Friction Coefficient Of Rubber Research Articles

A Study of the Friction Characteristics of Rubber Thermo-Mechanical Coupling.

The friction performance of tread rubber is related to the safety of the vehicle during driving, especially in terms of shifting speeds, cornering, and changing environmental factors. The experimental design used in this paper employed a self-developed automatic multi-working-condition friction tester to investigate the correlation between the friction coefficient of three tread formulations and various factors, including speed, pressure, temperature, side deflection angle, and lateral camber. This experimental study demonstrates that the coefficient of friction decreases with increasing load and increases with increasing sliding velocities due to changes in adhesion friction. Due to the increasing and decreasing changes in rubber adhesion and hysteresis friction caused by temperature, the coefficient of friction shows a tendency to increase and then decrease with the increase in temperature; thus, temperature has an important effect on the coefficient of friction. Based on the basic theory of friction and experimental research, the Dorsch friction model was modified in terms of temperature, and the analytical relationship between the rubber friction coefficient and the combined variables of contact pressure, slip velocity, and temperature was established, which is more in line with the actual situation of rubber friction. The model predictions were compared with the experimental results, and the error accuracy was controlled within 5%. This verifies the accuracy of the model and provides a theoretical basis for the study of rubber friction.

Effect of zinc oxide/layered double hydroxide on friction properties of silicone rubber at low temperature

Effect of zinc oxide/layered double hydroxide on friction properties of silicone rubber at low temperature

A Discrete Tire Model for Cornering Properties Considering Rubber Friction

In this paper, a discrete tire model of cornering properties for road vehicles relating to tire grip performance, which is important for driving stability and safety, is presented. The proposed tire model combines realistic rubber friction related to velocity and tire grip performance with deformation of the carcass. The model can describe the stress and strain of the carcass and tread, and the rubber friction coefficient at each point of the contact patch, which is affected by the distribution of the slip velocity. Meanwhile, the model incorporates the effects of the viscoelastic rubber material and power spectrum of the road, which are explicitly reflected in the rubber friction model. First, an improved rubber friction model based on the Persson theory of rubber friction is introduced in this paper. A discrete analytical tire model, which considers carcass compliance and the discretization of the tread, is then proposed. In addition, important phenomena of tire properties arising from the carcass compliance and rubber friction are analyzed and the effectiveness of the discrete analytical tire model is validated experimentally. The proposed model provides a new way to optimize the grip performance of a tire by adjusting the tire or rubber physical parameters even before the tire is made.

A Study on Testing of Rubber Friction Coefficient and Its Wear Surface by UMT-2

For some products as tire, shoes and other wear parts products, friction performance is a very important performance index. A series of theories had been put forward to study the friction properties. With the development of science, the method of rubber friction was more and more abundant, from the friction wear properties to the microstructure, as well as the simulation, all the friction performance of the study provided a reliable basis. UMT - 2 multifunctional friction and wear testing machine, friction properties of the rubber material to make relatively objective evaluation, can provide reliable basis for research on the properties of friction. Due to many factors influencing the rubber materials, rubber friction behaviour of the friction and wear mechanism of exploration would still need a lot of research work.

Experimental study on friction coefficients between tire tread rubber and ice

The tire tread pattern affects driving significantly on icy roads, and different kinds of rubber pattern mean different friction coefficients when moving on the ice surface. Based on the latest friction test rig, a simulation method of such tests was created. Therefore, the continuous sampling at low slip velocity was proposed. During the sampling, the typical pattern of the rubber specimen was employed. The friction test of the tire tread specimen on the ice surface was implemented with different slip velocities and pressure, and the results were fitted and analyzed. To research the effect of tire tread on the friction coefficient, the rubber ratio parameter (the ratio of the rubber contact area to the total contact area) was given for proper evaluation. It is found that rubber as the major component of the tire possesses a special friction property, which is against Coulomb’s law. In addition to that, the friction coefficient of rubber is influenced by the contact state to a great extent, especially in some extreme conditions. The experiment of rubber friction on ice can serve as an important reference for the study on tire mechanical properties.

Experimental Investigations on Rubber Friction Coefficient Dependence on Visco-Elastic Characteristics, Track Roughness, Contact Force, and Slide Velocity

ABSTRACT The results of an experimental activity, carried out using a prototype of pin on disk machine and aimed at investigating the frictional behavior of visco-elastic materials in sliding contact with rigid asperities, are presented. The pin is a rubber specimen coming from three different passenger automotive tires, while the disk is covered with glass, marble, or 3M anti-slip tape surfaces. Tests, performed both in dry and wet conditions, highlighted that the friction coefficient is strongly influenced by the effect that surface roughness plays on friction mechanisms of adhesion and hysteresis. The results confirmed the theoretical dependence of friction on vertical load, sliding velocity, rubber characteristics, and track conditions.

