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The target of the activities described in the PhD thesis, fixed in collaboration with a motorsport racing team, with a high performance vehicle manufacturing company and with a tyre research and development technical centre is the development of a procedure able to estimate tyre interaction characteristics, reproducing them in simulation environments taking into account the fundamental friction and thermal phenomena concerning with tyre/road interaction. A first tool, called TRICK, has been developed with the aim to process data acquired from experimental test sessions, estimating tyre interaction forces and slip indices. Once characterized the vehicle, filtering and sensors output correction techniques have been employed on the available data, creating a robust procedure able to generate as an output a "virtual telemetry" and, following a specifically defined track driving routine, to provide tyre interaction experimental curves. TRICK virtual telemetry can be employed as an input for the second tool, TRIP-ID, developed with the aim to identify the parameters of a Pacejka Magic Formula tyre model. The advantage of this kind of procedure is the possibility to simulate the behaviour of a tyre without the bench characterizations provided by tyremakers, with the further benefit to reproduce the real interactions with road and the phenomena involved with it, commonly neglected in bench data. Among such phenomena, one of the most important is surely the effect that temperature induces on tyre performances, especially in racing applications. For this reason a specific model, called TRT, has been realized and characterized by means of proper thermodynamic tests, becoming a fundamental instrument for the simulation of a tyre behaviour as close to reality as possible. One of the most useful features provided by the model is the prediction of the so called "bulk temperature", recognized as directly linked with the tyre frictional performances. With the aim to analyse and understand the complex phenomena concerning with local contact between viscoelastic materials and rough surfaces, GrETA grip model has been developed. The main advantage to which the employment of the grip model conducts is constituted by the possibility to predict the variations induced by different tread compounds or soils on vehicle dynamics, leading to the definition of a setup able to optimise performances as a function of tyre the working conditions. The described models and procedures can cooperate, generating a many-sided and powerful instrument of analysis and simulation; the main features of the available employment solutions can be summarised as follows:  full geometric, thermodynamic, viscoelastic and structural characterization of tyres on which the analyses are focused;  estimation of the tyre interaction characteristic curves from experimental outdoor test data;  definition of a standard track driving procedure that employs tyres in multiple dynamic and thermal conditions;  identification of Pacejka Magic Formula tyre models parameters on the basis of the estimated tyre interaction characteristic curves;  estimation of surface, bulk and inner liner tyre temperatures for variable working conditions and real-time reproduction of tyre thermodynamic behaviour in simulation applications;  correlation of tyre thermal conditions with friction phenomena observable at the interface with road;  prediction of tyre frictional behaviour at tread compound and soil roughness variations;  modelling of tyre interaction by means of MF innovative formulations able to take into account grip and thermodynamic effects on vehicle dynamics;  definition of the optimal wheels and vehicle setup in order to provide the maximum possible performances improvement.
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... The tire dynamic behavior has to be considered from an early design stage as stability, comfort, handling, and noise, vibration, and harshness (NVH) performances depend on it. [1][2][3] On the other side, the characterization of the tire behavior is one of the toughest things because to provide a complete and precise insight on the tire entire working range, the tire should be tested with the measurement accuracy obtainable only in laboratory-controlled conditions and on the vehicle moving on the real road surface by means of an expensive instrumentation. 2,4 above parameters of the vehicle dynamics itself, as the sliding speed of the compound upon road granularity varying the excitation frequency of the stress distribution within the rubber viscoelastic material. ...
... [1][2][3] On the other side, the characterization of the tire behavior is one of the toughest things because to provide a complete and precise insight on the tire entire working range, the tire should be tested with the measurement accuracy obtainable only in laboratory-controlled conditions and on the vehicle moving on the real road surface by means of an expensive instrumentation. 2,4 above parameters of the vehicle dynamics itself, as the sliding speed of the compound upon road granularity varying the excitation frequency of the stress distribution within the rubber viscoelastic material. 6,7 It is worth to highlight that the majority of the test rigs analyze the tires on smooth surfaces and in steadystate conditions. ...
