The Coefficients of Friction between Rubber and Other Materials. Frictional Grip of Rubber-Tired Wheels

1930 ◽  
Vol 3 (1) ◽  
pp. 67-73
Author(s):  
R. Ariano
Keyword(s):  
Coefficient Of Friction ◽  
Static Friction ◽  
Systematic Difference ◽  
Road Surface ◽  
Dynamic Friction ◽  
Simple Relationship ◽  
Inflation Pressure ◽  
The Coefficient Of Friction ◽  
Individual Design ◽  
Increasing Load

Abstract (i) The coefficients of friction (ƒI and ƒnI) of rubber tires on dry non-dusty surfaces are practically independent of the load on the wheel, and (with pneumatics) of the inflation pressure; on muddy surfaces the coefficients (especially ƒnI tend to decrease with increasing load. (ii) Dust, mud, or water reduces the friction with rubber tires, but not with iron tires. (iii) The tread pattern reduces the friction on dry surfaces, but increases it on muddy surfaces. (iv) There is no systematic difference between pneumatic, semi-pneumatic (cushion) and solid tires as regarda coefficient of friction; the details of individual design and material are the deciding factors; this is in agreement with the results of Bredtscheiner (Verkehrstechnik, 1922; see Schaar, “Die Beanspruchung der Strassen durch die Kraftfahrzeuge,” Zementverlag, 1925). (v) There is no simple relationship between the coefficient of friction and the compressibility or area of contact of the tire. (vi) The static friction perpendicular to the direction of travel is greater than in this direction. (vii) The coefficient of friction depends on the type of road surface, its de-formability, and especially on the presence or absence of dust, mud, or water. (viii) Rubber tires have a much higher coefficient of friction than iron tires, especially on dry hard surfaces. (ix) The static friction is 10 to 20 per cent higher than the dynamic friction.

Coefficients of Friction: Static Versus Dynamic

2020 ◽  
Author(s):  
Jack Youqin Huang
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Force ◽  
Inertial Force ◽  
Static Friction ◽  
Theory And Practice ◽  
Dynamic Friction ◽  
Kinetic Friction ◽  
The Coefficient Of Friction ◽  
Static Versus Dynamic ◽  
New Discovery

Abstract This paper deals with the problem of static and dynamic (or kinetic) friction, namely the coefficients of friction for the two states. The coefficient of static friction is well known, and its theory and practice are commonly accepted by the academia and the industry. The coefficient of kinetic friction, however, has not fully been understood. The popular theory for the kinetic friction is that the coefficient of dynamic friction is smaller than the coefficient of static friction, by comparison of the forces applied in the two states. After studying the characteristics of the coefficient of friction, it is found that the comparison is not appropriate, because the inertial force was excluded. The new discovery in the paper is that coefficients of static friction and dynamic friction are identical. Wheel “locked” in wheel braking is further used to prove the conclusion. The key to cause confusions between the two coefficients of friction is the inertial force. In the measurement of the coefficient of static friction, the inertial force is initiated as soon as the testing object starts to move. Therefore, there are two forces acting against the movement of the object, the frictional force and the inertial force. But in the measurement of the coefficient of kinetic friction, no inertial force is involved because velocity must be kept constant.

scholarly journals Efficiency of sorbents used to restore the grip of the surface of the oily road

2018 ◽  
Vol 247 ◽  
pp. 00024
Author(s):  
Mirosław Sobolewski ◽  
Dominika Gancarczyk ◽  
Piotr Książek
Keyword(s):  
Coefficient Of Friction ◽  
Static Friction ◽  
Road Surface ◽  
Asphalt Pavements ◽  
Fire Departments ◽  
Initial Coefficient ◽  
The Road ◽  
Road Users ◽  
The Coefficient Of Friction ◽  
High Degree

The use of sorbents is one of the methods most commonly used by the fire departments to remove spilled hydrocarbon liquids. Sorbents approved for use by fire brigades must meet the requirements of the Ministry of Internal Affairs. However, this requirement does not include the assessment of the degree of roughness of the road surface after removal of oily spills. The high degree of restoration of road surface grip is extremely important for the safety of road users. The article presents the results of research on the effectiveness of restoring the coefficient of friction by different sorbents. The tests were carried out for three different asphalt pavements, determining the coefficients of friction for dry, wet and oily surfaces and after applying sorbents. Static friction coefficients were determined by measuring the angle of the inclination of the tested surface specimen, at which the probe imitating the car tire slid. It turned out that none of the used sorbents fully restored the initial coefficient of friction on the asphalt surface. The use of professional sorbents allowed for the restoration of about 80% of the initial coefficient of friction of the dry surface. Significantly poorer results were obtained for the most commonly used sorptive replacement materials, i.e. sand or sawdust.

