Realistic Tire Research Articles

Tyre contact surface for the fatigue design of orthotropic steel bridge decks

The fatigue life of orthotropic steel bridge decks in road bridges depends on the load effects exerted by heavy lorries. The contact surface of tyres is one of the important variables. Measurements described in the literature demonstrate that the actual tyre contact surfaces of today’s traffic representative for Europe are shorter and slightly wider than the contact surface defined for the load model in the European standard for fatigue loads in bridges — EN 1991-2. This paper derives a new, realistic tyre contact surface to be used with the tyre loads in EN 1991-2, in such a way that the load effects for fatigue are realistically captured and that the required safety level is met.

Three-dimensional FEM–DEM coupling simulation for analysis of asphalt mixture responses under rolling tire loads

As traffic grows by leaps and bounds, deterioration of asphalt surface layers emerges as the primary cause of road network costs. A deep understanding of the tire–pavement interaction is essential for optimizing the surface design of asphalt pavements in the context of aging infrastructure and limited maintenance resources. Most of the current tire–pavement interaction studies have been conducted in the continuum mechanics framework using Finite Element Methods (FEM), which shows limitations in modeling the discontinuity nature of asphalt mixtures. Discrete Element Methods (DEM) offer a promising way to examine the mechanical properties of asphalt mixtures at the particle level, but it is inadequate for modeling deformable tire structure and capturing realistic tire contact forces on the pavement surface. In this study, a FEM–DEM coupling strategy was developed for the modeling of tire–pavement interaction by implementing a DEM model of asphalt mixtures with rolling tire loads from a FEM model. Based on simulations with realistic rolling tire load conditions, this coupling algorithm allows the investigation of particle force chain network evolution, particle displacement and velocity distributions, movements of individual particles, and particle contact force characteristics inside an asphalt mixture. This study offers an enriching expansion of both continuum and discrete mechanics methods for analyzing asphalt mixture responses under rolling tire loads, which can provide insight into pavement surface design.

On Pre-Emptive In-Wheel Motor Control for Reducing the Longitudinal Acceleration Oscillations Caused by Road Irregularities

Road irregularities induce vertical and longitudinal vibrations of the sprung and unsprung masses, which affect vehicle comfort. While the vertical dynamics and related compensation techniques are extensively covered by the suspension control literature, the longitudinal dynamics on uneven road surfaces are less frequently addressed, and are significantly influenced by the tires and suspension systems. The relatively slow response of internal combustion engines does not allow any form of active compensation of the effect of road irregularities. However, in-wheel electric powertrains, in conjunction with pre-emptive control based on the information on the road profile ahead, have some potential for effective compensation, which, however, has not been explored yet. This paper presents a proof-of-concept nonlinear model predictive control (NMPC) implementation based on road preview, which is preliminarily assessed with a simulation model of an all-wheel drive electric vehicle with in-wheel motors, including a realistic tire model for ride comfort simulation. The major improvement brought by the proposed road preview controller is evaluated through objective performance indicators along multiple maneuvers, and is confirmed by the comparison with two benchmarking feedback controllers from the literature.

Rutting and surface-initiated cracking mechanisms of semi-flexible pavements with cement asphalt emulsion pastes

ABSTRACT The semi-flexible pavement (SFP) has been used as a promising wearing course in heavy traffic roads. It is crucial to investigate the main failure mechanisms caused by different influencing factors on SFPs at medium and high temperatures. In this research, utilising a three-dimensional (3D) finite-element model (FEM), the performance of SFP and conventional pavement under realistic tire–pavement contact stresses was compared by computing the critical responses associated with rutting and top-down cracking (TDC). Besides, experimental studies were conducted on typical asphalt concrete (AC16) and four types of SFP mixtures grouted with cement paste and cement asphalt emulsion pastes (CAEPs) to evaluate their rutting resistance and fatigue cracking potential at medium and high temperatures. The numerical analysis results indicated that SFP mixtures with lower asphalt emulsion (AE) content enhanced rutting resistance significantly while TDC potential was reduced at higher percentages of AE. Compared to dual-tire assembly, the wide-base tire led to less TDC damage and asphalt layer (primary) rutting, but more subgrade (secondary) rutting once carrying the same load. Moreover, based on the findings of laboratory evaluation, SFP with CAEP presented the best performance in terms of fatigue life and permanent deformation when AE to cement by weight (AE/C) was no more than 0.4.

