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.

Effect of Hardness and Position on Wear Behavior of Steel Pairs

2012 ◽  
Vol 263-266 ◽  
pp. 95-98
Author(s):  
Zhu Jun Li ◽  
Zheng Wu Jiang ◽  
Huan Wei Zhou
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Room Temperature ◽  
Wear Behavior ◽  
Friction Pair ◽  
Wear Volume ◽  
Average Value ◽  
Small Impact ◽  
Test Conditions ◽  
The Coefficient Of Friction

In this paper, the effect of hardness and position on the 40CrNiMoA steel and 18Cr2Ni4WA steel friction pairs’ friction coefficient and wear volume were studied without lubrication, at room temperature. The results show that: Under test conditions, the fluctuation in the friction coefficient is bigger, when the up specimen is the harder 18Cr2Ni4WA steel. And when the up specimen is the softer 40CrNiMoA steel, the fluctuation in the friction coefficient is relatively small. When the up specimen is the 40CrNiMoA steel, the hardness of 40CrNiMoA steel is a relatively small impact on the average value of the coefficient of friction.When the up specimen is the softer 40CrNiMoA steel, the coefficient of friction is relatively larger than that when the up specimen is the harder 18Cr2Ni4WA steel. The wear volumes is relate to the position of friction pair. When the up specimen is the harder 18Cr2Ni4WA steel, both sides of the friction pairs has the same wear volumes when the hardness of 40CrNiMoA steel is about 43HRC. When the up specimen is softer 40CrNiMoA steel, and its hardness is about 54HRC, the wear volumes curves of two materials intersect.

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.

Experimental investigation on Stribeck curves of different elastic modulus materials under oil and water lubrication conditions

2020 ◽  
Vol 72 (6) ◽  
pp. 805-810
Author(s):  
Hua Zhang ◽  
Guangwu Zhou ◽  
Ping Zhong ◽  
Kepeng Wu ◽  
Xingwu Ding
Keyword(s):  
Elastic Modulus ◽  
Friction Coefficient ◽  
Friction Pair ◽  
Water Lubrication ◽  
Contact Friction ◽  
Friction Coefficients ◽  
Content Type ◽  
Low Viscosity ◽  
Stribeck Curves ◽  
Lubrication Conditions

Purpose The purpose of this paper is to study the influence of friction coefficient of materials with different elastic modulus on the variation of velocity and load under water lubrication and oil lubrication conditions. Design/methodology/approach Low-viscosity lubricating oil and water were used as lubricants to test the friction performance of the ball-disc contact friction pair in the lubrication state on the universal micro-tribometer multi-functional friction and wear test system. Findings In the same speed range, the lubrication states from soft to rigid materials are not necessarily similar to each other. Generally, the material with low elastic modulus is suitable in low-viscosity lubricant environments, while the material with high elastic modulus has relatively smaller friction coefficients in oil-lubricated environments compared with water lubrication. However, the coefficients of polyethylene, polytetrafluoroethylen and polyoxymethylene are exceeded by rubber’s coefficients under water lubrication in the same experiment environments, and their lubrication states are not affected by lubricants. The friction coefficient of the friction pair decreases with the increase of loads; however, it does not apply to all materials. The friction coefficients of materials with smaller elastic modulus such as rubber under high loads are rather large. Therefore, the elastic modulus of the material under high loads is a factor to be considered. Originality/value The Stribeck curves study of the ball-disk contact friction pair comprising soft and rigid materials, whose elastic modulus is from hundreds of GPa to a few of MPa, was carried out. The influence of different speeds, loads and lubricants on the friction coefficient of the friction pair was revealed, which provided a research basis for the selection and matching of friction pair materials.

scholarly journals Anisotropic Vibration Tactile Model and Human Factor Analysis for a Piezoelectric Tactile Feedback Device

Micromachines ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 448 ◽  
Author(s):  
Jichun Xing ◽  
Huajun Li ◽  
Dechun Liu
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Ciliary Body ◽  
Human Factor ◽  
Sliding Friction ◽  
Excitation Frequency ◽  
Tactile Feedback ◽  
Body Structure ◽  
Full Coverage ◽  
The Coefficient Of Friction

Tactile feedback technology has important development prospects in interactive technology. In order to enrich the tactile sense of haptic devices under simple control, a piezoelectric haptic feedback device is proposed. The piezoelectric tactile feedback device can realize tactile changes in different excitation voltage amplitudes, different excitation frequencies, and different directions through the ciliary body structure. The principle of the anisotropic vibration of the ciliary body structure was analyzed here, and a tactile model was established. The equivalent friction coefficient under full-coverage and local-coverage of the skin of the touch beam was deduced and solved. The effect of system parameters on the friction coefficient was analyzed. The results showed that in the full-coverage, the tactile effect is mainly affected by the proportion of the same directional ciliary bodies and the excitation frequency. The larger the proportion of the same direction ciliary body is, the smaller the coefficient of friction is. The larger the excitation frequency is, the greater the coefficient of friction is. In the local-coverage, the tactile effect is mainly affected by the touch position and voltage amplitude. When changing the touch pressure, it has a certain effect on the change of touch, but it is relatively weak. The experiment on the sliding friction of a cantilever touch beam and the experiment of human factor were conducted. The experimental results of the sliding friction experiment are basically consistent with the theoretical calculations. In the human factor experiment, the effects of haptic regulation are mainly affected by voltage or structure of the ciliary bodies.

