Tire Interface Research Articles

Evaluation for long-term skid resistance of ultra-thin asphalt overlay based on texture characteristics

To evaluate the durability of ultra-thin asphalt overlays in terms of skid resistance accurately, the long-term degradation trends in texture characteristics need to be carried out comprehensively. In this paper, three types of ultra-thin asphalt overlays with different gradations were selected. The long-term abrasion test was conducted, with friction coefficient and texture characteristics tested in each abrasion cycle. Additionally, the stress state changes at the interface of the tire and mixtures were also obtained. Finally, the reliability of texture characteristics was validated based on the correlation between different indicators. The results show that the friction coefficient and texture characteristic show a two-stage decay pattern during the abrasion process, with a significant decrease in stress between 0.75 and 2.5 MPa at the interface of tire and mixtures. The surface mean texture depth (SMTD), root-mean-square deviation of surface (Sq), peak density of surface (Spd), and spatial fluctuations of texture (Δα) were correlated with British pendulum number (BPN) strongly, and the Sq and Δα were recommended as reliable evaluation parameters for the long-term skid resistance of ultra-thin asphalt overlays. This study provides theoretical guidance for the optimal design and field monitoring of ultra-thin asphalt overlays from the perspective of surface texture characteristics.

Airway contraction and cytokine release in isolated rat lungs induced by wear particles from the road and tire interface and road vehicle brakes

The dominant road traffic particle sources are wear particles from the road and tire interface, and from vehicle brake pads. The aim of this work was to investigate the effect of road and brake wear particles on pulmonary function and biomarkers in isolated perfused rat lungs. Particles were sampled from the studded tire wear of three road pavements containing different rock materials in a road simulator; and from the wear of two brake pad materials using a pin-on-disk machine. Isolated rat lungs inhaled the coarse and fine fractions of the sampled particles resulting in an estimated total particle lung dose of 50 μg. The tidal volume (TV) was measured during the particle exposure and the following 50 min. Perfusate and BALF were analyzed for the cytokines TNF, CXCL1 and CCL3. The TV of lungs exposed to rock materials was significantly reduced after 25 min of exposure compared to the controls, for quartzite already after 4 min. The particles of the heavy-duty brake pads had no effect on the TV. Brake particles resulted in a significant elevation of CXCL1 in the perfusate. Brake particles showed significant elevations of all three measured cytokines, and quartzite showed a significant elevation of TNF in BALF. The study shows that the toxic effect on lungs exposed to airborne particles can be investigated using measurements of tidal volume. Furthermore, the study shows that the choice of rock material in road pavements has the potential to affect the toxicity of road wear PM10.

Relationship between the 3D Footprint of an Agricultural Tire and Drawbar Pull Using an Artificial Neural Network

HighlightsImprovement of tractor traction provides better field efficiency.Drawbar pull increased with tire footprint length.Drawbar pull decreased with increasing tire footprint volume and depth.3D footprint parameters, which the 2D footprint do not contain, affected the drawbar pull significantly.The ANN highlighted the relation adequately.Abstract.Improving the traction of an agricultural tractor on the field increases its working efficiency and capacity. Heavy work, like plowing, entails high levels of tire slip, which is directly related to power loss when the transmission of drawbar pull is required. Accordingly, it is possible to hypothesize that a tire with a higher traction capability could increase the working efficiency of the machine. The natural evolution for measuring the geometrical parameters of tires has led to the consideration of three-dimensional (3D) footprints since the distribution of the vertical stresses at the soil–tire interface may be highly non-uniform. In this study, the data acquired from 3D footprints of 10 sets of tires underwent processing along with the data from drawbar tests carried out with the same tires on soil terrain at different slip ratios. Subsequently, artificial intelligence multivariate methods based on artificial neural networks allowed traction prediction and verified the importance that the acquired geometrical parameters have on the measured drawbar pull. The study confirmed the correlation of the geometrical parameters of the 3D tire footprint with the drawbar pull and the results of the artificial intelligence modelling underlined the impact of these acquisitions. However, further work that considers various lug geometries is required to extend the generalizability of the studied methodology. Keywords: Field efficiency, Phenolic resin, Traction, Tractor.

