bluuebunny/crossref_metadata_2025 huggingface dataset:
Tire Vibration Modes and Effects on Vehicle Ride Quality
Authors: Scavuzzo R. W. , Richards T. R. , Charek L. T.
Published: June 2006

Tire vibration modes are known to play a key role in vehicle ride, for applications ranging from passenger cars to earthmover equipment. Inputs to the tire such as discrete impacts (harshness), rough road surfaces, tire nonuniformities, and tread patterns can potentially excite tire vibration modes. Many parameters affect the frequency of tire vibration modes: tire size, tire construction, inflation pressure, and operating conditions such as speed, load, and temperature. This paper discusses the influence of these parameters on tire vibration modes and describes how these tire modes influence vehicle ride quality. Results from both finite element modeling and modal testing are discussed.
On the Incorporation of Frictional Effects in the Tire/Ground Contact Area
Authors: Gall R. , Tkacik P. , Andrews M.
Published: June 2006

This paper introduces a three-dimensional finite element model of a tire with a detailed tread block structure to more accurately describe the stress distribution in the tire/ground contact area. Because of the importance of properly modeling the contact, several preliminary studies are detailed. First, the frictional contact between a rib and the ground is presented using a plane strain model. In particular, the edge effects are studied. Second, a combined experimental and numerical method for determining the coefficient of friction between a rubber block and a glass plate is described. A friction law is developed which includes the well-known dependence of the coefficient of friction on the normal stress. Finally, the three-dimensional tire model is discussed and results are given.
Belt Construction Optimization for Tire Weight Reduction Using the Finite Element Method
Authors: Weiss M. , Tsujimoto S. , Yoshinaga H.
Published: June 2006

The influence of five belt constructions on high speed endurance, ride comfort, and rolling resistance was investigated for a high performance 225/50R16 92V radial passenger car tire, using the finite element method. The belt constructions were combinations of belt edge shapes (cut, folded) and reinforcement materials (steel, aramid). The goal was to find optimized belt constructions for tire weight reduction, considering important tire properties like high speed endurance, ride comfort, and rolling resistance. A full aramid belt construction with a folded belt around a cut belt was chosen for design parameter variation calculations to reduce rolling resistance. This leads to a tire with smaller belt width, increased folding width, additional center cap ply, and reduced non-skid base and depth. The effect of inflation pressure and speed on rolling resistance was evaluated for this construction.
Application of the Boundary Element Method and Modal Analysis to Tire Acoustics Problems
Authors: Nakajima Y. , Inoue Y. , Ogawa H.
Published: June 2006

Road traffic noise needs to be reduced, because traffic volume is increasing every year. The noise generated from a tire is becoming one of the dominant sources in the total traffic noise because the engine noise is constantly being reduced by the vehicle manufacturers. Although the acoustic intensity measurement technology has been enhanced by the recent developments in digital measurement techniques, repetitive measurements are necessary to find effective ways for noise control. Hence, a simulation method to predict generated noise is required to replace the time-consuming experiments. The boundary element method (BEM) is applied to predict the acoustic radiation caused by the vibration of a tire sidewall and a tire noise prediction system is developed. The BEM requires the geometry and the modal characteristics of a tire which are provided by an experiment or the finite element method (FEM). Since the finite element procedure is applied to the prediction of modal characteristics in a tire noise prediction system, the acoustic pressure can be predicted without any measurements. Furthermore, the acoustic contribution analysis obtained from the post-processing of the predicted results is very helpful to know where and how the design change affects the acoustic radiation. The predictability of this system is verified by measurements and the acoustic contribution analysis is applied to tire noise control.
A Mathematical Model for Tire/Wheel Assembly Balance
Authors: Ni E. J.
Published: June 2006

A mathematical model is developed to calculate the weight required on a tire/wheel assembly to balance wheel nonuniformity effects such as the lateral runout. A finite element model of a tire mounted on a rigid wheel is used to simulate the free spinning about a skewed axis. The result showed that Euler's equation of motion in rigid body dynamics can be used to calculate the imbalance caused by wheel lateral runout. This equation is then used in a Monte Carlo model to simulate a production distribution. The model can be used to define tire and wheel specification limits, and to predict the number of assemblies that will have unacceptable imbalances. The verification of the model and results of the Monte Carlo simulation are presented.
Tire Tread Temperatures in Actual Contact Areas
Authors: Fujikawa T. , Funazaki A. , Yamazaki S.
Published: June 2006

This report treats the temperature in an actual contact area between the pavement and the tread of a cornering tire. A method to compute the temperature by using Jaeger's formula for a moving heat source is proposed. Additionally, a temperature measurement was conducted. The computed value is consistent with the measured value. The computed results for various pavement parameters show that the actual contact area size and pavement thermal diffusivity significantly affect the temperature, and that the distribution of tire tread temperature around the actual contact area varies considerably along the slip direction of the tread.
The Effect of the Environment on the Friction and Wear of Blended Rubber
Authors: Uchiyama Y.
Published: June 2006

