• 제목, 요약, 키워드: Wear

검색결과 6,898건 처리시간 0.041초

급속응고법으로 제조한 과공정 Al-Si합금분말 압출재의 마멸특성 (Wear Characteristics of the Extruded Bars of Hypereutectic Al-Si Alloy Powders produced by Rapid Solidification Process)

  • 안영남;조규섭;나형용
    • 한국주조공학회지
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    • v.14 no.5
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    • pp.447-454
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    • 1994
  • Wear resistance and wear mechanism of hypereutectic Al-($15{\sim}40$)wt%Si alloys were investigated. Primary Si particles under $20{\mu}m$ size were formed in hypereutectic Al-Si alloy powders due to rapid solidification. But the Si particles of extruded bars were finely distributed in smaller size than that of atomized powders. The wear mechanism of hypereutectic Al-Si alloys was divided into three types of wear phenomena, which were abrasive wear, delamination wear and severe adhesive wear according to sliding speed and load. At low sliding speed and load, wear mechanism was abrasive wear, so Al-15wt%Si alloy showed the best wear resistance. At high sliding speed and load, wear mechanism was adhesive wear, and Al-40wt%Si alloy showed the best wear resistance.

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Ferrography에 의한 마멸분 정량분석

  • 오성모;이봉구
    • 대한기계학회논문집A
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    • v.24 no.10
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    • pp.2420-2427
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    • 2000
  • In contacting between surface, there is wear and the generation of wear particles. The particles contained in the lubricating oil carry detailed and important information about the condition monitoring of the machine. Therefore, This paper was undertaken for Ferrography system of wear debris generated from lubricated moving machine surface. The lubricating wear test was performed under different experimental conditions using the Falex wear test of Pin and V-Block type by Ti(C,N) coated. It was shown from the test results that wear particle concentration(WPC) ; wear severity Index(IS) and size\distribution have come out all the higher value by increases sliding friction time. By the Ferrogram a thin leaf wear debris as well as ball and plate type wear particles was observed.

핵연료 프레팅 마멸에서 마멸면적을 이용한 스프링 형상 영향 평가 (Evaluation of spring shape effect on the nuclear fuel fretting using worn area)

  • 이영호;김형규;정연호
    • 한국윤활학회:학술대회논문집
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    • pp.313-323
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    • 2003
  • The sliding wear behaviors of Zircaloy-4 nuclear fuel rod were investigated using two support springs with convex and concave shapes in room temperature air and water. The main focus is to compare the wear behavior of various test variables such as slip amplitude, environment, contact contours with different spring shape and a number of cycles. The results indicated that wear volume and maximum wear depth increased with slip amplitude in both air and water, but their trends tended to change according to the spring shapes and test environments. In air condition, the wear volume was controlled by wear debris behavior generated on worn surface. As a result, final wear volume and maximum wear depth decreased if a ratio of protruded wear volume to worn area $(D_p)$ would be saturated to specific value. This is because wear particle layer could accommodate large strain by accumulating and transforming wear particle layer. However, in water condition, metal-to metal contact was more dominant and wear volume was greatly affected by changed mechanical behavior between contact surfaces since wear debris should be generated after repeated plastic deformation and fracture. After wear test, worn surfaces were examined using optical microscope and SEM and details of wear mechanism were discussed using a ratio of wear volume to worn area $(D_e)$ at each test condition.

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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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    • 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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마멸모델을 이용한 금형마멸 예측에 관한 연구 (A Study on the Prediction of Die Wear using Wear Model)

  • 박종남
    • 한국금형공학회지
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    • v.7 no.1
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    • pp.28-33
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    • 2013
  • During the cold forming, due to high working pressure acting on the die surface, failure mechanics must be considered before die design. One of the main reasons of die failure in industrial application of metal forming technologies is wear. The mechanisms of wear are consisted of adhesion, abrasion, erosion and so on. Die wear affects the tolerances of formed parts, metal flow, and costs of process. The only way to control these failures is to develop a prediction method on die wear suitable in the design state in order to optimize the process. The wear system is used to analyse 'operating variables' and 'system structure'. In this study, with AISI D2, AISI 1020, AISI 304SS materials, a series of the wear experiments of pin-on-disk type to obtain the wear coefficients from Archard's wear model and the upsetting processes are carried out to observe the wear phenomenon during the cold forming process. The analysis of upsetting processes are performed by the rigid-plastic finite element method. The result of the analysis is used to investigate the die wear the processes, and the analysis simulated die wear profiles are compared with the experimental measured die wear profiles.

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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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    • v.32 no.10
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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.