A tire is an extremely integrated and multi-physical system. From only a mechanical point of view, tires are represented by highly composite multi-layered structures, consisting of a multitude of different materials, synthesized in peculiar rubber matrices, to optimize both the performance and the life cycle. During the tire motion, due to the multi-material thermodynamic interaction within the viscoelastic tire rubber matrix, the dynamic characteristics of a tire may alter considerably. In the following paper, the multibody research comfort and handling tire model is presented. The main purpose of the research comfort and handling tire is to constitute a completely physical carcass infrastructure to correctly transmit the generalized forces and torques from the wheel spindle to the contact patch. The physical model structure is represented by a three-dimensional array of interconnected nodes by means of tension and rotational stiffness and damper elements, attached to the rim modeled as a rigid body. Research comfort and handling tire model purpose is to constitute a structural physical infrastructure for the co-implementation of additional physical modules taking into account the modification of the tire structural properties with temperature, tread viscoelastic compound characteristics, and wear degradation. At the stage, the research comfort and handling tire discrete model has been validated through both static and dynamic shaker test procedures. Static test procedure adopts contact sensitive films for the contact patch estimation at different load and internal pressure conditions, meanwhile the specifically developed sel test regards the tire dynamic characterization purpose at the current stage. The validation of the tire normal interaction in both static and dynamic conditions provided constitutes a necessary development step to the integration of the tangential brush interaction model for studying the handling dynamics and to the analysis of the model response on the uneven surfaces.
... operating and boundary conditions concerning kinematics, dynamics, temperature, pressure, road roughness, etc.) [8,9]. In such a scenario, tyre-road interaction models cover a fundamental role in the modelling of the vehicle system [10,11], due to the tyre's composite structure and intrinsic non-linearity linked to inter-connected multiphysical phenomena [12][13][14], which must guarantee very strict computational constraints to allow the employment in even more severe real-time environments concerning onboard estimation and control logics [15,16]. An overview of modelling approaches and research activities addressing the complexity concerning an accurate mathematical representation of the highly non-linear tyre behaviour has been described in [17,18], highlighting that the biggest challenge is to ensure the trade-off condition between the necessary level of accuracy and the low computational load. ...
To cite this article: Aleksandr Sakhnevych (2021): Multiphysical MF-based tyre modelling and parametrisation for vehicle setup and control strategies optimisation, Vehicle System Dynamics, ABSTRACT Starting from the earliest phases of design of the vehicle and its control systems, the understanding of tyres is of fundamental importance to govern the overall vehicle dynamics. A properly charac-terised tyre-road interaction model is essential to achieve a reliable vehicle dynamics model on which more design variations can be studied directly in simulation environment optimising both cost and time. The possibility to count on computationally efficient and reliable formulations represents nowadays a great advantage, and the multiphysical Pacejka's Magic Formula (MF-evo) tyre model presented is one of the best trade-off solutions to meet the strict real-time requirements and to reproduce multiphysical variations of the tyre dynamic behaviour towards temperature, pressure and wear effects. A specific methodology has been developed to characterise and to identify the MF-evo parameters with a high grade of accuracy and reliability directly from experimental data. The proposed technique is based on a pre-processing procedure to remove non-physical outliers and to cluster the data, which allows to optimise the multidimensional parameterisation process. To the purpose of validation of the parametrisation routine, data from a motorsport case, exceptionally difficult to reproduce in simulation due particularly significant variations of the tyre dynamics during a single test, have been employed demonstrating the MF-evo model potential and robustness. ARTICLE HISTORY
... In a second step the force characteristics of the tire road contact are parametrized. As this is very much dependent on surface and environmental conditions like ambient and track temperature, an optimization approach is used here, an example can be found in [10]. The result is an adaption of tire stiffness and grip properties to match the measured vehicle motion states vehicle side slip angle, yaw rate and longitudinal acceleration. ...
