Stick-Slip Behavior under Fretting Conditions)

  • 이영제;정성훈;박치용
    • Tribology and Lubricants
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    • 제21권1호
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    • pp.33-38
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    • 2005
  • Fretting is the oscillatory motion with very small amplitudes, which usually occurs between two solid surfaces in contact. Fretting wear is the removal of material from contacting surfaces through fretting action. Fretting wear of steam generator tubes in nuclear power plant becomes a serious problem in recent years. The materials for the tubes usually are Inconel 690 (I-690) and Inconel 600 (I-600). In this paper, fretting wear tests for I-690 and I-600 were performed under various applied loads in water at room temperature. Results showed that the fretting wear loss of I-690 and I-600 tubes was largely influenced by stick-slip. The fretting wear mechanisms were the abrasive wear in slip regime and the delamination wear in stick regime. Also, I-690 had somewhat better wear resistance than I-600.

해수 중에서 STS304강의 프레팅 마멸특성 (Fretting Wear Characteristics of STS304 Steel in Seawater)

  • 김은구;김태형;김석삼
    • Tribology and Lubricants
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    • 제16권4호
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    • pp.302-307
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    • 2000
  • The fretting wear characteristics of STS304 steel in seawater were investigated experimentally. A fretting wear tester was designed to be suitable for this fretting test. This study was focused on the effects due to the combination of normal load, slip amplitude and number of cycles and corrosive environment as the main factors of fretting. The results of this study showed that the wear volume increased abruptly at slip amplitude between 70 $\mu\textrm{m}$∼100 $\mu\textrm{m}$ by fracture of oxide layers but above that slip amplitude the wear volume increased steadily.

TiN 코팅한 핵연료봉 피복재의 프레팅 마멸기구 (Fretting Wear Mechanisms of TiN Coated Nuclear Fuel Rod Cladding Tube)

  • 김태형;성지현;김석삼
    • Tribology and Lubricants
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    • 제17권6호
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    • pp.453-458
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    • 2001
  • The fretting wear of a nuclear fuel rod it a dangerous phenomenon. In this study, TiN coating was used to reduce the fretting wear of Zircaloy-4 tube, a nuclear fuel rod cladding material. TiN coating is probably one of the molt frequently and successfully used PVD coatings for the mitigation of fretting wear. The fretting tester was designed and manufactured for this experiment. The number of cycles, slip amplitude and normal load were selected as main factors of fretting wear. The results of this research showed that wear volume was improved 1.3∼3.2 times with TiN coating. The worn surfaces were observed by SEM. Wear mechanism at lower slip amplitude was the brittle cracks and rupture of TiN coating. However, adhesive and abrasive wear were mainly observed on most surfaces at higher slip amplitude.

TiAIN 코팅한 핵연료봉 피복재의 프레팅 마멸 평가 (Fretting Wear Evaluation of TiAIN Coated Nuclear Fuel Rod Cladding Materials)

  • 김태형;김석삼
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2002년도 제35회 춘계학술대회
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    • pp.88-95
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    • 2002
  • Fretting of fuel rod cladding material, Zircaloy-4 Tube, in PWR nuclear power plants must be reduced and avoided. Nowadays the introduction of surface treatments or coatings is expected to bean ideal solution to fretting damage since fretting is closely related to wear, corrosion and fatigue. Therefore, in this study the fretting wear experiment was peformed using TiAIN coated Zircaloy-4 tube as the fuel rod cladding and uncoated Zircaioy-4 tube as one of grids, especially concentrating on the sliding component. Fretting wear resistance of TiAIN coated Zircaloy-4 tubes was improved compared with that of TiN coated tubes and uncoated tubes and the fretting wear mechanisms were delamination and plastic flow following by brittle fracture at lower slip amplitude but severe oxidation and spallation of oxidative layer at higher slip amplitude.

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핵연료 피복관과 지지격자 사이에 발생하는 프레팅 마멸에 미치는 유동의 영향 (The Effect of Water Flow on Fretting Wear of the Nuclear Fuel Cladding Tubes against the Supporting Grids)

  • 이영제;김진선;박세민;박동신
    • Tribology and Lubricants
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    • 제24권4호
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    • pp.186-189
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    • 2008
  • The flow induced vibration in the nuclear fuel assembly causes the fretting wear between the fuel cladding tubes and the supporting grids. The reduction in tube thickness due to the fretting wear could be related to the serious damage on nuclear fuel assembly. In this paper, the effect of the water flow on fretting wear of nuclear fuel cladding tube against supporting grid was investigated through the fretting wear tester with water spout equipment. The test results were compared with the data conducted in the stationary water. At stationary water environment the wear debris was trapped between fretting surfaces, and then the fretting wear occurred by three-body abrasion. However, in the case of water flow, the two-body abrasive wear was the dominant wear mechanism, because the wear debris was easily removed by water flow.