bluuebunny/crossref_metadata_2025 huggingface dataset:
Irish experiences of the rural development possible lessons for Serbia
Authors: Malesevic Krstan
Published: June 2006

For the last fifteen years or so there has been an intensive discussion about the Irish "economic miracle". Since Irish economy has experienced a highest degree of sustained growth among the EU states in this very period this perception is an accurate one. The average GDP growth rate in this period has constantly been above five percent. The national income per capita rose dramatically to 27000 Euro and is the highest in the EU. The rate of employment is permanently on the increase while (qualified) workforce is becoming imported as well. In a very short period of time Ireland has achieved not only an impressive level of economic development but has also experienced a radical social transformation. From predominantly agrarian and traditionally emigrant country, Ireland has rapidly become a highly developed (post)industrial immigrant society. There is no doubt that the adequate strategy and the politics of rural development had an important role to play in achieving these enviable results. Regardless of how much this development is conditioned and influenced by the rural development policies of the EU, Irish model still has many authentic features. This paper explores the possibilities of using some of these experiences from the Irish developmental strategies in the context of an integral rural development of Serbia in the period of transition.
Economic and financial integration in emerging markets: A European policy
Authors: Theodoropoulos Theodore , Vojinovic Borut
Published: June 2006

This paper extends to test if the same short-run increase in cyclical volatility arising from financial integration is observed in this specific sample of "emerging markets". This work finds signs that, contrary to other emerging markets, this does not happen: for the future member states financial integration, similarly to the outcome observed in mature market economies, reduces cyclical volatility both in the short and in the long run. Weak indications are found that this may happen partially due to the anchoring of expectations provided by the EU Accession, and to the more robust institutional framework imposed by this process onto the countries in question.
The concept of stochastic dominance in ranking investment alternatives
Authors: Trifunovic Dejan
Published: June 2006

In order to rank investments under uncertainty, the most widely used method is mean variance analysis. Stochastic dominance is an alternative concept which ranks investments by using the whole distribution function. There exist three models: first-order stochastic dominance is used when the distribution functions do not intersect, second-order stochastic dominance is applied to situations where the distribution functions intersect only once, while third-order stochastic dominance solves the ranking problem in the case of double intersection. Almost stochastic dominance is a special model. Finally we show that the existence of arbitrage opportunities implies the existence of stochastic dominance, while the reverse does not hold.
Central tourist traffic artery: Agricultural and organizational opportunities
Authors: Pejcic Hristivoje
Published: June 2006

The idea of a central tourist traffic artery of the Balkan Peninsula is dealt with in this paper. In addition, the motives for its existence are explained. Regarding the specific interdependence of agriculture and tourism, the agricultural regions surrounding the proposed east Serbian artery are analyzed. Within the given scope of resources, exploitation of certain organizational opportunities is suggested.
Alice is not missing wonderland the eastward enlargement of the European Union
Authors: Prokopijevic Miroslav
Published: June 2006

In this paper I will try to show that the EU enlargement from 2004 is not a good economic move for eight newcomers from Central and Eastern Europe (CEECs). It is unlikely that newcomers will get larger FDI, speed up their economic growth and catch up with richer EU countries, although this was broadly advertised both academically and by the EU "propaganda for happiness." The EU subsidies, intended to offset accession costs, turn out to be useless if not damaging for acceding economies, because they change the structure of incentives. So, instead of being rewarded for accession accession countries are going to be punished twice. Firstly, by lower FDI and a persisting GDP gap. Secondly, by getting subsidies which worsen the situation. CEECs would be better off staying outside the EU and continuing to improve economic freedom and the rule of law. But even after they have acceded, there is still some space for reasonable objectives of the CEECs due to unintended consequences of the socialist enlargement design.
Uticaj spoljne trgovine na ekonomski rast
Authors: Nikolic Goran
Published: June 2006

This paper presents a survey of a great number of recent studies which investigate relation between trade (trade openness) and economic growth by means of regression analysis. On the basis of this research, it can be concluded that there are no firm connections between foreign trade and growth but prevailing majority of studies show positive and statistically revealed moderately significant impact of foreign trade (trade openness) on growth. For developing and transition countries (such as Serbia), a more consistent trade liberalization would produce higher and hopefully sustainable growth of GDP, with reliance on prudent fiscal and monetary policy, stable and undiscriminatory foreign exchange rate and a lower level of corruption.
Development perspective of transitional countries
Authors: Ilic Bogdan
Published: June 2006

