• Title, Summary, Keyword: Cylinder contact

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A Study on Wear Characteristics of Piston Running Part (피스톤 런닝부의 소재에 따른 마모특성 연구)

  • Jang, J.H.;Yi, H.K.;Joo, B.D.;Lee, J.H.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.375-378
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    • 2007
  • Abrasive wear between piston ring face and cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. Wear by abrasion are forms of wear caused by contact between a particle and solid material. Abrasive wear is the loss of material by the passage of hard particles over a surface. From the pin-on-disk test, particle dent test and scuffing test, abrasive wear characteristics of diesel engine cylinder liner-piston ring have been investigated. Pin-on-disk test results indicate that abrasive wear resistance is not simply related to the hardness of materials, but is influenced also by the microstructure, temperature, lubricity and micro- fracture properties. In particle dent test, dent resistance stress decreases with increasing temperature. From the scuffing test by using pin-on-disk tester, scuffing mechanisms for the soft coating and hard coating were proposed and experimentally confirmed.

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Automotive Manual Transmission Clutch System Modeling for Foot Effort Hysteresis Characteristics Prediction (자동차 수동 변속기 클러치 시스템의 답력 이력 특성 예측 모델)

  • Lee, Byoung-Soo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.5
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    • pp.164-170
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    • 2008
  • A typical clutch system for automotive manual transmissions transfers hydraulic pressure generated by driver's pedal manipulation to the clutch diaphragm spring. The foot effort history during the period of push is different than the period of the clutch pedal's return. The effort or load difference is called clutch foot effort hysteresis. It is known that the hysteresis is caused by friction. The frictional force and moment are produced between various component contact points such as between the rubber seal and the inner wall inside the hydraulic cylinder and between the diaphragm spring and the pressure plate, etc. Understanding the clutch pedal foot effort hysteresis is essential for a clutch release system design and analysis. The dynamic model for a clutch release system is developed for the foot effort hysteresis prediction and a simulation analysis is performed to propose a tool for analysing a clutch system.

Wear Characteristics of AlBC for Piston Head of Power Servo Cylinder (Power 서보 실린더의 피스톤 헤드용 AlBC의 마멸 특성)

  • Cho, Yon-Sang;Park, Heung-Sik
    • Tribology and Lubricants
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    • v.27 no.2
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    • pp.65-70
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    • 2011
  • The power servo cylinder for driving accurately turbine stop valve of an atomic power plant is necessary to do turn-over owing to a leakage of oil and a structure problem, especially, it of a power plant be in demand a high quality standard depends entirely on import. There are much problem that the AlBC be to used as a material of piston head in cylinder are caused by wear. Therefore, it is necessary to examine friction characteristics of it. In this study, wear test experiments was carried out with AlBC and SCM440, using reciprocating friction tester of pin on disk. This result was shown that the wear mechanism of AlBC on working condition is adhesive wear and the maximum temperature of infra redray thermal image of frictional surface show over 2 mm from contact surface of pin and disk.

A Study on the Effects of the Design Parameters and Sealing Mechanism of the Exhaust Gas in Engine Exhaust System (엔진 배기계의 배기가스 누설 메카니즘과 설계인자들의 영향에 관한 연구)

  • Choi, B.L.
    • Journal of Power System Engineering
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    • v.14 no.4
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    • pp.37-42
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    • 2010
  • This paper deals with the sealing mechanism of the gasket component and the effects of design parameters for the exhaust manifold. The finite element model includes hot-end exhaust system and a simplified gasket model supplied by ABAQUS software. The mechanical behaviors of bead and body of a gasket are measured after several times of cyclic loads by gasket supplier. From the finite element analysis due to the cyclic thermal loads, the flange of exhaust manifold shows thermal expansion and contraction in longitudinal direction as well as convex and concave deformations with respect to the engine cylinder head. And, the contact pressures of the gasket beads suddenly changes by normal deformation of inlet flanges. Therefore, the magnitudes of contact pressures could be used to determine the sealing characteristics of the exhaust gas in the exhaust system. The distributions of contact pressures in gasket bead lines shows a good agreement with the engine test results.

Simulation Method for Thermal appropriate Desing of Compound Cylinder using Bondgraph Modeling (원통결합부의 열특성 최적설계를 위한 예측 시뮬레이션 방법)

  • 민승환;박기환;이선규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.635-640
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    • 1996
  • A thermo-elastic system in the production machine has highly nonlinear dynamic characteristics. In general, the finite element method is utilized for accurate analysis. However, it requires large computing time. Thus, thermo-elastic systems are usuallymodeled as electric and fluid system using lumped para,eter. In this paper. we propose the bondgraph model and transient simulation methodology of thermo-elastic system in consideration of various boundary and joint contact conditions. Consequently, the proposed method ensures a possibility of its on-line compensation about undesirable phenomena by using real time estimate process and electronic cooling device for thermal appropriate behavior. Thermo-elastic model consisting of bush and shaft including contact condition is presented.

