• 제목/요약/키워드: Contact normal stress

검색결과 105건 처리시간 0.027초

접촉식 밀봉 링의 변형거동 안정성에 관한 유한요소해석 (Finite Element Analysis on the Deformation Behavior Stability of Contact Sealing Rings)

  • 김청균;김도현
    • 한국가스학회지
    • /
    • 제16권5호
    • /
    • pp.47-51
    • /
    • 2012
  • 본 연구에서는 3가지의 서로 다른 단면형상을 갖는 밀봉 링의 변형거동 안정성을 FEM으로 해석하였다. NBR 소재로 제조한 밀봉 링의 변형거동 안정성을 고찰하기 위해 초기 압축률로 25%를 적용하였다. 작동유체의 압력을 최대 $25kgf/cm^2$까지 올렸을 때 발생한 최대변형률, 최대응력, 최대접촉법선응력을 해석하였다. FEM 결과에 의하면, 밀봉 링의 중심부에 빈 공간을 확보한 중공오링과 중공사각링의 최대 변형률은 기존 오링에 비해 높아졌지만, 최대응력과 최대접촉법선응력은 떨어지는 것으로 나타났다. 결국, 밀봉 링이 장수명의 내구 안정성을 확보하기 위해서는 중심부에 빈 공간을 확보하는 것이 권장된다. 그렇지만, 접촉식 밀봉 링의 밀봉 안전성을 확보하기 위해서는 밀봉 링을 하나의 몸체로 설계하는 것이 바람직하다.

소수력 터빈용 기계평면시일의 최적형상설계에 관한 연구 (Optimized Sealing Profile Design of Mechanical Face Seals for a Hydro-power Turbine)

  • 김청균;김정일;신인철;임광현
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 한국신재생에너지학회 2006년도 춘계학술대회
    • /
    • pp.499-502
    • /
    • 2006
  • This paper presents computed results of FEM analysis on the tribological contact behaviors of a primary sealing components of mechanical face seals for a small hydro-power turbine. The FEM computed results present that the contact area between seal rings and seal seats is very important for a good tribological performance such as low friction heating, low wear, high contact normal stress in a primary seal ing components. Based on the FEM computation, model III in which has a small sealing contact area shows low dilatation of primary sealing components, and high contact stress between a seal ring and a 1)seal seat.

  • PDF

Determination of stress state in chip formation zone by central slip-line field

  • Andrey Toropov;Ko, Sung-Lim
    • 한국정밀공학회:학술대회논문집
    • /
    • 한국정밀공학회 2003년도 춘계학술대회 논문집
    • /
    • pp.577-580
    • /
    • 2003
  • Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along single of several shear surfaces. separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests new approach to the constriction of slip-line field, which Implies uniform compression in chip formation zone. On the base of given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination have been considered. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model could be useful in solution of various problems of machining.

  • PDF

표면 강화처리 레일의 마모 및 피로 특성 (Wear and Fatigue Properties of Surface-Hardened Rail Material)

  • 장세기;편영식
    • 한국생산제조학회지
    • /
    • 제25권5호
    • /
    • pp.380-385
    • /
    • 2016
  • Railway tracks are repeatedly overstressed and damaged owing to increase in passing tonnage and numerous contact cycles between wheels of train and rails. In order to ensure safe train operation, heat-treated rails are used in addition to regular inspection and maintenance of these rails. Normal rails were treated using ultrasonic nanocrystal surface modification (UNSM) to strengthen the surface of rails. A few changes in surface properties were detected with respect to hardness and compressive residual stress after UNSM treatment. Wear and rolling contact fatigue tests were performed using rails whose surfaces were hardened by UNSM and heat-treated rails. The amount of wear and fatigue life cycles were measured to estimate the effect of UNSM on the rail material. The material of the surfacehardened rail showed improved wear and rolling contact fatigue properties.

