• 제목/요약/키워드: Sliding behavior

검색결과 550건 처리시간 0.022초

경계윤활 및 무윤활 상태에서 선접촉을 하는 세라믹과 강의 마찰과 마멸 특성 (Friction and Wear of Ceramic-Steel Pairs in Boundary-Lubricated and Unlubricated Line-Contact Sliding)

  • 이영제;김영호;장선태
    • Tribology and Lubricants
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    • 제12권3호
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    • pp.12-25
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    • 1996
  • The friction and wear behaviors of ceramics against steels with lubricants were investigated and compared with those observed in air. Lubrications wbre done by a water and a commercial engine oil as received. The investigated ceramics were $Al_{2}O_{3}$, SiC, and $Si_{3}N_{4}$. Steels with 0.2 wt.% C were heat treated to obtain tempered structure. A cylinder-on-plate tribometer with rotated sliding motion was used to carry out the experiments. In the experiments reported here, the ranges of different testing speeds and loads were used. It was found that the friction and wear characteristics of tested pairs were significantly influenced by environments. In water and oil environments the wear of ceramics was reduced from 10$^{-6}$ g/s down to 10$^{-8}$ g/s in dry sliding at the same values of the frictional power which are the products of the friction coefficient, the load and the sliding speed. SiC showed excellent wear resistant behavior in water sliding, which was the lowest among tested ceramics, but it was, very poor in oils. In case of $Si_{3}N_{4}$, the wear rates were very low under oil environment, but the highest in water. The wear rates of $Al_{2}O_{3}$ were very low in both lubricating conditions at low values of the frictional power, but high at high values of the frictional power.

구름마찰 접촉하중시 Polyethylene Tibia 표면균열의 응력확대계 수와 복합전파거동에 관한 연구 (Stress Intensity Factors and Possible Crack Propagation Mechanisms for a Crack Surface in a Polyethylene Tibia Component Subject to Rolling and Sliding Contact)

  • 김병수;문병영
    • 대한기계학회논문집A
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    • 제27권12호
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    • pp.2019-2027
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    • 2003
  • Pitting wear is a dominant from of polyethylene surface damage in total knee replacements, and may originate from surface cracks that propagate under repeated tribological contact. In this study, stress intensity factors, K$\_$I/and $_{4}$, were calculated for a surface crack in a polyethylene-CoCr-bone system under the rolling and/or sliding contact pressures. Crack length and load location were considered in determination of probable crack propagation mechanisms and fracture modes. Positive K$\_$I/ values were obtained for shorter cracks in rolling contact and for all crack lengths when the sliding load was apart from the crack. $_{4}$ was the greatest when the load was directly adjacent to the crack (g/a=${\pm}$1). Sliding friction caused a substantial increase of both K$\_$I/$\^$max/ and $_{4}$$\^$max/. The effective Mode I stress intensity factors, K$\_$eff/, were the greatest at g/a=${\pm}$1, showing the significance of high shear stresses generated by loads adjacent to surface cracks. Such behavior of K$\_$eff/ suggests mechanisms for surface pitting by which surface cracks may propagate along their original plane under repeated rolling or sliding contact.

알루미늄 합금의 미끄럼마모 특성에 미치는 상대재 경도의 영향 (Analysis of Sliding Wear Properties for Aluminum Alloy According to the Hardness Values of the Mating Tool Steel)

  • 이한영;조용재;김태준;박원규
    • Tribology and Lubricants
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    • 제26권2호
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    • pp.105-110
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    • 2010
  • In order to investigate the wear behavior of aluminum alloy depended on different hardness of the mating tool steel, sliding wear tests were conducted. It was found that the wear characteristics pattern of aluminum alloy for sliding speed was not affected by the hardness of the mating tool steel. However, the effects of the hardness of the mating tool steel exhibited only in relatively low sliding speed ranges. At these ranges, the wear rate of aluminum alloy decreased when increasing the hardness of the mating tool steel. This was attributed by the fact that $Al_2O_3$ particles released from the aluminum worn surface were crushed and embedded on the mating worn surface with high hardness level. At the high sliding speed ranges, wear of aluminum alloy was hardly occurred by the formation of thick $Al_2O_3$ film on the worn surface, regardless of the hardness of the mating tool steel.