The end of 20th century witnessed the affirmation and development of information technology as well as the transformation of industrial into information, "new economy", which caused changes in people and circumstances. The role and importance of nonhuman factors was increased, causing entrepreneurship and knowledge-based information to become the most significant resources. The Internet became the basis of the "new economy". It changes the way of doing business, studying, researching, communicating and competition. It also reduces operating costs, crosses national borders and leads to the globalization of the world economy. Transitional countries have to fit into modern development flows by formulating their own strategy of national development and establishing their own competitive advantages in conditions of "new economy". These advantages lie predominantly in highly qualified and skilled younger labor which learns fast and adopts new knowledge and skills, through reducing transactional costs, shortening of certain development stages through which developed countries have already gone, using their experience, scientific-technological progress, a rise in work productivity, etc. Experience of other countries should be innovated and adapted to one's own material and social conditions, not copied. This enables the emergence of "European small tigers", which are similar to "Asian small tigers".
General kernel convolutions with slowly varying functions
Authors: Simic Slavko
Published: June 2006

We prove a theorem concerning asymptotic behavior of general complex-valued kernel convolutions with slowly varying functions in the sense of Karamata. In applications we showed that the content of some classical theorems can be naturally extended on some parts of complex z-plane.
Note on Gray codes for permutation lists
Authors: Lipschutz Seymour , Gao Jie , Dianjun Wang
Published: June 2006

Robert Sedgewick [5] lists various Gray codes for the permutations in Sn including the classical algorithm by Johnson and Trotter. Here we give an algorithm which constructs many families of Gray codes for Sn, which closely follows the construction of the Binary Reflexive Gray Code for the n-cube Qn.
Anisotropy in shrinkage during sintering
Authors: Zavaliangos A. , Missiaen J.M. , Bouvard D.
Published: June 2006

While significant progress in modeling of sintering has been accomplished since the original paper by Frenkel "Viscous flow of crystalline bodies under action of surface tension", there are still several issues that remain open. One of them is anisotropy during sintering. In this paper we present some recent developments that improve our understanding of sintering anisotropy based on simulations of a two- dimensional array of particles. A number of possible sources of anisotropy are examined and evaluated. .
Computer simulation of free settling and skeletal settling during liquid phase sintering
Authors: Nikolic Z.S.
Published: June 2006

In recent years, a range of computer simulation models leading to a better understanding of liquid phase sintering phenomena, have been developed with the aim of simulating the detailed evolution of microstructure during grain growth. Some liquid phase sintered materials show both macrostructural and microstructural effects associated with gravity force. Therefore we will develop a numerical procedure for the estimation of how much gravity will influence domain (two-dimensional particle representation) growth, domain boundary migration and solid skeleton formation due to gravity induced segregation during liquid phase sintering. The method used for the simulation of a gravity field will be based on the settling procedure. Gravity induced settling will be separated into two stages - Free Settling and Skeletal Settling. Isolated solid phase domains fall under gravity and slide down over the already settled domains (free settling). During settling they make point contacts with each other. Necks between them then form and start to grow until the equilibrium dihedral angle between the domain boundaries and the liquid is established. Thus a solid skeleton forms and skeletal settling of a connected solid structure takes place. .
Synthesis, characterization and stability of amorphous alloys
Authors: Minic Dragica
Published: June 2006

In this paper the results of chemical and electrochemical synthesis of Fe-P, Fe-W and Fe-Ni amorphous powders, investigations of their structural characteristics, stability and processes of their relaxation and stabilization during heating in the temperature range of 20-1000oC are presented. .
A New Computational Procedure to Predict Transient Hydroplaning Performance of a Tire
Authors: Okano T. , Koishi M.
Published: June 2006

“Hydroplaning characteristics” is one of the key functions for safe driving on wet roads. Since hydroplaning depends on vehicle velocity as well as the tire construction and tread pattern, a predictive simulation tool, which reflects all these effects, is required for effective and precise tire development. A numerical analysis procedure predicting the onset of hydroplaning of a tire, including the effect of vehicle velocity, is proposed in this paper. A commercial explicit-type FEM (finite element method)/FVM (finite volume method) package is used to solve the coupled problems of tire deformation and flow of the surrounding fluid. Tire deformations and fluid flows are solved, using FEM and FVM, respectively. To simulate transient phenomena effectively, vehicle-body-fixed reference-frame is used in the analysis. The proposed analysis can accommodate 1) complex geometry of the tread pattern and 2) rotational effect of tires, which are both important functions of hydroplaning simulation, and also 3) velocity dependency. In the present study, water is assumed to be compressible and also a laminar flow, indeed the fluid viscosity, is not included. To verify the effectiveness of the method, predicted hydroplaning velocities for four different simplified tread patterns are compared with experimental results measured at the proving ground. It is concluded that the proposed numerical method is effective for hydroplaning simulation. Numerical examples are also presented in which the present simulation methods are applied to newly developed prototype tires.
New Predictive Model for the Study of Vertical Forces (up to 250 Hz) Induced on the Tire Hub by Road Irregularities
Authors: Belluzzo D. , Mancosu F. , Sangalli R. , Cheli F. , Bruni S.
Published: June 2006