Experimental Determination of Mechanical Properties of Waste Tyre Bales Used for Geotechnical Applications.

Waste tyre-derived products (TDP) are used in some engineering applications and thereby reduce the potential impact on the environment, for example, as lightweight materials in geotechnical engineering projects. One of TDPs is the baling of whole waste tyres to produce rectilinear, lightweight, permeable bales of high bale-to-bale or bale-to-soil friction. The use of lightweight tyre bales in road construction has the potential to satisfy the demand for low-cost materials exhibiting such a beneficial property. This paper presents a laboratory study on the mechanical properties of tyre bales. The laboratory tests included measurement and evaluation of full-scale tyre bales to determine basic values for the geometry and unit weight, compressibility characteristics of tyre bales, including Young’s modulus and Poisson ratio, shear strength along the tyre–tyre and tyre–soil surfaces, creep and stiffness degradation under cyclic load. The respective test procedures and results of these tests are presented in the paper. The paper provides the mechanical properties of tyre bales required for geotechnical projects, as follows: the unit weight—0.515 Mg/m3, the Young’s modulus—826 kPa, the Poison’s ratio—0.11, the dry tyre–tyre interface: cohesion of 0.03 kPa and friction angle of 46.0°, the wet tyre–soil interface: cohesion 0.77 kPa and a friction angle of 29.6°, creep deformation of 6.1% of the average height of the bale, and no stiffness degradation of tyre bales under cyclic load. These results could be directly applied for the designing and construction of the tyre-baled structures.

Tire Lateral Vibration Considerations in Vehicle-Based Tire Testing

ABSTRACT Vehicle-based tire testing can potentially make it easier to reparametrize tire models for different road surfaces. A passenger car equipped with external sensors was used to measure all input and output signals of the standard tire interface during a ramp steer maneuver at constant velocity. In these measurements, large lateral force vibrations are observed for slip angles above the lateral peak force with clear peaks in the frequency spectrum of the signal at 50 Hz and at multiples of this frequency. These vibrations can lower the average lateral force generated by the tires, and it is therefore important to understand which external factors influence these vibrations. Hence, when using tire models that do not capture these effects, the operating conditions during the testing are important for the accuracy of the tire model in a given maneuver. An Ftire model parameterization of tires used in vehicle-based tire testing is used to investigate these vibrations. A simple suspension model is used together with the tire model to conceptually model the effects of the suspension on the vibrations. The sensitivity of these vibrations to different operating conditions is also investigated together with the influence of the testing procedure and testing equipment (i.e., vehicle and sensors) on the lateral tire force vibrations. Note that the study does not attempt to explain the root cause of these vibrations. The simulation results show that these vibrations can lower the average lateral force generated by the tire for the same operating conditions. The results imply that it is important to consider the lateral tire force vibrations when parameterizing tire models, which does not model these vibrations. Furthermore, the vehicle suspension and operating conditions will change the amplitude of these vibrations and must therefore also be considered in maneuvers in which these vibrations occur.

Evaluation of vehicle-based tyre testing methods

The demand for reduced development time and cost for passenger cars increases the strive to replace physical testing with simulations. This leads to requirements on the accuracy of the simulation models used in the development process. The tyres, the only components transferring forces from the road to the vehicle, are a challenge from a modelling and parameterization perspective. Tests are typically performed on flat belt tyre testing machines. Flat belt machines offers repeatable and reliable measurements. However, differences between the real world road surface and the flat belt can be expected. Hence, when using a tyre model based on flat belt measurements in full vehicle simulations, differences between the simulations and real prototype testing can be expected as well. Vehicle-based tyre testing can complement flat belt measurements by allowing reparameterization of tyre models to a new road surface. This paper describes an experimental vehicle-based tyre testing approach that aims to parameterize force and moment tyre models compatible with the standard tyre interface. Full-vehicle tests are performed, and the results are compared to measurements from a mobile tyre testing rig on the same surface and to measurements on a flat belt machine. The results show that it is feasible to measure the inputs and outputs to the standard tyre interface on a flat road surface with the used experimental setup. The flat belt surface and the surface on the test track show similar characteristics. The maximum lateral force is sensitive to the chosen manoeuvres, likely due to temperature differences and to vibrations at large slip angles. For tyre models that do not model these effects, it is vital to test the tyres in a manoeuvre that creates comparable conditions for the tyres as the manoeuvre in which the tyre model will be used.

