• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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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.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.121-122
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• 2002

This paper presents contact behavior of an Polyperfluoroalkoxyethylene(PTFE) ring seals by a non-linear finite element method using the thermomechanical analysis. PTFE elastomer was assumed as odgen model for numerical analysis in FEM commercial code because elastomer has nonlinear behaviour character. The shape effects are investigated for sealing performance of ring seal in boundary conditions which as gas pressure, groove temperature and various O-ring seal models. Also contact stress and equivalent total strain are investicated. An O-ring seals was modeled four shape which are circle, two sunflower and X. The highest contact stress occurs at sunflower-ring seal with groove deapth of 0.35mm. the equivalent total strain of sunflower-ring seal is lower than that of the others under low gas pressure condition but under gas pressure condition over 4Mpa, that of sunflower-ring seal is higher. The calculated FEM results shows that the Sunflower-ring seal with groove depth of 0.35mm has excellent performance compared with other seal models.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1576-1580
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• 2007

Typical lip seals are widely used as sealing mechanism of rotary and reciprocating shaft. Double lip seal has comparatively high stiffness and dynamic radial eccentricity. Usually material of these seals is made of elastomer and nonlinear finite element analysis is required to analyze behaviour of this material because Young's modulus is varied with working load. In this paper, MSC MARC/MENTAT is used for nonlinear analysis of double lip seal with pressure variation and interference. The contact normal force of double lip seal between lip and shaft is analyzed to reduce power loss when shaft rotates.

• Elastomers and Composites
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• 제50권4호
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• pp.251-257
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• 2015

The rubber seal is a part inserted into servo cylinder to keep the air pressure constant. In order for efficient movements of the servo cylinder, the frictional coefficient of the rubber seal needs to be minimized while the sealing is maintained. In this work the friction characteristics of rubber seal specimen are tested on metal plate at various conditions. The experimental conditions include roughness level, applied pressure, lubrication, and rubbing speed. The design of experiment approach is taken to assess the effect of each parameter. The nonlinear frictional response of the rubber is applied to the FEM model simulating the servo cylinder movement. The result demonstrates that precise optimization of the servo cylinder movement must be preceded by preliminary experiments coupled with the theory and FEM model.

• 한국정밀공학회지
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• 제23권12호
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• pp.80-87
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• 2006

Seals are usually made from elastomer, a kind of rubber, and it has the non-linearity and hyper-elasticity. U-type seals are used to prevent the leakage of internal fluid sealed in hydraulic actuator because they have more excellent performance than O-rings or rectangular seals. As a core part of hydraulic actuator, U-type seal gives much effect on performance and reliability of actuator. This study considers an NBR U-type seal under high pressure of a hydraulic actuator, and provides its deformation, stress-strain characteristic and contact force using the non-linear finite element analysis. Analysis results are compared with the experimental ones performed by the self-developed testing equipment. Verification result shows that this study presents a good application process for the effective design of U-type seals under high operation pressure.

• Design & Manufacturing
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• 제14권4호
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• pp.1-10
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• 2020

The seal plays a role in preventing oil leakage when the lip and the rotating shaft come into contact with the fluid and air pressure. Recently, micro dimples or micro pockets are processed and used on the lubrication surfaces of thrust bearings, mechanical bearings, and piston rings. Compared to a smooth surface, micro dimples reduce friction and increase the life of parts. This paper analyzed various kinds of micro dimple shapes on the sealing surface, i.e. circle, rectangle, triangle, and trapezoid. For this purpose, Introduced the design of experiments to work out a micro dimple configuration, unlikely to be damaged from cracks and low in contact stress. As a result, the triangular dimple showed the best results. Optimal factors were dimple size 0.15 mm, dimple depth 0.0383 mm, dimple density 40%, and the maximum equivalent stress was 9.1455 MPa, and the maximum contact pressure was 9.6612 MPa. This paper analyzed the optimal shape of dimples by finite element analysis. As a research project, experiments and comparative analysis of micro dimple shapes are needed.

