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This paper describes research aimed at the experimental determination of the influence of rubber hysteresis on the friction coefficient between rubber samples for making soles and granite tiles. In the experiments, four types of shoe rubber with similar hardness and different hysteresis properties and two granite tiles with different roughnesses (smooth and anti-slip) were used. The determination of rubber hysteresis was carried out experimentally on a uniaxial testing machine. The friction coefficient was measured using a device specially developed for this type of test, which was based on the pulling force method, while the measurement conditions were based on the EN 13893:2011 standard. The friction coefficient was measured at two different speeds, 50 mm/s and 300 mm/s, with different surface conditions. Using regression analysis and the Taguchi method, the data obtained from the experiments were analyzed to determine the influence of parameters on the friction coefficient. The experimental research shows that different rubber mixtures with the same or similar hardness could have different hysteresis properties but also different friction properties. [ABSTRACT FROM AUTHOR]

To explore the research status on mechanism of the skid-resistance for asphalt pavement, the related achievements of the rubber friction, the tire–road contact, and the influence factors were reviewed. The rubber friction was reviewed from the mechanism and rubber friction model. The tire-road contact was studied from the modeling methods, the evaluation methods, and the skid-resistance mechanisms at different conditions. The influence factors of skid-resistance were summarized from different designing processes. This review showed that the appropriate contact or evaluation model should be selected according to the required parameters. Although the finite element method is widely used, the accuracy of the model, the boundary conditions, and the load cases need to be further improved. The optimized aggregates and asphalt binders, reasonable gradation, reasonable geometric design, and strict construction quality control are necessary for good initial skid-resistance. Pavement texture as an important factor affecting skid-resistance should be considered in pavement gradation design, especially for wearing layer technology. [ABSTRACT FROM AUTHOR]

This study proposes a mechanical tire model with deduced friction coefficient based on multiscale friction theory. In the proposed model, the contact shape and contact pressure distribution are calculated based on the elliptical contact tire model. In the calculation of longitudinal stress in the adhesion region, not only the longitudinal deformation in length direction owing to the slip ratio, but also the nonlinear deformation in width direction owing to the tread radius are considered. The coefficient of friction in the sliding region is deduced from the viscoelasticity of tread rubber by multiscale friction theory, with contributions from adhesion and hysteresis friction. The validity of theoretical calculation of coefficient of friction was verified by linear friction tests of a rubber piece conducted under two conditions: a dry road surface and a wet road surface with a water film mixed with detergent. It was confirmed that, with appropriate parameter settings, the longitudinal stress distribution in the tire contact plane calculated by the proposed method can reproduce the experimental results by inner drum tire tester better than the classical brush model. The proposed method can be applied to rubber compound design to achieve the desired braking and driving characteristics of tires because it analytically links the longitudinal forces of tire to the viscoelasticity of tread rubber.

This paper describes research aimed at the experimental determination of the influence of rubber hysteresis on the friction coefficient between rubber samples for making soles and granite tiles. In the experiments, four types of shoe rubber with similar hardness and different hysteresis properties and two granite tiles with different roughnesses (smooth and anti-slip) were used. The determination of rubber hysteresis was carried out experimentally on a uniaxial testing machine. The friction coefficient was measured using a device specially developed for this type of test, which was based on the pulling force method, while the measurement conditions were based on the EN 13893:2011 standard. The friction coefficient was measured at two different speeds, 50 mm/s and 300 mm/s, with different surface conditions. Using regression analysis and the Taguchi method, the data obtained from the experiments were analyzed to determine the influence of parameters on the friction coefficient. The experimental research shows that different rubber mixtures with the same or similar hardness could have different hysteresis properties but also different friction properties.

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. [ABSTRACT FROM AUTHOR]

Abstract To explore the research status on mechanism of the skid-resistance for asphalt pavement, the related achievements of the rubber friction, the tire–road contact, and the influence factors were reviewed. The rubber friction was reviewed from the mechanism and rubber friction model. The tire-road contact was studied from the modeling methods, the evaluation methods, and the skid-resistance mechanisms at different conditions. The influence factors of skid-resistance were summarized from different designing processes. This review showed that the appropriate contact or evaluation model should be selected according to the required parameters. Although the finite element method is widely used, the accuracy of the model, the boundary conditions, and the load cases need to be further improved. The optimized aggregates and asphalt binders, reasonable gradation, reasonable geometric design, and strict construction quality control are necessary for good initial skid-resistance. Pavement texture as an important factor affecting skid-resistance should be considered in pavement gradation design, especially for wearing layer technology.

