The influence of mean contact pressure on the friction coefficient of a traction fluid at high pressure

2000 ◽  
Vol 214 (2) ◽  
pp. 309-312 ◽  
Author(s):  
M F Workel ◽  
D Dowson ◽  
P Ehret ◽  
C M Taylor
Keyword(s):  
High Pressure ◽  
Friction Coefficient ◽  
Contact Pressure ◽  
High Pressures ◽  
Friction Coefficients ◽  
Ball Impact ◽  
Good Consistency ◽  
Traction Fluid ◽  
Very High

A new ball impact apparatus has been developed for measuring the friction coefficients of solidified lubricants under very high pressures. Results obtained for Santotrac 50 showed a decrease in friction coefficient with increasing mean contact pressure and showed good consistency with values reported elsewhere from several different forms of apparatus.

Measurements of the coefficients of friction of different lubricants during impact under high pressure and shear

2003 ◽  
Vol 217 (2) ◽  
pp. 115-124 ◽  
Author(s):  
M. F. Workel ◽  
D Dowson ◽  
P Ehret ◽  
C. M. Taylor
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Large Range ◽  
Shear Stresses ◽  
Ball Impact ◽  
Shear Rates ◽  
Impact Experiment ◽  
Decreasing Functions ◽  
Very High ◽  
Good Agreement

For a comprehensive set of lubricants the friction coefficients were determined under very high pressures and shear rates by means of a ball impact experiment. Measurements of the limiting shear stresses were obtained for a large range of pressures, from about 2 to 4 GPa, as typically encountered in elastohydrodynamic contacts. It was shown that under these conditions the limiting shear stresses increased less than proportionally with the pressure; i.e. the coefficients of friction were decreasing functions of the pressures. The results were compared with previously reported values from the literature and in general good agreement was obtained.

scholarly journals Gaseous combustion at high pressures. —Part X. The co-volume corrections, maximum temperatures and dissociation of steam and carbon dioxide in explosions

1928 ◽  
Vol 119 (782) ◽  
pp. 464-480
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Internal Energy ◽  
High Temperatures ◽  
High Pressures ◽  
Internal Combustion ◽  
Systematic Survey ◽  
Explosion Method ◽  
Maximum Temperatures ◽  
Very High

During the researches upon high-pressure explosions of carbonic oxide-air, hydrogen-air, etc., mixtures, which have been described in the previous papers of this series, a mass of data has been accumulated relating to the influence of density and temperature upon the internal energy of gases and the dissociation of steam and carbon dioxide. Some time ago, at Prof. Bone’s request, the author undertook a systematic survey of the data in question, and the present paper summarises some of the principal results thereof, which it is hoped will throw light upon problems interesting alike to chemists, physicists and internal-combustion engineers. The explosion method affords the only means known at present of determining the internal energies of gases at very high temperatures, and it has been used for this purpose for upwards of 50 years. Although by no means without difficulties, arising from uncertainties of some of the assumptions upon which it is based, yet, for want of a better, its results have been generally accepted as being at least provisionally valuable. Amongst the more recent investigations which have attracted attention in this connection should be mentioned those of Pier, Bjerrum, Siegel and Fenning, all of whom worked at low or medium pressures.

Friction and Adhesion of Copper in Vacuum

1967 ◽  
Vol 89 (4) ◽  
pp. 425-431 ◽  
Author(s):  
R. D. Brown ◽  
R. A. Burton
Keyword(s):  
Friction Coefficient ◽  
Contact Duration ◽  
Friction Coefficients ◽  
Dry Air ◽  
Very High

Friction and adhesion coefficients of copper on copper were measured in vacuum (5 × 10−10 to 4 × 10−7 torr) at temperatures ranging from −270 to 1000 F, and in controlled pressures of dry air ranging from 10−9 to 760 torr at 75 F. The effects of duration of exposure of surfaces to vacuum, and the effects of contact duration on adhesion were studied. Friction coefficients were very high (2.2 to over 16) and increased greatly with temperature; adhesion coefficients also increased with temperature, but at given temperatures, were about one-tenth the magnitudes of the friction coefficient.

scholarly journals Ultra High Pressure Liquid Chromatography for Crude Plant Extract Profiling