The friction and wear of rubber are properties that are affected by the environment, especially by the oxygen in the air. Natural rubber (NR) is most sensitive to air, butadiene rubber (BR) is scarcely affected by the presence of air, while styrene butadiene rubber (SBR) is intermediate compared to NR and BR. Both the abrasive and fatigue wear rates of NR and BR blends are known to decrease by increasing the BR content. To reduce the wear rates of NR vulcanizates in the air, SBR was blended with NR. In severe rubbing experiments against abrasive cloths, the wear rate of the NR-SBR blends slightly decreased by increasing the SBR content. The NR-SBR blends showed considerable reduction in wear under fatigue wear conditions against metal gauze. Similar experiments were also conducted for SBR-BR blends. Blending with BR showed a substantial reduction in wear, especially in fatigue wear. When NR-BR, NR-SBR, and SBR-BR blends were rubbed against metal gauze in vacuum, the friction and wear of these three blended rubbers was lower in vacuum than in room air. It is concluded that the wear resistance of the blended rubber is affected by its sensitivity to air as well as by the mechanochemical properties of the blends under fatigue wear conditions.
Testing and Evaluation of Aircraft Tire Coupons
Authors: Singh M. , Pai D. M. , Sadler R. L. , Avva V. S.
Published: June 2006

Coupons from unused aircraft tires were pre-loaded in tension and conditioned in three ways: static thermal aging, room temperature dynamic aging, and dynamic thermal aging. The degradation of peel strength between plies was then studied. The results indicate that elevated temperature is more important than flexural stress or hoop stress in affecting the degradation of peel properties. A micrographic study indicates that there is a difference in failure mechanisms between unconditioned and conditioned coupons.
Effect of Tire Rolling Loss on Vehicle Fuel Consumption
Authors: Schuring D. J.
Published: June 2006

Empirical data published since 1925 suggest a linear relation between tire rolling loss and vehicle fuel consumption. The background of this relation is discussed and then updated to include current passenger cars and trucks. Finally, the relation is transformed into a simple rule that would allow an estimate of the fuel savings achieved by tire rolling loss reductions.
An Analytical and Experimental Study of a Tire Rolling Over a Stepped Obstacle at Low Velocity
Authors: Mousseau C. W. , Clark S. K.
Published: June 2006

The ring on elastic foundation (REF) model has been used as a pneumatic tire analog for many types of two-dimensional contact problems. This paper investigates the suitability of the model to reproduce hub forces during large deformation, quasi-static contact. Two types of tire contact problems are considered in this paper. The first problem is a tire deforming against a flat plate, and the second is a tire rolling over a 50 mm step. The REF model is implemented in a nonlinear, finite element program with elements that accommodate large deformation and contact. Experimental hub force measurements verify the simulation results. This paper shows that the best match with experimental data is accomplished with a model that consists entirely of beam elements and includes a softening foundation. Also, it shows that the hub force is strongly dependent on the radial stiffness of the foundation and the inflation pressure.
Modeling Tire Performance During Antilock Braking
Authors: Padovan J. , Padovan P.
Published: June 2006

This paper develops an analytical-numerical model of antilock braking system (ABS) cycles, vehicle slowdown dynamics and their concomitant influence on tire tread lug wear. Overall, the model handles the effects of tire slip-friction behavior, brake-slip behavior, vehicle slowdown dynamics including lift and drag, ABS cycling, tire wheel rotation and vibration dynamics, and local tread level thermomechanical-chemical degradation “shear off” of the surface rubber. The results of several benchmark studies are also presented. These demonstrate potential tire wear characteristics under ABS.
Characteristics of Tire Force and Moment Data
Authors: Pottinger M. G. , Fairlie A. M.
Published: June 2006

Tire force and moment data are fundamental inputs to vehicle handling simulations. Tire asymetries and tire and test variability must be considered in force and moment testing.

This article provides a discussion of asymmetries in tire force and moment behavior and of variation in their data. The asymmetry discussion is thoroughly general. The variability discussion is philosophically general, but the data are specific to the test specifications and tests used. Variability data are presented for the range from −14 to +14 degrees slip angle.

