Dissertations / Theses on the topic 'Tire'

The proper management of scrap tires is relatively resource-intensive. Two features of waste tires produce internal and external costs. Their donut-like shape occupies vast space on transportation vehicles and in general landfills. It also allows the breeding of disease-carrying mosquitoes in populated areas. Their rubber and steel composition makes them durable and at the same time costly to reduce in size. Tire rubber can also generate air and ground pollutants during fires. Mosquito and fire outbreaks are associated with scrap tire stocks of any size. Faced with increasing flows of scrap tires (and other solid and hazardous waste), local officials consider a policy to decrease the waste tire generation rate, i.e., source-reduction. To implement such a policy, a critical first step is to determine, theoretically and empirically, the factors that influence tire demand. Consequently, this thesis applies basic consumer theory to specify important economic determinants of tire demand. Their empirical counterparts form the basis of the explanatory variables in the econometric demand model. Tire sales quantities are derived from state revenue collections of a per unit tire tax on new tire purchases. Measurement errors in the dependent variable and lack of explanatory data motivate the use of the generalized least-squares fixed effects estimator in a pooled tire demand model comprising 28 states. The qualitative results of the econometric estimation are in conformity with economic theory. Quantitatively, the model produces an income elasticity of 0.4; a ten percent increase in real per capita income increases tire sales per vehicle by four percent, ceteris paribus. This effect is very likely to measure increased gasoline consumption, i.e., vehicle utilization. The calculated own price elasticity of tire demand is about -15, which is too large to reflect a pure price effect. Unless statistical problems generate this estimate, it probably captures a movement of and along the tire demand curve.

A tire is an essential part on a vehicle. Different tires have different properties, and one of them is the longitudinal stiffness of the tire. Tire stiffness can be explained by modelling the tire as small thread compounds. These small thread compounds will have contact with the surface and will contain one adhesion and one sliding region. The slip is the motion of the thread compounds relative to the surface. The forces that act on the thread compounds are divided by slip and this is defined as tire stiffness. This thesis presents a method to estimate the tire stiffness in real-time. By using different algorithms, such as Recursive Least Squares and Least Mean Square, a good approximation of the tire stiffness can be achieved.

La riduzione del rumore generato dagli pneumatici in rotolamento rappresenta una delle principali e più difficili sfide per le case produttrici di pneumatici. Negli ultimi anni, infatti, c’è stato un sempre crescente interesse verso questo argomento a seguito delle richieste provenienti dal mondo automobilistico e delle nuove normative in termini di riduzione dell’inquinamento acustico, che impongono un forte abbattimento del rumore generato dagli pneumatici. Oggigiorno, le case automobilistiche tendono a richiedere pneumatici sempre più silenziosi per garantire livelli di confort sempre più elevati all’interno dell’abitacolo e in quest’ottica gli pneumatici giocano un ruolo fondamentale. Col passare degli anni, è stato fatto un notevole passo avanti in termini di abbattimento del rumore generato dal sistema di propulsione, principalmente attraverso l’isolamento acustico dell’abitacolo e, dal momento che la seconda fonte di rumore dopo il motore è rappresentata proprio dagli pneumatici, si capisce come mai ci sia la richiesta di pneumatici silenziosi. Il rotolamento degli pneumatici sull’asfalto, infatti, genera un rumore piuttosto fastidioso che viene percepito in maniera fortemente sgradevole all’interno del veicolo. Inoltre, questo aspetto sta diventando ancor più importante a seguito della massiccia diffusione delle auto ibride ed elettriche, in cui il rumore del motore è fortemente ridotto o addirittura eliminato. Dall’altro lato ci sono le nuove normative riguardo la riduzione dell’inquinamento acustico delle nostre città che impongono anch’esse un forte abbattimento delle emissioni sonore dello pneumatico, per di più da conseguire anche in tempi molto stretti. La somma di queste due richieste impone quindi uno studio approfondito di questo aspetto a partire dalla necessità di approfondire quali sono i meccanismi di generazione del rumore. Quando si parla di rumore generato dagli pneumatici, occorre fare una distinzione tra “in-vehicle noise” and “exterior noise”: il primo rappresenta il rumore percepito dagli individui all’interno dell’abitacolo, mentre il secondo si riferisce al rumore emesso dallo pneumatico nell’ambiente esterno ed è la componente che viene percepita dalle persone all’esterno della vettura. Esiste poi anche una seconda distinzione basata sul meccanismo di generazione del rumore. Secondo questa classificazione, è possibile distinguere tra “Structureborne noise” e “Airborne noise”: nel primo caso il rumore è legato all’interazione dello pneumatico con