Investigation of the Effect of Tire Deformation on Open-Wheel Aerodynamics

<div class="section abstract"><div class="htmlview paragraph">This paper introduces a finite element (FE) approach to determine tire deformation and its effect on open-wheeled racecar aerodynamics. In recent literature tire deformation was measured optically. Combined loads like accelerating at corner exit are difficult to reproduce in wind tunnels and requires several optical devices to measure the tire deformation. In contrast, an FE approach is capable of determining the tire deformation in combined load states accurately. The FE tire model was validated using computer tomography images, 3D scan measurements, contact patch measurements and stiffness measurements. The deformed shape of the FE model was used in a computational fluid dynamics (CFD) simulation. A sensitivity study was created to determine the effect of the tire deformation on aerodynamics for unloaded and loaded tires. In addition, the influence of these tire deformations was investigated in a CFD study using a full vehicle model. The CFD model was validated through full scale wind tunnel tests as well as on-road tests. Finally, a straight-line and a steady state cornering maneuver based on a vehicle dynamics simulation were simulated using this combined approach of FE and CFD. The tire deformation included proper wheel load, wheel speed and slip angle for each wheel. The CFD full vehicle model took chassis slip angle, body roll angle and wheel steering angle into account in order to match the real driving situation. The results show that realistic tire deformations provide better insight into the effect of rotating wheels on aerodynamics of full vehicles, especially that of race cars.</div></div>

Performance evaluation of cord material models applied to structural analysis of tires

Tires are, in essence, a composite structure made of reinforced elastomers. As in other composite structures, the accuracy of finite elements (FEs) in predicting the performance of a tire is highly dependent on the validity of the material models chosen to describe the mechanical behavior of its constituents. This paper concentrates on the material modeling of tire reinforcements, and analyzes several material models, namely linear, Yeoh and Marlow, which are quite common in these investigations. A realistic tire is considered as a general system and the most relevant results are discussed concerning precision, computational efficiency and complexity in parameters identification. The advantages of non-linear material models, especially of the Marlow model, are outlined. To the authors’ knowledge, no study has addressed the abovementioned aspects of the application of tire cord models in FE analysis of tires in such detail or directly compared the performance of cord models in a realistic example.

Thermodynamics modeling of a novel nonpneumatic mechanical elastic wheel for predicting its mechanical–thermal behavior

An advanced thermodynamics model based on brush-type tire model was developed here to investigate the mechanical–thermal behavior of a novel nonpneumatic mechanical elastic wheel (ME-wheel), operating under rolling conditions. Herein, first, we proposed a novel brush-type tire physical model wherein the factors of realistic tire deformable and frictional behavior were introduced. Next, the heat generation and dissipation mechanism of ME-wheel was investigated to develop its thermal model. By combining the brush-type tire physical model and thermal model through the factors involving tire deformable energy loss and frictional power loss, we established this thermodynamics model to predict the temperature-dependent mechanical characteristics and corresponding thermal behavior of ME-wheel under rolling operating conditions. It is found that the computation results agree well with the obtained experimental data (tire static and dynamics testing), which demonstrated the capability of this model in precisely predicting the mechanical characteristics and thermal behavior of ME-wheel, particularly those designed for off-road vehicle under typical real operating conditions.

An experimental and computational investigation of air-borne noise generation mechanisms in tires

The complex nature of the tire/road noise generation process makes it difficult to isolate and study each mechanism individually. This paper presents an experimental and numerical investigation of air-borne tire noise generation mechanisms for a realistic tire. Experimentally, a single slot is cut into the tire and the noise data are measured and studied. Air-borne noise is isolated by filling the slot with foam and comparing the resulting frequency spectra. Numerically, a previously developed computational fluid dynamics tire noise prediction model is employed to predict the air-borne noise for the same tire, under similar operating conditions. A direct comparison between the experimental and computational results is also presented in terms of pressure time traces and spectral characteristics. Comparisons indicate that the computational model is capable of predicting the noise generated by the air pockets in the tire. While providing a deeper understanding of the causes of air-borne noise, this paper also aims to demonstrate the use of a computational tool that can be used to obtain a reasonably accurate prediction of air-borne tire noise.

