Tire Tread Block Research Articles

Measurement of the three-directional contact force using a smart tire with a force sensor

While designing tire performance, understanding the relationship between the tire belt or tread rubber and the road surface is crucial, as represented by the cornering performance and wear characteristics. To survey this relationship, the force generated when a tire moves over a force sensor installed on the drum side of a tire drum tester or a sheet-type sensor installed on the road surface is measured to estimate the contact pressure distribution. The former method does not allow measurements on a flat surface, whereas the latter uses an actual vehicle; thus, obtaining stable data is challenging. In this study, we measured the triaxial forces acting on the tread block of a tire with a slip angle applied to the tire alone and discussed the characteristics of these forces. In the proposed measurement method, a tire tread block is machined, and a small triaxial force sensor is embedded. This method enables measuring the forces between the tire belt and the road surface. Finally, the force generated via the tire/road interaction on the tread block was measured using a flat-belt tester. The characteristics of the forces generated by the tread block are reported based on the obtained results.

Target Conflict for Force Transmission in Lateral and Longitudinal Direction of Rotated Tread Block Samples on Different Road Surfaces (Dry, Wet, Snow, and Ice)

ABSTRACT It is known that different weather conditions require a specific design to take into account the main mechanisms acting between the tire tread block and the road surface. When developing all-season tires, additional research is necessary to find the best solution considering various road conditions. This paper analyzes the influence of the inclination angle of tire tread blocks and the tire tread blocks siping design on different surfaces on the friction forces in lateral and longitudinal directions. The tests were conducted on the hybrid test rig Realistic Pattern Testing in Lab at the Institute for Dynamics and Vibration Research of the Leibniz University of Hanover with different single tread blocks. Tire tread blocks with different numbers of sipes were rotated with an angle between 0° to 90° in 15° increments. To simulate different road conditions, artificially produced ice and snow tracks and real road wet and dry asphalt were used. For a better understanding of the mechanisms, high-speed images of the same samples sliding over a wet glass track were taken from below. On the one hand, the measurement results and videos help to understand the influence of the inclination angle of a tread block sample on the friction process and show the different friction mechanisms on different surfaces and resulting forces in the two directions. On the other hand, the results show clear favorites for optimizing performance on individual surfaces.

Investigation of the Influence of Snow Track Density on Tire Tread Block Traction by Experiments and Discrete Element Method Simulation

ABSTRACT While in nature, snow properties change from day to day or even minute by minute, one of the great advantages of lab tests is the stability and reproducibility of testing conditions. In our labs at the Institute of Dynamics and Vibration Research, Leibniz Universität Hannover, we currently run three test rigs that are able to conduct tests with tire tread blocks on snow and ice tracks: High-Speed Linear Tester (HiLiTe), Portable Friction Tester (PFT), and Reproducible Tread Block Mechanics in Lab (RepTiL). In the past years, we have run a project on the influence of snow track properties on friction and traction test results with those test rigs. In this article, we will present a first excerpt of the results concentrating on the RepTiL test rig. Because this rig reproduces the movement of rolling tire tread blocks, we executed a test campaign with special samples for the analysis of snow friction mechanics. We evaluated penetration into the snow, maximum longitudinal force level, and longitudinal force gradient. On the other hand, we varied the snow density while preparing our tracks to assess the influence of the snow track density on the friction mechanics. In parallel, we have accompanied our experiments with discrete element method simulations to better visualize and understand the physics behind the interaction between snow and samples. The simulation shows the distribution of induced stress within the snow tracks and resulting movement of snow particles. Hypotheses for the explanation of the friction behavior in the experiments were confirmed. Both tests and simulations showed, with good agreement, a strong influence of snow density and sample geometry.