altri componenti del veicolo che genera delle forze al mozzo che si traducono in vibrazioni e rumore a bassa frequenza (250 Hz); la seconda componente dipende solamente dallo pneumatico e dalla sua interazione con l’aria. Questo secondo gruppo è responsabile principalmente del rumore esterno, ma ha anche una componente ad alta frequenza (fino a 2000 Hz) che rientra all’interno dell’abitacolo. Da questa breve introduzione si capisce come il fenomeno analizzato sia molto complesso, in quanto comprende diverse componenti che sono molto diverse tra loro, sia in termini di meccanismo che di range di frequenza, e pertanto richiedono studi e contromisure dedicate. Per ottenere una riduzione del rumore così consistente, è necessario un drastico cambiamento del modo in cui viene approcciato il problema, poiché si è capito come sia necessario considerare questo aspetto fin dalle prime fasi dello sviluppo di un nuovo pneumatico, accanto a tutte le performance classiche, quali bassa resistenza al rotolamento, handling o braking. Finora, invece, la silenziosità era vista come una caratteristica secondaria o un optional. Generalmente ci si occupava di questo aspetto solo in caso di reclami da parte di una casa automobilistica o se le emissioni sonore dello pneumatico erano di poco al di sopra dei limiti e non c’era quindi la possibilità di ricevere l’omologazione ed essere immesso sul mercato. Si trattava comunque di problemi di piccola entità che con piccoli cambiamenti a livello di pattern era possibile in qualche modo risolvere. Tuttavia, si capisce come si trattasse di un approccio basato sull’esperienza degli ingegneri, ma non sorretto da una base teorica. Per poter abbattere le emissioni acustiche dello pneumatico è necessario in primo luogo comprendere quali sono i meccanismi di generazione del rumore, in modo da sviluppare uno pneumatico che abbia una struttura e un disegno del battistrada cosiddetti “noise-oriented”. Secondo diversi studi, tra i tanti meccanismi di generazione del rumore, il più importante è rappresentato dalle vibrazioni dello pneumatico in rotolamento, pertanto questo lavoro è incentrato proprio su questo aspetto. Il lavoro è diviso in due sezioni principali; la prima parte è focalizzata sulla caratterizzazione dinamica dello pneumatico, mentre nella seconda parte viene presentata un’innovativa caratterizzazione dinamica di alcuni suoi componenti per valutare la loro influenza sulle emissioni acustiche. In entrambi i casi vengono presentati dei casi studio per esporre i principali risultati conseguiti all’interno di questo progetto. Come detto, la prima parte della presente tesi è dedicata alla misura delle vibrazioni dello pneumatico attraverso lo sviluppo di un set-up innovato basato sulla tecnica 3D Digital Image Correlation (3D-DIC). Questa tecnica ha diversi vantaggi e permette di superare i limiti dello stato dell’arte, rappresentato dalle misure effettuate con il Vibrometro Laser Doppler. Per una misura di questo tipo occorre una tecnica che sia in grado di misurare un oggetto in movimento, quindi deve essere una tecnica senza contatto e deve essere in grado di misurare all’interno di un range molto ampio (0 – 2000 Hz). Finora l’unico strumento in grado di eseguire una tale misura era il Vibrometro Laser Doppler, anche se con diversi limiti, come ad esempio la possibilità di misurare solamente il fianco dello pneumatico o i tempi molto lunghi, in relazione al numero di punti da acquisire, che possono provocare variazioni delle condizioni al contorno. La DIC è una tecnica nata principalmente per misure statiche o quasi statiche di deformazioni o spostamenti, tuttavia le moderne fast cameras possono rappresentare una valida alternativa al vibrometro laser in quanto sono caratterizzate da frame rate molto elevati, ragion per cui è possibile misurare spostamenti estremamente piccoli e, quindi, è possibile usare tale tecnica anche per misure di vibrazioni ad alta frequenza. L’utilizzo di tale set-up ha richiesto un lungo lavoro di ottimizzazione, ampiamente descritto in questa tesi, necessario per valutare l’effetto di tutti i principali parametri che influenzano l’acquisizione e, in particolare, è stato necessario capire come poter sfruttare al meglio la strumentazione disponibile per poter eseguire le misure necessarie. Gli attuali limiti tecnologi, infatti, permettono di avere frame rate estremamente elevati, ma al tempo stesso non è possibile avere risoluzioni troppo spinte, altrimenti la dimensione delle immagini sarebbe troppo grande e le attuali velocità di trasferimento dei dati non sarebbero in grado di seguire la frequenza con cui vengono acquisite le immagini stesse. Per tale motivo è richiesto un adattamento dell’inquadratura a seconda del range di frequenze che si vuole studiare. Le vibrazioni dello pneumatico in rotolamento si dividono in due grandi gruppi: le vibrazioni a bassa frequenza (fino a circa 250 Hz) sono caratterizzate da spostamenti di ampiezza elevata che investono tutta la struttura dello pneumatico e per questo sono detti modi di carcassa; ad alta frequenza, le vibrazioni sono generate dagli impatti dei blocchetti del battistrada sull’asfalto che causano spostamenti molto piccoli dei punti localizzati intorno la zona di contatto e sono vibrazioni che rimangono fortemente localizzate in