Experimental Investigation of Porous Bronze Bearings

1973 ◽  
Vol 95 (2) ◽  
pp. 173-179 ◽  
Author(s):  
C. Cusano ◽  
R. M. Phelan
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Operating Conditions ◽  
The Coefficient Of Friction ◽  
Theoretical Analyses ◽  
Lubrication Conditions

An experimental study was made of the performance of porous bronze bearings under different operating conditions. A PV value of 50,000 psi ft/min was found to be too high for the assembly used when the bearings were lubricated only by the oil initially provided within their structure. Tests at a PV value of 33,000 psi ft/min gave satisfactory results. The coefficient of friction was found to vary with load and to be almost independent of speed for the bearings tested under boundary lubrication conditions. Except for relatively light loads and moderate and higher speeds, the bearings operate under boundary lubrication conditions. When pressurized oil was supplied to the bearings, it was found that, for the same operating conditions, porous bearings run at higher eccentricity ratios than solid bearings, as predicted by theoretical analyses.

scholarly journals An Experimental Study on Starved Grease Lubricated Contacts

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 82 ◽  
Author(s):  
David Gonçalves ◽  
Armando Campos ◽  
Jorge Seabra
Keyword(s):  
Experimental Study ◽  
Film Thickness ◽  
Coefficient Of Friction ◽  
Contact Area ◽  
Operating Conditions ◽  
Thickness Profile ◽  
Lubricated Contacts ◽  
The Coefficient Of Friction ◽  
Over Time ◽  
Ball On Disc

The film thickness of a ball-on-disc contact lubricated with four greases of different formulations was measured under different operating conditions until starvation. Two polymer-thickened greases and two lithium-thickened greases, formulated with base oils of different nature and/or viscosity, were tested. The central film thickness was measured under constant operating conditions (load, temperature, slide-to-roll ratio) varying only the entrainment speed. In a separate test, the film thickness was measured over time with all operating conditions set to constant. Pictures of the film thickness profile across the contact area were also registered. The results were compared with the fully flooded results. The coefficient of friction (COF) was measured in a ball-on-disc contact under equal operating conditions and the results were correlated with the film thickness findings. The different grease formulations and the influence of the operating conditions on the film thickness and COF were discussed. The polymer thickened the greases, promoting lower COF and higher film thickness, especially when there is thickener material crossing the contact which happens quite often for these greases.

Experimental Investigation of aluminum doping crumb rubber/epoxy composite in reciprocating motion

2015 ◽  
Vol 3 ◽  
pp. 1
Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak
Keyword(s):  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Epoxy Composite ◽  
Normal Load ◽  
Crumb Rubber ◽  
The Other ◽  
Reciprocating Motion ◽  
Molding Process ◽  
Friction Tester ◽  
The Coefficient Of Friction

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

Boundary lubrication of friction contacts steel/steel with Cr—DLC-coatings

2020 ◽  
pp. 558-563
Author(s):  
I.A. Buyanovskii ◽  
M.M. Khruschov ◽  
V.D. Samusenko ◽  
Yu.I. Schsherbakov ◽  
M.V. Atamanov ◽  
...  
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Tribological Characteristics ◽  
Coated Steel ◽  
Dlc Coatings ◽  
Dlc Coating ◽  
Lubrication Mode ◽  
Maximum Coefficient ◽  
Surface Active

The results of an experimental study of the tribological characteristics of inactive, surface-active, and chemically active lubricants in the boundary lubrication mode when steel is rubbed against steel with a carbon diamond-like (Cr—DLC)-coating. For comparison, also tested friction in these friction contacts under similar conditions, but without lubricant. The maximum coefficient of friction and maximum wear was obtained by tribological testing of steel on steel. The minimum coefficient of friction was obtained when steel was rubbed against Сr—DLC-coated steel in a surface-active lubricant medium.

Skin-skin contact: The normal-force dependence of the coefficient of friction between a bare finger and artificial skin changes randomly

2021 ◽  
Author(s):  
Koki Inoue ◽  
Shogo Okamoto ◽  
Yasuhiro Akiyama ◽  
Yoji Yamada
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Normal Force ◽  
Skin Surface ◽  
Artificial Skin ◽  
Skin Changes ◽  
Root Cause ◽  
Skin Contact ◽  
The Coefficient Of Friction ◽  
Frictional Forces

Abstract This study investigates the dependence of the coefficients of friction on the normal force produced by sliding a bare finger over different artificial skins with seven levels of hardness. The coefficient of friction was modeled as a power function of the normal force. An experimental study that involved sliding a finger over artificial skin surfaces was carried out under two conditions: the fingertip being wiped by a dry cloth or a cloth soaked in ethanol. Although the exponential term was assumed to be nearly constant for identical tribological conditions, we observed that the exponent varied randomly and could be negative, zero, or positive. This probabilistic behavior has not been explicitly analyzed in previous studies on human fingertips. The probability density function of the exponent depended on the moisture content of the finger. The exponent was either nearly zero or positive when the finger sliding on the skin surface was wiped with an alcohol-soaked cloth and dried. These findings play an important role in analyzing the frictional forces produced during skin–skin contact in terms of determining the root cause behind the random variations in the dependence of the coefficient of friction on the normal force.

scholarly journals Providing the stability of the coefficient of friction of a vehicle disk brake under extreme operating conditions

2016 ◽  
Vol 37 (3) ◽  
pp. 230-236 ◽  
Author(s):  
Yu. Yu. Osenin ◽  
Douma Mansur Al-Makhdi ◽  
Yu. I. Osenin ◽  
O. V. Sergienko ◽  
I. I. Sosnov ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Operating Conditions ◽  
Disk Brake ◽  
The Coefficient Of Friction ◽  
The Stability