A physical model has been developed in order to study the forces induced on the tire by road irregularities. It works in a range of frequencies 0–250 Hz, i.e. up to frequencies that are felt by the passengers as noise and vibrations, but it can be easily improved to 400 Hz. The model can resolve road irregularities with wavelength greater than 5 cm (pavement megatexture). The parameters of this model have been identified by comparison with special virtual tests performed on a 3D finite element model of the tire, i.e. without using any experimental data. Once built, the model can be used to analyze the forces transmitted by the tire to the vehicle while passing over various pavement textures for testing both the tire-vehicle system and the pavement textures. Since the model doesn't require any experimental data, it can be used to predict the dynamical characteristics of tires which haven't been built yet, speeding up the optimization process of tires under development. Due to its characteristics, this model appears to be a powerful tool for a joint analysis of vehicle and tire, but it would require vehicle models with a similar frequency response range, currently not reported in literature. Comparisons with the results of indoor cleat tests and with measurements on a test car with an instrumented wheel hub have shown that the mathematical model reproduces with good accuracy the behavior of the tire in the frequency range of interest.
Influences of Thermo-Mechanical Properties of Polymeric Cords on Tires with and without Post-Cure Inflation
Authors: Chen B.
Published: June 2006

During manufacturing, tires are naturally cooled to room temperature after release from their molds. The manner in which the post-cure cooling process is performed can greatly influence a tires overall performance. As an effective procedure, post-cure inflation (PCI) had been commonly used during the post-cure cooling process to control dimensions and shapes of tires. However, since the introduction of dimensionally stable polyester as tire carcass cord material, PCI has been considered an unnecessary step and has been eliminated from some tire manufacturer's lines. By convention, tires manufactured with PCI are designated as PCI tires whereas tires manufactured without PCI are designated as no-PCI tires. As a result of the different loading histories experienced during the post-cure cooling process, PCI and no-PCI tires exhibit different behavioral aspects including dimensions and footprint shape. More specifically, when the same mold is used, the most prominent difference between PCI and no-PCI tires is the profile. No-PCI tires have smaller section widths and inflated crown radii than PCI tires due to the thermal shrinkage occurring in the cords during the post-cure cooling process. On the other hand, no-PCI tires exhibit more dimensional change than PCI tires when subjected to exercise. In this study, experimental passenger tires (235/75/R15) with and without PCI are built using the same curing mold, and a series of tests are conducted to establish the differences between these two kinds of tires. Meanwhile, material characterizations of the polyester tire cords used in the tire construction are conducted with various thermal-mechanical loading histories, and the influences of the post-cure cooling process on the cord properties are determined. Then an axisymmetric and a three-dimensional finite element model are constructed and the post-cure cooling processes with and without PCI are simulated. With the input of the cord material properties obtained through the material characterization, the numerical analyses successfully predict the tire dimensions, profile, and footprints for both PCI and no-PCI tires. The analytical results obtained are in agreement with the experimental measurements obtained from the experimental tires.
Application of Finite Element Analysis and Computational Fluid Dynamics to ATV Tire Design
Authors: Rooney T. , Satrape J. , Liu S.
Published: June 2006

All terrain vehicles (ATV) travel on every imaginable type of surface — from hard pack trails to muddy swamps. ATV tires must provide customer with acceptable ride and handling performance, and they must also generate extremely good wet traction characteristics in order to pull the vehicle through the tough stuff. This paper looks at a design tool that is routinely used to achieve one of these goals — optimum mud (wet) traction performance. Techniques described in this study evaluate the self-cleaning ability of tread patterns. Smooth tires were modeled at typical vehicle loads and inflation pressures using finite element analysis. Footprint shapes and pressure distributions were taken from the analysis and used as input into the flow model. Mud was modeled as a highly viscous, Newtonian fluid and forced through the tread pattern. Flow velocities and pressures were computed using computational fluid dynamics and these responses were used to generate an overall measure of the cleaning efficiency of the tread. By visualizing the results, potential “clog” areas were identified and the tread pattern modified to improve flow.
Thermomechanics of Elastomers Undergoing Scission and Crosslinking at High Temperatures
Authors: Wineman A. , Jones A. , Shaw J.
Published: June 2006

The elastomeric materials used in tires are frequently subjected to severe thermal, chemical, and mechanical stress conditions. These conditions produce significant changes in material properties that affect their service life. The prediction of service life has become an increasingly important part of the engineering design process, and there is a need for a robust life-prediction model.