The data and concepts concerning tire asymmetries and test data variability presented are especially important now because work to produce up-to-date force and moment testing standards is beginning under the auspices of the Society of Automotive Engineers (SAE).
A Statistical Model of Tire Uniformity Distributions
Authors: Schuring D. J.
Published: June 2006

Uniformity data on large populations of tires do not follow a normal distribution function. A more fitting model is described, one that is based on the general variations occurring in the manufacturing process. It is checked against actual distributions of force and runout data. A few predictive rules are derived.
Tire-Road Interactions — Harmony or Conflict?
Authors: Williams A. R.
Published: June 2006

This is a summary of work by the author and his colleagues, as well as by others reported in the literature, that demonstrate a need for considering a vehicle, its tires, and the road surface as a system. The central theme is interaction at the footprint, especially that of truck tires. Individual and interactive effects of road and tires are considered under the major topics of road aggregate (macroscopic and microscopic properties), development of a novel road surface, safety, noise, rolling resistance, riding comfort, water drainage by both road and tire, development of tire tread compounds and a proving ground, and influence of tire wear on wet traction. A general conclusion is that road surfaces have both the major effect and the greater potential for improvement.
Tire Design Theory Based on Optimization of Stress-Strain Cycles of its Elements (CSSOT)
Authors: Tretyakov O. B. , Sokolov S. L.
Published: June 2006

Some criteria are presented for evaluating the various tire design theories that are based on the equilibrium shape of the sidewall and on the rolling contour of a tire (RCOT). Tire failure types and the mathematical models by which they can be predicted by modern theories of rubber/cord fatigue are also described. A tire design theory based on stress-strain optimization of its elements is proposed as is a hierarchic system of complicated tire models for calculation of stress-strain cycles. Approaches are suggested for estimating fatigue strength of rubber-cord composites. Influence of the cross-section geometry and of the inner structure of the tire on stress-strain cycles in the belt and bead of radial tires is investigated. Results obtained with the different design theories are compared.
Computer Modeling of a Tire under Cornering Loads
Authors: Gardner I. , Theves M.
Published: June 2006

During a cornering maneuver by a vehicle, high forces are exerted on the tire's footprint and in the contact zone between the tire and the rim. To optimize the design of these components, a method is presented whereby the forces at the tire-rim interface and between the tire and roadway may be predicted using finite element analysis. The cornering tire is modeled quasi-statically using a nonlinear geometric approach, with a lateral force and a slip angle applied to the spindle of the wheel to simulate the cornering loads. These values were obtained experimentally from a force and moment machine. This procedure avoids the need for a costly dynamic analysis. Good agreement was obtained with experimental results for self-aligning torque, giving confidence in the results obtained in the tire footprint and at the rim. The model allows prediction of the geometry and of the pressure distributions in the footprint, since friction and slip effects in this area were considered. The model lends itself to further refinement for improved accuracy and additional applications.
Phase Lag of Tire Cornering Force
Authors: Hanada R. , Nagumo T. , Mashita T.
Published: June 2006

Automobile handling can be greatly improved by reducing the phase lag of tire cornering force behind imposed distortion. We have shown experimentally that this lag is related to in-plane stiffness of the belt and to radial, lateral, and circumferential stiffnesses of the sidewall. While the cornering stiffness is related to the belt rigidity, either can be changed without affecting the sidewall stiffnesses. The cornering stiffness, for example, is sensitive to design factors such as tread compound and tread pattern. The radial, lateral, and circumferential sidewall stiffnesses, however, are mutually perpendicular at a given point in a tire, so they cannot be changed independently of each other. In order to reduce the phase lag of the cornering force, the lateral and circumferential stiffnesses must be increased with a minimum increase in radial stiffness. This can be done by either lowering the radial location of the maximum section width of the inflated tire or by proper changes in material and/or design elements of the sidewall.
A Three-Dimensional Rolling Contact Model for a Reinforced Rubber Tire
Authors: Faria L. O. , Bass J. M. , Oden J. T. , Becker E. B.
Published: June 2006

A steady state formulation of the rolling contact problem with friction that allows the analysis of free rolling, cornering, acceleration, and braking is presented. This formulation is applied to the finite element analysis of tires. A layered shell finite element with shear deformation that allows for large deflection and rotation is developed. In each layer, orthotropic Hookean materials or Mooney-Rivlin type materials with fiber reinforcements can be used and the incompressibility constraint is enforced with Lagrange multipliers. The contact constraint is enforced with a penalty and the friction term, instead of the usual Coulomb friction, is regularized by a differentiable form that makes it more suitable for numerical analysis. A numerical example for a typical tire is also given.
Torsional Stiffness of a Steel-Cord-Reinforced Belt Structure
Authors: Akasaka T. , Katoh M. , Makinouchi H.
Published: June 2006

Torsional stiffness of its steel-cord-reinforced belt structure affects various characteristics of a radial tire, particularly when it is operating at a camber angle other than zero. We analyzed the torsional stiffness of the belt, with consideration of interply shear deformation, by modeling it with a laminated biased composite strip of unidirectional cord-reinforced rubber (UDCRR) layers. The coupled torsional-extensional deformation of the belt was shown to vanish at the particular bias angle of 54.7°. It is pointed out that the torsional rigidities of constituent steel cords, which were not considered in the classical lamination theory, could increase the twisting stiffness of the belt structure over that predicted by the conventional lamination theory. A test specimen of low aspect ratio was fixed at both ends under torque loading for the tests. Experimental results of the torsional stiffness together with the coupled torsional-extensional strain agreed well with the analytical results.
A Fundamental Study on Sliding Friction
Authors: Purushothaman N. , Tielking J. T.
Published: June 2006