Variation with load of the coefficient of friction and metallic transfer under conditions of boundary lubrication

1952 ◽  
Vol 212 (1111) ◽  
pp. 516-519 ◽  
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
General Pattern ◽  
Copper Plate ◽  
Experimental Conditions ◽  
Average Hardness ◽  
Boundary Lubricant ◽  
The Coefficient Of Friction ◽  
Fixed Load ◽  
Molecular Layers

Several papers have been published recently which show for a number of metals that, under certain experimental conditions, several molecular layers of boundary lubricant are necessary to give effective lubrication, i.e. a coefficient of friction of 0.1 or less. Recent experiments by the authors suggest that these results represent parts of a more general pattern. In the previous work, the experiments were carried out at a fixed load; in the present, the load has been varied. The apparatus used was a copy of that described by Bowden & Leben (1939) for studying friction at low speeds of sliding. A hemispherical copper slider of radius 0-45 cm was caused to slide upon a flat copper plate at a speed of approximately 1 cm/min. Several specimens were used; their average hardness was 100 v .p .h .

Paper 8: The Fundamentals of Lubrication Processes

1966 ◽  
Vol 181 (12) ◽  
pp. 32-38
Author(s):  
D. Dowson ◽  
J. A. Robertson
Keyword(s):  
Boundary Lubrication ◽  
Operating Conditions ◽  
Lubrication Conditions

The authors outline the fundamental aspects of lubrication conditions and distinguish between hydrodynamic, elastohydrodynamic, and boundary lubrication. The discussion is concerned with the physics rather than the mathematics. The important lubricant properties and the role of bearing geometry are considered. This discussion of modern views on lubrication is perfectly general but operating conditions encountered in textile machinery are considered so that the various types of lubrication in practice can be identified.

Predicting the Coefficient of Friction in Sliding-Rolling Contacts

1989 ◽  
Vol 111 (2) ◽  
pp. 386-390 ◽  
Author(s):  
Yufeng Li ◽  
Ali Seireg
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Thermal Regime ◽  
Surface Coating ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Published Data ◽  
Excellent Correlation ◽  
Rolling Contacts ◽  
The Coefficient Of Friction

This paper deals with the development of a dimensionless empirical formula for calculating the coefficient of friction in sliding-rolling steel on steel contacts under different operating conditions in the thermal regime. The effect of lubrication, surface roughness, and surface coating on friction are considered. The formula shows excellent correlation with the experimental tests conducted by many investigators and provides a unified relationship for all the published data.

Analysis of the Contribution of Adhesion and Ploughing to Shoe-Floor Lubricated Friction in the Boundary Lubrication Regime

2011 ◽  
Author(s):  
Caitlin Moore ◽  
Kurt Beschorner ◽  
Pradeep L. Menezes ◽  
Michael R. Lovell
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Ambient Conditions ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Material Hardness ◽  
Lubrication Layer ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Pin On Disk

Slip and fall accidents cost billions of dollars each year. Shoe-floor-lubricant friction has been shown to follow the Stribeck effect, operating primarily in the boundary and mixed-lubrication regimes. Two of the most important factors believed to significantly contribute to shoe-floor-lubricant friction in the boundary lubrication regime are adhesion and ploughing. Experiments were conducted using a pin-on-disk tribometer to quantify adhesion and ploughing contributions to shoe-floor friction in dry and lubricated conditions. The coefficient of friction between three shoe materials and two floor materials of different hardness and roughness were considered. Experiments were conducted under six lubricants for a sliding speed of 0.01 m/sec at ambient conditions. It was found that the contribution of adhesion and ploughing to shoe-floor-lubricant friction was significantly affected by material hardness, roughness, and lubricant properties. Material hardness and roughness are known to affect adhesion, with increased hardness or increased roughness typically resulting in decreased adhesion. The smoothest shoe material, while also being the hardest, resulted in the greatest adhesional contribution to friction. The roughest material, while also being the softest, resulted in the lowest adhesional contributions under dry conditions. Canola oil consistently resulted in the lowest percent of full adhesion and water consistently resulted in the highest percent of full adhesion, presumably due to the thickness, of the boundary lubrication layer. Ploughing contribution was dependent upon the hardness of the shoe and floor materials. A positive correlation was found between the shoe and floor hardness ratio and ploughing coefficient of friction.

Determination of Tire-Road Friction Coefficients for Skid Mark Analysis

1985 ◽  
Vol 13 (1) ◽  
pp. 41-64
Author(s):  
W. R. Garrott ◽  
D. A. Guenther
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Friction Coefficients ◽  
Pickup Truck ◽  
The Road ◽  
Heavy Trucks ◽  
Road Friction ◽  
Brake Application ◽  
The Coefficient Of Friction

Abstract An experimental study was made to compare the validities of methods currently used by accident reconstructionists to determine the coefficient of friction between the road and the vehicle tires at the time of an incident. This value could then be used in conjunction with skid mark length and vehicle weight to calculate the prebraking speed of the vehicle. Three automobiles and three trucks with a variety of tires and loadings were used on a variety of pavements. The accuracy and area of applicability of each of four methods for obtaining friction coefficients were determined by relating the prebraking speed calculated from each to the actual speed at the time of brake application. All four methods were satisfactory for automobiles and the pickup truck used, but only two were acceptable for heavy trucks. The most valid coefficients are obtained from skid mark lengths obtained under conditions duplicating those in an incident.

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