Changes in soil stress during repeated wheeling: A comparison of measured and simulated values

Agricultural machinery traffic is one of the main causes of soil compaction in modern agriculture. Soils with weak inherent soil structural stability already have low bearing capacity and, when subjected to intensive tillage with a high frequency of traffic, are susceptible to severe soil compaction. In this study, repeated wheeling experiments were carried out on an Iranian clay soil prepared at two water contents (corresponding to 0.9 and 1.35 × water content at the lower plastic limit), two wheel loads (light and heavy rear wheel loads of a two-wheel-drive tractor) and two vehicle travel speeds (0.5 and 1 m s–1). The experiments tested whether the stress variations due to repeated wheeling are mainly due to variations in rut depth with repeated tyre passes and whether traffic at a higher travel speed has a smaller compaction effect. Mean normal stress was measured at three depths (0.15, 0.25 and 0.35 m) beneath the centre of tyres using cylindrical Bolling probes. Rut depth and cone index were measured after each pass. The results showed a linear increase in rut depth with consecutive tractor passes, with a greater increase on wet soil. However, bulk density increased more in dry soil than in wet soil at 0.15 and 0.25 m depth, most likely due to soil water content being close to the optimum Proctor water content. At 0.35 m depth, the bulk density increase was larger for wet soil, with obvious impacts of wheel load and travel speed (greater increase for slower speed and heavier wheel). Cone index generally increased with repeated tractor passes, with the greatest increase at 0.35 m depth in wet soil under heavy rear wheel traffic. Stress generally increased with increasing rut depth due to repeated wheeling. Reduced distance between the soil–tyre interface and the Bolling probes with increasing rut depth was investigated as a potential reason using analytical stress simulations, but could not fully explain the increase in stress with rut depth. Therefore, additional factors (e.g. soil strength) must have contributed to the stress increase with increasing number of tractor passes.

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.

An overview of a unified theory of dynamics of vehicle–pavement interaction under moving and stochastic load

This article lays out a unified theory for dynamics of vehicle–pavement interaction under moving and stochastic loads. It covers three major aspects of the subject: pavement surface, tire–pavement contact forces, and response of continuum media under moving and stochastic vehicular loads. Under the subject of pavement surface, the spectrum of thermal joints is analyzed using Fourier analysis of periodic function. One-dimensional and two-dimensional random field models of pavement surface are discussed given three different assumptions. Under the subject of tire–pavement contact forces, a vehicle is modeled as a linear system. At a constant speed of travel, random field of pavement surface serves as a stationary stochastic process exciting vehicle vibration, which, in turn, generates contact force at the interface of tire and pavement. The contact forces are analyzed in the time domain and the frequency domains using random vibration theory. It is shown that the contact force can be treated as a nonzero mean stationary process with a normal distribution. Power spectral density of the contact force of a vehicle with walking-beam suspension is simulated as an illustration. Under the subject of response of continuum media under moving and stochastic vehicular loads, both time-domain and frequency-domain analyses are presented for analytic treatment of moving load problem. It is shown that stochastic response of linear continuum media subject to a moving stationary load is a nonstationary process. Such a nonstationary stochastic process can be converted to a stationary stochastic process in a follow-up moving coordinate.