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Evaluation of APR1400 Steam Generator Tube-to-Tubesheet Contact Area Residual Stresses

  • KIPTISIA, Wycliffe Kiprotich;NAMGUNG, Ihn
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.15 no.1
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    • pp.18-27
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    • 2019
  • The Advanced Power Reactor 1400 (APR1400) Steam Generator (SG) uses alloy 690 as a tube material and SA-508 Grade 3 Class 1 as a tubesheet material to form tube-to-tubesheet joint through hydraulic expansion process. In this paper, the residual stresses in the SG tube-to-tubesheet contact area was investigated by applying Model-Based System Engineering (MBSE) methodology and the V-model. The use of MBSE transform system description into diagrams which clearly describe the logical interaction between functions hence minimizes the risk of ambiguity. A theoretical and Finite Element Methodology (FEM) was used to assess and compare the residual stresses in the tube-to-tubesheet contact area. Additionally, the axial strength of the tube to tubesheet joint based on the pull-out force against the contact joint force was evaluated and recommended optimum autofrettage pressure to minimize residual stresses in the transition zone given. A single U-tube hole and tubesheet with ligament thickness was taken as a single cylinder and plane strain condition was assumed. An iterative method was used in FEM simulation to find the limit autofrettage pressure at which pull-out force and contact force are of the same magnitude. The joint contact force was estimated to be 20 times more than the pull-out force and the limit autofrettage pressure was estimated to be 141.85MPa.

Design of Capacitive Sensor for Measuring the Position of the Piston in Hydraulic Cylinder (유압 실린더 내 피스톤 위치측정을 위한 정전용량 센서 설계)

  • Lee, Soeng-hwi;Lee, Jae-gun;Kang, Yong-joo;Hong, Ic-pyo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.509-512
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    • 2015
  • In this paper, several capacitive sensors for measuring the position of the piston in hydraulic cylinder was studied and designed. The inductive LVDT sensor has been widely used to measure the position of the piston because of its high accuracy, but this type of sensor is very expensive and has difficulty in use because of its complexity. To overcome these disadvantages, we studied the optimized non-contact capacitive sensors and designed several capacitive sensors for accurate measuring the location of piston in hydraulic cylinder. The proposed capacitive sensor has the possibility of practical use for hydraulic cylinder through experiments.

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Crevice Corrosion Study of Materials for Propulsion Applications in the Marine Environment

  • Deflorian, F.;Rossi, S.;Fedel, M.;Zanella, C.;Ambrosi, D.;Hlede, E.
    • Corrosion Science and Technology
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    • v.14 no.6
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    • pp.288-295
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    • 2015
  • The present work addresses crevice and galvanic corrosion processes occurring at the cylinder head gasket/cylinder head interface and cylinder head gasket/cylinder liner interface of four-stroke medium-speed diesel engines for marine applications. The contact between these systems and the marine environment can promote formation of demanding corrosion conditions, therefore influencing the lifetime of the engine components. The electrochemical behavior of various metals and alloys used as head gasket materials (both ferrous alloys and copper alloys) was investigated. The efficacy of corrosion inhibitors was determined by comparing electrochemical behavior with and without inhibitors. In particular, crevice corrosion has been investigated by electrochemical tests using an experimental set-up developed starting from the requirements of the ASTM G-192-08, with adaptation of the test to the conditions peculiar to this application. In addition to the crevice corrosion resistance, the possible problems of galvanic coupling, as well as corrosive reactivity, were evaluated using electrochemical tests, such as potentiodynamic measurements. It was possible to quantify, in several cases, the corrosion resistance of the various coupled materials, and in particular the resistance to crevice corrosion, providing a basis for the selection of materials for this specific application.

An Experimental Study on The Friction Coefficient of Rubbers for Clutch Master Cylinder Cup-Seals (클러치 마스터실린더 컵-시일 고무의 마찰계수 실험 연구)

  • 이재천;임문혁;이병수;장지현;정용승;허만대;최병기
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.5
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    • pp.112-118
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    • 2003
  • The friction coefficients of the rubber for clutch master cylinder were experimentally measured in this study. The cylindrical rubber samples for primary cup-seal and secondary cup-seal were tested against the aluminum or the steel plates of master cylinder housing under the various conditions of brake oil temperatures and normal loads. Dry sliding friction coefficients were also measured under various load conditions. The test revealed following results. First, the friction coefficient under fluid lubrication condition in general decreases, as the oil temperature or normal load increases. Second, the steel plate of low surface roughness yielded comparatively low friction coefficient on the range of 0.30∼0.67. On the other hand, the aluminum plate of high surface roughness yielded high friction coefficient on the range of 0.31∼1.15. Third, the friction coefficient of dry surface contact decreases as the normal load increases. This is contrary to the general principle of friction coefficient between metal plates.

Influence of Groove Location on Lubrication Characteristics of the Piston and Cylinder in a Linear Compressor (그루브 위치가 리니어 압축기용 피스톤과 실린더의 윤활특성에 미치는 영향)

  • Jeon, W.J.;Son, S.I.;Lee, H.;Kim, J.W.;Kim, K.W.
    • Tribology and Lubricants
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    • v.32 no.1
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    • pp.24-31
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    • 2016
  • In this paper hydrodynamic lubrication analysis is carried out to investigate the effects of groove location on the lubrication performance of a piston and cylinder system in a linear compressor. The rectangle shaped grooves having a constant groove depth and width are applied on the lubrication area of the piston. The Universal Reynolds equation is used to calculate the oil film pressure, and the Elrod algorithm with the finite different method is used to solve the governing equation. The JFO boundary condition is applied to predict cavitation regions. Transient analysis for different locations of the grooves on the piston is carried out using the typical operating condition of the linear compressor in order to estimate the variations of frictional power losses and minimum film thicknesses. When the grooves are applied on the lubrication area, both the frictional power loss and the minimum film thickness decrease. The frictional power loss can be reduced effectively, while maintaining a minimum film thickness to enable the piston operation without direct contact with the cylinder surface, by means of choosing a proper location of the grooves. The optimum location of the grooves to improve a lubrication performance depends on the operation condition or the system requirements specification.