• Tribology and Lubricants
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• 제34권2호
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• pp.49-54
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• 2018

Hydraulic reciprocating seal has been widely used to prevent fluid leakage in hydraulic systems. Also, hydraulic reciprocating seal plays a significant role to provide lubricant film at contacting interface to minimize tribological problems due to sliding with counter material. To predict lifetime of hydraulic reciprocating seal, quantitative understanding of wear characteristics with respect to operating conditions such as normal force and sliding speed is needed. In this work, effect of sliding speed on wear of polyurethane (PU) hydraulic reciprocating seal were experimentally investigated using a pin-on-disk tribo-tester. The wear characteristics of PU specimens were quantitatively determined by comparing the confocal microscope data before and after test. It was found that the wear rate of PU specimens decreased from $4.9{\times}10^{-11}mm^3$ to $1.1{\times}10^{-11}mm^3/Nm$ as sliding speed increased from 120 mm/s to 940 mm/s. Also, it was observed that the friction decreased slightly as the sliding speed increased. Improvement of lubrication state with increasing sliding speed was likely to be responsible for this enhanced friction and wear characteristics. This result also suggests that decrease in sliding distance between PU elastomer and counter materials at lower sliding speed is preferred. Furthermore, the quantitative assessment of wear characteristics of PU specimen may be useful in prediction of lifetime of PU hydraulic reciprocating seal if the allowed degree of wear for failure of the seal is provided.

• 대한기계학회논문집A
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• 제32권9호
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• pp.733-739
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• 2008

The X-ring is a elastomer with X-shaped cross-section used as a mechanical seal or gasket. Such a X-ring was equipped in a groove and compressed between two or more parts, acts as a seal on the interface. This study aims to detect contact stress and deformed shape of a X-shaped ring shell under various compressive contact conditions. A contact stress analysis was carried out by finite element analysis. The effect of compression rates and thickness design variable was analyzed. X-ring kept up the double seal until a compression rate of 20%. The maximum stresses of the X-ring was occurred at the top and bottom corner. The maximum contact stress of X-ring was rapidly increased according with the compression rate. The X-rings with thickness design variable from 1.3 mm to 1.5 mm had comparative low stress levels.

• Tribology and Lubricants
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• 제25권4호
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• pp.225-230
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• 2009

Seals are very useful machine components in protection of leakage of lubricant or working fluid, and incoming of debris from outside. Various elastomer are widely used as sealing materials and the shaft surfaces are generally coated with high hardness material after heat treatment. It is generally known that the foreign debris and wear particles get stuck into sealing surface, the steel shaft surface can be damaged and worn by mainly abrasive wear. In this paper, using MARC, contact analysis are conducted to show the hard coated steel shaft surface can be fatigue failed by very small elastic particle intervened between seal and steel surface. Variations of contact and von-Mises stress distributions and contact half-widths with interference and coating thickness are presented. The maximum von-Mises stress occurs always in the coating layer or between coated layer/substrate interface. Therefore the coated sealing surface can be fatigued and then failed by very small particles. The results can be used in design of sealing surface and further studies are required.

• 한국전산구조공학회논문집
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• 제36권3호
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• pp.165-171
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• 2023

건설기계와 특장차의 상부와 하부 구조를 연결하는 로터리 조인트는 축과 하우징이 회전하면서 유압을 전달하는데 오일의 유로에 누유를 방지하기 위해 여러 개의 시일이 조립된다. 시일재료는 강성이 커서 조립에 어려움이 있기 때문에 자른 후 조립하는 방법을 모색하였다. 절단면의 모양은 L형과 /형으로 하였고 유압이 작용할 때 누유 기준은 절단면에 발생하는 접촉압력으로 하였다. 시일의 구조와 재료는 이중 탄성중합체로 구성되며 강성이 큰 PE 재질만 절단한 경우에 대하여 비선형 접촉 구조해석을 수행하였다. 연구결과 절단 길이가 짧을수록 누유 방지에 유리하며 PE와 하우징이 접촉하는 윗면보다 NBR과 PE가 접촉하는 아랫면으로 누유될 가능성이 큰 것으로 나타났다.