2011 ◽  
Vol 94 (1) ◽  
pp. 51-70 ◽  
Author(s):  
Philippe J Eugster ◽  
Davy Guillarme ◽  
Serge Rudaz ◽  
Jean-Luc Veuthey ◽  
Pierre-Alain Carrupt ◽  
...  
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
High Pressures ◽  
Product Analysis ◽  
Basic Principles ◽  
Ultra High Pressure ◽  
Crude Plant Extract ◽  
Phase Chemistry ◽  
Very High

Abstract Ultra high pressure liquid chromatography (UHPLC) systems operating at very high pressures and using sub-2 μm packing columns have allowed a remarkable decrease in analysis time and increase in peak capacity, sensitivity, and reproducibility compared to conventional HPLC. This technology has rapidly been widely accepted by the analytical community and is being gradually applied to various fields of plant analysis such as QC, profiling and fingerprinting, dereplication, and metabolomics. For many applications, an important improvement of the overall performances has been reported. In this review, the basic principles of UHPLC are summarized, and practical information on the type of columns used and phase chemistry available is provided. An overview of the latest applications to natural product analysis in complex mixtures is given, and the potential and limitations as well as some new trends in the development of UHPLC are discussed.

scholarly journals First-principles study of SnO under high pressure

2016 ◽  
Vol 30 (31) ◽  
pp. 1650228 ◽  
Author(s):  
M. A. Ali ◽  
A. K. M. A. Islam ◽  
N. Jahan ◽  
S. Karimunnesa
Keyword(s):  
High Pressure ◽  
Optical Properties ◽  
First Principles ◽  
High Pressures ◽  
Mechanical Stability ◽  
Generalized Gradient ◽  
First Principles Study ◽  
Anisotropic Factor ◽  
High Anisotropy ◽  
Very High

This paper reports the first-principles study of SnO under high pressure within the generalized gradient approximation (GGA). We have calculated the structural, elastic, electronic and optical properties of SnO. The elastic properties such as the elastic constants [Formula: see text], bulk modulus, shear modulus, Young’s modulus, anisotropic factor, Pugh’s ratio and Poisson’s ratio are calculated and analyzed. Mechanical stability of SnO at all pressures is confirmed using the Born’s stability conditions in terms of [Formula: see text]. It is also found that SnO exhibits very high anisotropy. The energy band structure and density of states are also calculated and analyzed. The results show the semiconducting and metallic properties at zero and high pressures, respectively. Furthermore, the optical properties are also calculated. All the results are compared with those of SnO where available but most of the results at high pressure are not compared due to the unavailability of results.

Friction Behavior Between Epoxy and Flexible Pipes Armor Wires

2016 ◽  
Author(s):  
Diego A. Lorio ◽  
Facundo J. Wedekamper ◽  
Fabiano Bertoni ◽  
Facundo S. Lopéz ◽  
George C. Campello ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Contact Pressure ◽  
Normal Load ◽  
Surface Profile ◽  
Repeated Measurements ◽  
Analytical Models ◽  
Friction Coefficients ◽  
Wire Sample ◽  
Flexible Pipes ◽  
The Wire

The offshore industry has presented an increasing demand over the last few decades, requiring the production in deep water fields. The end fittings (EF) are critical points within the production system. Therefore, structural and fatigue analyses are essential in the EF design, making it necessary to know the stress distribution experienced by the armor wires along the EF. Numerical and analytical models are often used in order to assess the stress state. However, characteristics like geometries, materials and interactions must be previously known in order to apply these models. The purpose of this work was to analyze the arithmetic mean surface roughness (Ra) and to determine the friction coefficient (μ) for two types of armor wires when in contact with resin used to fill the EF. The resin used in the interaction with the armor wires was an epoxy filled with metallic particles. For the experimental analysis straight carbon steel armor wires with different cross-sections, typically used in 2.5″ and 8″ flexible pipes were used. Surface profile was obtained for each wire by repeated measurements along two lines over each surface. A total of three repetitions were performed in each measure line. Longitudinal roughness was determined through these profiles. Finally, friction coefficients were obtained experimentally by means of a device that allows to simulate the wire pullout and sliding process. In this device, two epoxy pads were put in contact with the surface of the analyzed wire sample, and rigid bodies in contact with the pads were used to ensure that the normal load applied is transmitted uniformly through the contact surface. The displacement rate, contact pressure between the surface of the wire and the epoxy resin pads, and axial force were recorded. The roughness in the longitudinal direction of the wires was analyzed through descriptive statistic and compared by Student’s “t” test. The highest values were obtained on wires with larger sections. This behavior is exposed on the results obtained for the friction coefficient as a function of the contact pressure. Friction coefficient for both wires was analyzed and compared using a Mann-Whitney U test. Both friction coefficients have a positive slope, indicating a small increase as the contact pressure raise. The significance value obtained for the means comparisons was p = 0.0001 and confirms that the average friction coefficient of the two wires are really different. Because of that, we conclude that is necessary to treat the EF project for different flexible pipes differentially.