There are many physical factors that affect the durability of an elastomeric material, such as deformation, conversion of mechanical energy to heat arising from dissipative effects, heat transfer within the component, and changes in material properties because of changes in microstructure. The goal of this work is the development of a thermomechanics model that incorporates these factors.

This study focuses on the effect of high temperatures on an elastomeric component. There are two sources of temperature increase, a hot environment and internal heating attributed to mechanical loading such as occurs during cyclic loading. Internal mechanical heating can lead to substantial temperatures occurring within the component. When the temperature of the material becomes sufficiently high, macromolecules undergo time-dependent scission, recoil, and may crosslink to form new networks with new reference configurations. This process can affect the stiffness of the material system, induce anisotropy, and lead to permanent set.

A constitutive theory is presented that accounts for this temperature-dependent microstructural change on the mechanical response. It is based on experimental results and is motivated by the two-network theory of Tobolsky. The theory is applicable for large deformation and varying temperature histories. An example is presented that illustrates the implications of scission and re-crosslinking.
Effects of Sipes on the Viscous Hydroplaning of Pneumatic Tires
Authors: Lee K. S.
Published: June 2006

Using a finite element calculation, this study seeks to evaluate the effects of sipes on the transient behavior of viscous hydroplaning: fluid pressure distribution, fluid film thickness, and descending velocity as a function of time. From calculations on block-type tread elements with open or closed sipes, sipes in the low velocity region in the thin fluid film have been shown to be very effective in controlling the occurrence of viscous hydroplaning. Application of the transient analysis procedure to rib-type tread elements showed that highly zigzagged tread elements with a sipe at the line of symmetry are more effective for traction on wet pavement. Results from the study provide qualitative and quantitative guidelines to tire designers in the search for the optimum pattern of individual tread elements on the basis of thin film wet traction.
Tread Pitch Arrangement Optimization Through the Use of a Genetic Algorithm
Authors: Hoffmeister K. , Bernard J.
Published: June 2006

Urban communities throughout the United States and Europe are expressing a growing concern over the external noise emitted by automobiles and trucks. A major contribution to this noise can be tread whine generated by tires. This paper discusses how the tread pitch arrangement and its contribution to reducing tread whine can be optimized during the design phase. While there are numerous patented approaches to selecting pitch sizes and a pitch arrangement, traditional optimization algorithms are difficult to apply. This paper will show that a genetic algorithm is easily applied and very effective for pitch sequence optimization.
Tire Cornering Simulation Using an Explicit Finite Element Analysis Code
Authors: Koishi M. , Kabe K. , Shiratori M.
Published: June 2006

The finite element method has been used widely in tire engineering. Most tire simulations using the finite element method are static analyses, because tires are very complex nonlinear structures. Recently, transient phenomena have been studied with explicit finite element analysis codes. In this paper, the authors demonstrate the feasibility of tire cornering simulation using an explicit finite element code, PAM-SHOCK. First, we propose the cornering simulation using the explicit finite element analysis code. To demonstrate the efficiency of the proposed simulation, computed cornering forces for a 175SR14 tire are compared with experimental results from an MTS Flat-Trac Tire Test System. The computed cornering forces agree well with experimental results. After that, parametric studies are conducted by using the proposed simulation.
Fatigue of Unidirectional Cord-Rubber Composites
Authors: Liu Y. , Wan Z. , Tian Z. , Du X. , Jiang J. , Yao M.
Published: June 2006

A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out.

Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value.

The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency.

A method for evaluating the fatigue behavior of tires is proposed.
Hydroplaning Analysis by FEM and FVM: Effect of Tire Rolling and Tire Pattern on Hydroplaning
Authors: Seta E. , Nakajima Y. , Kamegawa T. , Ogawa H.
Published: June 2006

We established the new numerical procedure for hydroplaning. We considered the following three important factors; fluid/structure interaction, tire rolling, and practical tread pattern. The tire was analyzed by the finite element method with Lagrangian formulation, and the fluid was analyzed by the finite volume method with Eulerian formulation. Since the tire and the fluid can be modeled separately and their coupling is computed automatically, the fluid/structure interaction of the complex geometry, such as the tire with the tread pattern, can be analyzed.

Since we focused the aim of the simulation on dynamic hydroplaning with thick water films, we ignored the effect of fluid viscosity. We verified the predictability of the hydroplaning simulation in the different parameters such as the water flow, the velocity dependence of hydroplaning, and the effect of the tread pattern on hydroplaning. These parameters could be predicted qualitatively.

