Magistrantūros studijų baigiamajame darbe pateikiami padangų riedėjimo pasipriešinimo, lauko sąlygomis, tyrimo duomenys, esant skirtingiems atraminio paviršiaus tipams (pieva, ražiena, sausas žvyrkelis), įvairioms padangų vertikalioms apkrovoms (nuo 1,4 kN iki 5,9 kN) bei skirtingiems oro slėgiams padangoje (nuo 0,5 bar iki 2,0 bar). Darbo objektas – padangos riedėjimo pasipriešinimo koeficientas, jo reikšmės kitimas, esant skirtingiems padangos, apkrovos, ir atraminio paviršiaus parametrams. Tyrimas atliktas naudojant BELCHINA 7.50L – 16 ФБел – 253 padangą. Darbo metodai: padangos tyrimams atlikti buvo suprojektuotas ir pagamintas mobilus stendas, kuris buvo tvirtinamas prie savaeigės važiuoklės T–16M. Darbo rezultatai. Oro slėgis padangoje ir vertikalios apkrovos dydis turėjo įtakos riedėjimo pasipriešinimo koeficiento reikšmių kaitai, esant skirtingiems atraminiams paviršiams (pievoje, ražienoje, sausame žvyrkelyje). Mažinant padangos slėgį riedėjimo pasipriešinimo jėga yra tiesiogiai proporcinga vertikalios apkrovos jėgai ir atvirkščiai proporcinga slėgiui padangoje. Pievoje mažiausia riedėjimo pasipriešinimo jėgos Fp reikšmė gauta esant 1,0 bar slėgiui ir padangą apkrovus 1,4 kN vertikalia apkrova (Fp = 14,375 kN). Ražienoje – esant 0,5 bar slėgiui padangoje, ir 1,4 kN vertikaliai apkrovai (Fp = 22,283 kN). Bandymą atliekant ant žvyrkelio – minimali riedėjimo pasipriešinimo jėgos Fp reikšmė buvo tada, kai padangą veikė 1,4 kN vertikali apkrova ir oro slėgis... [toliau žr. visą tekstą] / The Master’s thesis presents findings of the study of tire rolling resistance under field conditions with different types of support surfaces (grassland, stubble, dry gravel-road), different vertical loads of tires (from 1.4 kN to 5.9 kN) and different air pressures in a tire (from 0.5 bar to 2.0 bar). Object of the thesis – tire rolling resistance coefficient f, change of its values with different parameters of a tire, load and support surface. The study was carried out using the tire BELCHINA 7.50L – 16 ФБел – 253. Methods of the thesis: in order to carry out the tire study, mobile stand was designed and manufactured and attached to self-propelled chassis T – 16M. Results of the thesis. Air pressure in the tire and the value of vertical load influenced the change of rolling resistance coefficient with different support surfaces (grassland, stubble, dry gravel-road). At the tire pressure being decreased, the rolling resistance force was directly proportional to the force of vertical load and is inversely proportional to pressure in the tire. The lowest value of rolling resistance force Fp on grassland was obtained at the pressure of 1,0 bar and vertical load of 1,4 kN on the tire (Fp = 14,375 kN). On stubble – at the pressure of 0,5 bar in the tire and vertical load of 1,4 kN (Fp = 22,283 kN). When the test was performed on dry gravel-road, the minimal value of rolling resistance force Fp was when the tire was affected by vertical load of 1,4 kN and air pressure in the... [to full text]

