A Quantitative Theory for the Computation of Tire Friction Under Severe Conditions of Sliding

1986 ◽  
Vol 14 (1) ◽  
pp. 44-72 ◽  
Author(s):  
C. M. Mc C. Ettles
Keyword(s):  
Friction Coefficient ◽  
Flash Temperature ◽  
Contact Conditions ◽  
Quantitative Form ◽  
Heating Effects ◽  
Rubber Friction ◽  
Viscoelastic Effects ◽  
Tire Friction ◽  
Pavement Friction ◽  
Metal Polymer

Abstract It is proposed that tire-pavement friction is controlled by thermal rather than by hysteresis and viscoelastic effects. A numerical model of heating effects in sliding is described in which the friction coefficient emerges as a dependent variable. The overall results of the model can be expressed in a closed form using Blok's flash temperature theory. This allows the factors controlling rubber friction to be recognized directly. The model can be applied in quantitative form to metal-polymer-ice contacts. Several examples of correlation are given. The difficulties of characterizing the contact conditions in tire-pavement friction reduce the model to qualitative form. Each of the governing parameters is examined in detail. The attainment of higher friction by small, discrete particles of aluminum filler is discussed.

scholarly journals On rolling friction

2019 ◽  
Vol 485 (3) ◽  
pp. 295-299
Author(s):  
A. P. Ivanov
Keyword(s):  
Friction Coefficient ◽  
Angular Velocity ◽  
Viscous Friction ◽  
Rolling Friction ◽  
The Body ◽  
Normal Velocity ◽  
Contact Conditions ◽  
Combined Motion ◽  
Pure Rolling ◽  
Over Time

The dependence of rolling friction on velocity for various contact conditions is discussed. The principal difference between rolling and other types of relative motion (sliding and spinning) is that the points of the body in contact with the support change over time. Due to deformations, there is a small contact area and, entering into contact, the body points have a normal velocity proportional to the diameter of this area. For describing the dependence of the friction coefficient on the angular velocity in the case of “pure” rolling, a linear dependence is proposed that admits a logical explanation and experimental verification. Under the combined motion, the rolling friction retains its properties, the sliding and spinning friction acquiring the properties of viscous friction.

Optimal Design of Modified Cylindrical Gear Based on Minimum Flash Temperature of Tooth Surfaces

2013 ◽  
Vol 655-657 ◽  
pp. 573-577
Author(s):  
Jin Ke Jiang ◽  
Zong De Fang ◽  
Xian Long Peng
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Contact Line ◽  
Gear Tooth ◽  
Tooth Surface ◽  
Uniform Grid ◽  
Normal Vector ◽  
Flash Temperature ◽  
Oil Film ◽  
Tooth Surfaces

Considering the gap of the contact line of modified involute cylindrical gears influencing on loads, oil film thickness, the friction coefficient was determined on the basis theory of TCA、 LTCA and EHL. so oil film thickness and friction coefficient corresponded with loads on contact line were dispersed, which was used to computed discrete temperature according to the Blok flash temperature formula. and an approach of modified tooth surface optimum design based on the minimum flash temperature was proposed: the modified tooth surfaces was defined as a sum of theoretical tooth and cubic B-spline fit surface based on the uniform grid points created by double parabolas and a straight line and whose normal vector was deduced, besides, used genetic algorithm to optimize the parameter of curve, and get the best modified gear tooth surfaces. the results shows that oil film is thicker in engaging-out, coefficient of friction is contrary, which is responsible for lower flash temperature in engaging-in, besides the flash temperature has little changes in the single tooth meshing zone, and helical gear has a lower flash temperature than spur gear due to higher overlap ratio.

Fracture of metal/polymer/metal assemblies: Viscoelastic effects

2002 ◽  
Vol 78 (11) ◽  
pp. 987-996 ◽  
Author(s):  
S. Bistac ◽  
J. Guillemenet ◽  
J. Schultz
Keyword(s):  
Viscoelastic Effects ◽  
Polymer Metal ◽  
Metal Polymer

scholarly journals Asphalt Pavement Friction Coefficient Prediction Method Based on Genetic-Algorithm-Improved Neural Network(GAI-NN) Model

2021 ◽  
Author(s):  
Zhaoyun Sun ◽  
Xueli Hao ◽  
Wei Li ◽  
Ju Huyan ◽  
Hongchao Sun
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Friction Coefficient ◽  
Point Cloud ◽  
Spline Interpolation ◽  
Asphalt Pavement ◽  
3D Point Cloud ◽  
Cloud Data ◽  
Pavement Surface ◽  
Pavement Friction