quella zona e non possono essere misurate lavorando con un’inquadratura sull’intero fianco. Nonostante la DIC sia una tecnica di misura full-field, lavorando con un range in frequenza molto ampio e, considerando le dimensioni dello pneumatico, non è possibile sfruttare del tutto questa proprietà. Infatti, se il focus è la bassa frequenza, si può utilizzare un’inquadratura sull’intero fianco, ma se si vogliono studiare le alte frequenze, è necessario usare un’inquadratura focalizzata sulla zona di contatto, che è stato dimostrato essere la zona più rappresentativa del comportamento vibrazionale dell’intero pneumatico. Nell’ambito della misura delle vibrazioni dello pneumatico in rotolamento, l’utilizzo di tale set-up, ha permesso di raggiungere un importante obiettivo, cioè quello di misurare la corona dello pneumatico, che rappresenta una grande innovazione in quanto non è possibile eseguire questa misura con altre tecniche a causa delle discontinuità introdotte dal pattern che rendono impossibile l’utilizzo del vibrometro laser. In questo modo è possibile avere una caratterizzazione dinamica completa dello pneumatico e, attraverso due casi studio, è stato dimostrato come è possibile usare questa tecnica per fornire nuove utili informazioni agli ingeneri di sviluppo. In particolare, dallo studio di diversi pneumatici è emerso come sia possibile ottenere una forte riduzione del rumore con pneumatici in cui le vibrazioni del fianco sono molto smorzate, anche se questo comporta un incremento della mobilità della corona. Questa affermazione è stata dimostrata presentando due casi studio, in cui quest’effetto viene ottenuto con due differenti soluzioni tecniche. Infine, l’intero set-up di misura è stato validato sia in condizioni statiche che dinamiche attraverso il confronto con il vibrometro laser. Il confronto mostra come ci sia un’ottima corrispondenza tra le due misure e permette di evidenziare come la maggiore sensibilità del vibrometro permetta di misurare l’intero range di frequenza con un’unica misura, ma la risoluzione spaziale è piuttosto bassa. La seconda parte del lavoro, invece, introduce un innovativo approccio allo studio del problema, in quanto considera l’effetto di alcuni componenti della struttura dello pneumatico sull’emissione acustica. Tale metodo vuole far fronte alla difficoltà degli ingegneri di scegliere quale sia il materiale di rinforzo più adatto per la struttura di uno pneumatico silenzioso, dovendo scegliere tra una lista molto ampia di candidati. Finora tale problema veniva risolto producendo un prototipo per ogni soluzione tecnica o materiale da testare, i prototipi venivano testati acusticamente e quello che risultava essere più silenzioso veniva scelto. In questo modo si spendono molto tempo e molto denaro, ma soprattutto non si capisce quali siano i meccanismi di generazione del rumore, non si capisce perché un materiale sia migliori di un altro e per di più non viene fatta la caratterizzazione dei materiali. L’utilizzo di tale procedura è dettato dalla mancanza di una caratterizzazione dinamica dei materiali. Sebbene esista una caratterizzazione dinamica delle gomme utilizzate per produrre le mescole così come una dettagliata caratterizzazione dei materiali in termini di proprietà fisiche e meccaniche, non esiste una caratterizzazione di campioni compositi di gomma e corde di materiali di rinforzo. In realtà una minima caratterizzazione esiste, ma viene fatta su campioni molto piccoli e in condizioni quasi statiche che serve solo a definire i valori di rigidezza “in-plane” and “out-of.plane”. Il problema è che non si tratta di una caratterizzazione noise-oriented perché non tiene conto del comportamento dinamico del provino. L’approccio proposto, invece, considera dei campioni costruiti allo stesso modo in cui si possono trovare nella struttura dello pneumatico, cioè sono piccole travette di gomma calandrate con immerse delle corde di materiale di rinforzo. La nuova procedura si basa sulla caratterizzazione di tali provini utilizzando la tecnica DIC ed è possibile in questo modo definire l’effetto di ogni materiale in termini di mobilità dei campioni analizzati. In questo modo si possono selezionare i materiali che rispettano determinate condizioni e i test su pneumatico servono solo per conferma, quindi il loro numero sarà ridotto drasticamente con notevole risparmio di tempo e soldi. Anche in questo caso l’ottimizzazione del set-up ha richiesto molto tempo, in particolare per la definizione della struttura dei campioni. Il confronto di misure acustiche su pneumatico in rotolamento, caratterizzazione dinamica dello pneumatico e misure vibrazionali sui campioni ha permesso di definire che i materiali di rinforzo da preferire sono quelli che aumentano la mobilità della corona, in quanto si riduce la mobilità del fianco che è la principale sorgente di rumore. Tutto questo ragionamento è supportato da un caso studio presentato nell’ultimo paragrafo. In conclusione, un nuovo sistemata per la misura delle vibrazioni dello pneumatico in condizioni di rotolamento è stato sviluppato, ottimizzato e validato attraverso il confronto con il Vibrometro Laser Doppler, sia in condizioni statiche che dinamiche. Il nuovo set-up permette di eseguire misure anche sulla corona, non realizzabili con nessun’altra tecnica. Lo stesso set-up è stato utilizzato per la caratterizzazione dinamica di componenti dello penumatico.