In this paper we report on an experimental investigation on the friction of tire tread sections sliding over a variety of surfaces. The Texas A&M friction tester was used to measure sliding friction at various speeds and contact pressures. The friction test machine is also described. Actual bituminous and concrete road pavements and artificial 3M Safety Walk were used as surface samples. Tread rubber sections taken from passenger car, truck, and aircraft tires were tested. The influence of major test parameters such as sliding speed, surface texture and contact pressure on friction are discussed.
Nonlinear Cord-rubber Composites
Authors: Clark S. K. , Dodge R. N.
Published: June 2006

An analytical method is proposed for the prediction of load-deflection and stress-strain relations in two-dimensional elastomeric composites where the properties are highly nonlinear. Such materials are represented by various textile cords used as reinforcements in a rubber matrix. The analytical procedure involves a forward prediction process for simultaneous nonlinear equations and can readily be implemented for automated computer use. Experiments on nonlinear tubes are reported and computation of load-deflection relationships observed in those experiments are compared with experimental data. The predictions generally agree with the observed behavior.
Towards Predicting Relative Belt Edge Endurance With the Finite Element Method
Authors: De Eskinazi J. , Ishihara K. , Volk H. , Warholic T. C.
Published: June 2006

The paper describes the intention of the authors to determine whether it is possible to predict relative belt edge endurance for radial passenger car tires using the finite element method. Three groups of tires with different belt edge configurations were tested on a fleet test in an attempt to validate predictions from the finite element results. A two-dimensional, axisymmetric finite element analysis was first used to determine if the results from such an analysis, with emphasis on the shear deformations between the belts, could be used to predict a relative ranking for belt edge endurance. It is shown that such an analysis can lead to erroneous conclusions. A three-dimensional analysis in which tires are modeled under free rotation and static vertical loading was performed next. This approach resulted in an improvement in the quality of the correlations. The differences in the predicted values of various stress analysis parameters for the three belt edge configurations are studied and their implication on predicting belt edge endurance is discussed.
Finite Element Simulation of Destructive Tire Testing
Authors: Tseng N. T. , Pelle R. G. , Chang J. P. , Warholic T. C.
Published: June 2006

Three destructive tire tests, burst pressure, high speed free rotation, and DOT plunger energy are performed to check the ultimate strength of new tires. These tests represent some of the extreme, although unusual, overload conditions that may be applied to a tire. They are used to determine how far above normal service conditions one might take a tire before it reaches its ultimate strength.

A nonlinear incompressible rubber model and a nonlinear cord-rubber composite model were used in the tire analyses. Various rubber compounds as well as the rubber in the cord-rubber composite were modeled as nonlinear incompressible Mooney-Rivlin materials. The bimodulus cord and the cord angle change effect due to deformation were also considered. In addition, gap elements were used at the tire-rim interface and between tread grooves where required to provide appropriate boundary conditions.

Numerical simulations of these destructive tire tests represent three excellent benchmarks to verify and to evaluate the robustness of a finite element code due to very large strain and deformation occurring in the tire. The numerical results predicted by the finite element tire models agreed very well with the available experimental data.
A Beam Model for Tire Critical Speeds
Authors: Clark S. K.
Published: June 2006

A brief review of tire critical speeds is given using the beam under tension as a physical model. In its most common form, this model visualizes the critical speed as that speed just sufficient to sustain a continuous sinusoidal bending wave in the tire tread band. A number of studies have been published modifying this concept by the introduction of material damping, centrifugal effects, and other characteristics, some of which aid in explaining the fact that the wave pattern observed experimentally is local and decays rapidly away from the contact patch. This paper presents a different view of the wave pattern needed for a critical speed to exist, namely that a naturally occurring local wave can arise independent of material damping and that as a practical fact, material damping may have little to do with the onset of the phenomenon. A discussion on the effect of tire design variables on critical speed is given based on the expressions derived here.
Influence of Compound Heat Conductivity on the Temperature Distribution in Rotor Type Curemeters
Authors: Ernst G. K.
Published: June 2006

The effective temperature in rotor type curemeters is — according to DIN 53529 — controlled using an unfilled EPDM compound with dicumylperoxide as cross-linking agent. The rate of DCP decomposition has a well-known temperature dependence. This rate is also in all practical cases the same as the rate of cross-linking. Therefore, the measured rate of cross-linking indicates the effective temperature in the reaction cavity. The rotor in common curemeters is clamped. Because it can not be heated directly, this rotor is a heat sink in the cavity. The effect is a temperature gradient in the cavity depending on the heat conductivity of the tested compound. This temperature gradient in rotor type curemeters is compared to rotorless curemeters. It is shown that using the unfilled EPDM/DCP compound for temperature calibration leads to a too high effective temperature for filled compounds.
Mechanics of the Dynamic Flex Test
Authors: Assaad M. C.
Published: June 2006

