• Title, Summary, Keyword: Cylinder contact

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Forced vibration of the elastic system consisting of the hollow cylinder and surrounding elastic medium under perfect and imperfect contact

  • Akbarov, Surkay D.;Mehdiyev, Mahir A.
    • Structural Engineering and Mechanics
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    • v.62 no.1
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    • pp.113-123
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    • 2017
  • The bi-material elastic system consisting of the circular hollow cylinder and the infinite elastic medium surrounding this cylinder is considered and it is assumed that on the inner free face of the cylinder a point-located axisymmetric time harmonic force, with respect to the cylinder's axis and which is uniformly distributed in the circumferential direction, acts. The shear-spring type imperfect contact conditions on the interface between the constituents are satisfied. The mathematical formulation of the problem is made within the scope of the exact equations of linear elastodynamics. The focus is on the frequency-response of the interface normal and shear stresses and the influence of the problem parameters, such as the ratio of modulus of elasticity, the ratio of the cylinder thickness to the cylinder radius, and the shear-spring type parameter which characterizes the degree of the contact imperfectness, on these responses. Corresponding numerical results are presented and discussed. In particular, it is established that the character of the influence of the contact imperfection on the frequency response of the interface stresses depends on the values of the vibration frequency of the external forces.

The Subsurface Stress Field Caused by Both Normal Loading and Tangential Loading

  • Koo Young- Phi;Kim Tae-Wan;Cho Yong-Joo
    • Journal of Mechanical Science and Technology
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    • v.19 no.11
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    • pp.1967-1974
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    • 2005
  • The subsurface stress field caused by both normal loads and tangential loads has been evaluated using the rectangular patch solution. The effect of tangential loading on the subsurface stress field has been investigated in detail for both the cylinder-on-cylinder contact and a spur gear teeth contact. For the cylinder-on-cylinder contact, the subsurface stress fields are moved more to the direction of tangential loads and the positions where the maximum stress occur are getting closer to the surface with the increasing tangential loads. The subsurface stress fields of the gear teeth contact are expanded more widely to the direction of tangential loads with the increasing tangential loads. The friction coefficient of a gear teeth contact is low because they are operated in a lubricated condition, and therefore surface tractions in the EHL condition hardly affect on the subsurface stress field.

Analysis of the Room Temperature Fitting Process for Assembling the Part(Valve Seat and Cylinder Head) (Valve Seat/Cylinder Head 단품조립을 위한 상온압입공정 해석)

  • Bae, J.H.;Kim, M.S.;Woo, T.K.;Kim, T.J.;Ho, J.D.;Kim, C.
    • Transactions of Materials Processing
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    • v.18 no.8
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    • pp.607-616
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    • 2009
  • There are three sub-processes associated with the assembly of the valve seat and cylinder head; heat fitting, cold fitting, and shrink fitting. In the heat fitting stage, the cylinder head is heated to a specified temperature and then squeezed toward the outer diameter of the valve seat. The cold fitting process cools the valve seat and safely squeezes it toward the inner diameter of cylinder head. However, these methods increased the installations & running cost and curtailed productivity. To address these problems, we analyzed the shrink fitting process using the contact pressure caused by fitting interference between the outer diameter of the valve seat and the inner diameter of the cylinder head. In this study, a closed form equation for predicting the contact pressure and fitting load is proposed. For quality control of the assembly line, principal factors of the shrink fitting process influenced in contact pressure were simulated by the FEM. Actual loads measured in the field showed good agreement with the results obtained by theoretical and finite element analysis.

Finite Element Analysis of Contact Behavior Characteristics in LPG Filling Unit Depending on Multi-ball/Cylinder Rolling Friction Motions (LPG 충전기에서 다수 볼-실린더의 구름마찰운동에 따라 달라지는 접촉거동특성에 관한 유한요소해석)

  • Kim Chung-Kyun
    • Journal of the Korean Institute of Gas
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    • v.10 no.2
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    • pp.27-32
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    • 2006
  • In this paper, the contact stress and friction force between multi-balls and rolling friction contact surfaces of two cylinders have been presented using a finite element analysis. The multi-balls for a rolling friction motion may be contacted with a reciprocating mechanism of a parallel cylinder and a misaligned cylinder in a LPG filling unit. The FEM computed results indicate that SiC ceramic and SUS 304 balls show a high contact stress and friction force on the contact spot of rolling balls. But the PEEK balls show a low contact stress and friction loss due to a high flexibility of a PEEK polymer. In this study, we may recommend SiC and SUS 304 balls for high compressive loadings between a multi-ball and a cylinder contact mechanisms and PEEK balls for a low compressive force. And the misalignment between two cylinders should be restricted for a low contact stress and friction loss, especially.

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Numerical Study on the Sealing Safety of a Valve Packing in a LPG Cylinder (LPG 용기용 밸브패킹의 누설안전에 관한 수치적 연구)

  • Kim, Chung-Kyun;Kim, Tae-Hwan
    • Journal of the Korean Institute of Gas
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    • v.11 no.1
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    • pp.34-39
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    • 2007
  • In this paper, the FEM result has been presented for a sealing safety between a valve packing and a valve seat during a open and close operation in a LPG cylinder. The sealing operation of a LPG valve is completed when the valve packing in which is made by a nylon-66 polymer is to stop a LP gas flow, which flows out from the outlet of a brass pipe in a LPG cylinder. The contact sealing mechanism of the valve may be classified by a flat contact of an unused valve packing and a circular groove contact of an used valve packing in a current LPG valve. Based on the FEM and experimental investigations the sealing force, 4.9 MPa for a flat contact mode of the unused valve packing is a little high compared to that of the used valve packing, which shows a circular groove contact geometry against a valve seat. But these sealing pressures for two contact modes are very low compared to the ultimate strenath 83 MPa of the nylon-66 and this may be designed with a excess strength of the valve.

