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Real Time Thermo Racing Tyre Model
Abstract
New structure elements have been developed and implemented in the TRT thermo-dynamic tyre model. The updated model aims to provide a complete tool to study and understand all the phenomena concerning the tyre behaviour in thermal transient conditions, since all the elements constituting its structure are modelled. The computational cost, connected to a more complex model to manage, has been decreased by simplifying the mesh of the previous model version and, thus, by reducing the state vector length so making it suitable for real time analyses.
... A completely physical multibody structure, at the base of the RCH-tire model, becomes completely necessary when it comes to archive the goal of obtaining the interaction output in terms of velocity and pressure local distribution within the dynamic contact patch. 37 Once the physical structural model has been properly characterized and validated by means of specifically designed static and dynamic tests, 38,39 the aim of the RCH-tire model is to represent a physical infrastructure for interconnected physical phenomena (tread viscoelastic characteristics, thermal dynamics influence, road and wear impact influence), where the tire stiffness and compound properties can vary considerably depending on the thermal state, boundary and working conditions, and the wear degradation progress. ...
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.
The purposes of this research are to formulate the equations of motion of a flexible two-link system, to develop computational codes by a finite-element method in order to perform dynamics simulations with vibration control, to propose an effective control scheme and to confirm the calculated results by experiments of a flexible two-link manipulator. The system used in this paper consists of two aluminum beams as flexible links, two clamp-parts, two servo motors to rotate the links and a piezoelectric actuator to control vibration. Computational codes on time history responses, FFT (Fast Fourier Transform) processing and eigenvalues - eigenvectors analysis were developed to calculate the dynamic behavior of the links. Furthermore, a control scheme using a piezoelectric actuator was designed to suppress the vibration. A proportional-derivative (PD) control was designed and demonstrated its performances. The system and the proposed control scheme were confirmed through experiments. The calculated and experimental results revealed that the vibration of the flexible two-link manipulator can be controlled effectively.
In the paper new structure elements have been developed and implemented in the already-existing TRT thermo-dynamic tyre model. The updated model aims to provide a complete tool to study and understand all the phenomena concerning the tyre in thermal transient conditions, since all the elements constituting its structure are finally modelled. The computational cost, connected to a more complex model to manage, was decreased by simplifying the mesh of the previous version of the model and, thus, by reducing the state vector length.
Heat and vapour convective surface coefficients are required in practically all heat and vapour transport calculations. In building envelope research, such coefficients are often assumed constants for a set of conditions. Heat transfer surface coefficients are often determined using empirical correlations based on measurements of different geometry and flows. Vapour transfer surface coefficients have been measured for some specific conditions, but more often, they are determined with the Chilton-Colburn analogy using known heat transfer coefficients. This analogy breaks down when radiation and sources of heat and moisture are included. Experiments have reported differences up to 300%. In this paper, the heat transfer process in the boundary layer is examined using Computational Fluid Dynamics (CFD) for laminar and turbulent air flows. The feasibility and accuracy of using CFD to calculate convective heat transfer coefficients is examined. A grid sensitivity analysis is performed for the CFD solutions, and Richardson Extrapolation is used to determine the grid independent solutions for the convective heat transfer coefficients. The coefficients are validated using empirical, semi-empirical and/or analytical solutions. CFD is found to be an accurate method of predicting heat transfer for the cases studied in this paper. For the laminar forced convection simulations the convective heat transfer coefficients differed from analytical values by ±0.5%. Results for the turbulent forced convection cases had good agreement with universal law-of-the-wall theory and with correlations from literature. Wall functions used to describe boundary layer heat transfer for the turbulent cases are found to be inaccurate for thermally developing regions.
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THE MORE YOU KNOW VEHICLE DYNAMICS, THE MORE YOU'LL BE SURPRISED
Vehicle dynamics is often perceived as a quite intuitive subject. As a matter of fact, lots of people are able to drive a car. Nevertheless, without a rigorous mathematical formulation it is very difficult to truly understand the physical phenomena involved in the motion of a road vehicle.