To overcome the limitations of pavement skid resistance prediction using the friction coefficient, a Genetic-Algorithm-Improved Neural Network (GAI-NN) was developed in this study. First, three-dimensional (3D) point-cloud data of an asphalt pavement surface were obtained using a smart sensor (Gocator 3110). The friction coefficient of the pavement was then obtained using a pendulum friction tester. The 3D point-cloud dataset was then analyzed to recover missing data and perform denoising. In particular, these data were filled using cubic-spline interpolation. Parameters for texture characterization were defined, and methods for computing the parameters were developed. Finally, the GAI-NN model was developed via modification of the weights and thresholds. The test results indicated that using pavement surface texture 3D data, the GAI-NN was capable of predicting the pavement friction coefficient with sufficient accuracy, with an error of 12.1%.

Evaluating on the Skid Resistance of the Aggregates Based on Mineralogy

2011 ◽  
Vol 250-253 ◽  
pp. 3646-3651 ◽  
Author(s):  
Da Wei Wang ◽  
Chao En Yin ◽  
Xian Hua Chen ◽  
Bernhard Steinauer
Keyword(s):  
Friction Coefficient ◽  
Quartz Sand ◽  
Crystal Size ◽  
Flat Surface ◽  
Skid Resistance ◽  
Test Apparatus ◽  
Quartz Powder ◽  
Contact Conditions ◽  
Road Engineering

Four groups of granite aggregates with different mineral structures were investigated. They were formed into test plates with a flat surface and polished with the Aachen Rafeling Tester using quartz powder and quartz sand as the polishing agent respectively. At the end of each polishing stage, the friction coefficient of these plates was measured with the skid resistance tester (SRT) and the Wehner/Schulze test apparatus (PWS), which represent different contact conditions. By comparison of the different friction development in the course of polishing, the influence of mineral composition and crystal size on the polishing resistance and friction coefficient of the aggregates is determined. This new methodology can be applied to evaluate the long-term skid resistance of the aggregates for road engineering.

Fretting Fatigue and Contact Conditions: A Rational Explanation of Palliative Behaviour

1985 ◽  
Vol 199 (4) ◽  
pp. 325-337 ◽  
Author(s):  
T C Chivers ◽  
S C Gordelier
Keyword(s):  
Friction Coefficient ◽  
Fretting Fatigue ◽  
Relative Displacement ◽  
Literature Survey ◽  
Clamping Force ◽  
Contact Conditions ◽  
Tensile Stresses ◽  
Slip Regime ◽  
Rational Explanation ◽  
Complicated Situation

This paper considers what palliative effects can be achieved for fretting fatigue by modifying the contact conditions. A previous literature survey of palliatives by the authors is briefly reviewed to demonstrate the contrary nature of much of the evidence. Two simple geometries (sphere and cylinder on plane) are then considered, and the tensile stresses generated in the wake of the sliding contact derived. It is contended that fretting fatigue is the result of such tensile stresses contributing to the crack initiation process. The effect on these tensile stresses of modifying the contact conditions of the friction coefficient and clamping force is examined, so that successful palliatives can be identified. The analysis shows that conditions exist where increasing or decreasing either the friction coefficient or clamping force can be of benefit, and there is no panacea. The correct action depends on geometry, slip regime and the controlling factor for relative displacement. The analysis therefore provides an explanation of the apparent contradictions in the literature. Suggestions are made for the best approach to ameliorate a fretting fatigue problem, given this complicated situation.

A Micro-Contact Model for Boundary Lubrication With Lubricant/Surface Physiochemistry

2002 ◽  
Vol 125 (1) ◽  
pp. 8-15 ◽  
Author(s):  
H. Zhang ◽  
L. Chang ◽  
M. N. Webster ◽  
A. Jackson
Keyword(s):  
Plastic Deformation ◽  
Friction Coefficient ◽  
Oxide Layer ◽  
Contact Pressure ◽  
Friction Force ◽  
Boundary Lubrication ◽  
The State ◽  
Surface Generation ◽  
Contact Friction ◽  
Flash Temperature