The dynamic flex test is a comparative test used for screening synthetic cords. The test objective is to subject the cord through accelerated test conditions as observed in an underinflated and deflected tire. This test ultimately determines the percent break strength retained for flexed synthetic tire cords. It consists of a two-layer composite laminate subjected to a constant tensile load while dynamically flexing around a spindle. After flexing for two to six hours (the time depends on the cord material and construction), the break strength is determined for the flexed and for an unflexed cord and the percent retained break strength is reported. The objective of this paper is to quantify the stress and strain distributions in the cord under conventional laboratory conditions and identify the conditions required for prescribing the desired tension and compression cyclic strain for a cord construction. The tension-compression behavior is controlled by the location of the neutral plane which, in turn, is a function of the static tensile load, fiber reinforcement and rubber matrix moduli, epi, geometry of the laminate cross section, and the diameter of the spindle.
A Technique to Predict the Acoustic Radiation Characteristics of an Automobile Tire
Authors: Wright C. , Koopmann G. H.
Published: June 2006

A technique to predict the acoustic radiation characteristics of the predominant structural modes of an automobile tire is presented. A stationary tire is excited by an electrodynamic vibrator and, through conventional modal analysis methods, a description of the surface velocity is obtained. With this information, and a representation of the tire geometry, numerical procedures are used to predict the acoustic surface intensity and field pressure, for a given frequency of interest, based on a Helmholtz integral formulation. Predicted far field sound pressure levels are in close agreement with experimental measurements taken in an anechoic chamber. This provided the necessary validation of the technique.
Viscoelastic Loss Characteristics of Cord-Rubber Composites
Authors: Tabaddor F. , Clark S. K. , Dodge R. N. , Perraut J. M.
Published: June 2006

Calculated and experimentally generated complex moduli of tire cord-rubber composites are compared. Halpin-Tsai equations in complex form are defined and used to calculate the elastic and loss components of the composite moduli. Additionally, stress-strain relationships for bias ply composites are included. Experimental techniques consisted of prestrained cyclic tensile and torsional tests on tubular specimens. Composite properties of typical polyester and steel tire cord reinforcements were evaluated as functions of end count, cross-ply angle, and thickness of rubber filler between plies.
Effects of Some Environmental and Test Conditions on Tire Treadwear Indices
Authors: Bascunana J. L.
Published: June 2006

A treadwear investigation was carried out with four brands of radial tires having different tread rubber compounds. The tires were randomly selected, except for one brand in which they were selected from the same mold and date. Identical series of tests were conducted in cold and hot weather. Treadwear was measured by both tire weight and groove depth. A discussion of the results is included.
Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part I: Introduction and Details on the Organization of the Program
Authors: Veith A. G.
Published: June 2006

This four-part series of papers addresses the problem of systematic determination of the influence of several tire factors on tire treadwear. Both the main effect of each factor and some of their interactive effects are included. The program was also structured to evaluate the influence of some external-to-tire conditions on the relationship of tire factors to treadwear.

Part I describes the experimental design used to evaluate the effects on treadwear of generic tire type, aspect ratio, tread pattern (groove or void level), type of pattern (straight rib or block), and tread compound. Construction procedures and precautions used to obtain a valid and functional test method are included. Two guiding principles to be used in the data analyses of Parts II and III are discussed. These are the fractional groove and void concept, to characterize tread pattern geometry, and a demonstration of the equivalence of wear rate for identical compounds on whole tread or multi-section tread tires.
Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition. Part II: Results of the Primary Treadwear Test Series
Authors: Veith A. G.
Published: June 2006

In Part II, the influence of four construction parameters and one composition parameter on treadwear is studied. The treadwear rates obtained from the experimental design described in Part I are analyzed using regression analysis and simple averaging techniques. In general the analyses indicate that generic type has the strongest influence on the rate of treadwear; followed in order of importance by groove void fraction and aspect ratio which are about equivalent to each other, compound loss modulus (discussed in more detail in Part III), and groove pattern type. However, in addition to the main effects, treadwear rates also depend on the interaction between some of the variables as well as on the severity of the treadwear tests.
Evolving the Banded Radial Tire
Authors: Markow E. G.
Published: June 2006

Development of the banded radial tire is discussed. A major contribution of this tire design is a reliable run-flat capability over distances exceeding 160 km (100 mi). Experimental tire designs and materials are considered; a brief theoretical discussion of the mechanics of operation is given based on initial two-dimensional studies and later on more complete finite element modeling. Results of laboratory tests for cornering, rolling resistance, and braking are presented. Low rolling resistance, good cornering and braking properties, and low tread wear rate along with good puncture resistance are among the advantages of the banded radial tire designs.
A Laminated Composite Solid Element and its Application to Tire Analysis
Authors: Stechschulte R. A. , Luchini J. R.
Published: June 2006