In this book, mathematical models of vehicles are developed, always paying attention to state the relevant assumptions and to provide explanations for each step. This approach allows for a deep, yet simple, analysis of the dynamics of vehicles, without having to resort to foggy concepts. The reader will soon achieve a clear understanding of the subject, which will be of great help both in dealing with the challenges of designing and testing new vehicles and in tackling new research topics.
However, there is much more than that. Quite surprisingly, it is shown that several classical concepts, such as the understeer gradient or the roll axis, are either wrong or inadequate and need to be replaced.
The book covers handling and performance of both road and race cars. A new approach, called MAP (Map of Achievable Performance), is presented and thoroughly discussed. It provides a global and intuitive picture of the handling features of a vehicle. Moreover, the book also deals with several relevant topics in vehicle dynamics that have never been discussed before. Even very experienced people should find the book interesting and stimulating.
This new book is not a translation of the Italian Dinamica del Veicolo; by the same author. Actually, in some sense, this new book is totally different, with new topics and with new points of view for the topics covered in the Italian book as well.
In the paper a new physical tyre thermal model is presented. The model, called Thermo Racing Tyre (TRT) was developed in collaboration between the Department of Industrial Engineering of the University of Naples Federico II and a top ranking motorsport team.
The model is three-dimensional and takes into account all the heat flows and the generative terms occurring in a tyre. The cooling to the track and to external air and the heat flows inside the system are modelled.
Regarding the generative terms, in addition to the friction energy developed in the contact patch, the strain
energy loss is evaluated. The model inputs come out from telemetry data, while its thermodynamic parameters come either from literature or from dedicated experimental tests.
The model gives in output the temperature circumferential distribution in the different tyre layers (surface,
bulk, inner liner), as well as all the heat flows.
These information have been used also in interaction models in order to estimate local grip value.
In this paper an experimental test rig aimed to characterize mechanical properties of a pneumatic tyre, together with some results, is presented.
The objective is to determine tyre mechanical characteristics useful to physically model its behaviour; in particular: the normal interaction characteristic, the radial stiffness, the total stiffness and the longitudinal hysteretic cycles.
To this aim two different kind of tests have been executed: radial and longitudinal.
In the radial test the load is statically applied to the tyre, along the vertical direction, by means of an hydraulic press and it is measured together with the consequent radial deformation, so allowing the estimation of the tyre normal interaction characteristic and of its radial stiffness. Different radial tests can be conducted for an assigned tyre varying the inflation pressure.
The longitudinal tests are conducted applying, under an assigned constant vertical load, a variable horizontal strain to the tyre by means of a linear actuator, two profile rail guides and a system to transfer the horizontal motion to the contact patch of the tyre, opportunely placed on a moving steel plate placed on the two linear guide rails. During the tests the horizontal load and the resulting deformations are measured and acquired so allowing the estimation of tyre total stiffness and of its longitudinal hysteretic cycles.
Longitudinal tests can be conducted varying the assigned vertical load, the horizontal displacement law in terms of frequency and amplitude, the tyre inflation pressure.
All the different types of rim can be mounted on the test rig thanks to a universal quick flange.
A new technique for the determination of the thermal diffusivity of a tyre compound is proposed. The diffusivity is defined as the ratio between the thermal conductivity and the product of the specific heat and density. This technique is based on infrared measurement and successive analysis of the tyre cooling. Tyre samples were heated up by a laser at constant power rate and the heating and the next cooling of the tyres were registered versus time by mean of thermocouples and infrared cameras. Determination of the thermal diffusivity was thus estimated by mean of home-made model. The research activity was carried out in the laboratories of the department of Mechanics and Energetics of the University of Naples Federico II, in cooperation with the Combustion Institute of the CNR in Naples.
