The Efficiency of Involute Spur Gears

1981 ◽  
Vol 103 (1) ◽  
pp. 160-169 ◽  
Author(s):  
K. F. Martin
Keyword(s):  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Experimental Tests ◽  
Rolling Friction ◽  
Gear Train ◽  
Small Range ◽  
Load Effect ◽  
Coefficient Of Sliding Friction ◽  
The Coefficient Of Friction ◽  
Basic Characteristics

Approximate equations produced by Trachman |15| are used to predict the coefficient of sliding friction between the gear teeth. These equations apply when the lubrication regime is elastohydrodynamic; this is true during many gear contacts. The equations, which require only certain basic characteristics of the lubricant and the gears, are relatively simple and produce values for the coefficient of friction which are acceptable. The use of this coefficient of friction, together with a calculation for the rolling friction force allows the calculation of instantaneous and overall efficiency of the gear train. Contact ratios greater than one are accounted for and the load is assumed to be shared equally between the pairs of teeth. The computed values show that the load torque has a significant effect on both coefficient of friction and efficiency; as the load increases the coefficient of friction increases and the efficiency decreases. The effect of speed does not, over the small range of computations made, have as much significance as load, although it appears that efficiency will probably increase as the speed increases. Comparison of these predicted results with the few experimental tests which are relevant indicates some support, especially for the load effect.

ON THE FRICTION OF INFLATED RUBBER TIRES ON ICE

1958 ◽  
Vol 36 (5) ◽  
pp. 599-610 ◽  
Author(s):  
C. D. Niven
Keyword(s):  
Friction Force ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Rolling Friction ◽  
The Other ◽  
Slow Speed ◽  
Dry Ice ◽  
Load Axis ◽  
Cold Room ◽  
The Coefficient Of Friction

The friction on ice of some small inflated rubber tires was measured on a turntable in a cold room. When rolling-friction force was plotted against load, the relation was either linear or slightly curved away from the load axis; such curvature implies that Thirion's Law does not hold for rolling friction. On the other hand when sliding-friction force was plotted against load the curvature was toward the load axis as would be expected if Thirion's Law applied. The coefficient of friction can go as low as 0.01 or even lower for a hard-pumped tire when the temperature is near 0 °C, but at −1 °C. rolling friction on dry ice is quite appreciable. The results refer only to measurements at very slow speed.

scholarly journals Influence of Heat Treatment and the Coefficient of Friction on the Volume of Metal Removed During Grinding Steel 35

2015 ◽  
Vol 2 ◽  
pp. 72
Author(s):  
Igor Nikiforov ◽  
Pavel Maltsev
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Physical And Mechanical Properties ◽  
Abrasive Grain ◽  
Coefficient Of Sliding Friction ◽  
The Coefficient Of Friction ◽  
Relative Change

The role of external friction and chip contraction during microcutting by abrasive grain is showed. The method for determining the relative change in the coefficient of friction during grinding is proposed. The hypothesis about the influence of physical and mechanical properties and microstructure of steel 35 on the volume removes metal through the change in the coefficient of sliding friction of the chip by face of the abrasive grain is experimentally proved.

An Analysis of the Plastic Interaction of Surface Asperities and its Relevance to the Value of the Coefficient of Friction

1968 ◽  
Vol 10 (2) ◽  
pp. 101-110 ◽  
Author(s):  
C. M. Edwards ◽  
J. Halling
Keyword(s):  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Time Interval ◽  
Surface Films ◽  
Interfacial Forces ◽  
Molecular Adhesion ◽  
Coefficient Of Sliding Friction ◽  
The Coefficient Of Friction ◽  
History Of ◽  
Tangential Forces