Relative Pavement Performance for Dual and Wide-Based Tire Assemblies Using a Finite Element Method

Abstract There is a need to assess the realistic tire contact pressure created by a tire in contact with a pavement. The contact pressure is a function of tire type, axle loading, and tire inflation pressure (TiP). The research carried out considered dual tire and wide-based tire assemblies across a range of axle loading and TiP. These contact pressures were incorporated into a finite element package (CAPA-3D) and modelled on a simple pavement structure. The strains from this modelling were sorted to produce key strains associated with the mechanisms of surface distress, near surface distress, deep asphalt distress, and the subgrade. The main distress mechanisms were top down cracking, asphalt cracking/rutting, bottom-up fatigue cracking, and subgrade rutting. This gave a method to fairly compare the dual and wide-based tire assemblies with the same axle loading and TiP. The analysis gave interesting results for the different distress mechanisms of the pavement. The wide-based tire gives consistently higher shear strains for all the areas of distress investigated. There is great variation in surface and near surface shear strains due to the different combinations of axle loading and TiP. It is clear that the wide-based tire is a more damaging tire for all combinations of TiP and axle loading. It is also apparent that how these factors interact has a great influence on the damaging potential of a tire.

Lab and field studies into effectiveness of flat steel plate – rubber pad systems as tyre substitutes for local loading of cellular GFRP bridge decking

Abstract The current preferred approach to assessing the local tyre load fatigue performance of cellular FRP bridge decks entails cyclic loading of the decks using flat, rectangular steel plates faced with rubber pads. Significantly, the plate-pad details are taken from standards developed for concrete and steel decks. For this approach to succeed with FRP decking, the local load distribution on the deck from the plate-pad system must mimic that from a tyre. To that end, this paper presents contact pressure distributions (CPDs, recorded using an electronic mat pressure sensor) exerted on a FRP deck at different loads by plate-pad systems in lab tests and by lorry tyres at different inflation pressures in field tests. The field data reveal that as the tyre load increased, the tyre-deck contact patch evolved from a circle to an ellipse and then to a square, causing the contact load profile to morph from a triangle to a trapezium. This changing geometry of the tyre-deck CPD led to distinctly nonlinear variations, with the tyre load, of the local surface strains recorded from the deck. Empirical definitions of these tyre-deck load profiles are proposed, based partly on use of the field data in FE analysis. Across the spectrum of realistic tyre loads and inflation pressures investigated, the plate-pad systems (particularly with rubber pads) induced far less onerous CPDs on and local strain responses from the deck than did the tyres. In closing, the paper identifies the need to also quantify fibre waviness, in a move towards fatigue performance prediction for FRP decks.

Determination of relative damage of asphalt pavement from reduced tire contact area

Considering the traditional contact area which is a full circular contact area without any tread, in the current pavement design procedure, is an extreme overestimation of contact area and hence extreme underestimation of the real contact stress. Since the relationship between the contact stress and pavement damage is not linear but exponential, even a trivial difference between tire contact areas leads to significant difference in terms of induced pavement damage. This study was conducted to quantify the relative damage caused by realistic tire–pavement contact area with respect to the full contact area. Therefore, permanent deformation profiles of different contact areas at three tire load groups were obtained using an in-house Rotary Compactor and Wheel Tracker equipment and the relative damage analyses were done between tires with and without tread from various aspects. These aspects include operational life reduction ratio, rutting rate, linear and nonlinear relative damage concepts. It was concluded that on average real tires with tread cause 57% reduction in the operational life. In average, real tires with tread induce 1.23 times more mm per cycle. Based on linear relative damage analysis, in average, real tires with tread are 2.6 times more damaging. Furthermore, nonlinear relative damage analyses indicate that real tires with tread induce about three times more rutting compared to the worn-out control tread.

3D modelling of tyre-pavement contact pressure

Pavement design assumes uniform contact loading because of bottom-up traditional cracking (far from loading), but nowadays more and more surface damage (top-down cracking and rut) due to new technology in pavement and tyre design is observed. Then, a more realistic tyre–pavement contact modelling has to be considered. In order to go towards more realistic tyre–pavement contact, finite element method consumes a lot of calculation time; so in this article, we propose a semi-analytical model developed for the calculation of ball bearings. The contact is considered as a Hertzian contact, and the surface of the road is flat and that the tyre is smooth. Calculation of contact pressure is compared and validated with experimental data using a device called Stress-In-Motion, which allows contact pressure measurement. Different parameters are assumed in the modelling such as tyre pressure, axle loading and tyre shape. We have now a successful tool to analyse the tyre–pavement contact, more accurate and realistic and especially faster than those used at the moment.