The British pendulum tester (BPT) provides a method to measure the skid resistance of pavement, which possesses both theoretical and practical engineering significance. This article aims to establish a numerical hysteresis friction model for BPT to reproduce the dynamic motion of the slider and estimate the pavement friction based on surface texture roughness, rubber viscoelasticity property and contact characteristics. The analytical hysteresis friction model was introduced based on one of the modern rubber friction theories. As an input parameter of this model, the average penetration depth of rubber was calculated based on the interfacial separation assumption. A numerical model was established by combining the geometric and motion characteristics of BPT. To validate the model, the self-affine characteristics of texture from four types of asphalt pavement were analysed; simultaneously, the storage and the loss modulus of rubber slider at various frequencies were obtained using the Zener constitutive model. As a result, the velocity of the slider decreases gradually with the dynamic fluctuation of the friction coefficient. A significant linear correlation was found between the predicted values and the measured data. This numerical friction model performs some potential for friction estimation. However, more conditions need considering for the improvement and practicability of the model. [ABSTRACT FROM AUTHOR]

Soft-hard matter friction is a long-standing tribology problem that remains unclarified, requiring engineers to empirically predict the wear life. To clarify this issue, this study examines the transient running-in regime of rubber friction on a hard rough substrate and models the temporal wear progression using the spectrum curves of surface roughness for both materials. Performing a series of friction tests and three-dimensional surface-height measurements, the time-dependent behaviours of the power spectral densities (PSDs) are divided into two phases, namely the initial non-steady and long-term steady phases. The detailed spectral analyses of worn rubber surfaces in the initial phase lead to a blended PSD function between self-affine and K-correlation surface models, consisting of one variable (the Hurst exponent) that is saturated by the substrate self-affinity. Supported by the Greenwood--Williamson theory concerning rough contact mechanics, the volumetric estimate with the blended PSD function is used to assess the volume rate of wear debris in the steady phase, which is validated experimentally. These findings not only improve the wear predictions of soft materials from the initial measurements of worn surfaces but also help clarify the constrained multiscale mechanism of wear. [ABSTRACT FROM AUTHOR]

We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from −38 to −2 °C, and sliding speeds ranging from 3 µm/s to 1 cm/s. At low temperatures and low sliding speeds we propose that an important contribution to the friction force is due to slip between the ice surface and ice fragments attached to the rubber surface. At temperatures above −10 °C or for high enough sliding speeds, a thin premelted water film occurs on the ice surface and the contribution to the friction from shearing the area of real contact is small. In this case the dominant contribution to the friction force comes from viscoelastic deformations of the rubber by the ice asperities. We comment on the role of waxing on the friction between skis and snow (ice particles). [ABSTRACT FROM AUTHOR]

Abstract We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from −38 to −2 °C, and sliding speeds ranging from 3 µm/s to 1 cm/s. At low temperatures and low sliding speeds we propose that an important contribution to the friction force is due to slip between the ice surface and ice fragments attached to the rubber surface. At temperatures above −10 °C or for high enough sliding speeds, a thin premelted water film occurs on the ice surface and the contribution to the friction from shearing the area of real contact is small. In this case the dominant contribution to the friction force comes from viscoelastic deformations of the rubber by the ice asperities. We comment on the role of waxing on the friction between skis and snow (ice particles).

• A finite element sliding contact model between the rubber spreading roller and the cold-proof cloth was developed and verified. • The lateral offset behavior of the cold-proof cloth was investigated in dynamic conditions. • A prediction model of the lateral offset was established to optimize the spreading roller. • The optimized spreading roller effectively reduced wrinkles in the winding test of the cold-proof cloth. The groove pattern of the rubber spreading roller affected its spreading performance on the wrinkled cold-proof cloth. For analysing the spreading performance in dynamic conditions, a finite element sliding contact model between the rubber spreading roller and the cold-proof cloth was developed for studying the lateral offset with different contact pressures, slip velocities, and groove patterns of the spreading roller, which constituted a prediction model for the lateral offset. A new test device of the lateral offset was developed to compare the predictive and experimental results to verify the accuracy of the finite element model. The results showed that increasing the contact pressure was beneficial to increasing the lateral offset. The slip velocity had a significant effect on the lateral offset and the positive slip velocity promoted the lateral offset better than the negative slip velocity. The effect of groove pattern parameters on the lateral offset was independent of the slip velocity. Only the diameter, groove number, and pitch affected the lateral offset significantly. With the groove pattern parameters optimised by the prediction model, the relative error between the predictive and experimental results of the lateral offset was 8.62%, indicating the accuracy and reliability of the prediction model. Moreover, the optimised spreading roller could effectively weaken the wrinkles in the rolling experiment of the cold-proof cloth. The prediction of the lateral offset model based on the finite element analysis would be useful for the reliable design of the rubber spreading roller. [ABSTRACT FROM AUTHOR]