Racecar operation typically takes place in the near-limit range of the vehicle’s tires. Drivers attempt to exploit all of a vehicles potential to achieve the minimum possible laptime around a given circuit. As the vehicles will run on racetracks with varying characteristics and environmental conditions, racing cars are designed to offer a broad range of adjustability with respect to handling properties. Suspension parameters such and camber and toe, as well as aerodynamic parameters such as wing position are examples of commonly adjusted parameters on a racing vehicle. Since development time schedules are tight and ontrack testing time is limited, a virtual tuning process for vehicle parameters is required to remain competitive. Laptime Simulations are widely used to provide laptime prediction as well as insight into the sensitivity of lap time to vehicle parameters. For this reason, lap time simulation procedures for setup optimization are of special interest [1]. Due to the fact that these methods are purely virtual with no involvement of a human driver, it is likely that there are discrepancies between the predicted theoretical laptime and the laptime which is achieved by the driver-vehicle system in reality. The discrepancies between simulated and actual lap time can be attributed to many details, for example inaccurate component modelling or insufficient consideration of handling characteristics. The research found in this article will focus on the latter example.
... Furthermore, the dependence of the interaction between the tyre and the road on the tyre temperature can be described for extreme conditions using, for example, the tool TRICK (the name of which is derived from tyre-road interaction characterization and knowledge). 14,15 The method using the vehicle model does not allow separate characteristics to be obtained for the left tyres and the right tyres. The characteristics describe the lateral force acting on the axle (the sum of the forces acting on both wheels of the axle) as a function of not only the side-slip angle but also the dynamics of the curvilinear vehicle motion. ...
This paper presents a method of identifying the dynamic characteristics of tyres for non-steady-state conditions on the basis of road measurements on a vehicle. The side force acting on the tyre is presented as a function of not only the slip angle but also the slip angle derivative (i.e. the velocity of the change in the slip angle). Hence, the influence of the manoeuvre dynamics on the tyre characteristics and the difference between the characteristics obtained for steady-state conditions and the characteristics for non-steady-state conditions are shown. Also the results of computer simulations prepared for different types of tyre characteristics are presented in this paper. It is evident from the presented graphs that applying dynamic non-linear tyre characteristics for computer simulations instead of steady-state characteristics enables us to describe the real motion of a vehicle better.
... The input signal for these controllers is the error magnitude, while the output signal is the action which has to be carried out in order to minimize the error itself. In the tyre subsystem, an essential part of the whole vehicle model, an evolved MF set of equations [31] able to simulate the wheel behaviour has been introduced. In this subsystem it is possible to determine the tyres actual grip at any single time and to calculate the longitudinal and lateral interaction forces the tyre is able to perform. ...
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... To express the center of gravity's acceleration vector ‫ܩ‬ with respect to the LTP enu reference system it is necessary to implement a coordinate transformation, so all the calculations are performed in the absolute reference system. A crucial importance is assumed by the Euler Angles used since these highly affect the obtained accelerations in the ‫}ݖݕݔܩ{‬ reference system, and in turn the resulting velocities and sideslip angle [21]. ...
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Accurate measurement of the vehicle sideslip angle is fundamental to improve reliability of the vehicle dynamics control systems focused on stability and developed both for safety and performance optimization. Many experimental procedures to estimate the vehicle sideslip angle have been proposed in the last years, mainly based on GPS, INS and physical models. The aim of this paper is to compare different methods to estimate sideslip angle employing an instrumented vehicle, equipped with a system for data acquisition and time-synchronized storage capabilities, a stand-alone GPS, a GPS aided MEMS-based Attitude and Heading Reference System (AHRS) and specific sensors to collect data on the steering wheel angle and on the position of brake, throttle and clutch pedals. Further information is collected by capturing the available data at the OBD port of the vehicle. Data acquisitions (from all sensors) are synchronized by means of an external triggering signal. After driving sessions performed with specific manoeuvres in order to highlight the main phenomena concerned with the dynamic behaviour of the vehicle, the different estimation procedures have been applied, discussing on the advantages and the degree of reliability of each one of them.
The 3rd edition of The Science and Technology of Rubber provides a broad survey of elastomers with special emphasis on materials with a rubber-like elasticity. As in the 2nd edition, the emphasis remains on a unified treatment of the material; exploring topics from the chemical aspects such as elastomer synthesis and curing, through recent theoretical developments and characterization of equilibrium and dynamic properties, to the final applications of rubber, including tire engineering and manufacturing. Many advances have been made in polymer and elastomers research over the past ten years since the 2nd edition was published. Updated material stresses the continuous relationship between the ongoing research in synthesis, physics, structure and mechanics of rubber technology and industrial applications. Special attention is paid to recent advances in rubber-like elasticity theory and new processing techniques for elastomers. This new edition is comprised of 20% new material, including a new chapter on environmental issues and tire recycling.
