A Contribution to the Theory of Friction and Wear and the Relationship between them

1976 ◽  
Vol 190 (1) ◽  
pp. 477-488 ◽  
Author(s):  
J. Halling
Keyword(s):  
Shear Stress ◽  
Coefficient Of Friction ◽  
Interfacial Shear Stress ◽  
Failure Criteria ◽  
Elastic Behaviour ◽  
Total Load ◽  
Perfectly Plastic ◽  
The Coefficient Of Friction ◽  
Wear Law ◽  
The Relationship

The nature of the interaction between a rigid spherical asperity and an asperity governed by the stress/strain law [Formula: see text] is studied. The interfacial shear stress is defined by f τmax where 0 < f < 1, τ maxbeing the maximum allowable shear stress at the contact. By integrating the total effect of a population of such surface asperities expressions for the total frictional forces, and the total load are derived. The value of the coefficient of friction is thus obtained and the special conditions for perfectly plastic and elastic behaviour are considered. In both cases the friction coefficient is seen to contain a term defined by the deformation and dependent on surface roughness and a term totally defined by f. Using the same model a fatigue type failure criteria is introduced to predict the volume of wear. It is then possible to produce a wear law which is consistent with experience and which includes the relationship between the wear and the coefficient of friction.

Experimental study on the relationship between the friction coefficient and interference in locomotive axle press-fitting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ting Wang ◽  
Hanfei Guo ◽  
Jianjun Qiao ◽  
Xiaoxue Liu ◽  
Zhixin Fan
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Friction Pair ◽  
Rolling Stock ◽  
Content Type ◽  
Press Fitting ◽  
The Press ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Locomotive Wheels

PurposeTo address the lack of data in this field and determine the relationship between the coefficient of friction and the interference between locomotive wheels and axles, this study evaluates the theoretical relationship between the coefficient of friction and the interference under elastic deformation.Design/methodology/approachWhen using numerical analyses to study the mechanical state of the contacting components of the wheels and axle, the interference between the axle parts and the coefficient of friction between the axle parts are two important influencing factors. Currently, as the range of the coefficient of friction between the wheel and axle in interference remains unknown, it is generally considered that the coefficient of friction is only related to the materials of the friction pair; the relationship between the interference and the coefficient of friction is often neglected.FindingsA total of 520 press-fitting experiments were conducted for 130 sets of wheels and axles of the HXD2 locomotive with 4 types of interferences, in order to obtain the relationship between the coefficient of friction between the locomotive wheel and axle and the amount of interference. These results are expected to serve as a reference for selecting the coefficient of friction when designing axle structures with the rolling stock, research on the press-fitting process and evaluations of the fatigue life.Originality/valueThe study provides a basis for the selection of friction coefficient and interference amount in the design of locomotive wheels and axles.

Investigation of the causes of damage to freight cars during disbanding on non-mechanized sorting slides and development of measures to prevent them

2021 ◽  
pp. 4-13
Author(s):  
S. V. Tankeev ◽  
◽  
A. E. Kolodin ◽  
V. B. Sverdlov ◽  
A. V. Nazarov ◽  
...  
Keyword(s):  
Low Power ◽  
Coefficient Of Friction ◽  
Damage Assessment ◽  
Laboratory Tests ◽  
Rolling Stock ◽  
Third Body ◽  
Normative Documents ◽  
The Coefficient Of Friction ◽  
Loading And Unloading ◽  
The Relationship

The damage assessment of freight cars during shunting and loading and unloading operations was made. The need to review the normative documents regulating the relationship between the owners of rolling stock, owners of non-public tracks and the carrier is noted. The reasons for formation of damage on the wheel pairs of freight cars when disbanding on low-power sorting slides are considered. The conditions for ensuring the deceleration of detachments on non-mechanized sorting slides without damaging the wheels are determined. The analysis of methods for ensuring braking on low-power slides is carried out. A method was chosen to ensure the wheel set rotation by introducing a third body between the rubbing surfaces during the braking of cars, which will take over a part of the resulting heat flow, reducing the temperature and increasing the coefficient of friction in the «wheel-rail» contact zone. A method is proposed to provide braking on the non-mechanized sorting slide during shoe braking by applying a friction compound to a non-working rail. Laboratory tests were carried out, which showed that the introduction of a friction additive can achieve the necessary coefficient of friction to comply with the standard parameters of deceleration of the car in the braking zone.