scholarly journals Effect of Stick - Slip Phenomena between Human Skin and UHMW Polyethylene

2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Emad Kamil Hussein ◽  
Kussay Ahmed Subhi ◽  
Tayser Sumer Gaaz
Keyword(s):  
Friction Coefficient ◽  
Human Skin ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Static Friction ◽  
Time Interval ◽  
Dynamic Friction ◽  
Sliding Velocity ◽  
Stick Slip ◽  
The Coefficient Of Friction

The present paper investigates experimentally effect of applied load and different velocity on the coefficient of friction between two interacting surfaces (human skin and Ultra-high-molecular-weight polyethylene (UHMW- polyethylene) at static and dynamic friction. It is possible to conclude specific point based on the above practical part and frictional analysis of this investigation as the most important mechanical phenomenon was creep has been observed a stick time interval where the static friction force is significantly increased during this stroke. The analytical model for stick-slip of skin and UHMWPE is proposed. The difference between static and kinetic friction defines the amplitude of stick-slip phenomena. The contact pressure, the sliding velocity, and rigidity of system determine the stability conditions of the movement between skin and UHMWPE. Experiments were carried out by developing a device (friction measurement). Variations of friction coefficient during the time at different normal load 4.6 and 9.2 N and low sliding velocity 4, 5, 6 and 7 mm/min were experimentally investigated. The results showed that the friction coefficient varied with the normal load and low sliding velocity. At static friction, the coefficient of friction decreased when the time increases, whereas, at dynamic friction, the coefficient of friction decreased when the time increased at normal load 4.6 and 9.2 N.

Frictional Vibrations

1955 ◽  
Vol 22 (2) ◽  
pp. 207-214
Author(s):  
David Sinclair
Keyword(s):  
Coefficient Of Friction ◽  
Equations Of Motion ◽  
Static Friction ◽  
Uniform Motion ◽  
Friction Characteristic ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Brake Lining ◽  
Solid Bodies ◽  
Frictional Vibrations

Abstract Frictional vibrations, such as stick-slip motion and automobile-brake squeal, which occur when two solid bodies are rubbed together, are analyzed mathematically and observed experimentally. The conditions studied are slow uniform motion and relatively rapid simple harmonic motion of brake lining over a cast-iron base. The equations of motion show and the observations confirm that frictional vibrations are caused primarily by an inverse variation of coefficient of friction with sliding velocity, but their form and occurrence are greatly dependent upon the dynamical constants of the mechanical system. With a constant coefficient of friction, the vibration initiated whenever sliding begins is rapidly damped out, not by the friction but by the “natural” damping of all mechanical systems. The coefficient of friction of most brake linings and other organic materials was essentially invariant with velocity, except that the static coefficient was usually greater than the sliding coefficient. Most such materials usually showed a small decrease in coefficient with increasing temperature. The persistent vibrations resulting from the excess static friction were reduced or eliminated by treating the rubbing surfaces with polar organic compounds which produced a rising friction characteristic.

A Theory of Dynamic Rubber Friction

1966 ◽  
Vol 39 (2) ◽  
pp. 320-327 ◽  
Author(s):  
A. Schallamach
Keyword(s):  
Coefficient Of Friction ◽  
Time Lag ◽  
Quantitative Agreement ◽  
Dynamic Friction ◽  
Average Life ◽  
Thermally Activated ◽  
Molecular Adhesion ◽  
Rubber Friction ◽  
The Coefficient Of Friction ◽  
Rate Processes

Abstract Assuming dynamic friction to arise from the shearing and subsequent breaking of distinct bonds between the rubbing members, a general equation is derived for the frictional force which involves the number and average life of the bonds as well as the average time lag between breaking and re-making of a bond at a given site. In the case of friction between rubber and smooth, hard surfaces, the bonds are attributed to local molecular adhesion between rubber and track, both formation and breaking of the bonds being thermally activated rate processes. A theory developed on this basis reproduces the experimental results obtained by Grosch in that the coefficient of friction as function of the velocity has a pronounced maximum. The height of the maximum and the velocity at which it occurs are in semi-quantitative agreement with Grosch's findings.