Effect of crystal size on the tribological properties of lithium disilicate glass-ceramics sliding against alumina and tungsten carbide spheres

2020 ◽  
Vol 72 (9) ◽  
pp. 1109-1116
Author(s):  
Crislaine da Cruz ◽  
Ivan Mathias ◽  
Mariza Veiga Senk ◽  
Gelson Biscaia de Souza ◽  
Francisco Carlos Serbena
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Glass Ceramic ◽  
Crystal Size ◽  
Glass Ceramics ◽  
Stationary Regime ◽  
Content Type ◽  
Dental Restorations ◽  
The Coefficient Of Friction ◽  
Dental Prosthetics

Purpose Lithium disilicate glass-ceramics (LS2 GC) are widely used as dental prosthetics and dental restorations. Based LS2 GC have hardness and translucency similar to that of natural teeth. This study aims to investigate the tribological features of LS2 GC with crystalline volume fraction of 64% and different crystal sizes from 8 µm to 34 µm for different counterparts. Design/methodology/approach The tribological behavior was investigated using a pin-on-disc tribometer with alumina and tungsten carbide (WC) spheres, applied load of 5 N and sliding speed of 5 cm/s at normal conditions. The coefficient of friction was measured continuously up to 10,000 sliding cycles. The specific wear rate was calculated from tribological and profile measurements. The wear mechanism was investigated by surface morphology analysis. Findings The coefficient of friction during running-in varied from 0.8 to 1.0 for the alumina counterpart, because of severe wear. Afterwards, it reduced and reached a stationary regime, characterized by a mild wear regime and the formation of a tribolayer formed by the debris. For the WC counterpart, the coefficient of friction curves increased initially with sliding cycles up to a stationary regime. The samples tested against WC presented the lowest specific wear rate (k), and no variation of wear rate with crystal size was observed. For samples tested against the alumina, crystallization and crystal size increased the wear resistance. Originality/value This study evaluated the effect of different counterfaces on the tribological properties of the LS2 GC, an important glass-ceramic base for many dental prosthetics and dental restorations, discussing results in light of the contact mechanics. Different specific wear rates, wear regimes and dependence on the glass-ceramic microstructure were observed depending on the counterpart. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0352/

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.

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.

The Size of the Friction Coefficient Depending on the Size and Course of Normal Load

2014 ◽  
Vol 474 ◽  
pp. 303-308 ◽  
Author(s):  
Eva Labašová
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Testing Machine ◽  
Constant Load ◽  
Current Component ◽  
Rectangular Shape ◽  
The Coefficient Of Friction ◽  
Ring Method ◽  
Run Up

The coefficient of friction for the bronze material (CuZn25Al6) with inset graphite beds is investigated in the present paper. Friction coefficient was investigated experimentally by the testing machine Tribotestor`89 which uses the principle of the ring on ring method. Tribotestor`89 machine may be classed to the rotary tribometers. The tested sliding pairs were of the same material. The internal bushing performed a rotational movement with constant sliding speed (v = 0.8 m s-1). The external fixed bushing was exposed to the normal load, which was of different sizes and different variations. Process of load was increased from level 50 N to 200 N (400 N, 600 N) during run up 600 s, after the run up the appropriate level of load was held.The forth test had a rectangular shape of loading with direct current component 400 N and the amplitude 200 N period 600 s, the whole test took 1800 s. The obtained results reveal that friction coefficient decreases with the increase of normal load. Further, that the coefficient of friction was found smaller at constant load, as compared to rectangular shape of loading.

scholarly journals Research of the drawing of bars plate in the refiners

2021 ◽  
Vol 2094 (4) ◽  
pp. 042038
Author(s):  
S N Vikharev ◽  
VA Morkovin
Keyword(s):  
Friction Coefficient ◽  
Contact Interaction ◽  
Coefficient Of Friction ◽  
Wood Pulp ◽  
Contact Processes ◽  
Low Concentration ◽  
The Coefficient Of Friction ◽  
Radial Arrangement

Abstract Object of research of article is the drawing of bars plate in the refiners at refining of chips and wood pulp. On the basis of the theory of contact interaction of bars influence of the drawing of plate on characteristics of contact processes is investigated. The friction coefficient between plate decreases at increase in density of contact of bars. At increase in an angle of crossing of bars rotor and stator and refining of pulp with concentration up to 6% the coefficient of friction decreases. At increase in an angle of crossing of bars chips and pulp with concentration over 10% the coefficient of friction increases. Therefore it is recommended to increase the angle of crossing of bars rotor and stator at refining of pulp of low concentration, and at refining of pulp of concentration over 10% and chips - to reduce, up to a radial arrangement.

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