We also developed the procedure of the global-local analysis to apply the hydroplaning simulation to a practical tire tread pattern design, and we found that the sloped block tip is effective in improving hydroplaning performance.
A Mathematical-physical 3D Tire Model for Handling/Comfort Optimization on a Vehicle: Comparison with Experimental Results
Authors: Mancosu F. , Sangalli R. , Cheli F. , Ciarlariello G. , Braghin F.
Published: June 2006

A new 3D mathematical-physical tire model is presented. This model considers not only the handling behavior of the tire but also its comfort characteristics, i.e., the dynamic properties in the lateral and the vertical planes. This model can be divided into two parts, the structural model and the contact area model. The structural parameters are identified by comparison with frequency responses of a 3D finite element model of the tire, whereas the contact parameters are directly calculated with a finite element model of the tread pattern. The 3D physical model allows predicting both steady state and transient behavior of the tire without the need of any experimental tests on the tire. The steady state analysis allows obtaining the friction circle diagram, i.e., the plot of the lateral force against the longitudinal force for different slip angles and for longitudinal slip, and the Gough plot, i.e., the diagram of the self-aligning torque versus the lateral force. The transient analysis allows obtaining the dynamic behavior of the tire for any maneuver given to the wheel. Among its outputs there are the relaxation length and the dynamic forces and torque transmitted to the suspension of the vehicle. Combining the tire model with the vehicle model it is possible to perform any kind of maneuver such as overtaking, changing of lane and steering pad at growing speed with or without braking, or accelerating. Therefore the 3D tire model can be seen as a powerful tool to optimize the tire characteristics through a sensitivity analysis performed with tire and vehicle models linked to each other without the need of building prototypes. Some preliminary comparisons with experimental data have been carried out.
Simulation of Dynamically Rolling Tire
Authors: Shiraishi M. , Yoshinaga H. , Miyori A. , Takahashi E.
Published: June 2006

The dynamically rolling tire is simulated by using an explicit finite element method. In this simulation, the complicated pattern shape and internal construction of the tire are modeled exactly since both these factors are very important for the performance properties of the tire. A very long calculation time is necessary for refined tire models, but, for practical tire development, the calculation time of this simulation is acceptable because of major advances in hardware, FEM software, and modeling techniques.

The authors describe the model used in the simulation and report on the results of several properties under various rolling conditions of the tire evaluated by this method. The correlation between the simulation and the experiment appears good. Therefore, this simulation technique can be assumed very useful for actual tire development.
Analysis of the Contact Deformation of a Radial Tire with Camber Angle
Authors: Kagami S. , Akasaka T. , Shiobara H. , Hasegawa A.
Published: June 2006

The contact deformation of a radial tire with a camber angle, has been an important problem closely related to the cornering characteristics of radial tires. The analysis of this problem has been considered to be so difficult mathematically in describing the asymmetric deformation of a radial tire contacting with the roadway, that few papers have been published.

In this paper, we present an analytical approach to this problem by using a spring bedded ring model consisting of sidewall spring systems in the radial, the lateral, and the circumferential directions and a spring bed of the tread rubber, together with a ring strip of the composite belt.

Analytical solutions for each belt deformation in the contact and the contact-free regions are connected by appropriate boundary conditions at both ends. Galerkin's method is used for solving the additional deflection function defined in the contact region. This function plays an important role in determining the contact pressure distribution. Numerical calculations and experiments are conducted for a radial tire of 175SR14. Good agreement between the predicted and the measured results was obtained for two dimensional contact pressure distribution and the camber thrust characterized by the camber angle.
Some Notes on the Finite Element Analysis of Tires
Authors: Gall R. , Tabaddor F. , Robbins D. , Majors P. , Sheperd W. , Johnson S.
Published: June 2006

Over the past ten years the Finite Element Analysis (FEA) has been increasingly integrated into the tire design process. The FEA has been used to study the general tire behavior, to perform parameter studies, and to do comparative analyses. To decrease the tire development cycle, the FEA is now being used as a replacement for certain tire tests. This requires the accuracy of the FEA results to be within those test limits. This paper investigates some of the known modeling techniques and their impact on accuracy. Some of the issues are the use of shell elements, assumptions for boundary conditions, and global/local analysis approaches. Finally, the use of new generation supercomputers, massively parallel processing systems (MPP), is discussed.
Measurement and Visualization of the Contact Pressure Distribution of Rubber Disks and Tires
Authors: Sakai E. H.
Published: June 2006

