Experimental Investigation for Finite Line Contact Edge Effect of Elastohydrodynamic Lubrication

2012 ◽  
Vol 538-541 ◽  
pp. 1945-1951 ◽  
Author(s):  
Yu Xue ◽  
Tong Shu Hua ◽  
Hao Yang Sun
Keyword(s):  
Experimental Investigation ◽  
Film Thickness ◽  
Contact Area ◽  
Elastohydrodynamic Lubrication ◽  
Line Contact ◽  
Heavy Load ◽  
Entrainment Velocity ◽  
Finite Line Contact ◽  
Finite Line ◽  
Lubricant Viscosity

To reveal the principle of the close effect about the EHL finite roller, contraposing the log-convex roller, the finite line contact EHL film shape and thickness were observed through self-made heavy-load optical EHL experimental device. Experiments were carried out under several different pressure and viscosity, and three groups of interference pictures were obtained under three different entrainment velocities. As the load increased, both the length and width of the roller contact area added, and the width of the contact zone in the end was larger than that in the centre, the close effect was more obvious; when the entrainment velocity and lubricant viscosity increased, the film thickness in the central roller became thicker while the increase in the roller end was little, the high film thickness difference enhanced the close effect. The entrainment velocity, load and lubricant viscosity all have great effect on the EHL characteristics of the finite roller.

A thermal EHL investigation on plate-pin hinge pairs in silent chains using a narrow finite line contact

2020 ◽  
Vol 72 (10) ◽  
pp. 1139-1145
Author(s):  
Mingyu Zhang ◽  
Jing Wang ◽  
Jinlei Cui ◽  
Peiran Yang
Keyword(s):  
Film Thickness ◽  
Temperature Rise ◽  
Elastohydrodynamic Lubrication ◽  
Radius Of Curvature ◽  
Line Contact ◽  
Equivalent Radius ◽  
Content Type ◽  
Finite Line Contact ◽  
Pressure Peak ◽  
Finite Line

Purpose The purpose of this paper is to numerically study the variations of oil film pressure, thickness and temperature rise in the contact zone of plate-pin pair in silent chains. Design/methodology/approach A steady-state thermal elastohydrodynamic lubrication (EHL) model is built using a Ree–Eyring fluid. The contact between the plate and the pin is simplified as a narrow finite line contact, and the lubrication state is examined by varying the geometry and the plate speed. Findings With increase in the equivalent radius of curvature, the pressure peak and the central film thickness increase. Because the plate is very thin, the temperature rise can be neglected. Even when the influence of the rounded corner region is less, a proper design can beneficially increase the minimum film thickness at both edges of the plate. Under a low entraining speed, strong stress concentration results in close-zero film thickness at both edges of the plate. Originality/value This study reveals the EHL feature of the narrow finite line contact in plate-pin pairs for silent chains and will support the future works considering transient effect, surface features and wear.

Influence of Different Viscosity Lubricant to Finite Line Contacts on Elastohydrodynamic Lubrication (EHL) under Oscillating

2012 ◽  
Vol 538-541 ◽  
pp. 1939-1944
Author(s):  
Yan Fei Wang ◽  
Tong Shu Hua ◽  
Hao Yang Sun
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Oil Film ◽  
Entrainment Velocity ◽  
Finite Line Contact ◽  
Line Contacts ◽  
Finite Line ◽  
Contact Roller ◽  
Two Parameters ◽  
Experimental Rig

To make further researches into the elastohydrodynamic lubrication properties of a finite line contact roller, oscillating experiments were carried out on made overload experimental rig for oil film measurement using optical interference technique. Film thickness and shape were measured in two kinds of viscosity polyisobutylene. This study indicates that both lubricant viscosity and roller entrainment velocity play an important role on EHL of finite line contacts. On motion, the more increase in viscosity or speed, the thicker the oil film thickness, simultaneity edge effect is distinctly intensified and film thickness increases less on roller end, difference of the film thickness is increased between roller end and the central. Above two parameters are significant for logarithmic profile roller in crowning design.