This paper describes a solid isoparametric element which can incorporate multiple composite layers in the same element and still predict in-plane and out-of-plane coupling. Finite element models using this element have been used with good success to predict the global response of a tire during contact. This element, used in conjunction with any of a number of global-local methodologies, offers potential for reducing the computational effort required in the analysis of tires.
Sensitivity of Temperature Rise in a Rolling Tire to the Viscoelastic Properties of the Tire Components
Authors: Beringer C. W. , Kwon Y. D. , Prevorsek D. C.
Published: June 2006

The sensitivity coefficient of tire temperature to heat generation rate of tire compounds is derived based on a simplified tire geometry and one-dimensional heat transfer approximation. This provides a simple and quick means for estimating the magnitude of change in the steady-state tire rolling temperature resulting from the difference in the heat generation rates of cord and rubber in the tire. The use of this sensitivity coefficient in several tire temperature analyses gave good indications of the temperature change. Shortcomings and limitations of the approach are also discussed.
On the Characterization of Mechanical Properties of Rubber Vulcanizates
Authors: Chow C. L. , Cundiff C. H.
Published: June 2006

A method for characterizing rubber vulcanizates for engineering design analysis is described. The material characterization is based on the elastic strain energy functions expressible in terms of both Mooney-Rivlin and Valanis-Landel types of formulation. The specimens are flat sheets and long thin cylinders. Considering both accuracy of the predicted stress-strain results and testing time, the pure shear method is preferred over other forms of biaxial loading. This method was automated using an MTS testing machine equipped with a PDP 11/04 mini-computer. A filled vulcanizate under load exhibits progressive stress-softening before it reaches an equilibrium state; this behavior was incorporated into the automatic testing procedure to ensure consistent and reproducible results. The adequacy and accuracy of the material coefficients derived from this method were checked against measured results and found to be satisfactory.
An Axisymmetric Finite Element and Its Use to Examine the Effects of Construction Variables on Radial Tires
Authors: Satyamurthy K. , Hirschfelt L. R.
Published: June 2006

A nonlinear axisymmetric formulation has been developed which allows circumferential as well as radial and lateral displacements. Significant circumferential displacements occur in radial tires under an inflation load both in the crown region and in the sidewall of the tire. The model is used in this study to assess the types of deformations that occur and the effect of construction variables on these deformations. The variables considered include belt angle, belt width, belt edge filler modulus, and chafer angle. The effect of changes in these variables on both in-plane and circumferential deformations, as well as cord loads and interply shear strains are reported. Wherever possible the numerical results are compared with experimental measurements. Predicted deformations due to chafer orientations were sometimes unexpected, but were confirmed by experiment.
Transient Properties of Truck Tires on Real Road Surfaces
Authors: Weber R. , Münster M.
Published: June 2006

The cornering, or lateral force response of heavy-duty truck tires, has been evaluated on real road surfaces at speeds of 10–60 km/h. The special mobile truck tire dynamometer has a two-test-tire carriage mounted just ahead of the rear support tires of an articulated truck (tractor) trailer. Equal slip angles may be applied simultaneously to both test tires.

The frequency response was evaluated by typical phase angle methods. The phase angle (lag of lateral force behind instantaneous angle) increased with frequency (time rate of application of angle) and decreased with increasing speed.
Four-Wheel Drive Cars Without Intermediate Differential Gear: Impact on Tire Tread Wear
Authors: Bottasso F. , Bandel P.
Published: June 2006

Longitudinal tire forces on four-wheel drive cars, both with and without a differential gear between the axles, are compared with those on two-wheel drive cars; tests were made on a curved trajectory.

A “critical speed” may be defined which depends solely on characteristics of the car and test tires; this is usually of the order of a few tens of kilometers per hour. Above that speed, for the lateral accelerations normally reached, the additional longitudinal forces caused by lack of an intermediate differential do not increase the relative tread wear rate relative to that on a two-wheel drive car. Cars almost always operate above this critical speed. Below it, however, the additional longitudinal forces caused by lack of a differential are much higher and obviously would lead to higher rates of tread wear.
A New Type of Precision Tire
Authors: Tretyakov O. B.
Published: June 2006

A process is suggested for improving the rubber-cord composite in a radial tire through precision stage-by-stage molding of its parts. This starts by casting an inner elastomeric envelope of the carcass from a liquid oligomer mix. The full molding technology uses acoustic and resonance effects to optimize the degree of order of the structure and of rubber uniformity. The resultant precision tires should have a higher degree of order of both macro- and microstructure than do present commercial tires. Reduced stress concentration in locations that have high failure rates in commercial tires are considered. A new theory, CSSOT, is used for optimizing tires from results of stress-strain cycles.
Twisting Stiffness and Lateral Vibration of a Radial Tire Sidewall
Authors: Yamazaki S. , Akasaka T.
Published: June 2006