KHP Main & Nose Wheel 개발을 위한 구조해석

본 연구는 KHP(Korean Helicopter Program) main & nose wheel 국산화 개발을 위한 구조해석으로서 상용프로그램인 ANSYS를 사용하여 wheel의 구조적 안정성을 평가하였다. Wheel과 tire의 interface를 고려한 연구로서, Tire의 공기압과 정하중, 반경하중 그리고 복합 하중을 main & nose wheel에 적용하여 응력해석을 수행하였다. 해석결과는 소성변형이 발생하는 항복강도를 고려하여, maximum stress와 항복강도를 비교분석 후 구조적 안정성을 더 높일 수 있는 방안을 제시하였다. This study performed the structure analysis for development and localization of main and nose wheel in Korean Helicopter Program(KHP). Structural stability of wheel is evaluated using ANSYS. Considering wheel and tire interface, Stress analysis was conducted by applying pneumatic of tire, static load, radial load and combined load on main and nose wheel. Considering yield strength at which plastic deformation occurs, simulation results suggest the method which increases structure stability after comparing maximum stress and yield strength.

Data acquisition system for soil–tire interface stress measurement

In today’s production agriculture industry, a renewed interest has been placed on input costs and energy efficiency. The fact that the soil–tire interface of a tractive vehicle is inherently inefficient is widely known but not widely understood. To support evaluation of the soil–tire interface a measurement system was created to sense the normal stress at the interface of the tire and soil. To acquire and log the data from this sensor array, a unique data acquisition system was developed and is presented in this paper. The system utilized a microcontroller to process and write data to a compact flash card from a total of 56 analog channels. It also used a two-dimensional accelerometer to determine the angular position of the vehicle tire and the attached sensors. Custom data acquisition software was developed to log the data to the compact flash card in an efficient, organized manner. Results confirmed that the data acquisition system was capable of operating at 887 Hz per-channel analog sampling frequency. Data from field testing illustrated the capability of the accelerometer to determine wheel angular rotation and associate the applied normal stress with that angular rotation. Results also confirmed the capability of the data acquisition system to estimate the rotational angle of contact of the tire while engaging soil.

Finite element modeling of interfacial forces and contact stresses of pneumatic tire on fresh snow for combined longitudinal and lateral slips

Significant challenges exist in the prediction of interaction forces generated from the interface between pneumatic tires and snow-covered terrains due to the highly non-linear nature of the properties of flexible tires, deformable snow cover and the contact mechanics at the interface of tire and snow. Operational conditions of tire–snow interaction are affected by many factors, especially interfacial slips, including longitudinal slip during braking or driving, lateral slip (slip angle) due to turning, and combined slip (longitudinal and lateral slips) due to brake-and-turn and drive-and-turn maneuvers, normal load applied on the wheel, friction coefficient at the interface and snow depth. This paper presents comprehensive three-dimensional finite element simulations of tire–snow interaction for low-strength snow under the full-range of controlled longitudinal and lateral slips for three vertical loads to gain significant mechanistic insight. The pneumatic tire was modeled using elastic, viscoelastic and hyperelastic material models; the snow was modeled using the modified Drucker–Prager Cap material model (MDPC). The traction, motion resistance, drawbar pull, tire sinkage, tire deflection, snow density, contact pressure and contact shear stresses were obtained as a function of longitudinal slip and lateral slip. Wheel states – braked, towed, driven, self-propelled, and driving – have been identified and serve as key classifiers of discernable patterns in tire–snow interaction such as zones of contact shear stresses. The predicted results can be applied to analytical deterministic and stochastic modeling of tire–snow interaction.

Evaluation of pavement temperature on skid frictional of asphalt concrete surface

This paper presents the investigation of the effect of pavement surface temperature on the frictional properties of the pavement–tyre interface. Many skid tests were carried out on different wearing surfaces and under different climatic conditions using both ribbed and smooth tyres over 15 months. The pavement and air temperatures were obtained in each test using thermocouples located directly under the wearing course and close to the pavement surface, respectively. Regression analyses were carried out to determine the effect of pavement temperature on the measured skid number at different speeds, along with friction model parameters. The main conclusion of this investigation demonstrates that the pavement temperature has a significant effect on pavement frictional measurements and on the sensitivity of the measurements to the test speed. Both the skid number at zero speed (SN0) and the per cent normalised gradient tend to decrease with increased pavement temperature. At low speed, pavement friction tends to decrease with increased pavement temperature, and at high speed, the effect is reverted and pavement friction tends to increase with increasing pavement temperature. Temperature-dependent friction vs. speed models were developed for one of the mixes studied. These models could be used to define temperature correction factors.