Introducing realistic tire–pavement contact stresses into Pavement Analysis using Nonlinear Damage Approach (PANDA)

Realistic tire–pavement interface contact areas and stresses were incorporated into the Pavement Analysis using Nonlinear Damage Approach (PANDA) user interface (PUI). PANDA is a software library developed to simulate the complex thermo-viscoelastic–viscoplastic–viscodamage responses of the pavement to mechanical and environmental loads. The PUI is an interface generating a finite element representation of the pavement within PANDA. The application of realistic tire loading is necessary to calculate accurate pavement responses. The PUI incorporates a database of tire contact areas and stresses obtained from tire finite element simulations. The database includes tire interface characteristics with pavements for various applied loads, tire inflation pressures, vehicle speeds and scenarios of different rolling simulations. A parametric study was conducted to investigate the effect of simulations of tire contact stresses that match field measurements on viscoelastic and viscoplastic pavement responses. Pavement responses are greatly affected using realistic tire loading contact stresses and contact geometry as compared to simplified contact models. The impact on rutting and damage predictions cannot be ignored if reliable projections of pavement performance are to be made. This study confirms the importance of considering realistic three-dimensional contact stresses to design and analyse pavements.

The effect of tyre and rider properties on the stability of a bicycle

To work towards an advanced model of the bicycle-rider-environment system, an open-loop bicycle-rider model was developed in the commercial multibody dynamics software ADAMS. The main contribution of this article to bicycle dynamics is the analysis of tyre and rider properties that influence bicycle stability. A system identification method is used to extract linear stability properties from time domain analysis. The weave and capsize eigenmodes of the bicycle-rider system are analysed. The effect of tyre properties is studied using the tyre’s forces and torques that have been measured in several operating conditions. The main result is that extending simplified models with a realistic tyre model leads to a notable decrease in the weave stability and a stabilization of the capsize mode. This effect is mainly caused by the twisting torque. Different tyres and tyre inflation pressures have little effect on the bicycle’s stability, in the case of riding straight at a constant forward speed. On the other hand, the tyre load does have a large effect on bicycle stability. The sensitivity study of rider properties shows that body stiffness and damping have a small effect on the weave and capsize mode, whereas arm stiffness destabilizes the capsize mode and arm damping destabilizes the weave mode.

Measurement of bitumen–tyre adhesion temperatures at realistic loading rates

A small-scale apparatus was constructed to measure the ‘adhesion temperature’, at which bitumen ‘pick-up’ onto tyre rubber (and subsequent tracking) occurs. Loading frequencies equivalent to traffic speeds of over 100 km hr−1 and realistic tyre footprint pressures were used. The adhesion temperature increased with loading frequency, but all of the bitumens and polymer-modified bitumens studied had adhesion temperatures (i.e. the temperature at which the bitumen failed cohesively) at or below 60 °C, a temperature easily reached in the field. The results confirm the findings of an earlier slow-speed study (at 1.6 km hr−1) and indicate that the adhesion temperature under realistic loading conditions is governed by the properties of the bitumen, i.e. the bitumen yield stress is lower than that of the adhesive bond formed as the tyre traverses the bitumen.

Nonlinear viscoelastic approach to model damage-associated performance behavior of asphaltic mixture and pavement structure

This paper presents an integrated experimental–numerical effort to more accurately model the damage characteristics of asphalt mixtures and pavement structures than conventional elastic and (or) linear viscoelastic approaches can. To this end, Schapery's nonlinear viscoelastic constitutive model was implemented into a finite element software via user defined subroutine (user material, or UMAT) to analyze an asphalt pavement subjected to heavy truck loads. Then, a series of creep and recovery tests were conducted at various stress levels and at different temperatures to obtain the stress-dependent and temperature-sensitive viscoelastic material properties of asphalt mixtures. With the viscoelastic material properties characterized and the UMAT code, a typical pavement structure subjected to repeated heavy truck loads was modeled with the consideration of the effect of material nonlinearity with a realistic tire loading configuration. Three-dimensional finite element simulations of the pavement structure present significant differences between the linear viscoelastic approach and the nonlinear viscoelastic modeling in the prediction of pavement performance with respect to rutting and fatigue cracking. The differences between the two approaches underline the importance of proper and more realistic characterization of pavement materials and should be addressed in the process of performance-based pavement design.