Transient abrasion on a rubber sample due to highly dynamic contact conditions

Abrasive processes, primarily the local slip, are the dominant contributor to friction and wear of vehicle tires in service. The time history of forces accompanying acceleration, braking, and cornering in particular, lead constantly to changing contact conditions under the tire. Consequently, a laboratory test taking into account not only surface texture but also tire contact times (in the range of milliseconds) as well as realistic contact forces in a freely controllable temporal sequence is desirable. This paper presents the study of the dynamic contact between a rubber block and the abrasive surface at conditions close to those in a tire footprint. In our case, the test samples are a miniaturized tread block allowing to reproduce the intermittent tire contact including correct contact timings, pressure and friction coefficients in dependence on the driving maneuver to be tested. An analysis and comparison of friction and wear mechanisms for continuous contact and defined contact times is presented surpassing the characterization capabilities of DIN abrasion testers.Two different compounds with a variation of stiffness are examined. The grip and wear rates are analyzed and compared. It is shown that understanding the dominant mechanisms and quantifying tire tread friction and wear in detail require the consideration of realistic transient dynamics of a tire tread block impacting the road at each revolution of the tire.

Dynamic Behavior of Fractional Viscoelastic Tire Tread Blocks on Different Ice Surfaces

ABSTRACT The component of vehicle tires that contacts the road is the tire tread. It consists of several tread blocks with different shape and can be realized by siped structures to improve the traction on the pavement, in particular in wet, icy, or snowy conditions. The blocks are usually made of elastomer materials, which possess viscoelastic behavior. Viscoelasticity can be described by classical rheological models or, alternatively, as shown in this paper, by fractional viscoelastic models. Fractional models can fit the material properties better with fewer parameters. Each single tire tread block shows periodically frictional impacts with the pavement. The contact configurations and transitions among stick and slip or impact and detaching can be formulated as a linear complementarity problem, whose solution estimates the local contact forces. We simulate transient deformations of a tire tread block by developing a discretized fractional viscoelastic model. The focus is on the deformation process of a tread block with siped structure on different ice tracks with frictional contact. In particular the interlocking of the tread block lips with the edges on the ice surface and the self-contact of the lips are considered. The simulation results are compared to measurements on a high velocity linear testing bench. The contact forces of the frictional contact for plane and rough surfaces on ice and also the deformation process of siped tread blocks, where self-contact can occur, are investigated. The qualitative comparison between results out of simulations and experiments shows a good agreement.

Distributed Parallel Performance of Compression Molding Model for Some Characteristics Identification of Tire Tread Block

A control process based on the mathematical modeling of phase change simulations was used to address process limitations of tire tread manufacturing process. The objective of this model was to predict and monitor expected characteristic identifications respect to space and time. This paper proposes a high-performance control process for visualizing the temperature behavior of a compression molding process using pressure, density, elasticity, crack propagation, volume, space, and time during tire tread block manufacturing operations. The control process modeling of tire tread blocks at the liquid-solid interface enabled the use of large sparse computations for solving the real time molding process of a Rubber Compression Molding Machine (RCMM) LWB VRE 1000 type at the Malaysia Rubber Board Research Center (LGM). The modeling simulation emphasized parallel algorithms, domain decomposition, and parallel processing techniques on Distributed Parallel Computer Architecture (DPCS). This study identified alternative numerical methods and their parallelization by comparing numerical analysis and parallel performance indicators using tables, graphs, and multidimensional visualizations. The multidimensional visualization of characteristics using the high-performance control process model accurately illustrated the heating and cooling profile of the compression molding process.

Distributed Parallel Performance of Compression Molding Model for Some Characteristics Identification of Tire Tread Block.

A control process based on the mathematical modeling of phase change simulations was used to address process limitations of tire tread manufacturing process. The objective of this model was to predict and monitor expected characteristic identifications respect to space and time. This paper proposes a high-performance control process for visualizing the temperature behavior of a compression molding process using pressure, density, elasticity, crack propagation, volume, space, and time during tire tread block manufacturing operations. The control process modeling of tire tread blocks at the liquid-solid interface enabled the use of large sparse computations for solving the real time molding process of a Rubber Compression Molding Machine (RCMM) LWB VRE 1000 type at the Malaysia Rubber Board Research Center (LGM). The modeling simulation emphasized parallel algorithms, domain decomposition, and parallel processing techniques on Distributed Parallel Computer Architecture (DPCS). This study identified alternative numerical methods and their parallelization by comparing numerical analysis and parallel performance indicators using tables, graphs, and multidimensional visualizations. The multidimensional visualization of characteristics using the high-performance control process model accurately illustrated the heating and cooling profile of the compression molding process.