O pneu é o único vínculo entre o veículo e o solo, é ele que transmite toda a potência e carga, e garante a dirigibilidade e condução do automóvel. A estrutura resistente de um pneu é um dos pontos de maior importância para o rendimento, tipo de aplicação e segurança. E conhecê-la é condição primária para o projeto. Pneus convencionais, via de regra, apresentam uma estrutura par de lonas cruzadas (cross-ply), dispostas em ângulos opostos, menores que 90º. Este trabalho visa avaliar as influências de uma estrutura ímpar de lonas cruzadas, em pneus convencionais. Objetiva-se com isso uma redução na matéria prima e uma otimização no tempo de processo. As influências da estrutura ímpar foram verificadas através de uma análise de elementos finitos, examinando o andamento das tensões internas na carcaça do pneu e observando a geometria da região de contato pneu/solo. Verificou-se também a variação da uniformidade utilizando-se do ensaio SAE J332 em uma máquina Akron FD90. A utilização de uma estrutura ímpar, em pneus de lonas cruzadas, acarreta numa deformação na região de contato pneu/solo, devido ao desbalanceamento de tensões nos fios da carcaça, um aumento das componentes de ply-steer e uma variação de força lateral nas componentes dinâmicas avaliadas. A utilização de uma estrutura ímpar deve ser cuidadosamente selecionada dependendo da velocidade, severidade e condições de utilização. / The tire is the only bond between the vehicle and the ground, is it that transmits all the power and load, and guarantees the driven and conduction of the automobile. The resistant structure of a tire is one of the most important factors for the efficiency, type of application and security. Knowing these parameters is the primary condition to design a tire. Conventional tires, usually have a pair structure, made of crossed plies (cross-ply) in opposite angles lesser than 90º. The present work aim to evaluate the influence of an odd cross-ply structure, in conventional tires, looking forward to a material reduction and also an optimization on time process. The influence of an odd structure was evaluated through a finite element analysis, examining the cord stress at the tire carcass and the tire/ground contact region (foot-print). The variation of the uniformity was also verified through a SAE332 test did on Akron FD90 machine. It was observed that the use of an odd structure in cross-ply tires cause a tire/ground contact region deformation, because of the unbalance internal cord stress (at the carcass), and an increase of uniformities components (ply-steer and variation of lateral force). The use of an odd structure must be carefully selected, depending on the speed, severity and condition of use.

The main goal of this thesis is to obtain lateral parameters of the Magic Formula tire model of a tire commonly used in Formula Student competition. Both the author and the supervisor of the thesis know the tire name and its specification, but the research company that did the tire testing and provided me with the date prohibits sharing this of data publicly, so the tire designation is not mentioned in this thesis. The first chapter covers main theoretical facts related to a tire, briefly describes some of the tire models and shows possibilities how to determine tire characteristics that are used in a tire model. The thesis describes how to process raw tire data measured during a laboratory experiment using scripts created in Matlab software. The inputs variables are slip angle, lateral force, normal force and inclination angle. Raw data are splitted into parts, main coefficients of the Magic formula model (B, C, D, E, Sh, Sv) are calculated and subsequently the lateral parameters are obtained using least square method to fit parameters into the measured data. The works gives two main outcomes. The first output is a set of Matlab scripts that can be used to determine lateral parameters of any tire that has the same input data format as presented. A TIR file of the Formula Student tire in case of lateral slip is the second result of the work. This can be used for vehicle dynamics simulation of Formula Student racing car. The thesis also offers a comparison between parameters, which I calculated, and those gained thanks to Optimum Tire software by Calspan research company. Additionally the work shows the effect of load and inclination angle on lateral force.