Estimation of a three-dimensional tyre footprint using dynamic soil–tyre contact pressures

A method for estimating the three-dimensional (3D) footprint of a 16.9R38 pneumatic tyre was developed. The method was based on measured values of contact pressure at the soil–tyre interface and wheel contact length determined from the contact pressures and the depths and widths of ruts formed in the soil. The 3D footprint was investigated in an area of the field where the pressure sensors of the tyre passed in a soft clay soil. The tyre was instrumented with six miniature pressure sensors, three on the lug face and the remaining three on the under-tread region between two lugs. The instrumented tyre was run at a constant forward speed of 0.27 m/s and 23% slip on a soft soil, 0.48 MPa cone index, 25.6% d.b. moisture content for four wheel load and tyre pressure combination treatments. The 3D footprint assessment derived from soil–tyre interface stress used in this research is a unique methodology, which could precisely relate the trend profile of the 3D footprint to the measured rut depth. The tyre–soil interface contact pressure distributions results showed that as inflation pressure increased the soil strength increased significantly near the centre of the tyre as a compaction increase sensed with the cone penetrometer.

The ability of agricultural tyres to distribute the wheel load at the soil–tyre interface

Bigger tyres with lower inflation pressure at equivalent wheel loads are expected to reduce the stresses transmitted to the soil. We measured the contact area and the vertical stress distribution near the soil–tyre interface for five agricultural implement tyres at 30 and 60 kN wheel load and rated inflation pressures. Seventeen stress transducers were installed at 0.1 m depth in a sandy soil at a water content slightly lower than field capacity and covered with loose soil. The recently developed model FRIDA was successfully fitted to the experimental stress data across the footprint. The contact area reflected the size of the tyres. The small tyres had identical contact area at the two loads, while it increased with load for the two biggest tyres. The small tyres presented uneven stress distributions with high peak stresses. Across the tests, the tyre inflation pressure described well the measured peak stress as well as the modelled maximum stress. The latter seems to be appropriate in evaluating vehicle trafficability. We found significant differences among tyres for the slope of a linear regression between the mean ground pressure and the inflation pressure, while the tyres displayed the same interception on the mean ground pressure axis. Our results therefore suggest that the slope of this relation is the most sensitive expression of tyres’ ability to deflect and transfer stresses to the soil. The two small tyres performed poorer in this respect than the larger tyres. Tests were limited to one soil strength, with future research directed toward a broader spectrum of soil strengths.

Experimental analysis of vertical soil reaction and soil stress distribution under off-road tires

In this study, the vertical soil reaction acting on a driven wheel was measured by strain gages bonded to the left rear axle of a 2WD tractor driven under steady-state condition on different soil surfaces, tractor operations, and combinations of static wheel load and tire inflation pressure. In addition, the measurements of radial and tangential stresses on the soil–tire interface were made simultaneously at lug’s face and leading side near the centerline of the left rear tire using spot pressure sensors. The experimental results indicate that the proposed method of vertical soil reaction measurement is capable of monitoring the real-time vertical wheel load of a moving vehicle and provides a tool for further studies on vehicle dynamics and dynamic wheel–soil interaction. Furthermore, the measured distributions of soil stresses under tractor tire could provide more real insight into the soil–wheel interactions.

Modelling effects of tyre inflation pressure on the stress distribution near the soil–tyre interface