Modeling of the surface coverage and application to the calculation of friction on surfaces contaminated by particles

This paper deals with the modeling of the coverage of surfaces contaminated by fine particles, the objective being the prediction of the skid resistance of road surfaces when it rains after a long dry period. The research methodology is based on the identification of particles' flows in the tribological circuit composed of the particles (3rd body) and the tire and the road (1st bodies). Experiments are conducted in laboratory where sliding friction is measured between a rubber pad (simulating a tire tread block) and a sandblasted aluminum surface (simulating a microtextured road surface) covered by particles. The test program includes particle concentrations representative of deposits of particles on the road surface at different dry periods and different particle size fractions. The test protocol consists in repeating passages of a rubber pad on the test surface and visualizing the particles’ movements by means of high-speed cameras. Two particles' flows are identified: particles ejected from the contact and those raised by the rubber pad then fall back to the surface. Similarities are established with the removal and deposition of gas species in vapor-phase lubrication. An analytical model was derived to express the surface coverage as a function of the number of passages and two parameters (values between 0 and 1) called respectively the ejection and recirculation ratios. The proposed model is included in a linear rule-of-mixtures equation for the calculation of friction. Calculated friction coefficients compare favorably to experimental data and the model's parameters are determined. A master curve for different particles' sizes is obtained when relating the surface coverage to the mass of particles. Relationships between the ejection and recirculation ratios, the particles' characteristics and the surface texture are presented. Discussions are made in terms of transposition of the model to real road surfaces.

Digital image correlation to analyze slip state of tire tread block in the cornering condition

Under the tire cornering condition, the slip state of the tread is extremely important for the calculation of the tire force. The cornering-slip motion of a tread rubber specimen was researched on a transparent toughened glass plate. A new equipment was developed for measuring the torque and the strain. In the absolute nodal coordinate system, the strain distribution of tread block was observed by digital image correlation method and compared with the measured torque data. The marker point track and the state switch point from stick slip to full slip were acquired by analysis of marker point displacement and strain. The effect of angular velocity on the state switch point and track shape was discussed. The results of this study indicated that the image analysis conclusions were in alignment with the torque experimental data.

Simulation and Investigation of Tire Tread Blocks Interaction with Ice

The car tire is an essential subject analysing its interaction with the road. From tire’s tread condition, geometry and rubber compound depends grip and vehicle stability. This is especially relevant in winter time, when roads are covered with the layer of snow or ice. Generally, new tires are tested in real traffic conditions using vehicles. However, ensuring these conditions requires many resources and sometimes it could be a big challenge. For this reason, simulation of the tire interaction with the road becomes more important in nowadays tire researches. Since the tire is a complex engineering subject, the tire tread blocks could be separated for individual analysis. The interaction between the dry ice and the tread block with sipes was analysed using finite element analysis. The tread block was described using hyperelastic Mooney­Rivlin material model. The deformations, distribution of the contact pressure and shear stresses were obtained for the soft and hard rubber compounds with different vertical load conditions. Also a solid tread block interaction was analysed and it was found that values of contact pressure and shear stresses are much lower comparing to siped tread block.