Tires, being the only component of the vehicle in contact with the road surface, are responsible for generating the forces for maintaining the vehicle pose, orientation and stability of the vehicle. Additionally, the on-board advanced chassis control systems require estimation of these tire-road interaction properties for their operation. Extraction of these properties becomes extremely important in handling limit maneuvers such as Double Lane Change (DLC) and cornering wherein the lateral force transfer is dependent upon these computations. This research focuses on the development of a high-fidelity vehicle-tire model and control algorithm framework for vehicle trajectory tracking for vehicles operating in this limit handling regime. This combined vehicle-tire model places an emphasis on the lateral dynamics of the vehicle by integrating the effects of relaxation length on the contact patch force generation. The vertical dynamics of the vehicle have also been analyzed, and a novel double damper has been mathematically modeled and experimentally validated. Different control algorithms, both classical and machine learning-based, have been developed for optimizing this vertical dynamics model. Experimental data has been collected by instrumenting a vehicle with in-tire accelerometers, IMU, GPS, and encoders for slalom and lane change maneuvers. Different state estimation techniques have been developed to predict the vehicle side slip angle, tire slip angle, and normal load to further assist the developed vehicle-tire model. To make the entire framework more robust, Machine Learning algorithms have been developed to classify between different levels of tire wear. The effect of tire tread wear on the pneumatic trail of the tire has been further evaluated, which affects the aligning moment and lateral force generation. Finally, a Model Predictive Control (MPC) framework has been developed to compare the performance between the conventional vehicle models and the developed vehicle models in tracking a reference trajectory. / Doctor of Philosophy / In our rapidly advancing world, self-driving or autonomous vehicles are no longer a vision of the future but a reality of today. As we grow more reliant on these vehicles, ensuring their safety and reliability becomes increasingly critical. Unlike traditional vehicles, self-driving cars operate without human intervention. Consequently, the onus of passenger and pedestrian safety falls squarely on the vehicle's control systems. The efficiency and effectiveness of these control systems are pivotal in preventing accidents and ensuring a smooth ride. One vital aspect of these control systems lies in understanding the tires' behavior, the only parts of the vehicle that are in contact with the road surface. A tire's interaction with the road surface significantly impacts the vehicle's handling and stability. Information such as how much of the tire is in contact with the road, the forces and moments generated at this contact point, becomes valuable for optimizing the vehicle's performance. This is particularly crucial when a vehicle is turning or cornering, where the forces developed between the tires and the road are key to maintaining control and stability. In this research, a framework has been designed to improve the vehicle performance, primarily by improving the modeling of tire lag dynamics. This refers to the delay or 'lag' between a change in tire conditions (such as pressure, wear, and temperature) and the corresponding change in tire behavior. In addition, in this research a vertical dynamics model of the vehicle has also been developed incorporated with a novel double damper suspension system. To complete the entire framework, the effect of tire wear over time and how this affects its performance and safety characteristics has also been examined. By estimating and understanding this wear, we can predict how it will affect the dynamic properties of the tire, thus improving the reliability and efficiency of our autonomous vehicles. The last piece of this framework comprises the development of an MPC controller to track a reference trajectory and evaluate the performance of the developed model.

Our society is heavily and intrinsically dependent on energy transformation and usage. In a world scenario where resources are being depleted while their demand is increasing, it is crucial to optimize every process. During the last decade the concept of energy efficiency has become a leitmotif in several fields and has directly influenced our everyday life: from light bulbs to airplane turbines, there has been a general shift from pure performance to better efficiency. In this vein, we focus on the mobility and tractive efficiency of off-road vehicles. These vehicles are adopted in military, agriculture, construction, exploration, recreation, and mining applications and are intended to operate on soft, deformable terrain. The performance of off-road vehicles is deeply influenced by the tire-soil interaction mechanism. Soft soil can drastically reduce the traction performance of tires up to the point of making motion impossible. In this study, a tire model able to predict the performance of rigid wheels and flexible tires is developed. The model follows a semi-empirical approach for steady-state conditions and predicts basic features, such as the drawbar pull, the driving torque and the lateral force, as well as complex behaviors, such as the slip-sinkage phenomenon and the multi-pass effect. The tractive efficiency of different tire-soil configurations is simulated and discussed. To investigate the handling and the traction efficiency, the tire model is implemented into a four-wheel vehicle model. Several tire geometries, vehicle configurations (FWD, RWD, AWD), soil types, and terrain profiles are considered to evaluate the performance under different simulation scenarios. The simulation environment represents an effective tool to realistically analyze the impact of tire parameters (size, inflation pressure) and torque distribution on the energy efficiency. It is verified that larger tires and decreased inflation pressure generally provide better traction and energy efficiency (under steady-state working conditions). The torque distribution strategy between the axles deeply affects the traction and the efficiency: the two variables can't clearly be maximized at the same time and a trade-off has to be found. / Ph. D.