Pressurfect™ CNG-Advanced Material Grade for High Pressure CNG Fuel Line Applications

2017 ◽  
Author(s):  
Vikram Pandit
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Extensive Study ◽  
Stainless Steel 316L ◽  
Gas Stations ◽  
Production Route ◽  
Pressure Line ◽  
The People ◽  
The Government ◽  
Very High

In line with the government of India’s philosophy of going green to reduce emission levels in cities there is a thrust to increase the gas distribution network. With an increase in CNG vehicles, comes the safety of the people and we need to ensure that Safety is not comprised at any level. To follow the Safety aspect, CNG is an excellent alternate fuel which can be used to minimize risks and increase life of the vehicles. Since this gas is used at very high pressures (in the range of 230–250 bar) and under severe conditions, special tubing must be used for the transportation to gas stations and in the vehicles. Therefore, the tubing should be able to not only withstand high pressure of the gas within but also the corrosion issues arising due to the extreme conditions the tubes within. Sandvik did an extensive study of the conditions and came up with a material which is specifically developed for this high pressure application. The high pressure line is of Stainless Steel 316L but this material comes with certain modifications for this particular requirement. In this tubing the C content is lowered to 0.025% for better corrosion resistance, Ni is min 13% along with Mo min 2.5% this makes sure that the material not only has sufficient passivation properties but the strength also to withstand that kind of a pressure. Alongside a special production route also has been developed for the manufacturing of these tubing. This ensures Safety for the people throughout the life of the vehicle.

Seismic parameter φ: Computation at very high pressure from laboratory data

1966 ◽  
Vol 56 (3) ◽  
pp. 725-731
Author(s):  
Orson L. Anderson
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Ultrasonic Velocity ◽  
Pressure Range ◽  
High Pressures ◽  
Equations Of State ◽  
Laboratory Data ◽  
Second Derivative ◽  
Velocity Measurements ◽  
Very High

abstract By using the accuracy inherent in ultrasonic velocity measurements taken at pressures less than 10 kb, the seismic parameter φ=vp2−(43)vS2 can be computed at very high pressures. The equation used requires the assumption that the second derivative with respect to pressure of the bulk modulus be negligible at all pressures considered. This assumption is checked by computing the compression (V/V0) in the pressure range by equations of state using the assumption, and comparing the resulting values with measured compression. Illustrations are given for MgO and Al2O3.

Bearing Friction Torque in Threaded Fasteners With Non-Flat Underhead Contact

2018 ◽  
Author(s):  
Sayed A. Nassar ◽  
Marco Gerini Romagnoli ◽  
Joon Ha Lee
Keyword(s):  
Friction Coefficient ◽  
Contact Pressure ◽  
Friction Torque ◽  
Sliding Speed ◽  
Friction Coefficients ◽  
Threaded Fasteners ◽  
Tension Testing ◽  
Contact Surfaces ◽  
Flat Contact ◽  
Bearing Friction

This study provides experimentally validated formulation of underhead bearing friction torque component during tightening of threaded fasteners with non-flat contact with the joint. Motosh model is utilized for spherical and conical contact surfaces for various scenarios of contact pressure. For each pressure scenario, a single non-dimensional 3-D graph is generated for the corresponding values of an effective bearing friction radius. A rotating sliding speed-dependent friction coefficient model is also investigated for its impact of the results of bearing friction radius. Torque-Tension testing is used to measure the bearing friction torque and the corresponding bearing friction coefficients using Motosh model, in which the newly formulated bearing friction radius expressions are entered. Obtained bearing friction coefficient values are then compared with those published by the threaded fastener manufacturer.

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