To provide a potential method for predicting friction coefficients with pavement texture parameters, the Hilbert-Huang Transformation was used to extract relevant parameters from the pavement profile. Eight parameters of the Optimal Intrinsic Mode Function (OIMF) were calculated based on the Hilbert-Huang Transformation. A correlation analysis was conducted between these parameters and friction, taking into account the influence of velocity. Furthermore, a multiple linear regression model was developed to explore friction prediction. The results revealed that the parameter representing the peak density divided by sharpness in the OIMF exhibited the strongest correlation with friction (R2 =0.78), with this correlation being influenced by velocity. The multiple regression model may provide a reliable method for friction prediction (R2 =0.77), and the predicted friction coefficients demonstrated no significant deviation from the measured values (p-value < 0.0001). • Proposed a high- R2 texture profile parameter with friction using HHT method. • Investigated effects of velocity on R2 between texture parameters and friction. • A multiple regression model based on HHT is developed for friction prediction. [ABSTRACT FROM AUTHOR]

Predicting tyre–road friction requires various inputs that are known with differing levels of confidence. This paper studies the prediction and associated experimental confirmation of rubber friction on real roads at high sliding speeds. Friction predictions are obtained from Persson's flash temperature model: the topography of the road surface is measured using an optical profilometer, while the rubber's viscoelastic modulus is obtained through Dynamic Mechanical Analysis. A newly developed friction tester performs in-situ friction measurements, while controlling and monitoring bulk and contact surface temperature, respectively. Local topographical road roughness variations were identified as a major contributing factor leading to predicted friction variations of over 50%, while the flash temperature predictions showed good correlation with temperature measurements from near the rubber–road interface. • Rubber friction testing with flash temperature measurement under real conditions. • Persson's flash temperature model without adhesion showed agreement with experiment. • Rubber background temperature is less important in practical situations. • Partial validation of flash temperature predictions. [ABSTRACT FROM AUTHOR]

In order to investigate hysteresis friction separately from other friction contributions (mainly adhesive friction), linear friction tests are performed with cut out tread specimens from passenger car tires on 3D-printed sinusoidal surfaces under dry and wet conditions. In this work, a multiscale approach based on the finite element method (FEM) is used to reproduce the hysteresis friction features obtained in the laboratory. On each scale, finite element simulations at block level are evaluated at different contact pressure, sliding velocity and temperature conditions, which are homogenized with respect to time, to build up a friction characterization for the next coarser scale. The height difference correlation function is applied to consider microscopic asperities, which originate from the printing process. Using the Williams - Landel - Ferry equation, the thermal influence on the viscoelastic rubber material is taken into account. By comparing the output of the friction tests against the results of the multiscale simulations, an analysis of contact temperature as well as friction contribution of each length scale is enabled. • Friction tests on 3D-printed surfaces at dry and different wet conditions. • Numerical friction approach to compute scale-dependent hysteresis friction. • Numerical validation of multiscale friction model. • Numerical studies of micro- and macroscale hysteresis friction. • Comparison of experimental and simulated friction results. [ABSTRACT FROM AUTHOR]

We present a comprehensive investigation of the adhesive rubber-solid contact problem by analytical and numerical methods. Theories of rubber friction are reviewed and a new contact theory is developed. The adhesive contact problem is solved using the boundary element method. The introduction of adhesion leads to full coverage below a certain length scale. Friction coefficients are calculated from the spectral density of the rubber surface by splitting the numerical problem into two length scales. Adhesion is shown to increase friction at low velocities. The influence of filler is modeled by assuming that their size corresponds to a linear cross-over dimension separating the bulk elastomer from the composite. Finally, we discuss open problems and describe a simplified picture of rubber friction. • Adhesion increases low-velocity friction by increasing low-wavelength deformation amplitude. • Rubber has to be viewed as composite material at length scales relevant for friction. • Rubber's contour generally has a higher Hurst exponent than the substrate. • (Adhesion-induced) elastic instabilities probably determine friction at lowest velocities. [ABSTRACT FROM AUTHOR]

This paper reports a thermo-viscoelastic (TVE) contact model of layered materials, subjected to frictional and viscoelastic heating. The mathematical formulation includes the frequency-domain solutions for TVE fields, built on velocity-frequency-temperature relationships. The numerical implementation includes the development of a contact-pressure solver, a heat-partition solver, and a temperature-dependent modulus solver. The model is verified with experimental and numerical results. Both rubber coating-elastic substrate and elastic layer-rubber substrate systems are analyzed. The results reveals that, for the former, the rubber-coating temperature rises with increasing velocity, while for the latter, the rubber-substrate temperature becomes lower with increasing elastic-layer thickness. Moreover, the modulus modification due to higher temperatures leads to higher pressures, and that ignoring the velocity effects on modulus overestimates the temperature rise. [Display omitted] • The thermo-viscoelastic contact problem of layered materials is formulated considering frictional and viscoelastic heating. • The frequency-domain thermo-viscoelastic solutions are derived based on velocity-frequency-temperature relationships. • The thermo-viscoelastic contact is numerically solved via the discrete convolution-fast Fourier transform algorithm. • Contact-mechanics solver, heat-partition solver, and temperature-dependent modulus solver, are developed and integrated. [ABSTRACT FROM AUTHOR]