Tire-pavement interaction is a dominant noise source for passenger cars and trucks above 25 mph (40 km/h) and 43 mph (70 km/h), respectively. For the same pavement, tires with different tread pattern and construction generate noise of different levels and frequencies. In the present study, forty-two different tires were tested over a range of speeds (45-65 mph, i.e., 72-105 km/h) on a non-porous asphalt pavement (a section of U.S. Route 460, both eastbound and westbound). An On-Board Sound Intensity (OBSI) system was instrumented on the test vehicle to collect the tire noise data at both the leading and trailing edge of the tire contact patch. An optical sensor recording the once-per-revolution signal of the wheel was also installed to monitor the vehicle speed and, more importantly, to provide the data needed to perform the order tracking analysis in order to break down the tire noise into two components. These two components are: the tread pattern and the non-tread pattern noise. Based on the experimental noise data collected, two artificial neural networks (ANN) were developed to predict the tread pattern (ANN1) and the non-tread pattern noise (ANN2) components, separately. The inputs of ANN1 are the coherent tread profile spectrum and the air volume velocity spectrum calculated from the digitized 3D tread pattern. The inputs of ANN2 are the tire size and tread rubber hardness. The vehicle speed is also included as input for the two ANN's. The optimized ANN's are able to predict the tire-pavement interaction noise well for different tires on the pavement tested. Another outcome of this work is the complete literature review on Tire-Pavement Interaction Noise (TPIN), as an appendix of this dissertation and covering ~1000 references, which might be the most comprehensive compilation of this topic. / PHD / A lot of people think the car noise is mostly from the engine, exhaust, or wind. However, this is not true. The noise in the exterior mainly comes from tires at over 25 mph. At normal highway speed, e.g., 60 mph, tire noise contributes over 70% of total noise. A quiet tire is desired for driving comfort. A number of attempts to reduce tire noise have been made in tire industries, including the tread pattern optimization and the tire structure design. In this work, a model was developed to predict the tire noise based on the tread pattern, tire size, tread rubber hardness, and vehicle speed. The model is called Artificial Neural Network Model of Tire-Pavement Interaction Noise (ANN Model of TPIN, or AMOT). This model is able to predict the noise contributions from the tread pattern and the pavement separately. Tire companies can use the model to design quite tires while customers can have an insight on choosing quite tires based on the tread patterns and/or tire structure.

The contact between the tire and the road is the key enabler of vehicle acceleration, deceleration and steering. However, under the circumstances of sudden changes to the road conditions, the driver`s ability to maintain control of the vehicle maybe at risk. In many cases, this requires intervention from the chassis control systems onboard the vehicle. Although these systems perform well in a variety of situations, their performance can be improved if a real-time estimate of the tire-road contact parameters (ranging from kinematic conditions of the tire to its dynamic properties) are available. At the present stage of development, tire-road contact parameters are indirectly estimated using observers based on vehicle dynamics measurements (acceleration, yaw and roll rates, suspension deflections, etc). Although these methods present a relatively accurate solution, they rely heavily on tire and vehicle kinematic formulations and break down in case of abrupt changes in the measured quantities. To address this problem, researchers have been developing certain sensor based advanced tire concepts for direct measurement of the tire-road contact parameters. Thus the new terms "Intelligent Tire" and "Smart Tire", which mean online tire monitoring are thus enjoying increasing popularity among automotive manufacturers and formed the motivation for this thesis to explore the possibility of developing an intelligent tire system. The development of the so called "intelligent tire/ smart tire system" is expected to spur the development of a new generation of vehicle control system with modified control strategies, leveraging information directly coming from the interface between the tire and the road, and in turn significantly reducing the risk of accidents. The specific contributions of this thesis include the following: • Development of an intelligent tire system, with a special attention to development of measurement and sensor feature extraction methodologies of acceleration signals coming from sensors fixed to the tire innerliner • Design of an integrated vehicle state estimator for application to global chassis control • Development of a model-based tire-road friction estimation algorithm • Development of an intelligent tire based adaptive wheel slip controller for anti-lock brake system (ABS) • Development of a piezoelectric vibration energy harvesting system with an adaptive frequency tuning mechanism for intelligent tires / Master of Science

The diploma thesis is focused on the measurement of forces acting between the tire and the road. There is an outline of tire and tire models problematic in the opening part. In the following part, the rear right suspension of the formula student car was mounted with strain gauges and the data logging system was described. There is also a multi-body model of the rear axle created in Adams/Car and SAMS software, that is able to calculate forces acting between the tire and the road, taking the measured forces in the suspension, rocker position, and throttle position into consideration. After a series of calibrations and verification measurements, the measurement on the test track was made, with data analysis focused on forces acting between the tire and the road.

