Tread Block Research Articles

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.

Printed Electronic Sensor Array for Mapping Tire Tread Thickness Profiles

Tire tread wear is a significant vehicular safety concern; yet, monitoring tread depth (or thickness) still relies on manual detection, which is rarely done by consumers and is time-consuming for service lane technicians. In this paper, we present a fully printed, one-dimensional electrode array that is able to electrically measure the thickness profile of tread across the width of a tire. The sensor array consists of printed millimeter-sized electrodes composed of a hybrid silver nanoparticle-carbon nanotube (CNT) structure. The array is positioned directly against the outside of a tire (simulating a vehicle driving over the sensors). The thickness profile is then determined by applying an oscillating voltage between each of the electrode pairs in the array and measuring the associated electrical response. Correlation between the electrical response and tread depth across a tire is demonstrated for two distinct, measurable parameters: signal reflectance (S11) and impedance. A 2D electrostatic simulation is applied to explain the operation of the sensors and how the differentiation between grooves and tread blocks is possible based on differing electric field attenuation with distance. This printed sensor array shows promise for electrically monitoring tread profiles using relatively low-cost, readily implemented components.

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.

Computational model of shoe wear progression: Comparison with experimental results

Worn shoes increase the risk of slip-and-fall accidents. Few research efforts have attempted to predict the progression of shoe wear. This study presents a computational modeling framework that simulates wear progression in footwear outsoles based on finite element analysis and Archard's equation for wear. The results of the computational model were qualitatively and quantitatively compared with experimental results from shoes subjected to an accelerated wear protocol. Key variables of interest were the order in which individual tread blocks were worn and the size of the worn region. The order in which shoe treads became completely worn were strongly correlated between the model and experiment (rs > 0.74, p < 0.005 for all of the shoes). The ability of the model to predict the size of the worn region varied across the shoe designs. Findings demonstrate the capability of the computational modeling methodology to provide realistic predictions of shoe wear progression. This model represents a promising first step to developing a model that can guide footwear replacement programs and footwear design with durable slip-resistance.

In-Plane Flexible Ring Tire Model—Part 2: Parameterization

ABSTRACT The flexible ring tire model has recently gained significant attention in vehicle dynamics and analysis of road loads because it is able to capture the tire belt deflection under various driving conditions and compute more efficiently than the complex finite element tire model. This article presents the second part of the in-plane flexible ring tire model study with the recently developed flexible ring tire model to investigate several important aspects about tire model parameterization. First, we use the FTire® model in the MSC ADAMS/View® virtual test rig to generate five sets of spindle longitudinal and vertical loads on cleats with different heights, static loads, and speeds. These spindle loads are considered the “experimental data” in view of proving the accuracy of the commercial FTire® model that can accurately predict the spindle loads, especially in well-controlled test rigs. Next, one set of tire model parameters identified with a specific cleat test case is applied to other cleat test cases to predict the tire spindle forces, which are then compared with those corresponding experimental data. Similarly, this process is repeated for each cleat test case to yield different sets of parameters, respectively. Afterward, the predicted spindle loads are compared with the experimental data, respectively, based on SAE Standard J2812, and the predicted errors are assessed to determine which cleat test case is the best choice to identify parameters of the tire model. Finally, the effects of the belt point number and tread block number on the prediction accuracy and efficiency are discussed.

Numerical and Experimental Predictions of Texture-Related Influences on Rolling Resistance

To overcome rolling resistance (RR) a typical vehicle on average consumes 4152 MJ/119 L of fuel annually as a result of both vehicle and pavement factors. A slight improvement in surface texture arrangement may therefore decrease fuel consumption bringing substantial long-term socio-economic benefits. This aligns with ever-tighter limits on CO2 in the USA (163 g/km until 2025) fostering sustainable construction/exploitation of tires/pavements. This paper describes a multi-scale 3-D numerical methodology to calculate micro-distortional RR and contact indentations of surface aggregates into visco-elastic tread compound accounting for loading, velocity, temperature, and compound properties. It consists of a micro-scale tread block single aggregate model and a macro-scale car tire finite element model, rolling in steady-state mode over a rigid smooth surface. The surface texture is idealized in terms of hemispherical indenters. The micro-distortional RR estimates are based on contact force and energy lost per single stone. The computed contact/normal forces peak significantly due to visco-elastic effects at the beginning of the tire–surface contact phase, followed by a gradually relaxing stress region with a sudden release at the end of the interaction. The contact forces appear to be of a reasonable distribution and magnitude. It is found that micro-distortional RR is higher on a rougher and sparsely packed surface compared with a smoother and more tightly packed case. To determine the total tire-related RR, macro-distortional RR can then be added. The predictions were qualitatively confirmed and adjusted against real bituminous mixes by experimental testing, showing a reasonable agreement.

