The determination of the pressure—viscosity coefficient of a lubricant through an accurate film thickness formula and accurate film thickness measurements

2009 ◽  
Vol 223 (8) ◽  
pp. 1143-1163 ◽  
Author(s):  
H van Leeuwen
Keyword(s):  
Film Thickness ◽  
Viscosity Coefficient ◽  
Test Fluid ◽  
Limited Data ◽  
Ehd Lubrication ◽  
Spacer Layer ◽  
Wide Range ◽  
Approximation Formulas ◽  
Thickness Measurements

The pressure—viscosity coefficient is an indispensable property in the elastohydrodynamic (EHD) lubrication of hard contacts, but often not known. A guess will easily lead to enormous errors in the film thickness. This article describes a method to deduct this coefficient by adapting the value of the pressure—viscosity coefficient until the differences between accurate film thickness approxi-mation values and accurate film thickness measurements over a wide range of values are at a minimum. Eleven film thickness approximation formulas are compared in describing the film thickness of a test fluid with known value of the pressure—viscosity coefficient. The measurement method is based on spacer layer interferometry. It is concluded that for circular contacts the newer more versatile expressions are not better than some older approximations, which are limited to a smaller region of conditions, and that the older fits are as least as appropriate to find the pressure—viscosity coefficient of fluids, in spite of the limited data where they have been based on.

Optimized External IR Reflection Spectroscopy for Quantitative Determination of Borophosphosilicate Glass Parameters

1997 ◽  
Vol 51 (2) ◽  
pp. 259-264 ◽  
Author(s):  
Lizhong Zhang ◽  
James E. Franke ◽  
Thomas M. Niemczyk ◽  
David M. Haaland
Keyword(s):  
Film Thickness ◽  
Quantitative Determination ◽  
Least Squares ◽  
Partial Least Squares ◽  
Reflection Spectroscopy ◽  
Ir Radiation ◽  
Ir Reflection ◽  
Wide Range ◽  
Borophosphosilicate Glass

Infrared (IR) external reflection spectroscopy has been optimized for the quantitative determination of composition and film thickness of borophosphosilicate glass (BPSG) deposited on silicon wafer substrates. The precision of the partial least-squares calibrations for boron and phosphorus contents and thin-film thickness were measured as the cross-validated standard error of prediction statistic. The results showed that BPSG IR reflection spectra collected over a wide range of incident IR radiation angles (15°, 25°, 45°, and 60°) can be used for the simultaneous quantification of these three BPSG parameters. When high angles of incidence were employed, the measurement was found to be more sensitive to small errors in the angle of incidence. The polarization state of the incident IR radiation did not noticeably affect the prediction of the three calibrated BPSG parameters. The results achieved in this study provide guidelines for at-line process monitoring and quality control of BPSG thin films used in the fabrication of microelectronic devices. Index Headings: IR reflection; Multivariate calibration; Partial least-squares

scholarly journals Elastohydrodynamic Film Thickness Model for Heavily Loaded Contacts

1974 ◽  
Vol 96 (3) ◽  
pp. 472-479 ◽  
Author(s):  
S. H. Loewenthal ◽  
R. J. Parker ◽  
E. V. Zaretsky
Keyword(s):  
Film Thickness ◽  
Measured Data ◽  
Type Ii ◽  
X Ray ◽  
Polyphenyl Ether ◽  
Load Dependence ◽  
Test Conditions ◽  
Wide Range ◽  
Minimum Film Thickness ◽  
Thickness Measurements

An empirical elastohydrodynamic (EHD) film thickness formula for predicting the minimum film thickness occurring within heavily loaded contacts (maximum Hertz stresses above 1.04 × 109 N/m2 (150,000 psi)) was developed. The formula was based upon X-ray film thickness measurements made with synthetic paraffinic, fluorocarbon, Type II ester and polyphenyl ether fluids covering a wide range of test conditions. Comparisons were made between predictions from an isothermal EHD theory and the test data. The deduced relationship was found to adequately reflect the high-load dependence exhibited by the measured data. The effects of contact geometry, material and lubricant properties on the form of the empirical model are also discussed.