Simulation of tyre–pavement interaction for predicting contact stresses at static and various rolling conditions

This paper describes the development of a 3D tyre–pavement interaction model to predict the tyre–pavement contact stress distributions for future use in the mechanistic analysis of pavement responses. The ribbed radial-ply tyre was modelled as a composite structure (rubber and reinforcement), and the tyre material parameters were calibrated through load-deflection curves. The steady-state tyre rolling process was simulated using an arbitrary Lagrangian Eulerian formulation. The model results are consistent with previous measurements and validate the existence of non-uniform vertical contact stresses and localised tangential contact stresses. The analysis results show that the non-uniformity of vertical contact stresses decreases as the load increases, but increases as the inflation pressure increases. However, vehicle manoeuvring behaviour significantly affects the tyre–pavement contact stress distributions. For example, tyre braking/acceleration induces significant longitudinal contact stresses, while tyre cornering causes the peak contact stresses shifting towards one side of the contact patch. The model results provide valuable insights into understanding the realistic tyre–pavement interaction for analysing pavement responses at critical loading conditions.

Dynamic stability of an aerodynamically efficient motorcycle

Motorcycles exhibit two potentially dangerous oscillatory modes known as ‘wobble’ and ‘weave’. The former is reminiscent of supermarket castor shimmy, while the latter is a low frequency ‘fish-tailing’ motion that involves a combination of rolling, yawing, steering and side-slipping motions. These unwanted dynamic features, which can occur when two-wheeled vehicles are operated at speed, have been studied extensively. The aim of this paper is to use mathematical analysis to identify important stability trends in the on-going design of a novel aerodynamically efficient motorcycle known as the ECOSSE Spirit ES1. A mathematical model of the ES1 is developed using a multi-body dynamics software package called VehicleSim [Anon, VehicleSim Lisp Reference Manual Version 1.0, Mechanical Simulation Corporation, 2008. Available at http://www.carsim.com]. This high-fidelity motorcycle model includes realistic tyre–road contact geometry, a comprehensive tyre model, tyre relaxation and a flexible frame. A parameter set representative of a modern high-performance machine and rider is used. Local stability is investigated via the eigenvalues of the linearised models that are associated with equilibrium points of interest. A comprehensive study of the effects of frame flexibilities, acceleration, aerodynamics and tyre variations is presented, and an optimal passive steering compensator is derived. It is shown that the traditional steering damper cannot be used to stabilise the ES1 over its entire operating speed range. A simple passive compensator, involving an inerter is proposed. Flexibility can be introduced deliberately into various chassis components to change the stability characteristics of the vehicle; the implications of this idea are studied.

Impact of Wide-Base Tires on Pavements: Results from Instrumentation Measurements and Modeling Analysis

Wide-base tire technology can reduce vehicle fuel consumption and greenhouse gas emissions because there is less rolling resistance at the tire–pavement interface. This study investigated the impact of wide-base tires on two typical flexible pavement structures—full-depth and thin asphalt pavements—through accelerated pavement testing and advanced finite element modeling. Three tire configurations (dual, the first-generation 425, and the new generation 455 wide-base tires) and various pavement sections with different asphalt layer and granular base layer thicknesses were considered. In particular, the advanced modeling simulated realistic tire–pavement interaction and considered appropriate material properties for each pavement layer. It was evident from this study that, of the three possibilities, the wide-base 425 tire configuration caused the greatest pavement damage. The wide-base 455 tire was found to cause greater bottom-up fatigue cracking and increased potential for subgrade rutting than the dual-tire assembly on most tested sections except the thin pavement section with the thickest granular base layer. However, the impact of wide-base tires on fatigue cracking and subgrade rutting potential became less significant with a stronger pavement structure. The finite element modeling results indicated that, compared with the dual-tire assembly, the wide-base 455 tire resulted in similar or less primary rutting potential in thin asphalt pavements and less near-surface cracking potential in thick asphalt pavements.

Steady-state drifting stabilization of RWD vehicles

A control scheme to stabilize rear-wheel-drive (RWD) vehicles with respect to high-sideslip cornering (drifting) steady-states using coordinated steering and drive torque control inputs is presented in this paper. The choice of coordinated control inputs is motivated by the observed data collected during the execution of drifting maneuvers by an expert driver. In addition, the steering and drive torque input variables directly correlate to a human driver's steering wheel and throttle commands. The control design is based on a comprehensive vehicle model with realistic tire force and drive-train characteristics, and validated in a high-fidelity simulation environment.