scholarly journals The Effect of Elemental Composition and Nanostructure of Multilayer Composite Coatings on Their Tribological Properties at Elevated Temperatures

2020 ◽  
Author(s):  
Alexey Vereschaka ◽  
Sergey Grigoriev ◽  
Vladimir Tabakov ◽  
Mars Migranov ◽  
Nikolay Sitnikov ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Elevated Temperatures ◽  
Composite Coatings ◽  
Multilayer Composite ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Tribological Parameters ◽  
Adhesion Component

The chapter discusses the tribological properties of samples with multilayer composite nanostructured Ti-TiN-(Ti,Cr,Al,Si)N, Zr-ZrN-(Nb,Zr,Cr,Al)N, and Zr-ZrN-(Zr,Al,Si)N coatings, as well as Ti-TiN-(Ti,Al,Cr)N, with different values of the nanolayer period λ. The relationship between tribological parameters, a temperature varying within a range of 20–1000°C, and λ was investigated. The studies have found that the adhesion component of the coefficient of friction (COF) varies nonlinearly with a pronounced extremum depending on temperature. The value of λ has a noticeable influence on the tribological properties of the coatings, and the nature of the mentioned influence depends on temperature. The tests found that for the coatings with all studied values of λ, an increase in temperature first caused an increase and then a decrease in COF.

Prediction of the Coefficient of Friction for Pneumatic Tyres on Hard Pavement

1975 ◽  
Vol 189 (1) ◽  
pp. 259-266
Author(s):  
Shri Kant ◽  
D. L. Prasanna Rao ◽  
M. L. Munjal
Keyword(s):  
Coefficient Of Friction ◽  
Vertical Load ◽  
Contact Patch ◽  
The Coefficient Of Friction ◽  
The Relationship

The relationship between the coefficient of friction and the slip of a flexible wheel, such as the pneumatic tyre, plays a major role in the design of refined braking systems for vehicles. The available data being partly empirical in nature, it was desirable to be able to predict this relationship. In this paper an attempt is made to explain the mechanism defining this relationship for a pneumatic tyre operating on a hard pavement. The distinct roles of the flexibility of the tyre and the sliding of the wheel are identified and utilized in predicting the curve. A model of the tyre is proposed to explain the role of flexibility of the tyre. It is shown that the procedure suggested here can clearly bring out the effects of some of the operating paramenters of the vehicle, such as speed of the vehicle, presence of contaminants in the contact patch, stiffness of the tyre, and vertical load on the wheel.

The Influence of the Coefficient of Friction on the Elastic Stress Concentration Factor for a Pin-Jointed Connection

1962 ◽  
Vol 13 (1) ◽  
pp. 17-29 ◽  
Author(s):  
T. H. Lambert ◽  
R. J. Brailey
Keyword(s):  
Shear Stress ◽  
Stress Concentration ◽  
Coefficient Of Friction ◽  
Stress Concentration Factor ◽  
Elastic Stress ◽  
Maximum Shear Stress ◽  
Interference Fit ◽  
Stress Load ◽  
The Coefficient Of Friction ◽  
Very High

SummaryThe benefit to be obtained by using an interference fit between the pin and plate in a pin-jointed connection has already been established. An examination of the published results shows that some non-linearity occurs in the mechanism of load transference from the pin to the plate since, except at very high initial interference, doubling the load on the joint more than doubles the maximum shear stress in the plate. An examination of the stress-load relationship shows a distinct discontinuity, the load at which this discontinuity occurs being dependent upon both the initial interference and the coefficient of friction between the pin and the plate. It is shown that the results hitherto published correspond to a coefficient of friction between the pin and the plate of 0.3 and results for lower and higher coefficients are given.