The reduction of the noise generated by rolling tire is becoming one of the most important and difficult challenges for tire manufactures. The growing interest in tire noise performances is related both to the requirements coming from the car industry and the new regulations regarding the reduction of the acoustic pollution of our cities. Car manufacturers require silent tire in order to guarantee a high comfort level inside the car. During last years, a lot of work has been done in order to make the interior of the cars as comfortable as possible and the current cockpit insulation can significantly reduce the noise coming from the engine, so, in order to further increase the comfort level, they ask for silent tires. According to several studies, in fact, the engine is the first noise source in a moving car followed by the rolling tire noise, so it is easy to understand the reason why there is such a requirement. The noise generated by rolling tires is completely different from the engine noise in terms of frequencies and the cockpit insulation cannot reduce it in the whole frequency range of interest (0 – 2000 Hz). This aspect is even more important with the new electric or hybrid engines, where the noise is completely or partially deleted. When talking about rolling tire noise, two main classifications have been defined. According to the first classification, “in-vehicle” and “exterior noise” can be distinguished: the first one refers to the noise perceived inside the car, while the second one is the noise heard by the people outside the car, i.e. the noise that propagates in the external environment. The second classification is based on the noise generation mechanism. In this case, “Structureborne noise” and “Airborne noise” can be distinguished: the first one refers to that noise component related to the interaction between rolling tire and car components resulting in spindle forces causing low frequency vibrations (up to 250 Hz) that are mainly responsible for the in-vehicle noise, while the “Airborne noise” refers to those mechanisms which depends on the tire only and on its interaction with the air. This second group mainly generates high frequency noise propagating in the surroundings, but it has also a contribution entering inside the car. On the other side, there are new regulations that impose a significant reduction in terms of exterior noise. From this short introduction it is clear how complex the analysed phenomenon is, because, even if the noise source is the same, each noise component is different from the others and requires dedicated studies and countermeasures. Tire manufacturers have understood that, in order to satisfy these requirements in terms of noise reduction, it is necessary to complete change how the tire noise study is approached, because noise performance must be considered from the first stages of the development as well as the other classic performances, such as handling, braking, rolling resistance and so on. In fact, the noise reduction to be achieved is very consistent, so it necessary to deeply understand how noise is generated to define the features of a noise-oriented tire structure. In the past years, a low noise level was considered an optional, mainly because it was quite easy to respect the limits imposed by regulations to obtain the approval for the commercialization. If there were some noise problems, they were solved with some changes in terms of pattern design based on the experience of the engineers, but the reduction obtained was very low. To significantly reduce the noise emission, it is necessary to investigate and understand how noise is generated and evaluate the effect on the noise emission of every tire components and materials used in tire construction. To do this, it is necessary to better understand the noise generation mechanisms, in fact, even if a lot of researchers have studied this phenomenon for decades, it is still not completely clear how noise is generated. According to several studies, among all the mechanisms the most important are the vibrations of the rolling tire. This is the main topic of this work and it is analysed in two different ways: from a global point of view through a complete dynamic characterization of the rolling tire and from a more detailed point of view looking at the dynamic characterization of samples of tire components. The first part of the thesis deals with the measurement of tire vibrations using an innovative set-up based on the 3D - Digital Image Correlation (DIC) technique. It has several advantages if compared with the current techniques, among which the possibility to measure irregular and inhomogeneous surface is one of the most important because it allows to perform significative measurement on tire crown. This is one of the innovations introduced in this work, since this measurement cannot be performed with other techniques. As well as the state of art technique, that is the Laser Doppler Vibrometer (LDV), the DIC is a non-contact technique, but it does not require a smooth and homogenous surface and this feature is exploited to measure the crown of the rolling tire. It is characterized by the so-called tread pattern, that is a