The tyre is the integral part of the vehicle that transmits all normal and tangential forces between the vehicle and the road. The tyre tread block is the only tyre component that is in direct contact with the road surface and is thus of special interest. However, the contact situation between the tyre and the road is a very complex one, and therefore all its details are usually unknown. The Institute of Dynamics and Vibration Research at Leibniz University Hanover investigates the local contact phenomena in the tyre/road contact and developed a modular model that describes the dynamic behaviour of tyre tread blocks, taking into account the contact effects.
The tyre is the integral part of the vehicle that transmits all normal and tangential forces between the vehicle and the road. The tyre tread block is the only tyre component that is in direct contact with the road surface and is thus of special interest. However, the con- tact situation between the tyre and the road is a very complex one, and therefore all its details are usually unknown. The Institute of Dynamics and Vibration Research at Leibniz University Hanover investigates the local contact phenomena in the tyre/road contact and developed a modular model that describes the dynamic behaviour of tyre tread blocks, taking into account the contact effects.
The evolution of pneumatic tires has been alongside the evolution of the automobiles. The demand of the modern automotive industry has been driving the tire industry to come with high performance tire. The tire construction and geometry are very complex in nature especially tire design and stress analysis are very dif f icult. The study of tire perf ormance and def ormation are very challenging owing to the non-linearity associated with geometry as well as composition of material. The tire material is a cord-rubber composite, its properties anisotropic in nature. Failure analysis of cord-reinf orced rubber composite tires may be useful to predict the lif etime of a tire. In this background, the present attempt is to analyze the tire using artif icial neural network. The shear modulus and the temperature are measured against various f requencies. The above properties are analysed using artificial neural network. The study has been undertaken using MATLAB sof tware. The results were compared with those of dynamic moduli master curves obtained through f requency-temperature reduction of data measured by a commercial dynamic mechanical thermal analyser (DMTA), by scanning temperature at various f requencies in the range 0.3-30 Hz. The results obtained by DMTA are trained in the Neural Network. Very good agreement of the data obtained by the two diff erent approaches was f ound.
Currently used tire models have shown a certain lack of accuracy in some advanced handling applications. This lack of accuracy is believed to be partly due to thermal effects. In reality, the tire rubber temperature is not constant during the normal operating conditions and it's really well known that the tire friction coefficient strongly depends on the temperature level. The temperature generation, propagation and evolution are the result of a dynamic energy equilibrium between phenomena of different natures. Various mechanisms create a non-uniform temperature distribution in various parts of the tire structure: heat is generated in zones with large cyclic deformations due to the energy dissipated from the rubber strains and in the sliding part of the contact patch due to friction. The rubber cools down because the heat energy transferred to the air (internally and externally) and to the asphalt in the stick zone of the contact patch. The presented thermodynamic tire model allows for the simulation of all these local thermal phenomena and the thermal energy equilibrium is described by the Fourier diffusion equation solved with a finite volume approach. Furthermore the described thermal model is coupled with the structural MBD tire model ‘CDTire/3D’ and with an enhanced magic formula (MF) formulation. The coupling strategy naturally incorporates the structural tire model, while in the case of the MF model some empirical adaptations are needed. Both tire models' behavior is influenced by the local calculated temperature, e.g. by modifying the local friction of the tread/asphalt contact. One result the model clearly shows is the variation of the road holding performance as a consequence of the temperature evolution. The capabilities of the overall model are demonstrated and validated in some illustrative scenarios by using measured date from motorsport applications.
This paper deals with the frictional behaviour of a tyre tread elementary volume in sliding contact with road asperities. Friction is supposed as composed by two main components: adhesion and deforming hysteresis. The target, fixed in collaboration with a motorsport racing team and with a tyre manufacturing company, is to provide an estimation of local grip for on-line analyses and real time simulations and to evaluate and predict adhesive and hysteretic frictional contributions arising at the interface between tyre tread and road. A way to approximate asperities, based on rugosimetric analyses on macro and micro scale, has been introduced. The adhesive component of friction has been estimated by means of a new approach based on two different models found in literature, whose parameters have been identified thanks to a wide experimental campaign previously carried out. The hysteretic component of friction has been estimated by means of an energy balance taking into account rubber viscoelastic behaviour, characterized by means of proper DMA tests, and internal stress / strain distribution due to indentation with road. Model results are finally shown and discussed and the validation experimental procedure is described. The correct reproduction of friction phenomenology and the model prediction capabilities are highlighted making particular reference to grip variability due to changes in working conditions.