A thermal EHL investigation for size effect of finite line contact on bush-pin hinge pairs in industrial chains

2020 ◽  
Vol 72 (5) ◽  
pp. 695-701
Author(s):  
Mingyu Zhang ◽  
Jing Wang ◽  
Peiran Yang ◽  
Zhaohua Shang ◽  
Yi Liu ◽  
...  
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Contact Zone ◽  
Line Contact ◽  
Equivalent Radius ◽  
Content Type ◽  
Oil Film ◽  
Finite Line Contact ◽  
Finite Line ◽  
Thermal Ehl

Purpose This paper aims to study the influence of the dimension change of bush-pin on the pressure, oil film thickness, temperature rise and traction coefficient in contact zone by using a thermal elastohydrodynamic lubrication (EHL) model for finite line contact. Concretely, the effects of the equivalent curvature radius of the bush and the pin, and the length of the bush are investigated. Design/methodology/approach In this paper, the contact between the bush and pin is simplified as finite line contact. The lubrication state is studied by numerical simulation using steady-state line contact thermal EHL. A constitutive equation Ree–Eyring fluid is used in the calculations. Findings It is found that by selecting an optimal equivalent radius of curvature and prolonging the bush length can improve the lubrication state effectively. Originality/value Under specific working conditions, there exists an optimal equivalent radius to maximize the minimum oil film thickness in the contact zone. The increase of generatrix length will weaken the stress concentration effect in the rounded corner area at both ends of the bush, which can improve the wear resistance of chain. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0448.

scholarly journals A full numerical solution to the coupled cam–roller and roller–pin contact in heavily loaded cam–roller follower mechanisms

2017 ◽  
Vol 232 (10) ◽  
pp. 1273-1284 ◽  
Author(s):  
Shivam S Alakhramsing ◽  
Matthijn B de Rooij ◽  
Dirk J Schipper ◽  
Mark van Drogen
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Friction Model ◽  
Line Contact ◽  
Transient Effects ◽  
Power Losses ◽  
Lubricated Contacts ◽  
Finite Line Contact ◽  
Finite Line ◽  
Lubrication Characteristics ◽  
Lubrication Conditions

In cam–roller follower units two lubricated contacts may be distinguished, namely the cam–roller contact and roller–pin contact. The former is a nonconformal contact while the latter is conformal contact. In an earlier work a detailed transient finite line contact elastohydrodynamic lubrication model for the cam–roller contact was developed. In this work a detailed transient elastohydrodynamic lubrication model for the roller–pin contact is developed and coupled to the earlier developed cam–roller contact elastohydrodynamic lubrication model via a roller friction model. For the transient analysis a heavily loaded cam–roller follower unit is analyzed. It is shown that likewise the cam–roller contact, the roller–pin contact also inhibits typical finite line contact elastohydrodynamic lubrication characteristics at high loads. The importance of including elastic deformation for analyzing lubrication conditions in the roller–pin contact is highlighted here, as it significantly enhances the film thickness and friction coefficient. Other main findings are that for heavily loaded cam–roller follower units, as studied in this work, transient effects and roller slippage are negligible, and the roller–pin contact is associated with the highest power losses. Finally, due to the nontypical elastohydrodynamic lubrication characteristics of both cam–roller and roller–pin contact numerical analysis becomes inevitable for the evaluation of the film thicknesses, power losses, and maximum pressures.

Elastohydrodynamic Lubrication Analysis of Finite Line Contact Problem With Consideration of Two Free End Surfaces

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Haibo Zhang ◽  
Wenzhong Wang ◽  
Shengguang Zhang ◽  
Ziqiang Zhao
Keyword(s):  
Contact Problem ◽  
Finite Length ◽  
Elastohydrodynamic Lubrication ◽  
Line Contact ◽  
Free Boundaries ◽  
Finite Line Contact ◽  
Line Contacts ◽  
Speed Up ◽  
Finite Line ◽  
Overlapping Method

Elastohydrodynamic lubrication (EHL) analysis in finite line contacts is usually modeled by a finite-length roller contacting with a half-space, which ignores effect of the two free boundaries existing in many applications such as gears or roller bearings. This paper presents a semi-analytical method, involving the overlapping method and matrix formation, for EHL analysis in the finite line contact problem to consider the effect of two free end surfaces. Three half-spaces with mirrored loads to be solved are overlapped to cancel out the stresses at expected surfaces, and three matrices can be obtained and reused for the same finite-length space. The isothermal Reynolds equation is solved to obtain the pressure distribution and the fast Fourier transform (FFT) is used to speed up the elastic deformation and stress related calculation. Different line contact situations, including straight rollers, tapered rollers, and Lundberg profile rollers, are discussed to explore the effect of free end surfaces.