The Calculation of Roll Pressure in Hot and Cold Flat Rolling

1943 ◽  
Vol 150 (1) ◽  
pp. 140-167 ◽  
Author(s):  
E. Orowan
Keyword(s):  
Pressure Distribution ◽  
Yield Stress ◽  
Coefficient Of Friction ◽  
Static Friction ◽  
Rolled Stock ◽  
Theoretical Treatment ◽  
Frictional Drag ◽  
Roll Pressure ◽  
Plate Rolling ◽  
The Coefficient Of Friction

A numerical or graphical method is given for computing, in strip or plate rolling, the distribution of roll pressure over the arc of contact and the quantities derived from this (e.g. the vertical roll force, the torque, and the power consumption). The method avoids all mathematical approximations previously used in the theoretical treatment of rolling, and permits any given variation of the yield stress and of the coefficient of friction along the arc of contact to be taken into account. It can be used, therefore, in both hot and cold rolling, provided that the basic physical quantities (yield stress and coefficient of friction) are known. The usual assumption that the deformation could be regarded as a locally homogeneous compression has not been made, and the inhomogeneity of stress distribution has been taken into account approximately by using results derived by Prandtl and Nádai from the Hencky treatment of two-dimensional plastic deformation. It is found that the discrepancy between the roll pressure distribution curves calculated from the Kármán theory and those measured by Siebel and Lueg is due to the assumption in the theory that the frictional drag between the rolls and the rolled stock is equal to the product of the roll pressure and the coefficient of friction. If frictional effects are dominant, as in hot rolling, this product may easily exceed the yield stress in shear which is the natural upper limit to the frictional drag, and then static friction, instead of slipping, occurs. This has been taken into account in the present method, and the calculated curves of roll pressure distribution show good agreement with the curves measured by Siebel and Lueg.

scholarly journals Analisa Koefisien Gesek Kinetis Terhadap Struktur Permukaan Jalan Akibat Beban Dinamik Mobil

2018 ◽  
Vol 1 (1) ◽  
pp. 047-051
Author(s):  
Muhammad Nuh Hudawi Pasaribu ◽  
Muhammad Sabri ◽  
Indra Nasution
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Surface Texture ◽  
Road Surface ◽  
Vehicle Speed ◽  
Kinetic Friction ◽  
The Road ◽  
Road Condition ◽  
Asphalt Road ◽  
The Coefficient Of Friction

Tekstur permukaan jalan umumnya terdiri dari aspal dan beton. Kekasaran tekstur permukaan jalan dapat disebabkan oleh struktur perkerasan dan beban kendaraan. Kekasaran tekstur permukaan jalan, bebandan kecepatan kendaraan akan mempengaruhi koefisien gesek. Untuk mengetahui nilai koefisien gesek dilakukan penelitian dengan melakukan variasi beban mobil (Daihatsu Xenia, Toyota Avanza, Toyota Innova dan Toyota Yaris) terhadap kontak permukaan jalan (aspal dan beton) dan kecepatan kendaraan. Hasil penelitian menunjukkan bahwa massa, lebar kontak tapak ban terhadap permukaan jalan dan kecepatan sangat mempengaruhi nilai koefisien gesek kinetis. Koefisien gesek kinetis yang terbesar untuk ketiga kontak permukaan jalan (aspal lama IRI 10,1, Aspal baru IRI 6,4 dan beton IRI 6,7) dengan menggunakan mobil Daihatsu Xenia terjadi pada kondisi jalan beton yaitu 0,495 pada kecepatan 35 Km/Jam. Koefisien kinetis jalan beton > 52 % dibandingkan jalan aspal pada parameter IRI yang sama (6-8).Koefisien gesek kinetis > 0,33 diperoleh di jalan beton pada kecepatan 30 – 40 Km/Jam   The texture of road surface generally consists of asphalt and concrete. The roughness of the road surface texture could be caused by the structure of the pavement and the load of the vehicles. Roughness of road surface texture, load and speed of vehicles would affect to the coefficient of friction. This research was carried out to find out the value of the coefficient of friction by using various load of cars (Daihatsu Xenia, Toyota Avanza, Toyota Innova and Toyota Yaris) on road surface contact (asphalt and concrete) and vehicle speed. The result showed the mass, the width of the tire tread contact to the road surface, and speed very influenced the coefficient value of kinetic friction. The biggest kinetic friction coefficient for all three road surface contacts (IRI 10.1 old asphalt, IRI 6.4 and IRI 6.7) using the Daihatsu Xenia was on the concrete road condition i.e. 0.495 on a speed of 35 km/hour. The concrete road kinetic coefficient was >52% compared to the asphalt road in the same IRI parameter (6-8). The kinetic friction coefficient >0.33 was obtained on the concrete road on a speed of 30 - 40 km/hour.

