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

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.

Modelling the tribological response in dry sliding of boron modified as-cast Ti6Al4V on hardened steel

2021 ◽  
pp. 135065012110592
Author(s):  
Palash Roy Choudhury ◽  
Korimilli Eswar Prasad ◽  
John K. Schueller ◽  
Abhijit Bhattacharyya
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Boron Content ◽  
Normal Load ◽  
Operating Conditions ◽  
Dry Sliding ◽  
Contour Plots ◽  
The Coefficient Of Friction ◽  
En 31 ◽  
Full Factorial

Tribological characteristics of boron modified as-cast Ti6Al4V alloys are not very well known, but these alloys enjoy improved as-cast mechanical properties and favourable manufacturing economy. Experimental results are reported here for the effects of sliding speed and normal load on the wear rate and the coefficient of friction in dry sliding of these alloys on hardened EN 31 steel. Alloys having 0%, 0.30%, and 0.55% boron by weight were tested. A full factorial experiment assessed the effects of boron content, speed, and load on wear and friction. Interactions between speed and load were found to be statistically significant in influencing the wear rate and the coefficient of friction. Regression models are developed to predict the wear rate and coefficient of friction responses. The developed contour plots can assist designers in choosing operating conditions when selecting these alloys even if the wear mechanisms are unknown. Evidence shows that the wear resistance of Ti6Al4V can be improved by boron addition, and wear regimes are sensitive to boron content.

The Consequences of Spline Friction in Multiple Disk Brake and Clutch Packs

1968 ◽  
Vol 90 (1) ◽  
pp. 65-71 ◽  
Author(s):  
E. F. Finkin
Keyword(s):  
Pressure Distribution ◽  
Coefficient Of Friction ◽  
Mathematical Analysis ◽  
Test Apparatus ◽  
Disk Brake ◽  
Load Variation ◽  
Interfacial Pressure ◽  
The Coefficient Of Friction ◽  
Disk Test

A mathematical analysis is offered showing the various consequences of spline friction in multiple disk systems. Included are equations for the load variation through a multiple disk pack, the effect of interfacial pressure distribution on this load variation, the torque variation through a pack, and the total torque carried by a pack. The relation between friction and velocity is taken into account. The coefficient of friction determined from the data of a multiple disk test apparatus, ignoring spline friction, is shown to be significantly in error and an equation is derived for calculating the true coefficients of friction. Examples of the load variation in a pack are derived and the results plotted.

TRIBOLOGICAL CHARACTERISTICS OF POLYURETHANES USED FOR THE SOLES OF FOOTWEAR

Tribologia ◽  
2021 ◽  
Vol 294 (6) ◽  
pp. 71-75
Author(s):  
Jacek Przepiórka ◽  
Marian Szczerek ◽  
Marian W. Sułek
Keyword(s):  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Base Material ◽  
Operating Conditions ◽  
Test Results ◽  
Footwear Industry ◽  
Wear And Tear ◽  
Variable Friction ◽  
The Coefficient Of Friction ◽  
Shoe Soles

The inability to take into account the type of base material (floor, pavement, soil), as well as the inability to take into account the variable friction conditions – load, intermediary medium (water, loose abrasive, sand or other soil particles), sliding velocity, and ambient temperature – is a significant limitation the use of friction methods and devices used so far in the footwear industry to precisely anticipate the behavior of the bottom materials in the actual operating conditions of the footwear. These limitations prompted the authors to adapt a tribological tester for this purpose, used in the area of construction and operation of machines and material engineering. A research methodology was developed and, in order to verify it, measurements of the coefficient of friction and wear of polyurethane used for shoe soles in combination with a raw and varnished wooden substrate were carried out. The obtained test results are characterized by diversity, which proves the high research resolution of the developed method. It allows determining the coefficient of friction of associations influencing the slip of the footwear and the wear and tear that determines the length of use of the footwear.

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.

Stability of Frictional Sliding With the Coefficient of Friction Depended on the Temperature

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Vahid Mortazavi ◽  
Chuanfeng Wang ◽  
Michael Nosonovsky
Keyword(s):  
Thermal Conductivity ◽  
Temperature Field ◽  
Coefficient Of Friction ◽  
Temperature Dependency ◽  
Brake Disk ◽  
Frictional Sliding ◽  
Disk Brake ◽  
The Coefficient Of Friction ◽  
Surface Temperature Field

