Effects of Thermal Conductivity of Contacting Surfaces on Point EHL Contacts

2003 ◽  
Vol 125 (4) ◽  
pp. 731-738 ◽  
Author(s):  
M. Kaneta ◽  
P. Yang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Film Thickness ◽  
Temperature Variation ◽  
Optical Interferometry ◽  
The Other ◽  
Oil Film ◽  
Entrainment Velocity ◽  
Minimum Film Thickness ◽  
Thermal Ehl

With actual and virtual materials, the effects of the thermal conductivity of contacting surfaces on EHL are investigated through experimental analyses using the optical interferometry technique and the Newtonian thermal EHL analyses in consideration of the variation of oil properties in all directions within the film. A mineral bright stock is used as a lubricant. It is found that the distributions of pressure and film thickness, including the minimum film thickness, are influenced very much by the entrainment velocity and the slide-roll ratio. One of the causes is the temperature-viscosity wedge action produced by the temperature variation across the oil film, and the other is an increase in oil temperature at the entrance of the contact due to the heat produced by the compression work and the shearing of the oil. The degree of both influences depends on the thermal properties of contacting materials.

Effects of Thermal Properties of Contact Materials and Slide-Roll Ratio in Elastohydrodynamic Lubrication

2021 ◽  
pp. 1-34
Author(s):  
Motohiro Kaneta ◽  
Kenji Matsuda ◽  
Hiroshi Nishikawa
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Film Thickness ◽  
Thermal Inertia ◽  
Elastohydrodynamic Lubrication ◽  
Mechanical And Thermal Properties ◽  
Contact Materials ◽  
The Difference ◽  
Thermal Ehl

Abstract The effects of thermal conductivity, heat capacity, thermal inertia and slide-roll ratio on point elastohydrodynamic lubrication (EHL) are discussed with engineering ceramics and steel by a non-Newtonian thermal EHL analysis. When the thermal conductivities of contacting materials are significantly different, the film thickness is greatly affected by which material has the higher velocity. However, the film thickness is dominated by the heat capacity when the difference in thermal conductivity is not large. In contact of materials with the same mechanical and thermal properties, the central film thickness and friction coefficient are influenced by the thermal inertia.

Influence of Surface Waviness on the Thermal Elastohydrodynamic Lubrication of an Eccentric-Tappet Pair

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Wang ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Surface Waviness ◽  
Film Pressure ◽  
Oil Film ◽  
Working Cycle ◽  
Temperature Oscillations ◽  
Minimum Film Thickness ◽  
Traction Coefficient ◽  
Oil Film Pressure

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense.

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.

Oil Film Thickness in Lightly-Loaded Roller Bearings

1974 ◽  
Vol 16 (6) ◽  
pp. 386-390 ◽  
Author(s):  
H. Bahadoran ◽  
R. Gohar
Keyword(s):  
Film Thickness ◽  
Similar Condition ◽  
Thrust Bearing ◽  
Roller Bearing ◽  
Optical Interferometry ◽  
Oil Film ◽  
Roller Bearings ◽  
Tapered Roller

The effects of speed, load and roller geometry on the oil film thickness and shape in a complete roller bearing are demonstrated experimentally by means of optical interferometry. At quite moderate roller speeds, increase of film thickness becomes inhibited. This effect is attributed to a truncated inlet meniscus, a similar condition having been observed elsewhere with a ball-and-plate machine and with a model of a tapered-roller thrust bearing.

The effect of an oscillatory entrainment velocity on the film thickness in thermal EHL point contact

2015 ◽  
Vol 90 ◽  
pp. 519-532 ◽  
Author(s):  
Jianjun Zhang ◽  
Peiran Yang ◽  
Jing Wang ◽  
Feng Guo
Keyword(s):  
Film Thickness ◽  
Point Contact ◽  
Entrainment Velocity ◽  
Thermal Ehl

Thermal Properties of Rubber Compounds. II. Heat Generation of Pigmented Rubber Compounds

1935 ◽  
Vol 8 (1) ◽  
pp. 138-149 ◽  
Author(s):  
C. E. Barnett ◽  
W. C. Mathews
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Laboratory Test ◽  
Heat Generation ◽  
The Other ◽  
Moving Plate ◽  
Rubber Compounds ◽  
Time Required ◽  
Two Machines ◽  
Rubber Block

Abstract THE first paper (1) of this series discussed thermal conductivity of rubber and a number of compounding ingredients which were measured using the electric current as the source of heat. In this article the fundamental factors controlling the generation of heat and the variations possible by pigmentation are being studied. Results obtained for pigmented rubber in the pendulum and flexometer will be discussed and correlated. In the writers' laboratory two machines have been used extensively in studying the temperature developed in rubber compounds subjected to distortion by compressive forces. The first of these is a flexometer described by Cooper (2), and the second a compression machine in which a rubber block 14 cm. (5.5 inches) in diameter and 9.53 cm. (3.75 inches) high is pounded with a definite load a specified number of times per minute. The laboratory test block used in the flexometer is in the shape of a frustrum of a rectangular pyramid, of which the base is 5.4 × 2.86 cm. (2.126 × 1.125 inches), the top 5.08 × 2.54 cm. (2 × 1 inches), and the altitude 3.81 cm. (1.5 inches). This block of rubber is compressed between two plates under definite load, one of the plates being stationary while the other travels in a circular motion of definite magnitude. After the sample has been placed in the machine, the moving plate is set to one side of the center. Both the loading and the amount of offset may be varied within wide limits. With this machine one may study either the temperature developed over a period of flexing or the time required to compress the sample a predetermined amount.