Investigation of Snow Milling Mechanics to Optimize Winter Tire Traction

ABSTRACT A detailed understanding of effects occurring in the contact patch between tire tread and snow surface is needed to maximize tire grip in winter conditions. The main focus of this study is quantifying the snow milling effects of individual tire tread block elements during sliding. Tests are carried out using the high-speed linear friction tester (HiLiTe), located at the Institute of Dynamics and Vibration Research at Leibniz University of Hannover, Germany. Test tracks are prepared using artificially produced snow. To solely investigate snow milling effects and exclude material properties of rubber, in a first instance the tread block samples are made of polytetrafluoroethylene (PTFE). Because PTFE is at the same time rigid and hydrophobic, known friction mechanisms such as adhesion and hysteresis can be neglected, leaving only the tread pattern milling mechanics to transmit frictional forces to the snow track. The PTFE samples are shaped in such a way that they mimic the geometry of different siped rubber tread blocks under load, varying the sipes' number, shape, and tilt angle. Results show the benefit of multiple sipes and give information on the evolution of transmittable forces with respect to sliding distance. It is found that the block element shape and tilt angle are directly linked to the frictional force, showing a distinct optimum for specific angle and shape combinations. In addition, forces are not depending on sliding speed, but on sliding distance. The snow milling results of PTFE block elements are then compared to siped rubber block samples. Corresponding high-speed videos show that PTFE sample snow milling mechanics can be directly applied to rubber samples.

A compact internal drum test rig for measurements of rolling contact forces between a single tread block and a substrate

A novel test rig design is presented which enables detailed studies of the three force components generated in the impact and release phase of rolling contact between a tyre tread block and a subst ...

轮胎花纹块表面形状优化研究

轮胎花纹块接地压力分布对轮胎耐磨性能，抓地性能有着重要的影响。本文利用三维有限元软件，以花纹块表面的节点坐标为设计变量，以花纹块接地压力偏度值为目标函数对花纹块表面形状进行优化。结果表明，该方法可以优化花纹块接地压力，改善轮胎磨损性能和抓地性能。 The contact pressure distribution of the tire tread block has an important impact on tire wear re-sistance and grip performance. In this paper, a new optimization procedure to design the surface of tire patterns is combined with 3D finite element method. The coordinates of the nodes of the surface of the tread blocks were chosen as the design variables, and the deviation of contact pres-sure distribution was selected as target variable. The results confirmed that the optimization technique could lead to a final optimum distribution of contact pressure and better wear and grip performance.

A hybrid numerical-experimental analysis for tire air-pumping noise with application to pattern optimization

As a vehicle travels at moderate/high speeds, tire noise becomes dominant over other sources of vehicle noise. It is a challenging task to determine the spectral characteristics of the tire noise source and even much more challenging to predict the tire pattern noise. This paper proposes a hybrid experimental-numerical method to identify the tire air-pumping noise spectrum and to predict the pattern noise. A special designed test and cut tire are used to obtain the near field tire noise spectrum while the boundary element method (BEM) is used to determine the transfer characteristics between noise source and selected field points. Then, the spectral characteristics of the air pumping source can be identified by combined use of the numerical transfer characteristics and the measured noise of the cut tire by solving the Helmholtz equation. In the end, the proposed approach has been developed into an in-house software and practical tire pattern noise has been investigated successfully. The established model is able to predict the noise at any field point and the good agreement between the predicted results and tests can be found, demonstrating the reasonability of the proposed approach. In addition, an optimization method of tire tread block shift and mold shift, i.e. moving one of the two half molds and/or tread ribs along the circumferential direction to change their relative phases, are proposed based on the developed software. A practical example demonstrates that the proposed approach and in-house code can be used to predict and optimize tire tread pattern noise.

Application of a pattern recognition technique to the prediction of tire noise

Tire treads are one of the main sources of car noise. To meet the EU׳s tire noise regulation ECE-R117, a new method using a pattern recognition technique is adopted in this paper to predict noise from tire tread patterns, thus facilitating the design of low-noise tires. When tires come into contact with the road surface, air pumping may occur in the grooves of tire tread patterns. Using the image of a tread pattern, a matrix is constructed by setting the patterns of tire grooves and tread blocks. The length and width of the contact patch are multiplied by weight functions. The resulting sound pressure as a function of time is subjected to a Fourier transform to simulate a 1/3-octave-band sound pressure level. A particle swarm algorithm is adopted to optimize the weighting parameters for the sound pressure in the frequency domain so that simulated values approach the measured noise level. Two sets of optimal weighting parameters associated with the length and width of the contact patch are obtained. Finally, the weight function is used to predict the tread pattern noise of tires in the same series. A comparison of the prediction and experimental results reveals that, in the 1/3-octave band of frequency (800–2000Hz), average errors in sound pressure are within 2.5dB. The feasibility of the proposed application of the pattern recognition technique in predicting noise from tire treads is verified.