Effects of the thermal conductivity of contact materials on elastohydrodynamic lubrication characteristics

2010 ◽  
Vol 224 (12) ◽  
pp. 2577-2587 ◽  
Author(s):  
M Kaneta ◽  
P Yang
Keyword(s):  
Thermal Conductivity ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Fluid Film ◽  
Contact Materials ◽  
Entrainment Velocity ◽  
Pressure Distributions ◽  
Traction Coefficient ◽  
Lubrication Characteristics ◽  
Lubricant Viscosity

Isothermal elastohydrodynamic lubrication (EHL) theory has brought the improvement in function, performance, and durability of machine elements with concentrated contacts. The main reason is that the theory can evaluate the lubrication characteristics, such as film thickness and pressure distributions, from the shape and size of contacting materials, lubricant viscosity at the entrance to the EHL conjunction, entrainment velocity, equivalent elastic modulus, and applied load. However, in order to estimate the film thickness and pressure distributions more accurately and to make clear the traction behaviour based on lubricant rheology, it is necessary to establish thermal EHL theory, which incorporates heat generation in the fluid film and heat transfer in the machine system on the foundation of isothermal EHL theory. The thermal conductivity of contact materials controls temperature in the fluid film and consequently the lubricant viscosity. Therefore, the EHL characteristics are affected remarkably by the thermal conductivity of contact materials. In this article, the effects of the thermal conductivity of contacting materials on the film thickness, pressure, and traction coefficient are described.

scholarly journals Aligned and misaligned contacts of rollers to races in elastohydrodynamic finite line conjunctions

2002 ◽  
Vol 216 (11) ◽  
pp. 1051-1070 ◽  
Author(s):  
M Kushwaha ◽  
H Rahnejat ◽  
R Gohar
Keyword(s):  
Film Thickness ◽  
Edge Effects ◽  
Line Contact ◽  
Lubricant Film Thickness ◽  
Similar Work ◽  
Numerical Predictions ◽  
Finite Line Contact ◽  
Finite Line ◽  
Lubricated Contact ◽  
Contact Domain

The paper provides a solution for finite line concentrated contact of a roller-to-race under aligned and misaligned conditions. The lubricated contact conjunction is subject to an elastohydrodynamic regime of lubrication under isothermal conditions. Of particular interest are the edge stress discontinuities, represented by large secondary pressure spikes at the side constriction and to the rear exit in the contact domain. These pressure ‘pips’ are considerably larger in magnitude than those occurring in the central exit of the contact. The presence of pressure peaks inhibits the flow of lubricant in their vicinity, causing islands of minimum lubricant film thickness at the sides of the contact, referred to as the end closure films. The paper shows that the film shape and pressure distribution at the extremities of a finite line contact are not revealed by the traditional line contact solutions usually undertaken. The flow pattern becomes more complex with roller misalignment and the edge effects described are exacerbated. The paper provides the first ever solution of misaligned roller-to-race contact for moderate to high loaded elastohydrodynamic conjunctions. The numerical predictions conform well with both experimental and numerical findings of others for the cases where similar work has been reported.

scholarly journals Predicting Fatigue Life for Finite Line Contact under Starved Elastohydrodynamic Lubrication Condition

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Mingyong Liu ◽  
Haofeng Ku ◽  
Jinxi Zhang ◽  
Peidong Xu ◽  
Chenhui Wu
Keyword(s):  
Fatigue Life ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Line Contact ◽  
Finite Line Contact ◽  
Lubrication Performance ◽  
Finite Line ◽  
Lubrication Condition ◽  
Lubrication Characteristics

Surface contact fatigue is the main failure mode in many mechanical components, such as gears, bearings, and cam-followers. A fatigue life prediction model is proposed for finite line contact under starved thermal elastohydrodynamic lubrication (TEHL) condition in this paper. Then, the effects of inlet oil-supply thickness, slide-to-roll ratio (SRR), and operating conditions on the lubrication performance and fatigue life are investigated. The results show that the lubrication characteristics and fatigue life of finite line contact are obviously different from those of fully flooded situation by introducing the starved lubrication condition. For example, the severe starved conditions lead to a significant increase in friction coefficient and decreased fatigue life. The variation of SRR has an important influence on the fatigue life. With the increase of SRR, the fatigue life decreases firstly and then increases. The stress concentration occurs near the surface when speed is low. In addition, under the low-speed situation, rotation speed variation has little effect on the fatigue life.

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