지하철 레일의 미끄럼 마모거동을 고려한 재료설계에 대한 고찰 (A Study on the Rail Materials Technology for Subway Based on its Sliding Wear Behavior)

  • 이한영
    • Tribology and Lubricants
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    • v.30 no.6
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    • pp.364-369
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    • 2014
  • To assess the wear behavior of rails against subway rail car wheels, we investigate the sliding wear behavior of pins derived from two types of rails (normal rails and heat-treated rails) against a disc derived from a subway rail car wheel, using a pin-on-disc-type tribometer. We base the sliding wear test conditions on the sliding conditions for wheel flange-rail gauge corner contact. We demonstrate the remarkable transition in the wear behavior of the pins derived from the rails, from severe wear to mild wear, as a function of the sliding distance. The wear rate of the heat-treated rail material in the running-in wear region is much lower than that of the normal rail material. Furthermore, the wear rates of the pins in the running-in wear region decrease with increasing hardness and with decreasing sliding speed. However, there is little difference between the heat-treated rail pin and the normal rail pin in the wear rate in the steady-state wear region. Stricter controls on the decarburized layer beneath the surface of rails are required to reduce the wear rate in the running-in wear region.

마모해석을 위한 고유치해석과 Adaptive Meshing 알고리듬을 이용한 수치해석 비교 (A Comparative Study on Eigen-Wear Analysis and Numerical Analysis using Algorithm for Adaptive Meshing)

  • 장일광;장용훈
    • Tribology and Lubricants
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    • v.36 no.5
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    • pp.262-266
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    • 2020
  • Herein, we present a numerical investigation of wear analysis of sliding systems with a constant speed subjected to Archard's wear law. For this investigation, we compared two methods: eigen-wear analysis and adaptive meshing technique. The eigen-wear analysis is advantageous to predict the evolution of contact pressure due to wear using the initial contact pressure and contact stiffness. The adaptive meshing technique in finite element analysis is employed to obtain transient wear behavior, which needs significant computational resources. From the eigen-wear analysis, we can determine the appropriate element size required for finite element analysis and the time increment required for wear evolution by a dimensionless variable above a certain value. Since the prediction of wear depends on the maximum contact pressure, the finite element model should have a reasonable representation of the maximum contact pressure. The maximum contact pressure and wear amount according to this dimensionless variable shows that the number of fine meshes in the contact area contributes more to the accuracy of the wear analysis, and the time increment is less sensitive when the number of contact nodes is significantly larger. The results derived from a two-dimensional wear model can be applied to a three-dimensional wear model.

건식조건하(乾式條件下)에서 회주철(灰鑄鐵)의 로링마모(磨耗)에 관(關)한 연구(硏究) (Study on the Wear Characteristics of Gray Cast Iron under Dry Rolling Condition)

  • 최창옥;김동윤
    • 한국주조공학회지
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    • v.3 no.2
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    • pp.92-99
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    • 1983
  • This study has been carried out to investigate into the difference of rolling life and rolling wear characteristics for various gray cast iron under unlubricated dry rolling condition by amsler type wear test with 9.09% sliding.The results obtained from this study are summerized as follows: 1) It has been found that the amount of rolling wear id decreased when tensile strength and hardness are low, and then the rolling life up to generation of abnormal wear is conspicuously increased. 2) At the given condition the amount of rolling wear has been found to decrease as carbon equivalent of gray cast iron increases and resistance of crack propagation is an important factor on improvement of wear characteristics. 3) The amount of rolling wear is increased with increasing rolling revolution and wear of gray cast iron under dry rolling condition is characterized by three modes; initial wear, stationary wear and abnormal wear. 4) It has been found that the amount of rolling wear is increased with increasing maximum compressive stress and extremely increased when maximum compressive stress is over 59.1kg.f/mm.

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파이어링 상태의 일정 축 각속도에서 엔진베어링의 마모 해석 - Part II: 저어널베어링 마모 계산 (Wear Analysis of Engine Bearings at Constant Shaft Angular Speed during Firing State - Part II: Calculation of the Wear on Journal Bearings)

  • 전상명
    • Tribology and Lubricants
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    • v.34 no.4
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    • pp.146-159
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    • 2018
  • This paper presents a wear analysis procedure for calculating the wear of journal bearings of a four-strokes and four-cylinder engine operating at a constant angular crank shaft speed during firing conditions. To decide whether the lubrication state of a journal bearing is in the possible region of wear scar, we utilize the concept of the centerline average surface roughness to define the most oil film thickness scarring wear (MOFTSW) on two rough surfaces. The wear volume is calculated from the wear depth and wear angle, determined by the magnitude of each film thickness on a set of oil films with thicknesses lower than the MOFTSW at every crank angle. To calculate the wear volume at one contact, the wear range ratio during one cycle is used. The total wear volume is then determined by accumulating the wear volume at every contact. The fractional film defect coefficient, asperity load sharing factor, and modified specific wear rate for the application of the mixed-elasto-hydrodynamic lubrication regime are used. The results of this study show that wear occurs only at the connecting-rod big-end bearing. Thus, simulation results of only the big-end bearing are illustrated and analyzed. It is shown that the wear volume of each wear scar group occurs consecutively as the crank angle changes, resulting in the total accumulated wear volume.