Increasing vehicle performance requirements and virtualization of its development process require more understanding of physical background of tire behavior, especially in transient rolling conditions with combined slip. The focus of this research is physical description of transient generation of tire lateral force and aligning torque. Using acceleration measurement on the tire inner liner it was observed that the contact patch shape of the rolling tire changes nonlinearly with slip angle and becomes asymmetric. Optical measurement outside and inside the tire has clarified that carcass lateral bending features both shear and rotation angle of its cross-sections. A physical simulation model was developed, which considers the observed effects. A special iterative computing algorithm was proposed. The model was qualitatively validated using not only tire force and torque responses, but also deformation of the tire carcass. The model-based analysis explained which tire structural parameters are responsible for which criteria of tire performance. Contact patch shape change had a low impact on lateral force and aligning torque. Variation of carcass bending behavior perceptibly influenced aligning torque generation. As an example, the gained understanding was applied for feasibility analysis of a novel method to estimate the utilized friction potential rate of a rolling tire.:1 Introduction 1.1 Thesis structure 1.2 Motivation 1.3 State of the art 1.4 Mission statement 1.5 Main terms and hypotheses 1.6 Summary of chapter 1 2 Experimental investigation of tire deformation 2.1 Introduction to experimental research 2.2 Test samples 2.3 Experimental equipment 2.4 Contact patch pressure distribution 2.5 Contact patch geometry of the rolling tire 2.6 Tire carcass deformation 2.7 Tread block properties 2.8 Summary of chapter 2 3 Simulation method of tire deformation behavior 3.1 Concept development 3.2 Physical representation of the model 3.3 Model computing method 3.4 Model parameterization routine 3.5 Model validation 3.6 Summary of chapter 3 4 Model-based analysis 4.1 Understanding of the physical background 4.2 An example of application 4.3 Summary of chapter 4 5 Investigation summary and discussion 5.1 Key results 5.2 Discussion, critique and outlook References List of abbreviations List of symbols List of tables List of figures Appendix

Le bruit de roulement contribue fortement au bruit perçu à l'intérieur de l'habitacle des automobiles. Ce bruit a pour origine le contact du pneumatique sur une chaussée rugueuse. En basses fréquences (0-400 Hz), il est transmis dans l'habitacle du véhicule essentiellement par la voie solidienne. La méthode actuelle de prévision de ce bruit chez PSA Peugeot Citroën repose sur une approche mixte calcul-mesure longue, coûteuse et pas suffisamment prédictive. Pour contourner ces limitations, une filière purement numérique est envisagée. Elle demande de modéliser le comportement vibro-acoustique du pneumatique en prenant en compte les effets liés à la rotation et de résoudre le problème de contact avec une chaussée rugueuse. Concernant la modélisation d'un pneumatique en rotation, des formulations des effets tournants d'un solide déformable sont établies en utilisant une approche Arbitrairement Lagrangienne Eulérienne (ALE). Ces formulations sont validées par une application sur un nouveau modèle simplifié du pneumatique. Il s'agit d'un modèle d'anneau circulaire incluant les effets de cisaillement soumis localement à une charge représentative de la masse du véhicule. Un modèle plus complexe d'ensemble monté pneu/roue/cavité intégrant l'ensemble des effets liés à la rotation est également validé par une comparaison avec des essais. Ensuite, le contact avec une chaussée réelle est formulé par différentes approches permettant de réduire le temps de calcul pour une utilisation industrielle. En particulier, le calcul du contact est décomposé en un calcul statique non linéaire suivi d'un calcul dynamique linéaire. La validation du modèle de contact est réalisée par une comparaison calcul/essai. Les résultats sont très satisfaisants / The rolling noise contributes significantly to the noise inside cars. This noise comes from the tire/road contact. In low frequencies (0-400 Hz), it is mainly transmitted into the cabin through structural vibration. The current method used at PSA Peugeot Citroen to predict this noise, is a mixed simulation/experimental approach which is long, expensive and not sufficiently predictive. In order to overcome these difficult, a full numerical approach is considered. It requires modeling the tire vibration by taking into account the rotating effects and the contact with the rough surface. Concerning the model of rotating tire, a formulation of a deformable solid is constructed by using an Arbitrary Lagrangian Eulerian approach (ALE). This formulation is validated by an application on a new simplified tire model which is a circular ring including the shear stresses and the non linear effects due to the vehicle weight. A more complex model composed of tire/wheel/cavity including all the rotating effects is also validated by comparison with experiments. Then the contact with a real road is calculated by different approaches to get the acceptable computing time for industrial uses. In particular, the calculation of the contact is divided into a non-linear static analysis followed by a linear dynamic calculation. The validation of this model is successfully achieved by comparison test results