sequence of blocks, so the LDV cannot be used because every block causes a spike in the LDV signal, while the DIC does not have this problem, since it compares two images to define the displacement of the measurement points. Even if it is a full-field technique, this feature cannot be completely exploited on a rolling tire, because of the width of the frequency range of interest and the size of the tire compared with the current resolution of the available cameras. The DIC technique was born to perform displacement and deformation measurements in static or quasi-static condition, but the modern fast cameras, characterized by very high frame rates, suggest the possibility to use this technique to perform vibration measurement. Since the DIC measure the displacements, it is necessary to have a high frame rate in order to detect also the very small displacements that characterise the high frequency vibration and the modern fast cameras satisfy this requirement, even if the resolution it is not too high, because the size of the image will be too high and there would not be the possibility to transfer the images with the same rate of the acquisition one. For this reason the frame size must be adequate to the frequency range of interest: if the low frequency carcass modes are investigated, the full-view on the sidewall can be used, but if the high frequency vibrations must be studied, it is necessary to focus the cameras on the contact patch area, in order to measure the small displacement generated by the impact of tread blocks with the road. These displacements are strictly localized in the contact patch area and a full-sidewall view cannot detect them: when the cameras are focused on a smaller area, the resolution of the system is increased because the pixels are focused on a smaller area and smaller displacements can be measured. The new set-up has been validated through the comparison with LDV both in static and dynamic condition in both the framing configurations. This is probably one of the main disadvantages of this technique, but it is a limit of current technologies because it is not possible to produce cameras with high resolution and high frame rate. The correlation between DIC and LDV measurement is very good, the LDV’s accuracy is a little bit higher, but it depends on the measured quantity (velocity VS displacement). The new dynamic characterization of tire crown and its comparison with sidewall provide new information about rolling tire vibrations that suggest some countermeasures for the development of a noise-oriented tire structure. provide new information not available in the past years. Two case studies are described to demonstrate the potentialities of the new set-up and demonstrating how an important noise reduction can be achieved. In the second part of this PhD project, the same set-up has been used to perform an innovative dynamic noise-oriented characterization of cord-rubber composite samples to evaluate the effect of reinforcing materials on the noise emission. It represents a completely new approach to the problem because it is a tentative to correlate the noise emission with tire structure components. A lot of work has been done to characterize rubber and reinforcing cords, but there are some problems: they are characterized separately, the size of the samples is very small and it is not representative of what happens on the real tire, it is a static or quasi-static characterization and if, a composite sample is used, in these conditions the only in-plane and out-of-plane stiffness values can be extracted. This procedure is useful to completely characterize the rubber used for tire compound and the reinforcing materials in terms of their mechanical properties, but it is useless in predicting noise emission, because the frequency response of the samples is unknown. The lack of these information is related to the approach used until now. As previously stated, in the past years tire silence was a secondary requirement and, when the first limitations in terms of noise emission had to be satisfied, a very expensive strategy in terms both of time and money has been used: the choice of the reinforcing material is performed producing a tire prototype for each candidate material, testing all the tires and identifying the tire that score the lowest noise emission. Nowadays, the reduction imposed is so strong, that tire developers are forced to consider the noise target from the first stages of the development in order to produce a noise-oriented tire structure and the absence of such a characterization has emerged. The approach proposed in this thesis considers samples produced in the same way they can be found on the final tire and the analysis of their mobilities suggest which are supposed to produce a reduction of noise emission. The final response comes from the test of a prototype tire, but in this way the selection of the proper materials is faster and, at the same time, the number of tests on tire and the prototypes produced is significantly reduced and the mechanism understanding is improved. In order to obtain good and useful results it important to define the correct structure of the samples, in fact even if the idea is to characterize the cap ply or body ply layers, the sample must contain also the belt