Mechanism and Conditions of the Polygonal Wear of Vehicle Tire

Polygonal wear seriously decreases the lifespan of a tire of a passenger car and adversely affects vehicle dynamic safety. The present paper builds a model that reflects the dynamic contact characteristics of the tire and reveals the mechanism and conditions of polygonal wear of a tire. The model describes the dynamic contact behavior of the tread block and considers the characteristics of dynamic friction between the road and tread of a rolling tire. Conducting numerical bifurcation analysis, the paper reveals the conditions for self-excited vibration of the tread, i.e., the improper combination of the vertical load, wheel slip angle, tire pressure and vehicle speed considerably strengthen the lateral self-excited vibration of the tread, which is the direct vibrational source of abnormal circumferential polygonal wear. The polygonal wear of a tire occurs when a vehicle travels for a certain long distance at a so-called polygonal wear speed. The polygonal wear speed should induce lateral self-excited vibration on the contact tread of the tire and the frequency of the lateral self-excited vibration should be divisible by the rolling frequency of tire that is determined by the polygonal wear speed. Visible polygonal wear requires that the vehicle travels at a certain polygonal wear speed for a minimal distance to produce a stably developing polygonal wear pattern even for subsequent driving at variable speed.

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 Novel Multiscale Numerical Model for Prediction of Texture-Related Impacts on Fuel Consumption

ABSTRACT It is estimated that to overcome rolling resistance (RR) a typical vehicle, on average, consumes 4152 MJ/119 L of fuel annually, depending not only on vehicle-related factors but also on pavement-related factors. A slight improvement in surface properties may thus decrease fuel consumption, bringing substantial long-term socioeconomic benefits per capita per country. This aligns with ever-tighter limits on CO2 in the European Union (95 g/km until 2021), fostering sustainable construction and exploitation of tires and pavements. This paper outlines a newly developed multiscale three-dimensional numerical methodology to quantify texture-dependent RR due to indentation of aggregates into viscoelastic tread compound. It consists of a microscale tread block single-aggregate model and a macroscale car tire finite element model, rolling in a steady-state mode over a rigid smooth surface. Microscale interaction rates are deduced from the macroscale model. Tread compound is simulated by application of a time-dependent, linear, viscoelastic model. The microscale simulations enabled quantification of RR induced by an arrangement of surface aggregates. The outlined texture-dependent RR estimates are based on contact force moment around the contact patch center. The computed contact force results show a significant peak of normal force due to viscoelastic and inertia effects at the onset of the tire–surface contact phase, followed by a gradually decreasing/relaxing stress region with a sudden release at the end of the interaction. The contact forces seem to be of a reasonable distribution and magnitude. The proposed approach allows prediction of RR losses due to compressive forces at the microscale. Macro-distortional RR (which is not the subject of this paper) would then have to be added to find the total tire-related RR.

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 ...

Prediction of tread pattern block deformation in contact with road

Tire tread patterns re arrangements of grooves, blocks, sipes, and channels, which effects on the performance of the tire, such as braking, turning, noise and side slip properties. For analyzing the performance in static and dynamic conditions, deformation behavior of the tread block was investigated under the on-road condition. A new tread pattern block deformation test device has been developed for measuring the forces and deformation. A modified analytical model of the tread block was developed, which considered the influence of the compression on the deformation under sliding conditions. Finite element models of six different typical tread pattern blocks of TBR tires have been developed by ABAQUS for analyzing the dynamic stiffness and contact pressure. Results indicated that the predicted stiffness of the tread blocks was in good agreement with the experimental data.