Die Bedeutung der Reibung in unserem Alltag ist nicht zu unterschätzen. Vom Entfachen eines Feuers durch Aneinanderreiben von Stöckchen bis hin zu den heutigen Bemühungen, nanoelektromechanische Systeme herzustellen, hat die Reibung eine zentrale Rolle in der Technologieentwicklung der Menschheitsgeschichte gespielt. Reibung ist ein komplexes Phänomen, das sich auf vielen verschiedenen Längenskalen abspielt. Es hängt stark von den atomaren Wechselwirkungen innerhalb der Kontaktflächen, den makroskopischen elastischen und inelastischen Eigenschaften der Materialien sowie der unvermeidbaren stochastischen Rauigkeit realer Oberflächen ab. Trotz großer Fortschritte in der Tribologie -- der Reibungswissenschaft -- sind noch viele interessante Fragen offen. Diese Arbeit befasst sich unter Zuhilfenahme numerischer Methoden mit der Rolle der Oberflächenrauigkeit in der Tribologie auf den verschiedenen Längenskalen, von der atomaren bis zur makroskopischen Größenordnung. Wir haben verschiedene Aspekte der Kontakte rauer Oberflächen untersucht, zum Beispiel Adhäsions- und Reibungseigenschaften sowie die Leckströmungen von Flüssigkeiten an einer Dichtung. Außerdem haben wir wir das Benetzungsverhalten von Nanotröpfchen auf stochastisch rauen Oberflächen betrachtet. Für eine aussagekräftige Untersuchung der Mechanik des Kontaktes ist es notwendig, die Dicke des elastischen Materials vergleichbar mit der größten Wellenlänge der Oberflächenrauigkeit zu wählen. Obwohl man prinzipiell eine atomistische Beschreibung verwenden sollte, ist der numerische Aufwand bereits bei kleinen Systemen zu hoch. Deshalb haben wir eine Multiskalen-Molekulardynamik-Methode entwickelt, bei der wir eine atomistische Beschreibung nur in den kritischen Regionen, nämlich in den Nanokontakten und an der Oberfläche, verwenden; in den übrigen Gebiete wird die Physik der langreichweitigen elastischen Response durch ein gröberes Modell wiedergegeben. Die Kontaktfläche und die Grenzflächenseparation werden als Funktion des auf das System ausgeübten Drucks ohne und mit Adhäsion analysiert. Die tatsächliche Kontaktfläche beeinflusst die Reibungs- und Hafteigenschaften und die Abnutzung entscheidend. Die Grenzflächenseparation ist dagegen verantwortlich für Effekte wie die Kapilarität, optische Interferenz und die Leckrate einer Abdichtung. Durch numerische Simulationen konnten wir zeigen, dass bei kleinem Druck und ohne anziehende Wechselwirkung die effektive Kontaktfläche linear vom angewandten Druck abhängt, während die Grenzflächenseparation logarithmisch von diesem abhängt. Ferner haben wir das Gleiten von elastischen Materialien mit adhäsivem Kontakt bei glatten und rauen Oberflächen untersucht. Dabei haben wir eine starke Abhängigkeit der Gleitreibung vom Elastizitätsmodul festgestellt; dies ist eine der Hauptursachen der Gleitinstabilität. Bei elastisch harten Materialien mit glatten Oberflächen und inkommensurablen Gitterstrukturen beobachteten wir eine extrem niedrige Reibung (superlubricity), die bei sinkendem Elastizitätsmodul des Festkörpers abrupt ansteigt. Dieser Effekt wird allerdings schon durch eine kleine Oberflächenrauigkeit oder durch eine geringe Konzentration eines Adsorbats zerstört. Des weiteren haben wir das Benetzungsverhalten von Nanotröpfchen auf rauen hydrophilen wie hydrophoben Oberflächen untersucht. Dieses Problem ist relevant in der Nanoelektromechanik und der Nanofluiddynamik, die beide von großem aktuellen Interesse sind. Aufgrund thermischer Fluktuationen wurde für Nanotröpfchen auf hydrophoben Oberflächen keine Berührungswinkel-Hysterese gefunden. Der Kontaktwinkel steigt mit der mittleren quadratische Abweichung der Rauigkeit der Oberfläche und ist nahezu unabhängig von ihrer fraktalen Dimension. Wir konnten feststellen, dass thermische Fluktuationen auf der Nanoebene sehr wichtig sind. Auf hydrophilen Oberflächen ist die thermische Fluktuation allerdings nicht ausreichend, um die Hysterese des Kontaktwinkels zu beseitigen.