The contact conditions of a tire with the road surface have a close relationship to various properties of the tire and are among the most important characteristics in evaluating the performance of the tire. In this research, a new measurement device was developed that allows the contact stress distribution to be quantified and visualized. The measuring principle of this device is that the light absorption at the interface between an optical prism and an evenly ground or worn rubber surface is a function of contact pressure. The light absorption can be measured at a number of points on the surface to obtain the pressure distribution. Using this device, the contact pressure distribution of a rubber disk loaded against a plate was measured. It was found that the pressure distribution was not flat but varied greatly depending upon the height and diameter of the rubber disk. The variation can be explained by a “spring” effect, a “liquid” effect, and an “edge” effect of the rubber disk. Next, the measurement and image processing techniques were applied to a loaded tire. A very high definition image was obtained that displayed the true contact area, the shape of the area, and the pressure distribution from which irregular wear was easily detected. Finally, the deformation of the contact area and changes in the pressure distribution in the tread rubber block were measured when a lateral force was applied to the loaded tire.
Calculation of the Three-Dimensional Free Surface Flow Around an Automobile Tire
Authors: Grogger H. , Weiss M.
Published: June 2006

The 3D flow around a 195/65R15 automobile tire is calculated. To describe the free surface behavior with the usual conservation equations for mass and momentum, an additional equation for the water mass fraction is solved. For modeling the effects of turbulence, the well-known k,ε-model is used. The resulting fluid mechanics equation system is solved by a finite volume method. A finite element calculation considering inflation pressure and tire deflection gives the surface for the flow calculation. The goal is to determine the lift force of the tire at a certain velocity to predict the tendency of the tire to hydroplane. For a slick tire, the calculated pressure distribution in the water is presented. The lift and drag forces are evaluated from the pressure acting directly on the tire surface. The calculation is performed at three different velocities, 30, 60, and 90 km/h. A comparison with experimental data shows good agreement regarding the pressure distribution on the road in front of the tire.
Friction and Wear of Tire Tread Rubber
Authors: Sakai H.
Published: June 2006

Using a flat-belt tire test machine, this study investigated causal factors in the wear of tire tread. To ensure the success of the experiment, the accuracy of the testing device was improved and the trial conditions were kept under close control. As a measure against sticky particles of worn rubber clinging to the surfaces of the safety-walk and tires, a uniform amount of mica powder was electrostatically coated onto the tire tread surfaces. Surface whiteness was measured and controlled automatically to maintain a constant level. The amount of wear was calculated by weighing the tire on a precision six-order electrical balance sensitive down to 0.1 g. Consequently, in a relatively short time it was possible to ascertain measurable rates of wear, and the effects of main factors on the wear rate (the weight reduction per unit distance travelled) of car tires, the linear wear rate (the weight reduction per unit distance slid), the energetic wear rate (the weight reduction per unit energy lost), and friction coefficient were evident.
Three-Dimensional Deformation Comparison Between F-16 Bias and Radial Aircraft Tires
Authors: Lin P. P. , Chawla M. D. , Wagner P. M.
Published: June 2006

This paper presents an optical technique called fringe projection to measure 3D tire deformation subjected to different loads, percentages of deflection, and yaw angles. Unlike the well-known Moiré method, the proposed technique uses a single light source and one grating, thus requiring no image superposition. As a result, the measurement is not as sensitive to vibration as the Moiré method. The fringe projection also differs from the commonly used optical inspection technique in manufacturing industry via line scanning known as structured light, which cannot be applied to dynamic deformation measurements. The recently developed subpixel resolution was employed to accurately locate the optical fringe centers, which in turn improves the accuracy in 3D geometry determination. A fiber-optic displacement sensor was also placed close to the tire sidewall to measure the deformational change of the selected reference point. Finally, the deformations are compared between F-16 bias and radial aircraft tires when subjected to the same loading conditions.
Structure-Borne Tire Noise Statistical Energy Analysis Model
Authors: Lee J. J. , Ni A. E.
Published: June 2006

The application of the Statistical Energy Analysis (SEA) technique on vehicle high frequency noise has gained popularity. It is desirable to model the tire to provide the capability of vehicle system NVH prediction. An SEA model for the structure-borne noise has been developed. The point mobility shows good agreement with measurement. The modeling methodology on tread bands, sidewalls, and their coupling are discussed. The modeling requirements and prospects are also included.
Tire Pressure Loss and Intracarcass Pressure Modeling
Authors: Costemalle B.
Published: June 2006

The inflation pressure loss and carcass pressure build-up (intracarcass pressure or ICP) of tubeless tires can be predicted with a simple theoretical model. Tire construction and relative air permeabilities of the main tire components are significant factors in the pressure loss and ICP. Highly impermeable liners play a major role in obtaining optimum results. Application of the model to recent European passenger tire surveys is shown.
Normalization of Tire Force and Moment Data
Authors: Radt H. S. , Glemming D. A.
Published: June 2006

