Discrete Nature of Ultrathin Lubrication Film Between Mica Surfaces

1996 ◽  
Vol 118 (4) ◽  
pp. 832-838 ◽  
Author(s):  
Hiroshige Matsuoka ◽  
Takahisa Kato
Keyword(s):  
Film Thickness ◽  
Theoretical Prediction ◽  
Lubrication Theory ◽  
Molecular Effect ◽  
Lubrication Film ◽  
Structural Force ◽  
New Apparatus ◽  
Discrete Nature ◽  
Good Agreement

A new apparatus which can measure force and separation between surfaces accurately is developed. Ultrathin fluid lubrication film thickness between mica surfaces is measured using this apparatus. Octamethylcyclotetrasiloxane (OMCTS) is used as a lubricant. As a result of the experiment, it is found that when the film thickness is more than about 10 nm (ten times as large as the molecular diameter of OMCTS), there is good agreement with the conventional continuum fluid lubrication theory (EHL theory). In case of film thickness less than 10 nm, however, it deviates from the theoretical prediction and discretization of film thickness is observed. It is considered that this phenomenon is due to the solvation force (structural force), and that the molecular effect cannot be neglected in such an ultrathin lubrication phenomenon as in this experiment.

Experimental study of ultrathin liquid lubrication film thickness at the molecular scale

1997 ◽  
Vol 211 (2) ◽  
pp. 139-150 ◽  
Author(s):  
H Matsuoka ◽  
T Kato
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Film Thickness ◽  
Solid Surface ◽  
Experimental Measurements ◽  
Dynamic Measurements ◽  
Lubrication Film ◽  
Solid Specimen ◽  
Molecular Scale ◽  
New Apparatus

Ultrathin liquid lubrication film thicknesses at the molecular scale are measured by a new apparatus developed by the authors. Mica is used as the solid specimen and octamethylcyclotetrasiloxane (OMCTS), cyclohexane and n-hexadecane are used as liquid specimens. From experimental measurements, discretization of the lubrication film thickness is observed when the thickness is less than about 10 times the molecular diameter of the intervening liquid. Analysis of experimental data shows that the discretization of the lubrication film thickness is due to the solvation force. Dynamic measurements show that the solvation force is almost the same as the non-sliding case and is independent of the sliding speed of the solid surface.

Layer Moleculecular Dynamic Diffusion Model of Nano-Meter Lubricant Film on Hard Disk Surfaces at High Rotating Speed

2008 ◽  
Author(s):  
Bo Zhang ◽  
Hiroshi Chiba ◽  
Akira Nakajima
Keyword(s):  
Film Thickness ◽  
Theoretical Prediction ◽  
Molecular Dynamic ◽  
Rheological Behavior ◽  
Rotating Speed ◽  
Wide Range ◽  
Novel Model ◽  
Dynamic Diffusion ◽  
Good Agreement ◽  
The Continuum

Spin-off experiments for PFPE Z25 were conducted by using a 3.5 inch disk at a constant speed of 10,000 rpm. The initial film thickness was set to about 2.4 nm for all the experiments while temperature was changed in a wide range. It is found that the rheological behavior of the film is quite different from that expected from the continuum. A novel model based on Fick’s law of diffusion was proposed, which is called the layer molecular dynamic diffusion (LMDD) model. The theoretical prediction was compared with the experimental results and a good agreement was obtained, verifying the effectiveness of the model.

Some Limitations in Applying Classical EHD Film Thickness Formulas to a High-Speed Bearing

1981 ◽  
Vol 103 (2) ◽  
pp. 295-301 ◽  
Author(s):  
J. J. Coy ◽  
E. V. Zaretsky
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Heating Effects ◽  
Theoretical Predictions ◽  
Traction Fluid ◽  
Shear Heating ◽  
Thickness Measurements ◽  
Inner Race ◽  
Maximum Stresses ◽  
Good Agreement