A novel nonlinear nano-scale wear law for metallic brake pads

2018 ◽  
Vol 20 (17) ◽  
pp. 12027-12036 ◽  
Author(s):  
Sandeep P. Patil ◽  
Sri Harsha Chilakamarri ◽  
Bernd Markert
Keyword(s):  
Molecular Dynamics ◽  
Temperature Distribution ◽  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Brake Pads ◽  
Braking System ◽  
System P ◽  
The Coefficient Of Friction ◽  
Dynamics Simulations ◽  
Wear Law

In the present work, molecular dynamics simulations were carried out to investigate the temperature distribution as well as the fundamental friction characteristics such as the coefficient of friction and wear in a disc-pad braking system.

Junction growth in metallic friction: the role of combined stresses and surface contamination

1959 ◽  
Vol 251 (1266) ◽  
pp. 378-393 ◽  
Keyword(s):  
Shear Stress ◽  
Tangential Stress ◽  
Coefficient Of Friction ◽  
Tangential Force ◽  
Critical Shear Stress ◽  
Surface Contamination ◽  
Combined Stresses ◽  
The Coefficient Of Friction ◽  
True Contact ◽  
Metallic Friction

This paper extends earlier work on the adhesion mechanism of friction and considers in particular the growth in area of contact as the tangential force is increased to the point at which gross sliding occurs. The earlier studies assumed that the area of true contact A is the same as that produced under static loading so that A = W / p 0 where W is the normal load and p 0 the plastic yield pressure of the metal. If the junctions have a specific shear strength s , the friction F , that is the force to shear them, will be F = As and the coefficient of friction becomes μ = s / p 0 (Bowden & Tabor 1954). Recent studies, however, show that as the tangential stress is applied the area of true contact increases according to a relation of the type p 2 + αs 2 = p 2 0 where p is the normal and s the tangential stress in the contact region and α an appropriate constant. With thoroughly outgassed metals, junction growth generally proceeds until practically the whole of the geometric area is in contact and coefficients of friction of the order of 50 or more are observed (Bowden & Young 1951). If the interface is contaminated, the stresses transmitted through it cannot exceed the critical shear stress of the interface. The new point developed in this paper based on the work of Courtney-Pratt & Eisner (1957), is that until the shear stress reaches this value junction growth occurs as for clean metals. Beyond this point, however, further junction growth is impossible and gross sliding occurs within the interfacial layer itself. The analysis given here shows that if the interface is only 5% weaker than the bulk metal, junction growth ceases and gross sliding occurs when the coefficient of friction is of the order of unity. This corresponds to the experimental observation that minute amounts of oxygen or air reduce the friction of thoroughly clean metals from extremely high values to values of about 1. In the presence of a lubricant film the transmissible stresses are so small that little junction growth can occur before sliding takes place. The expression for the coefficient of friction now reduces to a form resembling that given by the earlier simpler theory, namely μ = s i / p 0 , where s i is the critical shear stress of the lubricant layer. The present treatment thus incorporates the effect of combined stresses and surface contamination into a more general theory of metallic friction.

Research of the effect of shot peening vibro-abrasive machining on the properties of the steel NC11LV

Mechanik ◽  
2017 ◽  
Vol 90 (1) ◽  
pp. 74-75
Author(s):  
Sławomir Spadło ◽  
Damian Bańkowski ◽  
Joanna Kowalczyk
Keyword(s):  
Coefficient Of Friction ◽  
Shot Peening ◽  
Friction And Wear ◽  
Abrasive Machining ◽  
Tribological Tests ◽  
Working Medium ◽  
The Coefficient Of Friction ◽  
Relationship Of ◽  
The Relationship

The article presents the results of the effect of vibro-abrasive machining using as a working medium balls of steel-check on the properties of disks made of steel NC11 (X160CrMoV121). Tribological tests using the tester T-01 made it possible to determine the relationship of time of shot peening on the coefficient of friction and wear linear-in. They were presented typical consumption profiles.

Sign in / Sign up

Export Citation Format

Share Document