Measurement of Ultrathin Film Mechanical Properties by Integrated Nano-scratch/indentation Approach

2007 ◽  
Vol 1049 ◽  
Author(s):  
Ashraf Bastawros ◽  
Wei Che ◽  
Abhijit Chandra
Keyword(s):  
Mechanical Properties ◽  
Film Thickness ◽  
Chemical Mechanical Planarization ◽  
Apparent Modulus ◽  
Wide Range ◽  
Tangential Forces ◽  
Indentation Experiment ◽  
Planarization Process ◽  
Thickness Measurements ◽  
Thickness Independent

AbstractThe thickness and property measurements of thin films on a substrate are crucial for a wide range of applications. Classical techniques have relied on various physical properties to identify film thickness, independent of its mechanical properties. Here, a new experimental technique is devised to evaluate the film thickness, its stiffness and its flow stress. The technique utilizes the variation of the measured apparent modulus of a ductile film on a substrate from a nano-indentation experiment, in conjunction with the measured normal and tangential forces and the scratch depth in a nano-scratch experiment. These combined measurements are calibrated through a simple statically admissible model to yield the unknown quantities. The measurements reasonably agree with the finite element predictions and are ascertained by XPS film thickness measurements. The technique is applied to study the formed oxide nano-layer during copper chemical mechanical planarization process.

Influence of Operating Condition and Geometry on the Oil Film Thickness in Aeroengine Bearing Chambers

2004 ◽  
Vol 128 (1) ◽  
pp. 103-110 ◽  
Author(s):  
P. Gorse ◽  
S. Busam ◽  
K. Dullenkopf
Keyword(s):  
Film Thickness ◽  
Film Flow ◽  
Jet Engines ◽  
Gravity Forces ◽  
Wide Range ◽  
Secondary Air ◽  
Oil Films ◽  
Analytical Approaches ◽  
Complex Film

Increasing the efficiency of modern jet engines does not only imply to the mainstream but also to the secondary air and oil system. Within the oil system the bearing chamber is one of the most challenging components. Oil films on the chamber walls are generated from oil droplets, ligaments, or film fragments, which emerge from bearings, seal plates and shafts, and enter the bearing chamber with an angular momentum. Furthermore, shear forces at its surface, gravity forces, and the design of scavenge and vent ports strongly impact the behavior of the liquid film. The present paper focuses on the experimental determination of the film thickness in various geometries of bearing chambers for a wide range of engine relevant conditions. Therefore, each configuration was equipped with five capacitive probes positioned at different circumferential locations. Two analytical approaches are used for a comprehensive discussion of the complex film flow.

scholarly journals ДО РОЗРАХУНКІВ ДЕТАЛЕЙ НА МІЦНІСТЬ В ЙМОВІРНІСНОМУ АСПЕКТІ

2018 ◽  
Vol 124 (4) ◽  
pp. 17-25
Author(s):  
Л. М. Березін ◽  
М. М. Рубанка
Keyword(s):  
Fatigue Strength ◽  
Strength Criterion ◽  
Subject Area ◽  
Statistical Characteristics ◽  
Limited Data ◽  
Statistics And Probability ◽  
Reliability Characteristics ◽  
Wide Range ◽  
Further Development

Generalization of regulations, empirical and analytical information concerning the determination of the statistical characteristics of the strength of metals and details for used in strength calculations in the probabilistic aspect. Are used modern methods of searching, describing and analyzing information to audit a variety of possible solutions in the subject area of research, developments with the strength of materials, mathematical statistics and probability theory. Is presented the possibility of using at the design stages for calculations of determine the statistical characteristics of the fatigue resistance of details at limited data on the mechanical characteristics of the strength of the material. The research results make it possible to take reasonable proposals to improve the fatigue strength of details. The further development of the theory and methodology of mathematical solutions for designing machine parts with specified reliability characteristics by the fatigue strength criterion while minimizing their weight and size. Is presented information that improves the quality and efficiency of design solutions for ensure the specified reliability of details. The calculation is performed on the example of cylindrical coil springs with a wide range of changes in their geometric, elastic and force parameters.

scholarly journals Normal haematology and blood biochemistry of wild Nile crocodiles (Crocodylus niloticus) in the Okavango Delta, Botswana

2007 ◽  
Vol 78 (3) ◽  
Author(s):  
C.J. Lovely ◽  
J.M. Pittman ◽  
A.J. Leslie
Keyword(s):  
Okavango Delta ◽  
Limited Data ◽  
Size Classes ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Wide Range ◽  
Significant Difference ◽  
High Prevalence ◽  
Diagnostic Investigations