A model is developed to study the tribological behavior of sliding micro-contacts. It provides a building block to the modeling of tribo-contacts in boundary lubrication. Three contact variables are calculated at the asperity-level by relating them to the state of contact and the state of asperity deformation. These variables include micro-contact friction force, load carrying capacity and flash temperature. The deformation of the contacting asperity is either elastic, elasto-plastic, or fully plastic. Furthermore, the asperity may be covered by the lubricant/additive molecules adsorbed on the surface, protected by a surface oxide layer or other chemical reaction films, or in direct contact with no boundary protection. The possibility of the contact in each of these three states is represented by a corresponding contact probability. A numerical method is developed to determine the contact state and contact variables in the course of an asperity-to-asperity collision. The asperity flash temperature, which governs the kinetics of lubricant/surface adsorption/desorption, is first calculated by integrating the Jaeger equation over the contact area and in time. Then, the probability of contact covered by an adsorbed film is determined using the Volmer adsorption isotherm, and the probability of contact protected by the oxide layer is estimated using a classical wear theory. For elastic/elasto-plastic deformation of the asperity, the friction coefficient is given by the linear combination of the friction coefficients of the three contact states with their contact probabilities as the weighting factors. For fully plastic deformation of the asperity, the contact pressure and friction force become dependent of each other. The shear stress is approximated by a linear function of the contact probabilities, and the contact pressure and friction coefficient then calculated. Meanwhile, the influence of fresh surface generation due to plastic flow on the contact probabilities is also modeled. Insights are provided into the asperity collision through numerical studies of a sample problem. In addition, parametric studies are carried out to analyze the effects of lubricant and surface parameters on the micro-contact severity and its load capacity.

scholarly journals Rubber Wear and the Role of Transfer Films on Rubber Friction on Hard Rough Substrates

2021 ◽  
Vol 69 (2) ◽  
Author(s):  
A. Tiwari ◽  
N. Miyashita ◽  
B. N. J. Persson
Keyword(s):  
Friction Coefficient ◽  
Sliding Friction ◽  
Present Theory ◽  
Concrete Surface ◽  
Relative Importance ◽  
Rubber Compound ◽  
Transfer Films ◽  
Rubber Compounds ◽  
Rubber Friction

AbstractWe study the influence of rubber transfer films on the sliding friction between rectangular rubber blocks and a concrete surface. We present experimental results for the friction coefficient for a rubber compound sliding on a concrete surface contaminated by another rubber compound, for two different pairs (A, B) and (C, D) of rubber compounds. For the same rubber compounds, we present theory results which illustrate the relative importance of the viscoelastic and adhesive contribution to the sliding friction. We correlate the calculated rubber friction with the nature of the observed transfer films (or wear processes). Graphical Abstract

scholarly journals Dependency of Rubber Friction on Normal Force or Load: Theory and Experiment

2017 ◽  
Vol 45 (1) ◽  
pp. 25-54 ◽  
Author(s):  
Gaetano Fortunato ◽  
Vincenzo Ciaravola ◽  
Alessandro Furno ◽  
Michele Scaraggi ◽  
Boris Lorenz ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Frictional Heating ◽  
Measured Temperature ◽  
Load Theory ◽  
Time Integral ◽  
Rubber Friction ◽  
Pressure Dependency ◽  
Road Surfaces ◽  
Good Agreement

ABSTRACT In rubber friction studies, it is often observed that the kinetic friction coefficient μ depends on the nominal contact pressure p. We discuss several possible origins of the pressure dependency of μ: (1) saturation of the contact area (and friction force) due to high nominal squeezing pressure; (2) nonlinear viscoelasticity; (3) nonrandomness in the surface topography, in particular the influence of the skewness of the surface roughness profile; (4) adhesion; and (5) frictional heating. We show that in most cases the nonlinearity in the μ(p) relation is mainly due to process (5), frictional heating, that softens the rubber, increases the area of contact, and (in most cases) reduces the viscoelastic contribution to the friction. In fact, because the temperature distribution in the rubber at time t depends on the sliding history (i.e., on the earlier time t′ < t), the friction coefficient at time t will also depend on the sliding history, that is, it is, strictly speaking, a time integral operator. The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures that may strongly affect the area of real contact and the friction force (and the wear-rate). This is the case for rubber sliding on road surfaces at speeds above 1 mm/s. Previously, we derived equations that described the frictional heating for solids with arbitrary thermal properties. Here, the theory is applied to rubber friction on road surfaces. Numerical results are presented and compared to experimental data. We observe good agreement between the calculated and measured temperature increase.

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