The present authors recently gave an analytical method for estimating three spring constants Kr, Ks, and Kt for sidewall stiffnesses of radial tires. These represent the radial, lateral, and in-plane rotational directions respectively [1,2,3]. The method is based on netting theory with special consideration to stiffness of the rubber matrices in the sidewall. These theoretical results were verified by experiment to have sufficient accuracy. In order to confirm the availability of these spring constants, the twisting stiffness Rt of a radial tire has been analyzed in the present paper by using a spring-supported ring model. An explicit formula for Rt, expressed in terms of the three components of the spring constant, was obtained. Experiments were conducted on a 175SR14 radial tire by increasing the inflation pressure while keeping the tread circumference constant. The theoretical results agreed well with the experimental results. A related problem is also referred to; this is the forced lateral vibration with fundamental eigen-modes of the inflated sidewall-rim system when the tread is fixed. Eigen-frequencies calculated by using those spring constants coincide well with the experimental results.
Elements in the Road Evaluation of Tire Wear
Authors: Brenner F. C. , Kondo A.
Published: June 2006

Experiments to evaluate the wear of tires on vehicles are run for various purposes. Compounds may be compared, tread on tire designs evaluated, or an assessment of tread life made. These are several but by no means the only experimental objectives. Although the objectives may vary, all evaluation methods include common steps. This paper describes the procedural steps to be followed to achieve a treadwear evaluation, discusses the results of such experiments, and makes the following recommendations concerning the design of the course. The course should: vary the terrain, the pavement composition, and its geometric features; demand a variety of vehicle maneuvers; wear tires at moderate rates for precise measurement and to insure that the test will extend over several weeks; and wear tires equally at front and rear for rear axle driven vehicles.
Laboratory Tire Treadwear Testing
Authors: McIntosh K. W.
Published: June 2006

An attempt to duplicate road testing of tires on a laboratory treadwear tester is described. A tilting drum abrader using tungsten carbide gritted bars as an abrasive medium achieved limited success in slow wear testing of tires. Fast wear results could not be duplicated.
Mathematical Prediction of Dynamic Tire Behavior
Authors: Zorowski C. F.
Published: June 2006

The subject of the problems and progress in predicting the mechanical behavior of tires subjected to dynamic loading is treated in two parts. The difficulties associated with this problem and various methods that have been proposed for its treatment are first discussed. The application of finite element techniques is emphasized, both with respect to current success and future potential. The second part presents a detailed analysis of this same problem using classical membrane theory. Although the model is developed using the same basic considerations employed by earlier investigators, its final formulation provides for greater generality and flexibility in application. It has the capability of defining meridian profiles and, consequently, cord strains under a condition of inflation and centrifugal loading as a function of geometric and cord load parameters designated at any point on the tire carcass. The result is a method of analysis which can be easily applied to study the effects of a variety of tire design and constructional constraints on carcass shape and cord tensions.
Improvement of Tire Traction with Chlorobutyl Rubber
Authors: Keller R. C.
Published: June 2006

The skid resistance of tires can be improved with tread compounds which have high hysteresis losses. Chlorobutyl rubber is a chlorinated isobutylene-isoprene copolymer of interest in tread compounds because of its high damping (low resilience) characteristics. The traction of tread stocks containing blends of Chlorobutyl and SBR has been evaluated in laboratory and tire tests. In the laboratory, traction performance is estimated using the Portable Skid Resistance Tester as well as the classical rebound tests. Typical results are summarized. The influence of compounding parameters, namely, composition of the polymer blend and carbon black loading, on the skid properties of the tread compound is also discussed. Tire traction performance is determined with an automated vehicle designed to measure both peak and sliding skid resistance. Overall, significant improvements in traction performance have been found for radial tires with Chlorobutyl-containing tire treads; the level of improvement is directly proportional to the Chlorobutyl content of the polymer blend. Some loss in treadwear appears unavoidable, however.
Scale Modeling of Equilibrium Tire Temperature
Authors: Schuring D. J.
Published: June 2006

Examination of heat generation in an earthmover tire traversing rigid terrain indicates that almost all heat originates in the tire bulk; heat generated in the contact area is small and can be neglected. Modeling of equilibrium bulk heat requires using the same compound for model and prototype, keeping both tires geometrically similar, and running them at constant speed long enough to reach equilibrium temperature. Then, three model rules apply; one allows for geometrical distortion of cord arrangement in static loading, and the others impose similar mechanisms of heat generation and dissipation on the model and prototype. The effect of cord distortion on heat generation is unknown, however, and has to be assessed experimentally.