마그네슘 합금에 대한 DLC 코팅의 온도에 따른 마찰기구 해석 (Friction Behavior of DLC Coating Slid Against AZ31 Magnesium Alloy at Various Temperatures)

  • 권혁우;김명곤;허하리;김용석
    • 소성∙가공
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    • 제24권6호
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    • pp.405-410
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    • 2015
  • Sheet-forming of Mg alloys is conducted at elevated temperatures (250℃) due to the low formability at room temperature. The high-temperature process often gives rise to surface damage on the alloy (i.e. galling.) In the current study, the frictional characteristics of DLC coating slid against an AZ31 Mg alloy at various temperatures were investigated. The coating has been used widely for low-friction processes. Dry-sliding friction and galling characteristics of an AZ31 Mg alloy (disk), which slid against uncoated and a DLC-coated STD-61 steel (pin), were investigated using a reciprocating-sliding tribometer at room temperature and 250℃. To represent the real sliding phenomena during a sheet metal forming process, single-stroke tests were used (10mm stroke length) rather than a reciprocating long sliding-distance test. The DLC coating suppressed adhesion between the alloy and the tool steel at room temperature, and exhibited a low friction coefficient. However, during sliding at 250℃, severe adhesion occurred between the two surfaces, which resulted in a high friction coefficient and galling.

구름마찰접촉하중 시 Polyethylene tibia 요소의 표면균열 복합전파 거동에 관한 연구 (Study for Possible Crack Propagation Mechanisms for a Surface Cracked in a Polyethylene Tibia Component Subject to Rolling and Sliding Contact)

  • 김병수;문병영
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.1222-1227
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    • 2003
  • Pitting wear is a dominant form of polyethylene surface damage in total knee replacements, and may originate from surface cracks that propagate under repeated tribological contact. In this study, stress intensity factors, $K_{I}$ and $K_{II}$, were calculated for a surface crack in a polyethylene - CoCr - bone system under the rolling and/or sliding contact pressures. Crack length and load location were considered in determination of probable crack propagation mechanisms and fracture modes. Positive $K_{I}$ values were obtained for shorter cracks in rolling contact and for all crack lengths when the sliding load was apart from the crack. $K_{II}$, was the greatest when the load was directly adjacent to the crack $(g/a={\pm}1)$. Sliding friction caused a substantial increase of both $K_{I}^{max}$ and $K_{II}^{max}$. The effective Mode I stress intensity factors, $K_{eff}$, were the greatest at $g/a={\pm}1$, showing the significance of high shear stresses generated by loads adjacent to surface cracks. Such behavior of $K_{eff}$ suggests mechanisms for surface pitting by which surface cracks may propagate along their original plane under repeated rolling or sliding contact.

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SUS 304에 대한 Inconel 600의 Sliding 마모거동 (The Sliding Wear Behavior of Inconel 600 Mated with SUS 304)

  • 김훈;최종현;김준기;박기성;김승태;김선진
    • 한국재료학회지
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    • 제11권10호
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    • pp.841-845
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    • 2001
  • The steam generator tubes of power plant damaged by sliding wear due to flow-induced motion of foreign object. Amount of wear have been predicted by Achard's wear equation until now. However, there are large error and low reliability, because this equation regards wear coefficient(k) as constant. The sliding wears tests have been performed at room temperature to examine parameters of wear (wear distance, contact stress). The steam generator tube material for wear test is used Inconel 600 and foreign object material is used 304 austenite stainless steel. The sliding wear tests show that the amount of wear is not linearly proportional to the wear distance(for 374 austenite stainless steel). According to experimental result, wear coefficient is not constant k but function k(s) of wear distance. The newly modified wear predictive equation V=k(s)F have small error and high reliability.