Semi-empirical theories of tire mechanics are employed to determine appropriate means to normalize forces, moments, angles, and slip ratios. Force and moment measurements on a P195/70R 14 tire were normalized to show that data at different loads could then be superimposed, yielding close to one normalized curve. Included are lateral force, self-aligning torque, and overturning moment as a function of slip angle, inclination angle, slip ratio, and combinations. It is shown that, by proper normalization of the data, one need only determine one normalized force function that applies to combinations of slip angle, camber angle, and load or slip angle, slip ratio, and load. Normalized curves are compared for the effects of inflation pressure and surface water thickness. Potential benefits as well as limitations and deficiencies of the approach are presented.
Viscohyperelastic Modeling of Rubber Vulcanizates
Authors: Johnson A. R. , Quigley C. J. , Young D. G. , Danik J. A.
Published: June 2006

The use of internal hyperelastic solids for modeling viscoelastic deformations of rubber vulcanizates is reviewed. The model is applied in one dimension to viscoelastic uniaxial tension and uniaxial shear experiments. Step-strain relaxation tests are used to determine the model's parameters. A hyperelastic energy function, which represents the sum of the internal solids' energy functions, is obtained by least squares fitting a constrained third-order invariant expansion of the Rivlin function to the difference between the step-strain stresses and the relaxed stresses (the standard hyperelastic solid's stresses). The difference energy function is split into two parts and relaxation parameters (related to the rate of change of the internal solids' reference lengths) are selected so that numerically simulated step-strain relaxation stresses approximate the experimental values (at approximately 50 ms). The model is then used to predict the experimental results from a different type of test, cyclic strain data, at three different strain rates (cyclic frequencies). Increased stress due to increased strain rate was indicated by the model for large strains.
Implementation of Material Stiffness Coefficients in Finite Element Applications to Rubber
Authors: Kim Y. , Saleeb A. F. , Chang T. Y. P.
Published: June 2006

Two classes of constitutive models are widely used in the current literature to describe the general strain state of rubber under large deformations: the Invariant-based (Rivlin type) and the Principal-value based (Ogden type). However, their predictive capabilities, coupled with the finite element method, will greatly depend on the material coefficients determined from experimental stress-strain curves by nonlinear curve fitting. In addition, special care must be exercised in their numerical implementations, which is particularly true for the Ogden type models, when evaluating the material tangent stiffness coefficients. Several issues in connection with these are discussed and a number of simulations and test comparisons are presented.
Study on Cornering Properties of Tire and Vehicle
Authors: Sakai H.
Published: June 2006

This paper presents theoretical analysis on the cornering properties of tire and vehicle. First, the side force, braking driving forces and self-aligning torque on the tire are shown as functions of slip angle, slip ratio, camber angle and load. Next, the steady cornering properties of the vehicle using these tires are analyzed with the rolling conditions. Slip angle, slip ratio, camber angle and load, and forces and moments of the four tires are calculated. Effects of main factors on the above vehicle properties such as the load distribution, camber/roll ratio, front/rear drive ratio, tire size, tire wear, tire inflation pressure and tire friction are discussed.
Loss of Adhesion of Cord-Rubber Composites in Aircraft Tires
Authors: Clark S. K.
Published: June 2006

The degradation of adhesive strength between plies in aircraft tires was studied as a function of aging temperature, time, and environment. Adhesive strength degraded much faster than the cord tensile strength under the aging conditions used. Adhesive strength degraded faster in air than in nitrogen during the long-term aging. A 50% loss in adhesive strength is suggested as a reasonable critical value in determining tire life.
A Simple Model for Cornering and Belt-edge Separation in Radial Tires
Authors: Popper P. , Miller C. , Filkin D. L. , Schaffers W. J.
Published: June 2006

A mathematical analysis of radial tire cornering was performed to predict tire deflections and belt-edge separation strains. The model includes the effects of pure bending, transverse shear bending, lateral restraint of the carcass on the belt, and shear displacements between belt and carcass. It also provides a description of the key mechanisms that act during cornering. The inputs include belt and carcass cord properties, cord angle, pressure, rubber properties, and cornering force. Outputs include cornering deflections and interlaminar shear strains. Key relations found between tire parameters and responses were the optimum angle for minimum cornering deflections and its dependence on cord modulus, and the effect of cord angle and modulus on interlaminar shear strains.
On the Three-Dimensional Computation of Steel-Belted Tires
Authors: Rothert H. , Gall R.
Published: June 2006

A geometrically-nonlinear finite element model of a complete tire is used in an analysis for inflation and footprint loadings. Each reinforced layer of the tire is approximated as being homogeneous, orthotropic, and linear elastic. The finite element model used in the analysis allows the computation of interply shear strains due to inflation and footprint loads. Some numerical results on loaded tires are also presented and compared with those obtained experimentally.
Finite Element Analysis of a Steady-State Rotating Tire Subjected to Point Load or Ground Contact
Authors: Kennedy R. , Padovan J.
Published: June 2006

A radial automobile tire undergoing steady-state rotation is analyzed by a finite element method. A special formulation is used which allows the finite element equations to be solved as a quasi-static problem using static analysis solution procedures, rather than as a dynamic problem requiring solution in the time domain. This is accomplished through a transformation of variable that changes time derivatives, present through inertia, to spatial derivatives. Solution time for the analysis is thereby shortened.