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.

Thermomechanical contact of rubber‐like solids on rough surfaces

AbstractThe contact between tires and the rough road surface is characterized by large local deformations of the tread rubber at high frequency, which result from the penetration of the tread blocks by the highest asperities. These deformations have an influence on the overall performance of tires regarding rolling resistance, sustainability as well as noise radiation. As the mechanical behavior of rubber compounds is strongly rate dependent these deformations cause local energy dissipation. The induced temperature increase affects the mechanical properties of the rubber. A description of the interdependence of mechanical and thermal behavior requires the solution of a coupled problem.In this contribution the tread rubber compound is modeled with an incompressible, thermo‐visco‐elastic constitutive law in the regime of finite deformations taking into account internal friction and the Gough‐Joule effect. The thermomechanical coupling is treated with the isothermal operator split scheme. Here, the mechanical subproblem is solved in a first phase at a constant temperature. Within this phase, the rough surface contact problem of the tread block with the road is treated. The road surface is a representation of a measured real road texture, which has been obtained by applying the fast Fourier transform. In the subsequent thermal phase the heat conduction problem is solved. Here, the mechanical dissipation within the bulk material acts as a heat source. The developed algorithm is applied for a detailed study on the thermomechanical effects occurring in the tire‐road contact interface. (© 2014 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

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.

Experimental Friction and Temperature Investigation on Aircraft Tires

ABSTRACT For modeling an aircraft tire using the brush model method, the friction coefficient μ between rubber and asphalt should not only be described in terms of the applied pressure and sliding velocity/slip ratio, but also by local temperature inside the contact area. Its influence cannot be neglected, since it leads to significant material property changes. Therefore, investigations on different test rigs are analyzed using thermal recordings of an infrared camera. First measurements are done on a high speed linear tester (HiLiTe), a test rig at the Institute of Dynamics and Vibration Research (IDS) at Leibniz University Hanover, Germany. It allows testing single tread block samples with a constant slip ratio of 100%, that is, pure sliding, on a variety of surfaces such as dry and wet asphalt or concrete, as well as on snow and ice. Results in this paper show that the convection has a smaller impact on tread block cooling than the actual contact between runway surface and sample. Since colder surface temperatures lead to higher friction, this effect antagonizes the excitation frequency, which heats up the rubber sample at high velocities. On long-lasting test sequences a quasi–steady-state friction coefficient might be achieved once these effects start to converge. Still, owing to permanent slip, the abrasion leads to cooling as the hot top layer of the rubber is removed occasionally. In addition to these quasi–steady-state measurements on HiLiTe, the thermal behavior of an aircraft tire is investigated with an autonomously running test rig. It allows realistic testing on an airfield runway by altering load, speed, and slip angle of the tire within and beyond the regions of a passenger aircraft. During the measurements, new and partially unknown effects could be observed. The temperature is mostly influenced by the slip angle followed by speed and load. Furthermore, the contact between tire and runway leads to cooling of the tread but does not affect the temperature inside the grooves. They heat up separately and tend to transfer heat to the tread if the cooling by the runway becomes too low.

Cyclic steady states of treaded rolling bodies

Author(s): Govindjee, S; Potter, T; Wilkening, J | Abstract: The analysis of spinning axisymmetric bodies undergoing finite deformation is useful for understanding the behavior of a wide variety of engineering systems - for example, rolling tires. However, progress beyond the axisymmetric case has been lacking. In this work, we present a methodology for the treatment of treaded rolling bodies by devising a Newton-Krylov shooting scheme for the computation of cyclic steady states of motion. The scheme advocated permits one to determine the entire transient (cyclically steady) motion of a spinning treaded body with consideration of viscoelasticity as well as contact. We demonstrate the viability of the method through three examples, (1) a viscoelastic cylinder with eight sinusoidal tread blocks, (2) a viscoelastic cylinder with 16 square tread blocks, and (3) a viscoelastic oval in which repeated contact and separation from a rigid plane excites distinct transient vibrational modes in the body during each cycle. For practical values of the viscoelastic relaxation time, the new approach is found to converge faster than the naive approach of evolving an initial guess over many cycles until a cyclic steady state is reached.