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Sliding Mode Control of SPMSM Drivers: An Online Gain Tuning Approach with Unknown System Parameters

  • Jung, Jin-Woo;Leu, Viet Quoc;Dang, Dong Quang;Choi, Han Ho;Kim, Tae Heoung
    • Journal of Power Electronics
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    • 제14권5호
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    • pp.980-988
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    • 2014
  • This paper proposes an online gain tuning algorithm for a robust sliding mode speed controller of surface-mounted permanent magnet synchronous motor (SPMSM) drives. The proposed controller is constructed by a fuzzy neural network control (FNNC) term and a sliding mode control (SMC) term. Based on a fuzzy neural network, the first term is designed to approximate the nonlinear factors while the second term is used to stabilize the system dynamics by employing an online tuning rule. Therefore, unlike conventional speed controllers, the proposed control scheme does not require any knowledge of the system parameters. As a result, it is very robust to system parameter variations. The stability evaluation of the proposed control system is fully described based on the Lyapunov theory and related lemmas. For comparison purposes, a conventional sliding mode control (SMC) scheme is also tested under the same conditions as the proposed control method. It can be seen from the experimental results that the proposed SMC scheme exhibits better control performance (i.e., faster and more robust dynamic behavior, and a smaller steady-state error) than the conventional SMC method.

Application of frictional sliding fuse in infilled frames, fuse adjustment and influencing parameters

  • Mohammadi-Gh, M.;Akrami, V.
    • Structural Engineering and Mechanics
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    • 제36권6호
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    • pp.715-727
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    • 2010
  • An experimental investigation is conducted here to study the effects of applying frictional sliding fuses (FSF) in concrete infilled steel frames. Firstly, the influences of some parameters on the behavior of the sliding fuse are studied: Methods of adjusting the FSF for a certain sliding strength are explained and influences of time duration, welding and corrosion are investigated as well. Based on the results, time duration does not significantly affect the FSF, however influences of welding and corrosion of the constitutive plates are substantial. Then, the results of testing two 1/3 scale single-storey single-bay concrete infilled steel frames having FSF are presented. The specimens were similar, except for different regulations of their fuses, tested by displacement controlled cyclic loading. The results demonstrate that applying FSF improves infill behaviors in both perpendicular directions. The infilled frames with FSF have more appropriate hysteresis cycles, higher ductility, much lower deteriorations in strength and stiffness in comparison with regular ones. Consequently, the infills, provided with FSF, can be regarded as an engineered element, however, special consideration should be taken into the affecting parameters of their fuses.

슬라이딩 모드제어에 의한 교류 서보 전동기의 위치제어에 관한 연구 (Position Control for AC Servo Motor Using a Sliding Mode Control)

  • 홍정표;홍순일
    • 융합신호처리학회논문지
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    • 제5권3호
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    • pp.210-215
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    • 2004
  • 교류 서보전동기 동적 모델은 비선형이고 2차 저항이 변동영향이 많다. 이러한 복잡한 제어는 견실제어가 요구된다. 이러한 시스템의 동특성은 슬라이딩 모드제어를 사용함으로 파라미터나 외란 변동에 대하여 견실성을 달성할 수 있다. 본 논문은 교류 서보전동기에 의한 위치제어에 슬라이딩 모드 제어의 적용을 나타내었다. 제어방법이 유도되고 제어시스템이 설계되었다. 교류 서보전동기의 견실제어를 위해 외부 부하 파라미터에 기초한 설계방법이 제안되었다. 제안된 제어방법은 가변구조 제어기와 슬립주파수형 벡터제어에 기초하여 주어졌다. 시뮬레이션 결과는 관성모우먼트, 점성마찰 및 부하외란 변동에 결실함을 나타내었고 슬라이딩 모드를 적용한 제안된 설계방법이 유용한 것을 구명한다.

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고온고압 미끄럼/충격조건에서 마멸평가 변수 연구 (A Study on the Evaluation Parameter of Sliding/Impact Wear in a High Temperature and Pressure Water Condition)

  • 이영호;송주선;김형규;정연호
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2004년도 학술대회지
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    • pp.37-40
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    • 2004
  • The impact/sliding wear tests have been performed in high temperature high pressure water in order to evaluate the effect of spring shape on the wear behavior of a spring supported tube for nuclear fuel fretting study. The results indicate that the tube wear volume and the size of the wear scar are closely related to each spring shape. From the analysis of the wear scar, it is possible to extract the real worn area (Aw) from the size of the wear scar (At). In addition, we found that the wear volume has a linear relation with the real worm area rather than the size of wear scar and this was only determined by each spring shape in the high temperature and pressure water condition. From the above results, it is possible to evaluate the wear resistant spring using the correlation between the variation of the real worn area and the wear behavior at each spring.

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