Friction-induced instabilities can be caused by different separate mechanisms such as elastodynamic or thermoelastic. This paper suggests another type of instability due to the temperature dependency of the coefficient of friction. The perturbations imposed on the surface temperature field during the frictional sliding can grow or decay. A stability criterion is formulated and a case study of a brake disk is performed with a simple model without including effects of transforming layer and chemical/physical properties change with temperature. The disk is rigid and the coefficient of friction depends on temperature. We show that the mechanism of instability can contribute to poor reproducibility of aircraft disk brake tests reported in the literature. We propose a method to increase the reproducibility by dividing the disk into several sectors with decreased thermal conductivity between the sectors.

scholarly journals Modelling of Frictional Conditions in the Wheel–Rail Interface Due to Application of Top-of-Rail Products

Lubricants ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 100
Author(s):  
Gerald Trummer ◽  
Zing Siang Lee ◽  
Roger Lewis ◽  
Klaus Six
Keyword(s):  
Simulation Model ◽  
Coefficient Of Friction ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Operating Conditions ◽  
Contact Forces ◽  
Rolling Contact ◽  
Application Site ◽  
Small Scale ◽  
The Coefficient Of Friction

The coefficient of friction between a wheel tread and the top of the rail should be maintained at intermediate levels to limit frictional tangential contact forces. This can be achieved by applying top-of-rail products. Reducing the coefficient of friction to intermediate levels reduces energy consumption and fuel costs, as well as damage to the wheel and rail surfaces, such as, e.g., wear, rolling contact fatigue, and corrugation. This work describes a simulation model that predicts the evolution of the coefficient of friction as a function of the number of wheel passes and the distance from the application site for wayside application of top-of-rail products. The model considers the interplay of three mechanisms, namely the pick-up of product by the wheel at the application site, the repeated transfer of the product between the wheel and rail surfaces, and the product consumption. The model has been parameterized with data from small-scale twin disc rig experiments and full-scale wheel–rail rig experiments. Systematic investigations of the model behaviour for a railway operating scenario show that all three mechanisms may limit the achievable carry-on distance of the product. The developed simulation model assists in understanding the interplay of the mechanisms that govern the evolution of the coefficient of friction in the field. It may aid in finding optimal product application strategies with respect to application position, application amount, and application pattern depending on specific railway operating conditions.

scholarly journals CAM FITTING UNIT OF DEVICEFOR UNSCREWING CATCHED PIPES IN THE WELL

2021 ◽  
pp. 151-164
Author(s):  
S. Yu. Gavryliv ◽  
M. M. Lyakh ◽  
Yu. L. Gavryliv
Keyword(s):  
Coefficient Of Friction ◽  
Operating Conditions ◽  
Geometric Parameters ◽  
Initial Angle ◽  
Friction Forces ◽  
Repair Work ◽  
Oil Companies ◽  
Urgent Task ◽  
The Coefficient Of Friction ◽  
The Moment

Improving the efficiency of repair work in elimination of drilling pipe accidents in the well is an urgent task of oil companies and is achieved through usage of special devices and tools. Authors patented and manufactured a device for unscrewing pipes in casing with a nominal diameter of D = 114 mm. Cycle of the device for unscrewing pipes in the well consists of three periods: freewheeling, jamming of the carrier of the device for unscrewing the trapped pipes and the period of wedging. The article analyses the operating conditions of the device locking unit during the first two periods. Formulas for determining the force of pressing the cams to the casing during freewheel, as well as the moment of friction forces and friction power for this case are proposed. We obtain the dependence of the maximum allowable initial angle of jamming on the coefficient of friction and geometric parameters of the device. It is planned to test the device for unscrewing pipes in industrial conditions of LLC "Factorial" (Poltava).

A Generalized Traction Curve for EHL Contacts

2000 ◽  
Vol 123 (2) ◽  
pp. 248-253 ◽  
Author(s):  
B. Jacod ◽  
C. H. Venner ◽  
P. M. Lugt
Keyword(s):  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Operating Conditions ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Friction Curve ◽  
The Subject ◽  
Friction Prediction ◽  
Elliptic Contact ◽  
Theoretical Results

In this paper the subject of friction prediction is revisited, with the aim of obtaining a general formula predicting the coefficient of friction over a wide range of operating conditions. By means of full numerical simulations of the smooth isothermal elliptic contact, and assuming an Eyring non-Newtonian behavior, the coefficient of friction is computed for a wide range of operating conditions. It is shown that with respect to sliding friction, all results can be presented on a single generalized friction curve relating a reduced coefficient of friction to a characteristic nondimensional shear stress. Finally, it is shown that some measured data presented in the literature when presented in terms of the derived parameters closely follow the derived behavior, which provides a validation of the theoretical results.

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