Preliminary tests indicate that the model rules of heat generation are basically correct. Problems associated with stress distortion (due to cord distortion), heat convection, and inflation pressure buildup (due to heat buildup) remain. Self-modeling tests on the same tire, and scale model tests with geometrically similar tires are recommended.
Effect of Polymer, Road Surface, and Driving Conditions on Wear Surface Characteristics of Tire Treads
Authors: Martin F. R. , Biddison P. H.
Published: June 2006

Treads made with emulsion styrene-butadiene copolymer (SBR), solution SBR, polybutadiene (BR), and a 60/40 emulsion SBR/BR mixture were built as four-way tread sections on G78-15 belted bias tires, which were driven over both concrete and gravel-textured highways and on a small, circular, concrete test track. The tires were front mounted. When driven on concrete highway, all except the BR tread had either crumbled- or liquid-appearing surfaces, thought to have been formed by mechanical degradation or fatigue. When cornered on concrete, these materials formed small cylindrical particles or rolls. The BR tread had a smooth, granular-textured surface when driven on concrete highway and a ridge or sawtooth abrasion pattern when cornered on concrete. All the materials appeared rough and torn when run on gravel-textured highway. The differences in wear surface formed on BR tread and the other three are thought to be due primarily to the relatively high resilience of BR.
Tire Traction Assessed by Shear Force and Vehicle Performance
Authors: Fancher P. S. , Segel L.
Published: June 2006

Tire shear force data for ten different types of passenger car tires tested on wet surfaces are studied to examine the influence of test surface, velocity, and load on the maximum lateral force, maximum braking force, maximum resultant force, and locked wheel braking force. Tire traction rankings based on these four measures are compared with each other and with rankings obtained from J-turn and diagonal braking tests on a vehicle equipped with the same types of tires using the rank difference correlation method. The findings show that rankings based on a small number of maximum lateral force tests correlate well with rankings based on J-turn tests.
Mechanics of the Pneumatic Tire. Part II. The Laminar Model under Inflation and in Rotation
Authors: Robecchi E.
Published: June 2006

Difficulties in the study of the tire are presented by the materials used in tire construction, specifically the problem of achieving a convenient representation of the elastic characteristics of the rubberized fabric. Notable progress has been made in the formulation of the theory of combined orthotropic laminae which includes the contribution of the rubber compound and, more importantly, the effects of combining layers or plies having different characteristics. The laminar model of the tire is of particular interest for the study of the radial tire in which the effect of the carcass-belt combination is very important. This study first considers the tire under inflation alone and gives illustrative examples of applications to several types of tires. The net model for the bias ply tire is discussed as a special case of the theory. The study is then extended to consideration of the effects of centrifugal force in rotation in addition to inflation pressure.
Development of a Vertical Stiffness Relationship for Belted Radial Tires
Authors: Rhyne T. B.
Published: June 2006

Vertical stiffness is a fundamentally important property of tires. This property is often expressed by some empirical formula not directly tied to the physics of the tire. It would be useful to have a physics-based formula that could reliably predict vertical stiffness from a minimum set of pertinent, easily obtained parameters. This paper extends the ring model used by Koutny in his thermodynamic studies of tire stiffness and applies it directly to the question of vertical stiffness without regard to thermodynamics. A master curve of tire vertical stiffness is obtained that includes all tires that meet the assumptions of the model, regardless of size. A simple formula for tire vertical stiffness is developed from the master curve. The formula is correlated to a wide variety of tire stiffness measurements. One use of such a formula could be to develop more reliable tire load capacity standards. In the course of the analysis, it is found that the vertical stiffness depends significantly on the structural shear stiffness of the tire sidewalls.
Truck Tire Operating Temperatures on Flat and Curved Test Surfaces
Authors: LaClair T. J. , Zarak C.
Published: June 2006

Operating temperature is critical to the endurance life of a tire. Fundamental differences between operations of a tire on a flat surface, as experienced in normal highway use, and on a cylindrical test drum may result in a substantially higher tire temperature in the latter case. Nonetheless, cylindrical road wheels are widely used in the industry for tire endurance testing. This paper discusses the important effects of surface curvature on truck tire endurance testing and highlights the impact that curvature has on tire operating temperature. Temperature measurements made during testing on flat and curved surfaces under a range of load, pressure and speed conditions are presented. New tires and re-treaded tires of the same casing construction were evaluated to determine the effect that the tread rubber and pattern have on operating temperatures on the flat and curved test surfaces. The results of this study are used to suggest conditions on a road wheel that provide highway-equivalent operating conditions for truck tire endurance testing.
A Simplified Model for Predicting the Pneumatic Stiffness of Conventional and Multi-Cell Inflation Mechanisms for Off-Road Tires
Authors: Summers T. W. , Richards C. M. , Jarboe N. E.
Published: June 2006

An efficient yet reliable model is developed to predict the static stiffness of pneumatic off-road motorcycle tires inflated by both traditional and non-traditional inflation mechanisms. The model does not include tire sidewall or carcass structural stiffness effects; instead, only the pneumatic component resulting from pressure and volume changes is considered. Model predictions are verified via experimentally measured static stiffness and internal tire pressure data. The analytical and experimental data presented compare the static stiffness behavior of an off-road motorcycle tire inflated with a traditional inner tube to the static stiffness behavior of the same tire inflated by a novel flat-proof inflation system composed of discrete air cells. Results show that the flat-proof inflation system produces performance enhancing static stiffness characteristics over those of the conventional inner tube.