• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.204-211
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• 2001

For the treatment of high compressibility number in the Reynolds equation, a new class of exponential high-order shape functions has been recently introduced in the literatures. In this paper a FE lubrication analysis method of high speed gas mechanical face seals is developed, implementing these shape functions. Their validity and usefulness are presented using 1-D gas bearing models. And a validation of developed 2-D analysis code is shown with a gas flat and spiral groove face seal models.

• Tribology and Lubricants
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• v.40 no.2
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• pp.54-60
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• 2024

This study experimentally identifies the effects of end shape, clearance, total damper length, journal eccentricity ratio, oil supply pressure, and oil flow rate on the damping coefficient of a squeeze film damper (SFD) with piston ring seal ends and a central groove. The SFD is composed of a lubricating fluid flowing between the outer race of a rolling element bearing and cartridge, along with an anti-rotation pin to prevent the rotation of the outer race. The device provides additional viscous damping to a rotating system. Additionally, piston ring seals attached at both ends of the damper increase the damping coefficient of the rotating system by reducing oil leakage. Because these different design conditions affect the damping coefficient of an SFD, we perform experiments including different conditions. Tests show that the damping coefficient increases significantly in the SFD with piston ring seal ends compared with the SFD with open ends. The damping coefficient also increases with increasing total damper length and journal eccentricity ratio, and decreases with increasing clearance. Additionally, in contrast to the trend observed for the SFD with open ends, the damping coefficient for the SFD with piston ring seal ends increases with increasing supply pressure and flow rate as the frequency decreases but shows consistent results as the frequency increases.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.283-288
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• 1999

The sealing performance of an elastomeric O-ring seat with a temperature gradient has been analyzed for the contact stress behaviors that develop between the O-ring seal and the surfaces with which it comes into contact. The leakage of an O-ring seal will occur when the pressure differential across the seal just exceeds the initial (or static) peak contact stress. The contact stress behaviors that develop in compressed O-rings, in common case of restrained geometry (grooved), are investigated using the finite element method. The analysis includes material hyperelasticity and axisymmetry. The computed FEM results show that the contact stress behaviors are related to a compression rate and a temperature gradient between the vacuum chamber with a groove and the contacting plate with a cooling jacket.

• Tribology and Lubricants
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• v.4 no.2
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• pp.68-75
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• 1988

서로 다른 그루브 깊이를 갖는 circumferentially-grooved 씨일들의 동특성 계수 및 누설량에 대한 실험결과를 분석하였다. 실험된 결과를 분석해 보면, 그루브 깊이가 증가함에 따라, 누설량이 서서히 증가함을 알수 있다. Smooth 씨일 및 damper 씨일과 비교할때, smooth 씨일은 최대의 direct stiffness를 가지며, 평균 씨일 간극의 증가함에 따라 direct stiffness가 감소한다. Effective damping에 있어서, circumferentially-grooved 씨일은 최소의 값을 가지는 반면, 누설량은 가장 적다. 이론과의 실험치 비교는 일반적으로 만족할만한 결과를 보인다.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.152-159
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• 2022

The role of the posterior palatal seal is important in retention of the maxillary complete denture. After taking the final impression, additional retention can be given to the maxillary denture through a mechanical method of forming a groove on master cast, but this is often overlooked in the clinical process. As a result, the posterior palatal seal is formed in a uniform way by the technician without considering the individual characteristics of the patient. Until now, various types of posterior palatal seal have been introduced by many people. This case report describes the process of manufacturing the maxillary complete denture by determining the position and form of an appropriate posterior palatal seal after considering the patient's anatomical palatal form and tissue displacement during function.

• Tribology and Lubricants
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• v.19 no.1
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• pp.9-14
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• 2003

The sealing performance of an elastomeric O-ring using the double layered material has been analyzed fer the contact stress behaviors that develop between the O-ring seal and the surfaces with which it comes into contact. The leakage of an O-ring will occur when the pressure differential across the seal Just exceeds the initial (or static) peak contact stress. The contact stress behaviors that develop in compressed O-rings, in common case of dovetail grooved geometry, are investigated using the finite element method. The FE analysis includes material hyperelasticity and axisymmetry. The computed FEM results show that the contact stress behaviors are related to the ratio of diameter between the inner ring and the outer ring, and the temperature of vacuum chamber.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.9
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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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• v.28 no.6
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• pp.283-288
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• 2012

In this study, a new sliding contact problem involving an elastomeric seal, a spherical particle and a hard coated steel counterface was modeled to investigate the detailed wear mechanisms related to the sealing surface. The model was also used to design the optimum coating conditions. A three-dimensional finite element contact problem was modeled and analyzed using the nonlinear finite element code, MARC. The deformed steel surface and stress distributions are presented for different coating layers and thicknesses. When the coating thickness is relatively small, the entrapped particle produces surface plastic deformations such as groove and torus. In addition, the sealing surface can be damaged by abrasive wear as well as fatigue wear. For a relatively thick and multi-layered coating, on the other hand, surface plastic deformation does not occur, and the amount of abrasive and fatigue wear is reduced. Therefore, the proposed contact model and results can be used in the design of various sealing systems, further intensive studies are required.

• Tribology and Lubricants
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• v.15 no.4
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• pp.297-303
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• 1999

O-rings in automotive engines are important components such as a coolant pipe, engine oil circulating lines and fuel injector for sealing that makes efficient performance of the engine. Life cycle of O-rings is effected in environments of the O-ring seal, like that applied pressure, working temperature, precompressed ratio and materials. It is related in extrusion, expansion and fatigue failure of O-rings. In this paper, an pressurized, compressed elastomeric O-ring inserted into a rectangular groove is analysed numerically using the nonlinear finite element method. The calculated FEM results showed that extrusion ratio and contact stress are strongly related to the gap clearance and edge radius of the groove.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.356-363
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• 2001

Piston seal is a device designed to prevent leakage in split connecctions or between relatively moving part. 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 Wearing by finite element analysis to understand Contact Behaviour Characters.