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on Contact Behaviour Characters of ACGT Seal for High pressure using Finite Element Analysis (고압용 ACGT 시일의 접촉거동 특성에 대한 유한요소 해석)

  • 최동열;김성원;김청균
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.350-355
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    • 2001
  • Minimum clearance between the piston seal groove of a piston and cylinder bore to ensure against extrusion of the piston seal and leakage of working fluids is an important design parameter for a seal designer in hydraulic cylinder application. Contact force, critical pressure at which extrusion occurs, leakage rate, fluid film thickness and friction force have been analyzed for some design parameter such as clearance between cylinder wall piston, depth of rectangular groove and pressure of sealed hydraulic fluid. In this paper, we analyze displacement and stress of ACGT seal by finite element analysis to understand Contact Behaviour Characters

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The Behavior and Characterization Analysis of Elastomer Seal for High Speed Pneumatic Cylinder (고속 공기압 실린더의 거동 및 특성 해석 기술 연구)

  • Hur, Shin;Woo, Chang-Su;Kim, Dong-Soo;Kim, Young-Seok
    • Proceedings of the KSME Conference
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    • pp.1215-1220
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    • 2008
  • The aim of this paper is to perform a finite element analysis that will have the ability to predict the seal performance characteristics, such as deformation, contact load and friction and also is to provide a means of potential seal designs, which can reduce the time and cost of designing the performance of the seal. The material property tests of elastomer seal are performed to obtain the hyperelastic properties and The Mooney-Rivlin constants are determined from these test results. A 2D modelling of the seal cross section is performed to simulate the contact behavior between the seal on the piston and the cylinder bore under operation conditions. The deformation behavior, contact load and friction of an elastomer seal is analyzed by a finite element method which performs three analytic phases of interference fit, the variations of pneumatic pressure and piston movement under the operational conditions.

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Experimental Study of Close-Contact Melting of Phase-Change Medium Partially Filled in a Horizontal Cylinder (수평원관내 부분적으로 채원진 상변화물질의 융해과정)

  • 서정세;노승탁
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2249-2260
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    • 1995
  • An experiment of close contact melting of phase-change medium partially filled in an isothermally heated horizontal cylinder is performed which involves the volume expansion of liquid induced by the solid-liquid density difference. The solid-liquid interface motion and the free surface behavior of liquid were reported photographically. The experimental results show that the curvature of upper solid-liquid interface varied to flat as melting progresses. In addition to the varying interface shape, the melting rate increases with the lower initial height of solid and the free surface height of liquid increases linearly. The experimental results of molten mass fraction were expressed in a function of dimensionless time Fo.Ste$^{3}$4/ and agreed well with the analytical solutions.

Sliding Contact Analysis between Chromium Plated Hydraulic Cylinder Rod and Seals (크롬 도금한 유압 실린더 로드와 시일 사이의 미끄럼접촉 해석)

  • Park, Tae Jo;Kim, Min Gyu
    • Journal of Drive and Control
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    • v.15 no.1
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    • pp.10-15
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    • 2018
  • The hydraulic cylinder seals are used not only to protect leakage of the working fluids but also to prevent incoming of foreign particles into the system. Chromium plating is generally applied to improve corrosion and wear resistance. It has been noticed that sealing surface damage occurs due to the hard foreign/wear particles contained in the hydraulic oil. In this study, a three-bodied sliding contact problem related with a PTFE seal, a spherical particle and chrome-plated steel substrate is modeled to investigate the relations to wear mechanism. Using the nonlinear finite element software, MARC/MENTAT, the deformed shapes, the von Mises and first principal stress distributions with plating thickness were compared. The sealing surface was mainly abraded by hard particles embedded in the seal. The plastic deformation of the steel substrate decreased with thicker plating. Hence it could be more effective to coat the sealing surface of a hydraulic cylinder with a hard material such as TiN, TiC and DLC.

Proposition of Copper - Foil Magnetic Sensor for the Two-axis Remote Measurement of Bending Vibration of a Non-metallic Cylinder (비금속 배관에서의 원격 2축 굽힘 진동 측정을 위한 동박 패치형 자기 센서의 제안)

  • Kim, Jin-Ki;Han, Soon-Woo;Kim, Yoon-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.4
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    • pp.381-385
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    • 2008
  • This paper suggests a non-contact sensor for measuring bending vibration of a non-metallic cylinder in two orthogonal directions simultaneously. Recent research shows that a solenoid can pick up bending vibrations of a nonmetallic cylinder based on the reversed Lorentz force mechanism if an electrically conductive patch is attached to the cylinder. In this work, pairs of specially designed patches are used to make two independent paths for the current induced by bending vibrations, which enables the measurement of bending vibrations along two orthogonal directions simultaneously. The working performance of the developed sensor was verified by using two accelerometers.