Wild Nile crocodiles (Crocodylus niloticus) of various size classes were captured in the Okavango Delta, Botswana. Blood was collected from the post occipital sinus and used for the determination of a wide range of haematological and biochemical parameters. These values were compared between the sexes and between 3 size classes. The values were also compared with the limited data available from farmed Nile crocodiles, as well as from other wild Nile crocodiles. The Okavango crocodiles were comparatively anaemic, and had comparatively low total protein and blood glucose levels. There was a high prevalence of Hepatozoon pettiti infection, however, there was no significant difference in haematological values between the infected and uninfected crocodiles. The values reported here will be useful in diagnostic investigations in both zoo and farmed Nile crocodiles.

Influence of Operating Condition and Geometry on the Oil Film Thickness in Aero-Engine Bearing Chambers

2004 ◽  
Author(s):  
P. Gorse ◽  
S. Busam ◽  
K. Dullenkopf
Keyword(s):  
Film Thickness ◽  
Jet Engines ◽  
Gravity Forces ◽  
Wide Range ◽  
Secondary Air ◽  
Oil Films ◽  
Analytical Approaches ◽  
Complex Film ◽  
Engine Bearing

Increasing the efficiency of modern jet engines do not only imply to the mainstream but also to the secondary air and oil system. Within the oil system the bearing chamber is one of the most challenging component. Oil films on the chamber walls are generated from oil droplets, ligaments, or film fragments, which emerge from bearings, seal plates and shafts, and enter the bearing chamber with an angular momentum. Furthermore, shear forces at its surface, gravity forces, and the design of scavenge and vent ports strongly impact the behavior of the liquid film. The present paper focuses on the experimental determination of the film thickness is various geometries of bearing chambers for a wide range of engine relevant conditions. Therefore, each configuration was equipped with five capacitive probes positioned at different circumferential locations. Two analytical approaches are used for a comprehensive discussion of the complex film flow.

Elastohydrodynamic Behavior of Elliptical Contacts Under Pure Rolling Situations

1987 ◽  
Vol 109 (4) ◽  
pp. 659-663 ◽  
Author(s):  
M. O. A. Mokhtar ◽  
A. A. Abdel Ghany
Keyword(s):  
Film Thickness ◽  
A Value ◽  
Ehd Lubrication ◽  
Pure Rolling ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Pressure Spike ◽  
Noticeable Reduction ◽  
Developed Pressure ◽  
Film Profile

This part is a complimentary work to a previously published work on EHD lubrication behavior under pure sliding and combined rolling and sliding situations. In order to cover all aspects of EHD lubrication, the experimental work has been herein extended to present the results attained when two disks describe a pure rolling motion. A wide range of loads and speeds has been applied to the contacting disks under EHD regimes. The recorded pressure values and distribution confirm the existence of a second peak (spike) near the exit of the contact zone also under pure rolling situation. The spike has a value higher than maximum Hertzian pressure. A local constriction of oil film profile to identify the minimum EHD film thickness at trailing (exit) end of the film is observed to be nearby the location of the pressure spike. The results, compared to theoretical predictions, concluded that under pure rolling conditions, any increase in the applied load results in a corresponding increase in the developed pressure while a noticeable reduction in the minimum film thickness is recorded with decreasing rolling speeds.

scholarly journals Isothermal Elastohydrodynamic Theory for the Full Range of Pressure-Viscosity Coefficient

1972 ◽  
Vol 94 (1) ◽  
pp. 35-43 ◽  
Author(s):  
H. S. Cheng
Keyword(s):  
Film Thickness ◽  
Full Range ◽  
Viscosity Coefficient ◽  
Exponential Model ◽  
X Ray ◽  
Line Contacts ◽  
Heavy Loads ◽  
Thickness Measurements ◽  
Theoretical Results ◽  
Viscosity Dependence

The isothermal, elastohydrodynamic (EHD) solutions in the inlet region of line contacts are extended to cover the full range of pressure-viscosity parameter, G, and the region of extremely heavy loads. The effect of a composite exponential model for the pressure-viscosity dependence on the film thickness is also studied. Results of the film thickness are compared with those based on work by Grubin, Dowson-Higginson, Bell and Kannel, and Herrebrugh. Comparison is also made between the theoretical results with the recently obtained X-ray film thickness measurements.

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