PRINCIPLES OF HEAT TRANSFER was first published in 1959, and since then it has grown to be considered a classic within the field, setting the standards for coverage and organization within all other Heat Transfer texts. The book is designed for a one-semester course in heat transfer at the junior or senior level, however, flexibility in pedagogy has been provided. Following several recommendations of the ASME Committee on Heat Transfer Education, Kreith, Manglik, and Bohn present relevant and stimulating content in this fresh and comprehensive approach to heat transfer, acknowledging that in today's world classical mathematical solutions to heat transfer problems are often less influential than computational analysis. This acknowledgement is met with the emphasize that students must still learn to appreciate both the physics and the elegance of simple mathematics in addressing complex phenomena, aiming at presenting the principles of heat transfer both within the framework of classical mathematics and empirical correlations.
This book attempts to find a middle ground by balancing engineering principles and equations of use to every automotive engineer with practical explanations of the mechanics involved, so that those without a formal engineering degree can still comprehend and use most of the principles discussed. Either as an introductory text or a practical professional overview, this book is an ideal reference.
Analyses have shown that the thermal state of a tire is influenced by both the size of and variation in the value of the convective heat transfer coefficient at the tire surface. In the work reported here, a test facility was constructed to permit the determination of convective heat transfer coefficients under a broad range of operating conditions. Data were obtained to show the effects of air speed, boundary layer thickness and turbulence level, humidity, tire surface contamination, tire surface roughness and unevenness, and tire surface wetness on convective heat transfer coefficients. The significance of these results to tire power loss is discussed.
This paper presents an industrial application of simulation-based optimization (SBO) in the scheduling and real-time rescheduling of a complex machining line in an automotive manufacturer in Sweden. Apart from generating schedules that are robust and adaptive, the scheduler must be able to carry out rescheduling in real time in order to cope with the system uncertainty effectively. A real-time scheduling system is therefore needed to support not only the work of the production planner but also the operators on the shop floor by re-generating feasible schedules when required. This paper describes such a real-time scheduling system, which is in essence a SBO system integrated with the shop floor database system. The scheduling system, called OPTIMISE scheduling system (OSS), uses real-time data from the production line and sends back expert suggestions directly to the operators through Personal Digital Assistants (PDAs). The user interface helps in generating new schedules and enables the users to easily monitor the production progress through visualization of production status and allows them to forecast and display target performance measures. Initial results from this industrial application have shown that such a novel scheduling system can help both in improving the line throughput efficiently and simultaneously supporting real-time decision making.
The Real-Time Concurrent Constraint Programming Calculus (rtcc) is a model of concurrency developed to specify systems with real-time behaviour. In this paper we provide the complete operational semantics of this calculus.
A study on fluid dynamic properties of a passenger tyre tube by using CFD
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Principles of Heat Transfer
- F Kreith
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F. Kreith, R. M. Manglik and M. S. Bohn, "Principles of Heat Transfer".
6 th ed. Brooks/Cole USA, 2010
Tyre/road friction modeling
- R Van Der Steen
R. Van der Steen, "Tyre/Road Friction Modeling", Ph.D. Thesis,
Eindhoven University of Technology, 2007.
Determination of surface convective heat transfer coefficients by CFD
- D Derome
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- J Carmeliet
D. Derome, B. Blocken, J. Carmeliet, "Determination of surface
convective heat transfer coefficients by CFD", 11th Canadian Conference
on Building Science and Technology, Banff, Alberta, 2007.
A full thermomechanical tire model for advanced handling applications
- F Calabrese
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F. Calabrese, M. Baecker, C. Galbally and A. Gallrein, "A full thermomechanical tire model for advanced handling applications", SAE 2015
World Congress, Detroit, USA, 2015.