Optical Measurement of EHL Film under Oscillating Needle Roller Contacts

2015 ◽  
Vol 642 ◽  
pp. 270-274
Author(s):  
Xue Jin Shen ◽  
Zhen Min Song ◽  
Xiao Yang Chen
Keyword(s):  
Film Thickness ◽  
Working Conditions ◽  
Applied Load ◽  
Optical Measurement ◽  
Rotation Velocity ◽  
Optical Interferometry ◽  
Oil Film ◽  
Pure Rolling ◽  
Rectangular Glass

In this paper, the EHL oil film thickness and shape between a needle roller and a flat rectangular glass in pure rolling oscillated working conditions had been measured based on optical interferometry. The EHL behavior affected by the applied load, oscillating frequency was investigated. The typical film shape varies of interference pictures on the maximum needle roller rotation velocity was obtained and compared each other. It is found the side constrictions are always the most severe and they are strongly speeds and loads dependence.

Thermal Elastohydrodynamic Lubrication of Rider Rings

1984 ◽  
Vol 106 (4) ◽  
pp. 492-498 ◽  
Author(s):  
Vilmos Simon
Keyword(s):  
Film Thickness ◽  
Numerical Solution ◽  
Temperature Variation ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Oil Film ◽  
The Real ◽  
Ring Geometry

The full thermal elastohydrodynamic analysis of the lubrication of rider rings is presented. A numerical solution of the coupled Reynolds, elasticity, energy, and Laplace’s equations for the oil film thickness, pressure, and temperature and rider rings temperatures is obtained. The temperature variation across the oil film is included. The real rider ring geometry is treated. The effect of the operating conditions on the performance characteristics is discussed.

The Elasto-Hydrodynamic Lubrication of Soft, Highly Deformed Contacts Under Conditions of Nonuniform Motion

1986 ◽  
Vol 108 (4) ◽  
pp. 545-550 ◽  
Author(s):  
C. J. Hooke
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Dynamic Analysis ◽  
Hydrodynamic Lubrication ◽  
Steady State Analysis ◽  
Entrainment Velocity ◽  
Sinusoidal Motion ◽  
Minimum Film Thickness ◽  
Rapid Reversal ◽  
Nonuniform Motion

A method is described for the calculation of the film thicknesses in soft, highly deformed contacts for situations where the entrainment velocity is not constant. Two particular results are presented. It is shown that, where there is a rapid reversal of motion, the steady state analysis remains acceptable. However, for a contact reciprocating with a sinusoidal motion, it does not, and here the minimum film thickness occurs at the end of the stroke. The minimum film thickness lies at the end of the contact furthermost from the area swept during the stroke and can only be determined by a dynamic analysis.

scholarly journals Thermal energy storage in embankments: Investigation of the thermal properties of an unsaturated compacted soil

2020 ◽  
Vol 205 ◽  
pp. 07011
Author(s):  
Mojdeh Lahoori ◽  
Sandrine Rosin-Paumier ◽  
Yves Jannot ◽  
Ahmed Boukelia ◽  
Farimah Masrouri
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Energy Storage ◽  
Temperature Variation ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Transient State ◽  
Temperature Sensors ◽  
Compacted Soils ◽  
Compacted Soil

Thermal energy storage in compacted soils can be considered as a new economically efficient and environmentally friendly technology in geotechnical engineering. Compacted soils are usually unsaturated; therefore, reliable estimates and measurements of their thermal properties are important in the efficiency analysis of these structures. In this study, a method is used to estimate the thermal properties of an unsaturated compacted soil. Several temperature sensors were placed in a thermo-regulated metric scale container to monitor the imposed temperature variation in the range of the 20 to 50 °C. This imposed temperature variation reproduced the temperature variation in the thermal energy storages. An inverse analytical model based on a one-dimensional radial heat conduction equation is used to estimate the thermal diffusivity using the temperature variation between two temperature sensors. The volumetric heat capacity was measured using a calorimeter in the laboratory, enabling the estimation of the thermal conductivity of the compacted soil. Then, this estimated thermal conductivity was compared with the thermal conductivity values measured with two other methods (steady-state and transient-state method). The difference between them are discussed in terms of the sample heterogeneity, sample size, and measurement method.

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