Elastohydrodynamic Lubrication

A special issue of Machines (ISSN 2075-1702). This special issue belongs to the section "Friction and Tribology".

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 10516

Special Issue Editor

Tribology Group, Imperial College London, London SW7 2AZ, UK
Interests: boundary lubrication; wear measurements; additives; fuel lubricity; EHL friction; MEMS; mechanochemistry; greases

Special Issue Information

Dear Colleagues,

It has been nearly 80 years since the first research work was published on elastohydrodynamic lubrication (EHL). Thereafter, extensive research work has broadened our EHL knowledge utilising both numerical modelling methods and advancing experimental techniques. EHL is a lubrication regime generally happens between non-conformal surfaces, in which applied load on a small contact area results in very high local pressure typically ranging from 1 to 3 GPa. This high contact pressure leads to an increase in lubricant viscosity and elastic deformation of surfaces. Such phenomenon can be widely observed in lubricated machine components, such as rolling bearing, gears, cams and tappets, vane pumps, etc. It, therefore, requires better understanding of EHL to optimize lubricant formulation, increase machine efficiency and durability, and improve machine performance.

This Special Issue welcomes researchers to present their recent progress and insights into the field of EHL and deliver guidance to both academia and industries. Research areas include, but are not limited to, EHL traction, film thickness, contact mechanics, surface engineering, machine efficiency, rheology, and mechanochemistry.

Dr. Jie Zhang
Guest Editor

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Keywords

  • elastohydrodynamic lubrication (EHL)
  • EHL traction
  • EHL film thickness
  • numerical solution
  • Hertzian contact
  • surface roughness
  • temperature distribution
  • shear stress
  • rolling bearing

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Published Papers (4 papers)

