scholarly journals The Grooved Lip Effect on Reciprocating Hydraulic Rod Seal Performances in Transient Condition: Elastohydrodynamic Lubrication

2020 ◽  
Vol 25 (2) ◽  
pp. 11-21
Author(s):  
Y. Bahi ◽  
M. El Gadari ◽  
M. Rahmoune
Keyword(s):  
Computational Models ◽  
Current Model ◽  
Elastohydrodynamic Lubrication ◽  
Axial Direction ◽  
Transient Condition ◽  
Slight Effect ◽  
Lip Seal ◽  
Sealing Performance ◽  
Pattern Shape ◽  
Average Film Thickness

AbstractIt is commonly known that the sealing performance of dynamic seals is significantly influenced by the surface finish. To reduce friction effect and leakage ratio, new generations of grooved lip or shaft have emerged, but only two computational models were performed up to now with a textured elastomeric lip: spiral groove in the axial direction or micro-cavities according to the circumferential direction. However, if the numerical results have confirmed the slight effect of the grooved lip on the rotary lip seal performances, it seems relevant to investigate the influence of such grooves on the reciprocating hydraulic rod seal behavior.Thus, the scope of this work is to perform a parametric study of the grooved lip throughout a one-dimensional elastohydrodynamic model by taking into account the elasticity of the lip and the shaft roughness.After confirming the validity of the current model, numerical simulations have been performed and compared with experiments. The effect of lip grooves on the hydraulic rod seal behavior in outstroke and instroke shaft motion has been underlined. Thereby, it is shown that the leakage and the average film thickness are sensible to both the depth and the density of the lip groove. Additionally, a slight effect of the pattern shape is observed on the friction force.

scholarly journals A mixed thermal elastohydrodynamic lubrication model of rotary lip seal

2020 ◽  
Vol 103 (1) ◽  
pp. 003685041988190
Author(s):  
Xiaokai Huang ◽  
Shouwen Liu ◽  
Chao Zhang
Keyword(s):  
Simulation Study ◽  
Elastohydrodynamic Lubrication ◽  
Fluid Viscosity ◽  
Asperity Contact ◽  
Influence Of Temperature ◽  
Lip Seal ◽  
Sealing Performance ◽  
Proposed Model ◽  
Influence Of Temperature On ◽  
Lubrication Models

Rotary lip seal is used in various applications where the rotation shaft needs to be sealed, such as hydraulic pumps, fuel pumps, camshafts, crankshafts, and so on. Many thermal elastohydrodynamic lubrication models of rotary lip seal have been introduced, and most of these models neglect the asperity contact. This article proposes a mixed thermal elastohydrodynamic lubrication model of rotary lip seal, in which the microstructure of sealing lip surface, influence of temperature on fluid viscosity, and deformation of lip surface, as well as the asperity contact, are taken into consideration. Simulation study is carried out, and the results show that the asperity contact should not be neglected for analyzing the sealing performance of the rotary lip seal. The influence of speed on the sealing performance is also analyzed based on the proposed model.

scholarly journals Mixed elastohydrodynamic lubrication model of rotary lip seal with non-Gaussian surfaces: experimentation verification and numerical analysis on effects of sealed pressure

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110170
Author(s):  
Di Liu ◽  
Shaoping Wang ◽  
Jian Shi
Keyword(s):  
Rough Surface ◽  
Fluid Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Periodic Variation ◽  
Simulation Method ◽  
Height Distribution ◽  
Lip Seal ◽  
System A ◽  
Sealing Performance ◽  
Non Gaussian

Many published models can be used to analyse the sealing performance of rotary lip seal. The surfaces are normally assumed to be periodic variation. However, the quasi-randomness of surface height distribution should be considered, especially the non-Gaussian distribution. Hence, a mixed elastohydrodynamic lubrication model with non-Gaussian surfaces is proposed and used to analyse the effects of sealed fluid pressure on the seal performance in this paper. Based on digital filter and Johnson’s translator system, a rough surface simulation method is introduced to simulate non-Gaussian rough surface. Based on this method the mixed lubrication model with non-Gaussian surfaces is built. The proposed model is verified by comparing the simulation results to experimental observations. Furthermore, it is hardly to find the research focused on the effects of sealed pressure. Hence, the effects of sealed fluid pressure on the seal performance is focused.