Several investigations have shown that the distribution of vertical stress in soil just below a loaded tyre is not uniform. The stress distribution and the size and form of the tyre–soil interface are decisive for the stress propagation in the soil profile. We measured the distribution of vertical stress in the contact area for two radial-ply agricultural trailer tyres (650/65R30.5 and 800/50R34) loaded with ∼60 kN. The study took place on a sandy soil at a water content slightly less than field capacity. We tested the effect of three different inflation pressures (50, 100 and 240 kPa) in a randomised block design with three replicates. The vertical stress was measured with load cells located in 0.1 m soil depth. The vertical stress data were used also for identifying the soil area in contact with the tyre, i.e. the tyre footprint. A model (named FRIDA) is proposed that describes the tyre footprint by a super ellipse and the stress distribution by a combined exponential (perpendicular to the driving direction) and power-law (along the driving direction) function. The contact area doubled when the inflation pressure was reduced from 240 to 50 kPa. For both tyres, the measured peak stress increased significantly with tyre inflation pressure and was generally about 90 kPa higher than tyre inflation pressure. The model-fitted maximum stress was about 50 kPa higher than the inflation pressure. The 650/65R30.5 tyre displayed a longer footprint and a more uniform stress distribution in the driving direction and performed better at non-recommended inflation pressures than the 800/50R34. At the recommended inflation pressure, both tyres displayed a stress distribution across the width of the wheel that could be evaluated as optimal with regard to a minimised topsoil compaction. The suggested model seems very well suited for describing real stress distributions at the soil–tyre interface, but should be validated also with other tyres, wheel loads, and soil conditions. It has the potential to improve soil compaction models considerably and also for use to evaluate important features of tyres with scope to improve future designs.

Vehicle dynamics with LMS Virtual.Lab Motion

LMS Virtual.Lab Motion is a complete and integrated solution to simulate realistic motion and loads of mechanical systems. It permits engineers to quickly analyse and optimize the real-world behavior of the mechanical design, before committing to expensive physical prototype testing. LMS Virtual.Lab Vehicle Motion simulates all types of vehicle ride and handling behavior from passenger cars and motor sport vehicles to multi-axle vehicles like trucks and buses. Through the multi-attribute nature of the LMS Virtual.Lab Solution, different vehicle performances can be balanced and optimized. This allows performing studies for example to improve the road noise while keeping the handling performance untouched. For handling analyses, LMS Virtual.Lab Motion Vehicle includes the possibility to quickly run standardized events. The industry driver ‘IPG-DRIVER’ is integrated in LMS Virtual.Lab Motion, which allows to simulate all the actions a human driver performs while driving a vehicle. The main tire models integrated in LMS Virtual.Lab Motion are the TNO Delft tire models (MF-Tyre and MF–SWIFT) and CDTire. Other tire models can be integrated using the Standard Tire Interface. The interface with Matlab/Simulink and LMS Imagine.Lab Amesim allows the integration of detailed models of electronic as well as hydraulic control systems in order to perform combined simulations to analyze for example the effect of active safety systems on the vehicle dynamics. As such, LMS Virtual.Lab Motion Vehicle provides a complete package to efficiently perform vehicle dynamics studies.

Tire model TMeasy

This paper describes the semi-physical tire model TMeasy for vehicle dynamics and handling analyses, as it was applied in the ‘low frequency tire models’ section of the research programme tire model performance test (TMPT). Despite more or less weak testing input data, the effort for the application of TMeasy remains limited due to its consequent ‘easy to use’ orientation. One particular feature of TMeasy is the wide physical meaning of its smart parameter set, which allows to sustain the identification process even under uncertain conditions. After a general introduction, the modelling concept of TMeasy is compactly described in this paper. Taking the standard tire interface (STI) to multibody simulation system (MBS) software into account, the way to apply TMeasy is briefly shown. This includes three selected examples of application. The final comments of the authors on TMPT describe the experiences and earnings received during the participation in that programme.

Seasonal Deterioration of Unsurfaced Roads

Seasonal deformation of unsurfaced roads was observed over several years and was studied using pavement deterioration models and finite-element analysis. The Mathematical Model of Pavement Performance is a model designed for pavement deterioration prediction and was successfully used for seasonal deterioration modeling because of its flexibility in defining the pavement structure, properties, and seasonal impact. However, these types of models are designed for highways and are somewhat limited in soils characterization and manipulation of the forces at the road–tire interface. Therefore, a three-dimensional dynamic finite-element model of a wheel rolling over soil was applied to simulate local vehicle traffic on a secondary unpaved road. These simulations were used to study the effects of vehicle speed, load, suspension system, wheel torque, and wheel slip on rutting and washboard formation. Modeling results are compared to field measurements and observations.