Surface asperities are considered as wedge-shaped bodies which are plastically deformed wherever relative motion occurs between mating surfaces. This plastic interaction produces interfacial forces between the surface asperities which are considered, in the collective sense, to represent the total applied normal and tangential forces acting on the sliding surfaces. A solution is proposed which enables the values of the interfacial forces to be obtained at each time interval during the life history of a junction interaction. Furthermore, it is shown that the nature of these forces is markedly dependent on both the initial asperity geometry and on the nature of any surface films which may be present at the asperity interfaces. From such results it is possible to predict the macroscopic values of the coefficient of sliding friction. Such results suggest that an earlier solution due to Tabor should be considered as the special case for perfectly plane surfaces. The solution also indicates the nature of the plastic deformation of the asperities and displays the phenomena of junction growth. Furthermore, it is demonstrated that very large values of the macro-scopic coefficient of friction are associated with very strong molecular adhesion of the surface asperities particularly for materials having high ductility.

scholarly journals Scaling theory of rubber sliding friction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Reinhard Hentschke ◽  
Jan Plagge
Keyword(s):  
Experimental Data ◽  
Dimensional Analysis ◽  
Coefficient Of Friction ◽  
Solid Surface ◽  
Viscoelastic Properties ◽  
Sliding Friction ◽  
Simple Expression ◽  
The Other ◽  
Coefficient Of Sliding Friction ◽  
The Coefficient Of Friction

AbstractCurrent theoretical descriptions of rubber or elastomer friction are complex—usually due to extensive mathematical detail describing the topography of the solid surface. In addition, the viscoelastic properties of the elastomer material itself, in particular if the rubber is highly filled, further increase the complexity. On the other hand, experimental coefficients of sliding friction plotted versus sliding speed, temperature or other parameters do not contain much structure, which suggests that a less detailed approach is possible. Here we investigate the coefficient of sliding friction on dry surfaces via scaling and dimensional analysis. We propose that adhesion promotes viscoelastic dissipation by increasing the deformation amplitude at relevant length scales. Finally, a comparatively simple expression for the coefficient of friction is obtained, which allows an intuitive understanding of the underlying physics and fits experimental data for various speeds, temperatures, and pressures.

scholarly journals Scaling Theory of Rubber Sliding Friction

2021 ◽  
Author(s):  
Reinhard Hentschke ◽  
Jan Plagge
Keyword(s):  
Experimental Data ◽  
Dimensional Analysis ◽  
Coefficient Of Friction ◽  
Solid Surface ◽  
Viscoelastic Properties ◽  
Sliding Friction ◽  
Simple Expression ◽  
The Other ◽  
Coefficient Of Sliding Friction ◽  
The Coefficient Of Friction

Abstract Current theoretical descriptions of rubber or elastomer friction are complex-usually due to extensive mathematical detail describing the topography of the solid surface. In addition, the viscoelastic properties of the elastomer material itself, in particular if the rubber is highly filled, further increase the complexity. On the other hand, experimental coefficients of sliding friction plotted versus sliding speed, temperature or other parameters do not contain much structure, which suggests that a less detailed approach is possible. Here we investigate the coefficient of sliding friction on dry surfaces via scaling and dimensional analysis. We propose that adhesion promotes viscoelastic dissipation by increasing deformation amplitude at relevant length scales. Finally, a comparatively simple expression for the coefficient of friction is obtained, which allows an intuitive understanding of the underlying physics and fits experimental data for various speeds, temperatures and pressures.

scholarly journals Solid Lubrication by Multiwalled Carbon Nanotubes in Air and in Vacuum for Space and Aeronautics Applications

2005 ◽  
Author(s):  
K. Miyoshi ◽  
K. W. Street ◽  
R. L. Vander Wal ◽  
R. Andrews ◽  
David Jacques ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Solid Lubrication ◽  
Multiwalled Carbon ◽  
Solid Lubrication Friction ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Steel Balls

To evaluate recently developed aligned multiwalled carbon nanotubes (MWNTs) and dispersed MWNTs for solid lubrication applications, unidirectional sliding friction experiments were conducted with 440C stainless steel balls and hemispherical alumina-yttria stabilized zirconia pins in sliding contact with the MWNTs deposited on quartz disks in air and in vacuum. The results indicate that MWNTs have superior solid lubrication friction properties and endurance lives in air and vacuum under dry conditions. The coefficient of friction of the dispersed MWNTs is close to 0.05 and 0.009 in air and in vacuum, respectively, showing good dry lubricating ability. The wear life of MWNTs exceeds 1 million passes in both air and vacuum showing good durability. In general, the low coefficient of friction can be attributed to the combination of the transferred, agglomerated patches of MWNTs on the counterpart ball or pin surfaces and the presence of tubular MWNTs at interfaces.