Elastohydrodynamic film thickness was measured for a 20-mm ball bearing using the capacitance technique. The bearing was thrust loaded to 90, 448, and 778 N (20, 100, and 175 lb). The corresponding maximum stresses on the inner race were 1.28, 2.09, and 2.45 GPa (185,000, 303,000, and 356,000 psi). Test speeds ranged from 400 to 14,000 rpm. Film thickness measurements were taken with four different lubricants: (a) synthetic paraffinic, (b) synthetic paraffinic with additives, (c) neopentylpolyol (tetra) ester meeting MIL-L-23699A specifications, and (d) synthetic cycloaliphatic hydrocarbon traction fluid. The test bearing was mist lubricated. Test temperatures were 300, 338, and 393 K. The measured results were compared to theoretical predictions using the formulae of Grubin, Archard and Cowking, Dowson and Higginson, and Hamrock and Dowson. There was good agreement with theory at low dimensionless speed, but the film was much smaller than theory predicts at higher speeds. This was due to kinematic starvation and inlet shear heating effects. Comparisons with Chiu’s theory on starvation and Cheng’s theory on inlet shear heating were made.

A New Postulation of Viscosity and Its Application in Computation of Film Thickness in TFL1

2002 ◽  
Vol 124 (4) ◽  
pp. 811-814 ◽  
Author(s):  
Chaohui Zhang ◽  
Jianbin Luo ◽  
Shizhu Wen
Keyword(s):  
Thin Film ◽  
Experimental Data ◽  
Film Thickness ◽  
Solid Surface ◽  
Contact Area ◽  
Elastohydrodynamic Lubrication ◽  
Thin Film Lubrication ◽  
Lubrication Film ◽  
Viscosity Modification ◽  
Film Lubrication

In this paper, a viscosity modification model is developed which can be applied to describe the thin film lubrication problems. The viscosity distribution along the direction normal to solid surface is approached by a function proposed in this paper. Based on the formula, lubricating problem of thin film lubrication (TFL) in isothermal and incompressible condition is solved and the outcome is compared to the experimental data. In thin film lubrication, according to the computation outcomes, the lubrication film thickness is much greater than that in elastohydrodynamic lubrication (EHL). When the velocity is adequately low (i.e., film thickness is thin enough), the pressure distribution in the contact area is close to Hertzian distribution in which the second ridge of pressure is not obvious enough. The film shape demonstrates the earlobe-like form in thin film lubrication, which is similar to EHL while the film is comparatively thicker. The transformation relationships between film thickness and loads, velocities or atmosphere viscosity in thin film lubrication differ from those in EHL so that the transition from thin film lubrication to EHL can be clearly seen.

Calculation of Elastohydrodynamic Lubrication Film Thickness for Hip Prostheses During Normal Walking

1990 ◽  
Vol 33 (2) ◽  
pp. 239-245 ◽  
Author(s):  
Cheng-Tao Wang ◽  
Yi-Ling Wang ◽  
Qing-Li Chen ◽  
Min-Run Yang
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Normal Walking ◽  
Hip Prostheses ◽  
Lubrication Film

Elastohydrodynamic Lubrication in Rolling and Sliding Contacts

1972 ◽  
Vol 94 (4) ◽  
pp. 324-329 ◽  
Author(s):  
C. M. Rodkiewicz ◽  
V. Srinivasan
Keyword(s):  
Film Thickness ◽  
Quadrature Formula ◽  
Fourth Order ◽  
Elastohydrodynamic Lubrication ◽  
Experimental Film ◽  
Kutta Method ◽  
Sliding Contacts ◽  
Runge Kutta Method ◽  
Runge Kutta ◽  
Good Agreement

A solution to the elastohydrodynamic lubrication problem for the case of two rolling cylinders, at different speeds, is presented. The lubricant is assumed compressible throughout the region. The fourth-order Runge-Kutta method for the lubricant and an improved quadrature formula for the elastic calculations are used. Pressure and film-thickness profiles are presented for different rolling velocities. There is a good agreement with the experimental film thickness data, available in literature.

The mmW Band Tamm States in One-Dimensional Magnetophotonic Crystals

2009 ◽  
Vol 152-153 ◽  
pp. 394-396 ◽  
Author(s):  
Sergey I. Tarapov ◽  
M. Khodzitskiy ◽  
S.V. Chernovtsev ◽  
D. Belosorov ◽  
A.M. Merzlikin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Theoretical Prediction ◽  
Experimental Results ◽  
One Dimensional ◽  
Magnetophotonic Crystals ◽  
Good Agreement

The mmW band photonic Tamm states in 1D magnetophotonic crystals are studied. It is shown the possibility to manipulate the eigenfrequencies of such states by an external magnetic field. Our experimental results are in a good agreement with theoretical prediction.

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