The hysteretic contribution of friction for the polished rubber on the concrete surface

The rubber friction coefficient, and the contact area during stationary sliding is calculated, for the contact of a polished rubber block and a concrete surface, when both surfaces are rough. The calculation is based on an extended version of Persson's contact mechanics theory. Compared to only the substrate being rough, when both of the surfaces are rough but their cross correlation is zero, the friction coefficient is larger. Introducing a positive correlation decreases the friction coefficient, while introducing a negative correlation increases the friction coefficient.To support these theoretical arguments, some experiments have been performed. We have produced roughness on the rubber surface, using abrasive paper, and measured the surface topographies for the concrete and the polished rubber surfaces. The auto spectral density functions for the both surfaces have been calculated, and the rubber viscoelastic modulus mastercurve has been obtained. We have measured the rubber friction at different sliding velocities, when the rubber surfaces are rough and smooth, and compared it to the theoretical results. It is seen that when the rubber surface is rough, the rubber friction coefficient is larger compared to the case the rubber surface is smooth. The theoretical results are in good agreement with experimental observation.

ゴム摩擦係数の圧力，速度依存性とタイヤ性能への影響

ゴム摩擦係数の圧力，速度依存性とタイヤ性能への影響

DESCRIPTIVE MODEL OF SLIDING FRICTION PROCESSES

Paper analyses the sliding friction coefficient of rubber on concrete, timber and ceramic tile surfaces depending on the weight of the sliding object and contact surface area. It has been established that increase in the weight of the object makes sliding friction coefficient to grow. In the case of increase in size of contact area, sliding friction coefficient between rubber and concrete also increases, but it decreases between rubber- timber and rubber- tile. The mathematical model for description of sliding friction process has been developed which can be used to determine optimal surface area and a pattern as well as optimal weight of the sliding object in order to provide sufficient sliding friction. Model has five independent constants. It includes the contact surface area, the weight and the velocity of the sliding object, sliding friction coefficient, temperature and time.

Frequency-wise correlation of the power spectral density of asphalt surface roughness and tire wet friction

Modern rubber friction theories predict the friction coefficient of rubber sliding against a rough surface. The key inputs of these theories are the roughness of the surface, the viscoelastic properties of the rubber, and the operating parameters like contact pressure, sliding speed and temperature. With regard to the surface roughness, it is important to know how road surface roughness should be analyzed. To increase the understanding on this topic, the surface topographies of different asphalt surfaces were measured and the roughness results at different spatial frequencies were correlated with wet tire friction results. The surface topographies were analyzed using a top-cutting technique and calculating the power spectral densities, or C(q) functions of the resulting data. The value of the C(q) function at each evaluated spatial frequency was then correlated individually to the friction results using linear regression. The results showed that the highest correlation was found at the highest evaluated frequencies, as limited by the spatial resolution of the measurement. When building a linear least-square fit model with the surface data and road surface temperature information, a good fit between the model parameters and the friction results could be achieved.

Effect of the friction coefficient for contact pressure of packer rubber

A systematic study of the packer rubber contact pressure under a fixed-displacement load is conducted to gain further insight into the packer seal mechanism. A Y221-114 double rubber packer is investigated using the finite element software ANSYS, where a design of experiments method is utilized to study the effects of the friction coefficient. The results show that the friction coefficient of the packer and the tubing had the greatest effect on contact pressure than other factors. Decreasing the rubber friction coefficient is conducive to forming the double rubber seal and increasing the maximum contact pressure working range. However, there is additionally a slight decrease in the value of maximum contact pressure. The results of the study provide valuable insight into the importance of packer design optimization.

Rubber steel friction in contaminated contacts

The effects of water, oil, and wear debris on the friction coefficient of rubber against steel were investigated. A pin-on-disk apparatus was used to simulate rubber tyres on track in a metropolitan transit system. Three methods of applying the water were used, and the results were compared with dry conditions. One method was to spray it, one was to drip it, and one was to use fully flooded conditions. The sprayed condition produced only a momentary drop in friction, but the fully flooded condition resulted in the lowest continuous reduction in friction. Oil and wear debris contaminants produced similar levels of friction. When dry sliding tests were conducted at a temperature of 200 °C, to simulate certain conditions observed in service, the friction coefficient exhibited values similar to those for oil and contaminants. This behaviour was correlated with the formation of blisters and thermal cracks on the rubber side, and the subsequent transfer of debris particles to the counterface as the softer rubber surface degraded.

Rubber friction for tire tread compound on road surfaces

We have measured the surface topography and calculated the surface roughness power spectrum for an asphalt road surface. For the same surface we have measured the friction for a tire tread compound for velocities 10−6 m s−1 < v < 10−3 m s−1 at three different temperatures (at −8 °C, 20 °C and 48 °C). The friction data was shifted using the bulk viscoelasticity shift factor aT to form a master curve. We have measured the effective rubber viscoelastic modulus at large strain and calculated the rubber friction coefficient (and contact area) during stationary sliding and compared it to the measured friction coefficient. We find that for the low velocities and for the relatively smooth road surface we consider, the contribution to friction from the area of real contact is very important, and we interpret this contribution as being due to shearing of a very thin confined rubber smear film.