Friction Characteristics of Porous Rubber Under Wet Conditions

2009 ◽  
Author(s):  
Yutaro Kosugi ◽  
Tomoaki Iwai ◽  
Yutaka Shokaku ◽  
Naoya Amino
Keyword(s):  
Friction Force ◽  
Coefficient Of Friction ◽  
Contact Surface ◽  
Road Surface ◽  
Water Removal ◽  
The Road ◽  
Rubber Specimen ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Tread Rubber

In recent years, porous rubber has been used as a tread matrix for studless tires. It is said that the pores in the tread rubber remove water between the tire and the wet road surface; however, the water removal is not sufficiently well understood. In this study, a rotating rubber specimen was rubbed against a mating prism to observe the contact surface. The friction force was also measured simultaneously with observation of contact surface. The water entering the pores was distinguished by the continuity method. As the result of these experiments, the coefficient of friction for rubber having pores on the surface was found to be larger than that of rubber without pores. Moreover, the difference in the coefficient of friction for rubber specimens with and without pores tended to be larger at lower sliding speeds. No water entered pores 3mm or less in diameter at any sliding speed in this experiment. An experiment to make the rubber specimen collide with the mating prism was conducted since actual tires seem to be deformed by the vehicle weight, such that the tire surface might contact the road collisionally. In the resulting collision experiment, the water did enter pores 3mm in diameter.

A Bifurcation Phenomenon of Static Friction

1961 ◽  
Vol 28 (2) ◽  
pp. 213-217 ◽  
Author(s):  
F. F. Ling ◽  
R. S. Weiner
Keyword(s):  
Contact Resistance ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Pure Shear ◽  
Static Friction ◽  
The Other ◽  
Electric Contact ◽  
Bifurcation Phenomenon ◽  
The Coefficient Of Friction

Measurements are reported of electric contact resistance, actual area of contact, static friction, adhesion and pure shear for lead on lead. The data exhibit a statistical bifurcation of friction. In other words, below extreme pressures, statistically there are two branches of the coefficient of friction versus normal load relationship. The nature of one of the branches is explicable exclusively in terms of the weld-junction or adhesion theory of friction. The nature of the other, however, is not so explicable. This points to the existence of what Holm [1] called the Y-term of friction, the nature of which has yet to be satisfactorily explained.

Clot friction variation with fibrin content; implications for resistance to thrombectomy

2017 ◽  
Vol 10 (1) ◽  
pp. 34-38 ◽  
Author(s):  
Gillian M Gunning ◽  
Kevin McArdle ◽  
Mahmood Mirza ◽  
Sharon Duffy ◽  
Michael Gilvarry ◽  
...  
Keyword(s):  
Blood Cell ◽  
Coefficient Of Friction ◽  
Red Blood Cell ◽  
Sliding Friction ◽  
Imaging Techniques ◽  
Static Friction ◽  
Cell Content ◽  
Content Ratio ◽  
Custom Made ◽  
The Coefficient Of Friction

BackgroundDespite significant advancements in the procedural efficacy of mechanical thrombectomy in patients with ischemic stroke in recent years, there still remains a portion of the population that does not achieve good recanalization. The reasons for this may be varied. We hypothesized that static friction between the clot and the vessel, or catheter wall might contribute to the difficulty in removing the clot.ObjectiveTo determine if there is a relationship between clot composition and the resistance to sliding (friction) which might contribute to resistance to clot removal.MethodsAs clot composition can vary significantly, we investigated five different types of clot in order to measure their respective frictional properties. To do this, a custom-made testing apparatus was created, consisting of various replaceable low-friction surfaces on which the clots could be placed. The surface was then gradually tilted until the clots began to slide; the angle at which this occurred is related to the coefficient of friction of the clots. The experiment was repeated on a bovine aortic surface in order to confirm the results.ResultsWe found that fibrin-rich clots (<20% red blood cell content) have a significantly higher coefficient of friction than clots with a red blood cell content >20%. This result was confirmed by repeating the experiment on a bovine aortic surface as a representation of the interaction between clots and the arterial wall.ConclusionsThe friction properties of clots were found to be related to the content ratio of fibrin to red blood cells. Future imaging techniques that could show fibrin and red blood cell content might help us to predict the ‘stickiness’ of a clot.

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