The tire is modeled first as a two-dimensional ring on an elastic foundation, then in its full three-dimensional geometry. Rotational speeds are those at which resonance occurs so that the dynamics can be easily visualized and the response easily verified. The models are subjected to point load excitation or ground contact. Point load is used to predict resonance responses of the undamped tire. Results agreed well with experimental measurements. The effect of inertia components and damping on vibrational response of the tire was studied by imposing ground contact at one of the resonance speeds. Damping is included in the model through a two-element Kelvin-Voight viscoelastic material model. Responses of the models were similar to standing wave deformations in a tire.
A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder
Authors: Oden J. T. , Lin T. L. , Bass J. M.
Published: June 2006

Mathematical models of finite deformation of a rolling viscoelastic cylinder in contact with a rough foundation are developed in preparation for a general model for rolling tires. Variational principles and finite element models are derived. Numerical results are obtained for a variety of cases, including that of a pure elastic rubber cylinder, a viscoelastic cylinder, the development of standing waves, and frictional effects.
Development and Validation of a Method for Approximating Road Surface Texture-Induced Contact Pressure in Tire-Pavement Interaction
Authors: Clapp T. G. , Eberhardt A. C. , Kelley C. T.
Published: June 2006

In tire-pavement interaction, road surface texture is an important variable that influences many properties such as tire noise, skid resistance, vehicle performance, and rolling resistance. Efforts to understand and quantify these texture effects have been limited by difficulties in experimentally and theoretically determining the many individual contact areas and contact pressures produced by irregularly-shaped asperities indenting the tire tread. The numerical method developed here to approximate the contact information is based on classical two-dimensional (2D) contact theory. The purpose of this paper is to describe this development. The method computes information on texture-induced contact pressure and length. The required inputs are 2D road surface texture data, tread rubber modulus, and tire inflation pressure. The approximated contact information is used to characterize road surfaces and advance understanding of how their textures affect tire-pavement interaction.
Principles of Tire Design
Authors: Curtiss W. W.
Published: June 2006

Design procedures based on sound mechanical principles have become a necessity to meet the ever-increasing demands of performance placed upon the tire of today. This discussion gives an overview of the design process and calculations employed in developing the modern tire: performance and sizing, envelope shape as a function of construction, structural stress, design of the tire skin, and construction of the “green” tire.
Tire Design Methodology Based on Safety Factor to Satisfy Tire Life (Simulation Approach to Truck and Bus Tire Design)
Authors: Kabe K. , Rachi K. , Takahashi N. , Kaga Y.
Published: June 2006

A tire is not only simply made of rubber, but also twisted cord, which we can call FRR (Fiber Reinforced Rubber). The rubber in FRR is made of many materials, including rubber compound, carbon black, silica, and other materials. FRR is a double composite material, which means a particle reinforced material in a microscopic view and also a fiber reinforced one in a macroscopic view. Therefore, it is very difficult to apply fracture mechanics to the evaluation of tire durability on a practical tire design level.

This paper gives a proposal for a new design methodology considering the actual tire condition which gives tire profile growth and rubber aging due to heat build-up under operation. These two issues are especially important for truck and bus tire design. Tire profile growth is a very important one because the change of tire profile induces different strains in the rubber at the same location in the tire during its life. We apply the FEM (Finite Element Modeling) based Double Inflation Pressure (DIP) method to simulate the experimental fact of the change of tire profile. In order to use the relationship between the change of the tire profile and change of rubber properties, like breaking strain in the tire as service time passes, the concept of safety factor is introduced. The low modulus rubber parts in the tire dominate the strain field and allow the large deformations of the tire. Safety factors derived from the strain field are called “Margin of Safety.” On the other hand, the durability of FRR, like the belt layer and carcass layer with the cord part, is evaluated by stress because the FRR part reacts to the stress of the internal pressure and load of the tire. But, the Margin of Safety of the rubber part is more important because the cord part has enough safety factor in comparison with the rubber part. Tire life is predicted with the Margin of Safety described above.