Relationship between Slip Resistance of Shoe Sole and Materials and Floor Conditions

Relationship between slip resistance of shoe sole and materials and floor conditions was studied by Mark II slipmeter in order to improve the slip resistance of shoe sole. The results indicate that all the materials of shoe sole and floor and the lubrication conditions of floor can affect the slip resistance of shoe sole. whereas the influence of the lubrication conditions of floor is more significant than the other two factors. Friction coefficient of rubber was highest in the three shoe sole materials. Friction coefficient of terrazzo was highest in the three floor materials. That is to say that the slip resistance of rubber is best in the three tested materials and the slip resistance of terrazzo is best in the three floor materials. Friction coefficient of oil condition was lowest among the three floor conditions and the probability of slips was very high.

Friction Coefficient of Rough Indoor Flooring Materials

The present study investigates the effect of the surface roughness of polymeric indoors floorings on the static friction of bare foot as well as foot wearing cotton and polymeric socks under dry, water, water + 5.0 vol. % soap, oil and water + 5.0 vol. % oil lubricated sliding conditions. Polymeric floor sheets of different roughness ranging from 0.05 and 11.0 µm were tested. The tested material is commonly used in entrance areas or corridors and in the sport halls. Cotton and polymeric socks as well as bare foot were frictionally tested. The results were compared to the friction caused by shoes as simulated by rubber test specimens of vee shape treads were prepared in the form of square sheets of 100 ´ 100 mm, 10.0 mm thickness. Experiments were carried out using a test rig designed and manufactured to measure the friction coefficient between the foot and the tested polymeric flooring materials. The experimental results showed that, at dry sliding, friction coefficient of rubber decreased with increasing surface roughness, while for bare foot and polymeric socks, friction coefficient decreased down to minimum then increased with increasing the surface roughness. Besides, friction coefficient decreased with increasing applied load. Minimum friction was observed at surface roughness ranging between 6-9 µm. In water lubricated sliding, friction coefficient of rubber increased up to maximum then decreased with increasing surface roughness. Maximum friction values were observed at surface roughness values ranging from 1.5 to 2.0 ?m Ra. Cotton socks showed the highest friction coefficient followed by rubber, bare foot then polymeric socks at 11 µm Ra. Friction coefficient drastically decreased with increasing surface roughness at water and detergent lubricated sliding. For the tested flooring materials lubricated by oil, friction coefficient of rubber increased up to maximum values then decreased with increasing the surface roughness of the flooring materials. The maximum friction values were noticed at 4.0 µm Ra. Bare foot displayed drastic reduction in friction coefficient, while cotton socks showed the highest values. When water was diluted by 5.0 wt. % oil, rubber smooth flooring surface displayed values of friction coefficient close to that observed for hydrodynamic lubrication where the two sliding surfaces are separated by the fluid film. As the roughness increased the fluid film was broken and friction increased. Cotton socks showed the highest friction compared to bare foot and polymeric socks.

Surface modification of natural rubber film by polymerisation of methyl methacrylate in water-based system

Polymerisation of methyl methacrylate (MMA) on the surface of natural rubber (NR) film was studied in order to increase the surface hardness, roughness and, hence, to decrease the friction coefficient of rubber. We used the two-step process: (i) swelling of MMA and tert-butyl hydroperoxide, emulsified in an aqueous solution of sodium dodecyl sulphate, onto the NR film surface, and (ii) subsequently immersing the swollen rubber strip into an alkaline aqueous solution of ferrous ion/fructose for redox initiation. The presence of PMMA on the NR surface was examined by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Increasing the concentration of ferrous ion caused an increase in MMA conversion. The surface morphology observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) in tapping mode revealed the aggregation of micronmetre-scale nodules on the modified surface. The surface hardness and roughness increased with increasing PMMA content.

Influence of self-affine roughness on the friction coefficient of rubber at high sliding velocity

In this work we investigate the influence of self-affine roughness on the friction coefficient of a rubber body onto a solid surface at high speeds. The roughness is characterized by the rms amplitude $w$, the correlation length $\ensuremath{\xi}$, and the roughness exponent $H$. It is shown that the friction coefficient decreases with increasing correlation length $\ensuremath{\xi}$ and increasing roughness exponent $H$ for sufficiently large correlation lengths. However, for small correlation lengths the opposite behavior takes place because the system is within the strong roughness limit or equivalently average local surface slopes larger than 1. Moreover, direct plots of the friction coefficient as a function of the roughness exponent $H$ indicate that as the correlation length $\ensuremath{\xi}$ decreases, a maximum of the friction coefficient develops. The latter is followed by a continous increment of the friction coefficient with increasing $H$ and decreasing $\ensuremath{\xi}$.

Friction coefficient of rubber with respect to some types of plastics

Friction coefficient of rubber with respect to some types of plastics