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Research

19 pages, 6159 KiB  
Article
Thermal Elastohydrodynamic Analysis of a Worm Gear
by Marko Tošić, Roland Larsson, Karsten Stahl and Thomas Lohner
Machines 2023, 11(1), 89; https://doi.org/10.3390/machines11010089 - 10 Jan 2023
Cited by 6 | Viewed by 2783
Abstract
This study explores the elastohydrodynamic lubrication (EHL) between the contacting tooth flanks of a worm gear with nonconjugate meshing action. The contact is characterized by a slender-like elliptical shape and high sliding. The geometry and contact conditions for the considered worm gear were [...] Read more.
This study explores the elastohydrodynamic lubrication (EHL) between the contacting tooth flanks of a worm gear with nonconjugate meshing action. The contact is characterized by a slender-like elliptical shape and high sliding. The geometry and contact conditions for the considered worm gear were obtained using tooth contact analysis. Based on that, the complete area of the worm gear contact was analyzed using a validated numerical EHL model considering non-Newtonian, thermal, and transient effects. The geometrical and kinematic design factors that influence EHL film formation in worm gears were identified and discussed. The results show the specific characteristics of worm gear EHL contacts, such as the very slender contact in the tooth root flank area, which diminishes the effect of the entrainment speed on film thickness. EHL film formation could be supported by increasing conformity between the flanks to make the contact less slender. By comparing the film thickness results against analytically obtained ones, relatively large differences were observed except for one formula for minimum film thickness. Full article
(This article belongs to the Special Issue Elastohydrodynamic Lubrication)
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25 pages, 12363 KiB  
Article
Analysis of Elastohydrodynamic Lubrication (EHL) Characteristics of Port Plate Pair of a Piston Pump
by Zhaoqiang Wang, Bo Han and Lingtao Sun
Machines 2022, 10(12), 1109; https://doi.org/10.3390/machines10121109 - 22 Nov 2022
Cited by 5 | Viewed by 1915
Abstract
This article presents a steady-state elastohydrodynamic lubrication model for the contact and sliding interface of an axial piston pump’s port plate pair. The wedge-shaped oil film thickness, pressure, viscosity, and elastic deformation distribution of the port plate pair were investigated by using the [...] Read more.
This article presents a steady-state elastohydrodynamic lubrication model for the contact and sliding interface of an axial piston pump’s port plate pair. The wedge-shaped oil film thickness, pressure, viscosity, and elastic deformation distribution of the port plate pair were investigated by using the finite difference method. The elastohydrodynamic lubrication characteristics for different operating parameters and two materials of the port plate pair were analyzed for comparison. Existing conditions for the EHL were calculated, and variations in leakage and friction coefficients were investigated. The results show that the elastic deformation of the interface greatly influences the oil film’s overall performance, which is related to the material, inlet pressure, velocity, viscosity, and the minimum oil film thickness that determines the EHL. The deformation caused by oil film pressure greatly influences the model leakage and friction coefficient, especially when the deformation is equal to the oil film clearance. Full article
(This article belongs to the Special Issue Elastohydrodynamic Lubrication)
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12 pages, 2729 KiB  
Article
Numerical Determination of the Frictional Coefficients of a Fluid Film Journal Bearing Considering the Elastohydrodynamic Lubrication and the Asperity Contact Force
by Gwanghee Hong, Kyobong Kim, Youngjun Park and Gunhee Jang
Machines 2022, 10(7), 494; https://doi.org/10.3390/machines10070494 - 21 Jun 2022
Cited by 3 | Viewed by 2546
Abstract
This paper proposes a numerical method to investigate the frictional characteristics of a fluid film journal bearing considering the elastohydrodynamic lubrication and the asperity contact force. We solved the average Reynolds equation by utilizing the FEM to determine the hydrodynamic force developed by [...] Read more.
This paper proposes a numerical method to investigate the frictional characteristics of a fluid film journal bearing considering the elastohydrodynamic lubrication and the asperity contact force. We solved the average Reynolds equation by utilizing the FEM to determine the hydrodynamic force developed by the lubricant of the journal bearing. We also used a modified GT model (Greenwood–Tripp model) developed by Greenwood and Tripp to decompose the asperity contact force into normal and tangential directions. Once we applied those forces to a rotor, we solved the equations of motion of a flexible shaft to determine the friction coefficient. We verified the proposed method by comparing the calculated friction coefficient with the measured one of journal bearings conducted by prior researchers. Then, the proposed method was applied to investigate the frictional characteristics of a journal bearing of a scroll compressor on which dynamic loads are applied. This paper can contribute to developing robust rotor systems supported by journal bearings. Full article
(This article belongs to the Special Issue Elastohydrodynamic Lubrication)
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25 pages, 8215 KiB  
Article
Mixed Lubrication Modeling of Multi-Lip Reciprocating Seals Based on Elastohydrodynamic Lubrication Theory
by Donghong Cheng, Lichen Gu and Yu Sun
Machines 2022, 10(6), 483; https://doi.org/10.3390/machines10060483 - 16 Jun 2022
Cited by 6 | Viewed by 2542
Abstract
Multi-lip reciprocating seals are extensively used in the subject of engineering equipment. However, the current research on the tribology of reciprocating seals mainly focused focuses on the numerical analysis of single-lip seals. In order to study the sealing performance of multi-lip seals, this [...] Read more.
Multi-lip reciprocating seals are extensively used in the subject of engineering equipment. However, the current research on the tribology of reciprocating seals mainly focused focuses on the numerical analysis of single-lip seals. In order to study the sealing performance of multi-lip seals, this paper takes double-acting seal (DAS) as the research object, and establishes a multi-lip mixed elastohydrodynamic lubrication (M-EHL) numerical simulation model from the perspective of solid mechanics, fluid mechanics, contact mechanics, and deformation mechanics. The sealing characteristics under different working conditions (sealed pressure, piston rod extension speed, and seal surface roughness) were analyzed by numerical calculation, and the variation trend of friction force corresponding to the experimental results was obtained. The model can provide a modeling guidance basis for the M-EHL characteristic analysis and structural optimization design of multi-lip reciprocating seals in the mechanical field. Full article
(This article belongs to the Special Issue Elastohydrodynamic Lubrication)
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