The paper presents an analysis of tangential interaction between flexural properties of tyres and frictional properties of the tyre-road interface. Using simple models to represent tyre structure and friction, the traction-slip characteristics are derived for various situations of practical interest: a standing tyre subjected to monotonic and oscillatory loading, a stationary rolling tyre and especially that of the transition from standing to steady rolling. To gain deeper insight into the requirements for modelling flexural and the complex friction properties, the study examines the influence of the normal pressure profile, tyre structural properties and friction in the contact region on the overall and detailed characteristics of tyre traction. The analysis presented serves as a basic framework for modelling the complex tyre-road interactions such as that encountered in the snap-start problem of road vehicles.
Filling the gaps between subjective vehicle assessment, classical vehicle dynamics and computer-based multibody approaches, The Multibody Systems Approach to Vehicle Dynamics offers unique coverage of both the virtual and practical aspects of vehicle dynamics from concept design to system analysis and handling development. The book provides valuable foundation knowledge of vehicle dynamics as well as drawing on laboratory studies, test-track work, and finished vehicle applications to gel theory with practical examples and observations. Combined with insights into the capabilities and limitations of multibody simulation, this comprehensive mix provides the background understanding, practical reality and simulation know-how needed to make and interpret useful models. New to this edition you will find coverage of the latest tire models, changes to the modeling of light commercial vehicles, developments in active safety systems, torque vectoring, and examples in AView, as well as updates to theory, simulation, and modeling techniques throughout. © 2015 Michael Blundell and Damian Harty. Published by Elsevier Ltd. All rights reserved.
A new 3D mathematical-physical tire model is presented. This model considers not only the handling behavior of the tire but also its comfort characteristics, i.e., the dynamic properties in the lateral and the vertical planes. This model can be divided into two parts, the structural model and the contact area model. The structural parameters are identified by comparison with frequency responses of a 3D finite element model of the tire, whereas the contact parameters are directly calculated with a finite element model of the tread pattern. The 3D physical model allows predicting both steady state and transient behavior of the tire without the need of any experimental tests on the tire. The steady state analysis allows obtaining the friction circle diagram, i.e., the plot of the lateral force against the longitudinal force for different slip angles and for longitudinal slip, and the Gough plot, i.e., the diagram of the self-aligning torque versus the lateral force. The transient analysis allows obtaining the dynamic behavior of the tire for any maneuver given to the wheel. Among its outputs there are the relaxation length and the dynamic forces and torque transmitted to the suspension of the vehicle. Combining the tire model with the vehicle model it is possible to perform any kind of maneuver such as overtaking, changing of lane and steering pad at growing speed with or without braking, or accelerating. Therefore the 3D tire model can be seen as a powerful tool to optimize the tire characteristics through a sensitivity analysis performed with tire and vehicle models linked to each other without the need of building prototypes. Some preliminary comparisons with experimental data have been carried out.
This paper addresses the systematic procedure using sequential approach for the analysis of the coupled thermo-mechanical behavior of a steady rolling tire. Not only the knowledge of mechanical stresses but also of the temperature loading in a rolling tire are very important because material damage and material properties are significantly affected by the temperature. In general, the thermo-mechanical behavior of a pneumatic tire is highly complex transient phenomenon that requires the solution of a dynamic nonlinear coupled themoviscoelasticity problem with heat source resulting from internal dissipation and friction. In this paper, a sequential approach, with effective calculation schemes, to modeling this system is presented in order to predict the temperature distribution with reasonable sccuracies in a steady state rolling tire. This approach has the three major analysis modules-deformation, dissipation, and thermal modules. In the dissipation module, an analytic method for the calculation of the heat source in a rolling tire is established using viscoelastic theory. For the verification of the calculated temperature profiles and rolling resistance at different velocities, they were compared with the measured ones.