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.

The development of wear-protective oxides and their influence on sliding friction

1980 ◽  
Vol 369 (1739) ◽  
pp. 557-574 ◽  
Keyword(s):  
Metal Oxide ◽  
Coefficient Of Friction ◽  
Metal Surfaces ◽  
Sliding Friction ◽  
Constant Thickness ◽  
Partial Pressures ◽  
Metal Wear ◽  
The Coefficient Of Friction ◽  
Metal Wear Particles ◽  
Clean Metal

The friction behaviour of iron and Fe-Cr alloys in unidirectional and reciprocating sliding motions at 293 K has been examined in oxygen of controlled partial pressure. During sliding, a progressive decrease in coefficient of friction accompanies the development of compacted oxide films on the metal surfaces, eventually resulting in a steady value of about 0.6 when almost complete oxide coverage is attained. This is achieved more rapidly at higher oxygen partial pressures. A model to account for the experimental observations is proposed, based on the growth of oxide on the clean metal surfaces and metal wear particles between each wear traversal and the removal of that oxide during the subsequent traversal. The oxidized debris is fragmented further and compacted on to the metal surfaces to form a layer of nominally constant thickness, the area of which increases progressively with the number of sliding traversals. The model relates the coefficient of friction to the area of compacted oxide in terms of several interfacial metal, oxide and metal-oxide parameters. The importance of some of these parameters on the frictional behaviour is discussed in light of the experimental observations.

Evaluation of drawing force by a new dimensionless method in deep drawing process

2020 ◽  
Vol 234 (13) ◽  
pp. 1604-1614
Author(s):  
Saeed Hajiahmadi ◽  
Majid Elyasi ◽  
Mohsen Shakeri
Keyword(s):  
Coefficient Of Friction ◽  
Deep Drawing ◽  
Experimental Tests ◽  
Geometric Parameters ◽  
Relational Model ◽  
Geometrical Parameters ◽  
Drawing Force ◽  
Dimensionless Parameters ◽  
Dimensionless Analysis ◽  
The Coefficient Of Friction

In this research, geometric parameters were given in dimensionless form by the Π- Buckingham dimensional analysis method in the dimensionless group for deep drawing of a round cup. To find the best group of dimensionless parameters and the fittest dimensionless relational model, three scales of the cup are evaluated numerically by a commercial finite element software and stepwise regression modeling. After analyzing all effective geometric parameters, a fittest relational model among dimensionless parameters is found. In addition, the results of the new dimensionless model were compared with the simulation process and experimental tests. From the results, it is inferred that the geometric qualities of a large scale can be predicted with a small scale by the proposed dimensionless model. Comparing the results of the dimensionless model with experimental tests shows that the proposed dimensionless model has fine precision in the determination of geometrical parameters and drawing force estimation. Moreover, to evaluate the accuracy of the proposed dimensionless model, the predicted value of the model has been compared by the experimental results. It is shown that the dimensionless ratios of geometrical parameters can significantly affect the estimation of the drawing force by the proposed dimensionless model, but based on similarity law, because of the constant value of these dimensionless parameters in different scales, they could not be used for dimensionless analysis separately. It is also inferred that because of the effect of contact area on the coefficient of friction, which is changed by scale changing, the only dimensionless parameter that can significantly change the drawing force is the coefficient of friction. Finally, it is shown that the dimensionless geometrical parameter and the coefficient friction should be combined for dimensionless analysis.

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.

Sign in / Sign up

Export Citation Format

Share Document