A framework of model validation and virtual product qualification with limited experimental data based on statistical inference

Virtual testing is a recent engineering development trend to design, evaluate, and test new engineered products. This research proposes a framework of virtual testing based on statistical inference for new product development comprising of three successive steps: (i) statistical model calibration, (ii) hypothesis test for validity check and (iii) virtual qualification. Statistical model calibration first improves the predictive capability of a computational model in a calibration domain. Next, the hypothesis test is performed with limited observed data to see if a calibrated model is sufficiently predictive for virtual testing of a new product design. An area metric and the u-pooling method are employed for the hypothesis test to measure the degree of mismatch between predicted and observed results while considering statistical uncertainty in the area metric due to the lack of experimental data. Once the calibrated model becomes valid, the virtual qualification process can be executed with a qualified model for new product developments. The qualification process builds a design decision matrix to aid in rational decision-making for product design alternatives. The effectiveness of the proposed framework is demonstrated through the case study of a tire tread block.

A laser-based sensor system for tire tread deformation measurement

Optical tire sensors are powerful engineering tools that can reveal the mechanisms behind tire-road interactions. This paper presents a laser-based sensor system to measure tire-tread block deformation. The methodology and corresponding procedure for the system are introduced. Practical issues, such as tire sensor localization, are discussed. Validation experiments were conducted on a chassis dynamometer, and an asymmetric tire tread deformation along the contact patch was observed. It is proposed that asymmetric tread deformation is due to rolling resistance. The measurements under different operational conditions, including the rolling direction, wheel load, rolling velocity, and inflation pressure, were analyzed in the context of rolling resistance.

Experimental and Numerical Studies on Tire Tread Block Friction Characteristics Based on a New Test Device

A new device was developed for tire tread block slip friction tests. Then the friction characteristics were investigated under different loads and contact roads. Based on this, a friction model for contact between tire tread block and different road surfaces was developed. A finite element slip friction model of rubber block was developed for studying the tread contact stress, stiffness under different pattern slope angles, and ditch radius. Results indicate that friction coefficient between tread and ice road increases when the temperature decreases; different tread patterns have a certain influence on the friction coefficient; its average difference was less than 10%. Different roads impact the coefficient of friction more significantly; the greater the pattern slope, the greater the radial stiffness.

Digital Image Correlation to analyse stick–slip behaviour of tyre tread block

Stick–slip behaviour is a common but not entirely understood tribological phenomenon. The sliding motion of a rubber sample was studied on a glass plate. The local sliding velocity field of the contact area was calculated by means of Digital Image Correlation and compared to the measured friction force. It was observed that the sliding of individual sipes nucleates from the side edge, whereas the sliding of a tread block propagates from the leading edge. Phase shifts between tread block detachments were observed. Furthermore, a velocity field for a precursor is presented which indicates only the local sliding of the contact without the triggering of a global detachment. The relevance of the result for rougher surfaces is discussed.

Tyre tread-block friction: modelling, simulation and experimental validation

Pneumatic tyres are used in vehicles since the beginning of the last century. They generate braking and steering forces for bicycles, motor cycles, cars, busses, trucks, agricultural vehicles and aircraft. These forces are generated in the usually very small contact area between tyre and road and their performance characteristics are of eminent importance for safety and comfort. Much research has been addressed to optimise tyre design with respect to footprint pressure and friction. In this context, the development of virtual tyre prototypes, that is, simulation models for the tyre, has grown to a science in its own. While the modelling of the structural dynamics of the tyre has reached a very advanced level, which allows to take into account effects like the rate-independent inelasticity of filled elastomers or the transient 3D deformations of the ply-reinforced tread, shoulder and sidewalls, little is known about the friction between tread-block elements and road. This is particularly obvious in the case when snow, ice, water or a third-body layer are present in the tyre–road contact. In the present paper, we give a survey on the present state of knowledge in the modelling, simulation and experimental validation of tyre tread-block friction processes. We concentrate on experimental techniques.