고체표면에 응축된 물 분자의 윤활특성에 대한 분자시뮬레이션 연구 (Lubrication Characteristics of Condensed Water Molecules at Solid Surface through Molecular Simulation)

  • 김현준
    • Tribology and Lubricants
    • /
    • 제37권5호
    • /
    • pp.195-202
    • /
    • 2021
  • This paper presents a numerical analysis of the lubrication characteristics of condensed water molecules on a solid surface by conducting molecular dynamics simulations. We examine two models consisting of a simple hexahedral substrate with and without water molecules to reveal the lubrication mechanism of mono-layered water molecules. We perform a sliding simulation by contacting and translating a single asperity on the substrate under various normal loads. During the simulation, we measure the friction coefficient and atomic stress. When water molecules were interleaved between solid surfaces, atomic stress exerted on individual atom and friction coefficient were smaller than those of model without water molecule. Particularly, at a low load, the efficacy of water molecules in the reduction of atomic stress and friction is remarkable. Conversely, at high loads, water molecules rarely lubricate solid surfaces and fail to effectively distribute the contact stress. We found a critical condition in which the lubrication regime changes and beyond the condition, significant plastic deformation was created. Consequently, we deduce that water molecules can distribute and reduce contact stress within a certain condition. The reduced contact stress prevents plastic deformation of the substrate and thus diminishes the mechanical interlocking between the asperity and the substrate.

차륜 답면과 레일의 경계영역에서의 마모 특성 (Wear characteristics depended on Wear Index in Wheel-Rail Interface)

  • 안종곤;권석진;손영진;김호경
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2011년도 춘계학술대회 논문집
    • /
    • pp.560-567
    • /
    • 2011
  • Wheel and rail wear is a fundamental and complicate problem in railway field. The life of railway is usually limited by wear. The wheel surface is subjected to high normal and tangential contact stress. The removal of material from the surface by wear is function of the sliding and contact stress. In the present paper, the wear characteristic depended on slip rate, contact pressure and temperature are investigated and is used to twin disc tester. The result shows that the wear in wheel-rail interface is remarkably depended on slip rate and contact pressure.

  • PDF

차륜 답면과 레일의 경계영역에서의 마모 특성 (Wear Characteristics Depended on Wear Index in Wheel-Rail Interface)

  • 김문기;안종곤;김성권;권석진;이희성
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
    • /
    • pp.1000-1007
    • /
    • 2011
  • Wheel and rail wear is a fundamental and complicate problem in railway field. The life of railway is usually limited by wear. The wheel surface is subjected to high normal and tangential contact stress. The removal of material from the surface by wear is function of the sliding and contact stress. In the present paper, the wear characteristic depended on slip rate, contact pressure and temperature are investigated and is used to twin disc tester. The result shows that the wear in wheel-rail interface is remarkably depended on slip rate and contact pressure.

  • PDF

실험계획법을 활용한 승용차용 등속조인트 설계기법 연구 (Study on the Design Methodology of Constant Velocity Joints for Passenger Cars using DOE)

  • 정창현;정도현;배원락
    • 한국자동차공학회논문집
    • /
    • 제16권6호
    • /
    • pp.121-133
    • /
    • 2008
  • We presented design methodology of constant velocity joint for passenger cars using design of experiment. On the basis of contact normal stress of internal components of constant velocity joints, we performed a sensitivity analysis of several design parameters. And then we performed robust design and optimization design process. As a result, we could find robust design and also propose the optimized design. Presented design process would be very helpful for engineers who are suffer for new constant velocity joint design.

부품간의 접촉을 고려한 유연체모델을 이용한 엔진 밸브트레인의 동특성 해석 (Dynamic Analysis of Engine Valve Train with Flexible Multibody Model Considering Contact between Components)

  • 황원걸;성원석;안기원
    • 한국자동차공학회논문집
    • /
    • 제19권1호
    • /
    • pp.125-132
    • /
    • 2011
  • The dynamic characteristics of valve train are responsible for the dynamic performances of engine. We derived the equation of motion for 6 degrees of freedom model of the valve train. Computer model is also developed with flexible multibody model considering contact between components. The simulation results with these two models are compared with experimental results. We investigated the effect of the two spring models, TSDA (Translational Spring Damper Actuator) element and flexible body model, on the valve behavior and spring force. It is found that the dynamic behavior of the two models are not very different at normal operational velocity of the engine. By modeling contact between cam and tappet, the stress distributions of the cam were found. Using stress distribution obtained, contact width and contact stresses of the cam surface were calculated with Hertz contact theory.