Simulation of Plasto-Elastohydrodynamic Lubrication in Line Contacts of Infinite and Finite Length

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Tao He ◽  
Jiaxu Wang ◽  
Zhanjiang Wang ◽  
Dong Zhu
Keyword(s):  
Surface Roughness ◽  
Finite Length ◽  
3D Model ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Axial Direction ◽  
Contact Length ◽  
Line Contact ◽  
Line Contacts ◽  
3D Surface Topography

Line contact is common in many machine components, such as various gears, roller and needle bearings, and cams and followers. Traditionally, line contact is modeled as a two-dimensional (2D) problem when the surfaces are assumed to be smooth or treated stochastically. In reality, however, surface roughness is usually three-dimensional (3D) in nature, so that a 3D model is needed when analyzing contact and lubrication deterministically. Moreover, contact length is often finite, and realistic geometry may possibly include a crowning in the axial direction and round corners or chamfers at two ends. In the present study, plasto-elastohydrodynamic lubrication (PEHL) simulations for line contacts of both infinite and finite length have been conducted, taking into account the effects of surface roughness and possible plastic deformation, with a 3D model that is needed when taking into account the realistic contact geometry and the 3D surface topography. With this newly developed PEHL model, numerical cases are analyzed in order to reveal the PEHL characteristics in different types of line contact.

Effects of the radial force on the static contact properties and sealing performance of a radial lip seal

2014 ◽  
Vol 57 (6) ◽  
pp. 1175-1182 ◽  
Author(s):  
XiaoHong Jia ◽  
Fei Guo ◽  
Le Huang ◽  
LongKe Wang ◽  
Zhi Gao ◽  
...  
Keyword(s):  
Radial Force ◽  
Lip Seal ◽  
Sealing Performance ◽  
Static Contact

scholarly journals Inducing Implicit Arguments from Comparable Texts: A Framework and Its Applications

2015 ◽  
Vol 41 (4) ◽  
pp. 625-664 ◽  
Author(s):  
Michael Roth ◽  
Anette Frank
Keyword(s):  
Computational Models ◽  
Current Model ◽  
Implicit Argument ◽  
Implicit Arguments ◽  
Argument Realization ◽  
Projection Approach ◽  
Implicit And Explicit ◽  
Graph Based Model ◽  
A Current ◽  
Sentential Meaning

In this article, we investigate aspects of sentential meaning that are not expressed in local predicate–argument structures. In particular, we examine instances of semantic arguments that are only inferable from discourse context. The goal of this work is to automatically acquire and process such instances, which we also refer to as implicit arguments, to improve computational models of language. As contributions towards this goal, we establish an effective framework for the difficult task of inducing implicit arguments and their antecedents in discourse and empirically demonstrate the importance of modeling this phenomenon in discourse-level tasks. Our framework builds upon a novel projection approach that allows for the accurate detection of implicit arguments by aligning and comparing predicate–argument structures across pairs of comparable texts. As part of this framework, we develop a graph-based model for predicate alignment that significantly outperforms previous approaches. Based on such alignments, we show that implicit argument instances can be automatically induced and applied to improve a current model of linking implicit arguments in discourse. We further validate that decisions on argument realization, although being a subtle phenomenon most of the time, can considerably affect the perceived coherence of a text. Our experiments reveal that previous models of coherence are not able to predict this impact. Consequently, we develop a novel coherence model, which learns to accurately predict argument realization based on automatically aligned pairs of implicit and explicit arguments.

Wear Behavior of Rotary Lip Seal Operating in a Magnetorheological Fluid Under Magnetic Field Conditions

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Peng Zhang ◽  
Kwang-Hee Lee ◽  
Chul-Hee Lee
Keyword(s):  
Magnetic Field ◽  
Smart Materials ◽  
Wear Behavior ◽  
High Volume ◽  
Magnetorheological Fluid ◽  
Engine Oil ◽  
Wear Properties ◽  
Lip Seal ◽  
Sealing Performance ◽  
Stiffness And Damping

A magnetorheological fluid (MRF) is one of many smart materials that can be changed their rheological properties. The stiffness and damping characteristics of MRF can be changed when a magnetic field is applied. This technology has been successfully employed in various low and high volume applications, such as dampers, clutches, and active bearings, which are already in the market or are approaching production. As a result, the sealing performance of MRF has become increasingly important. In this study, the wear properties of seals with MRFs were evaluated by a rotary-type lip seal wear tester. The test was performed with and without a magnetic field. The leakage time was monitored during the tests in typical engine oil conditions. The results showed that the wear resistance of the seal with MRF was decreased under the magnetic field.

Formation of Lubricant Film in Rotary Sealing Contacts: Part II—A New Measuring Principle for Lubricant Film Thickness

1992 ◽  
Vol 114 (2) ◽  
pp. 290-296 ◽  
Author(s):  
G. Poll ◽  
A. Gabelli
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Lip Seal ◽  
Tribological System ◽  
Lip Seals ◽  
Magnetite Particles ◽  
Rotary Speed ◽  
Fluid Film Thickness ◽  
Insight Into

The development of models for the elastohydrodynamic lubrication of rotary lip seals requires the measurement of the film thickness under a real seal. A new method has been developed for this purpose which is based on the use of lubricant oils in which magnetite particles are suspended (so-called magnetic fluids). A change in the fluid film thickness will create a change in the impedance of the coil of the measuring circuit, the magnetic flux of which is directed through the oil film of the contact area. The advantage of this technique is that minimal modifications have to be applied to the tribological system under examination. Initial measurements carried out with a model rubber lip seal provided new insight into the build-up of a lubricant film as a function of the rotary speed and allowed comparison with the results of a theoretical model for the analysis of lip seal lubrication developed in parallel.

Thermo-elastohydrodynamic lubrication simulation of reciprocating rod seals under transient condition

2021 ◽  
Vol 153 ◽  
pp. 106603
Author(s):  
Chong Xiang ◽  
Fei Guo ◽  
Xiang Liu ◽  
Hong Fang ◽  
Yuming Wang
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Transient Condition ◽  
Rod Seals

Research on sealing performance of oil seals with micro-dimple texture on lips

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fuying Zhang ◽  
Yuanhao Zhang
Keyword(s):  
Peer Review ◽  
Surface Texture ◽  
Elastohydrodynamic Lubrication ◽  
Friction Torque ◽  
Pumping Rate ◽  
Content Type ◽  
Rotation Direction ◽  
Sealing Performance ◽  
Pumping Efficiency ◽  
Shaft Seals

Purpose The purpose of this paper is to study the pumping efficiency of oil seals with different surface textures at different speeds, and the influence of the rotation direction of triangular texture on the sealing performance was further analyzed. Design/methodology/approach Based on the theory of elastohydrodynamic lubrication and the pumping mechanism of rotary shaft seals, establishing a numerical model of mixed lubrication in oil seal sealing area. The model is coupled with the lip surface texture parameters and the two-dimensional average Reynolds equation considering the surface roughness. Findings The results show that the application of lip surface texture technology has obvious influence on the oil film thickness, friction torque and pumping rate of oil seal. The triangular texture has the most significant effect on the increase of pump suction rate. When the rotation direction of triangular texture is 315 degrees, the pumping rate of oil seal is the largest compared with the other seven directions. Originality/value The model has a comprehensive theoretical guidance for the design of new oil seal products, which provides a certain basis for the application of surface texture technology in the field of sealing in the future. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2020-0198/

Multilink for bilingual language production

2018 ◽  
Vol 22 (04) ◽  
pp. 687-688 ◽  
Author(s):  
IVA IVANOVA ◽  
DANIEL KLEINMAN
Keyword(s):  
Lexical Decision ◽  
Language Production ◽  
Computational Models ◽  
Current Model ◽  
Word Naming ◽  
Major Benefit ◽  
Theoretical Assumptions

A major benefit of computational models is their ability to demonstrate which theoretical assumptions are truly necessary to explain a pattern of data. Dijkstra, Wahl, Buytenhuijs, van Halem, Al-jibouri, de Korte, and Rekké (in press) have impressively shown with Multilink that it is possible to account for a range of findings from bilingual lexical decision, word naming, and forward and backward translation tasks with an integrated lexicon, without lateral connections between translation equivalents, and without inhibition. In this commentary, we consider the applicability of the current model to other multilingual language production tasks, and note where the model's assumptions might need revision as its scope is expanded.

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