package for global stiffness and mass reasons: if the belt is not used, the samples produced are very lightweight and the variation of the cord cause significant variations in terms of mass and stiffness with a shift in terms of resonance frequencies that it is not related to mechanical properties of the cord materials or sample thickness, but it is related to the mass variation only. When the belts are applied, the samples have almost the same mass and stiffness and the effect of the different cap ply layers is a variation in terms of mobility. The results obtained for a group of samples have been compared with those coming from the dynamic characterization of the corresponding final tire and their acoustic measurements, showing a good correlation between the measurement on samples and entire tires. The performed measurements suggest that the new approach produce interesting results and this procedure can be effectively used. For sure other test on other samples must be performed to confirm the first results and to define a database of materials. In conclusion it can be said that an innovative measurement set-up for the dynamic characterization of rolling tire has been developed and validated. Both sidewall and crown can be characterized with the new set-up. At the same time, an innovative approach for noise reduction based on the characterization of tire components has been proposed.

Sensor-embedded tires, known as intelligent tires, have been widely studied because they are believed to provide reliable and crucial information on tire-road contact characteristics e.g., slip, forces and deformation of tires. Vehicle control systems such as ABS and VSP (Vehicle Stability Program) can be enhanced by leveraging this information since control algorithms can be updated based on directly measured parameters from intelligent tire rather than estimated parameters based on complex vehicle dynamics and on-board sensor measurements. Moreover, it is also expected that intelligent tires can be utilized for the purpose of the analysis of tire characteristics, taking into consideration that the measurements from the sensors inside the tire would contain considerable information on tire behavior in the real driving scenarios. In this study, estimation methods for the tire-road contact features by utilizing intelligent tires are investigated. Also, it was discussed how to identify key tire parameters based on the fusion technology of intelligent tire and tire modeling. To achieve goals, extensive literature reviews on the estimation methods using the intelligent tire system was conducted at first. Strain-based intelligent tires were introduced and tested in the laboratory for this research. Based on the literature review and test results, estimation methods for diverse tire-road contact characteristics such as slippages and contact forces have been proposed. These estimation methods can be grouped into two categories: statistical regressions and model based methods. For statistical regressions, synthetic regressors were proposed for the estimation of contact parameters such as contact lengths, rough contact shapes, test loads and slip angles. In the model-based method, the brush type tire model was incorporated into the estimation process to predict lateral forces. Estimated parameters using suggested methods agreed well with measured values in the laboratory environment. By utilizing sensor measurements from intelligent tires, the tire physical characteristics related to in-plane dynamics of the tire, such as stiffness of the belt and sidewall, contact pressure distribution and internal damping, were identified based on the combination of strain measurements and a flexible ring tire model. The radial deformation of the tread band was directly obtained from strain measurements based on the strain-deformation relationship. Tire parameters were identified by fitting the radial deformations from the flexible ring model to those derived from strain measurements. This approach removed the complex and repeated procedure to satisfy the contact3 constraints between the tread and the road surface in the traditional ring model. For tires with different specifications, identification using the suggested method was conducted and their results are compared with results from conventional methods and tests, which shows good agreements. This approach is available for the tire standing still or rolling at low speeds. For tires rolling at high speeds, advanced tire model was implemented and associated with strain measurements to estimate dynamic stiffness, internal damping effects as well as dynamic pressure distributions. Strains were measured for a specific tire under various test conditions to be used in suggested identification methods. After estimating key tire parameters step by step, dynamic pressure distributions was finally estimated and used to update the estimation algorithm for lateral forces. This updated estimation method predicted lateral forces more accurately than the conventional method. Overall, this research will serve as a stepping stone for developing a new generation of intelligent tire capable of monitoring physical tire characteristics as well as providing parameters for enhanced vehicle controls.
PHD

Tire performance over soft soil influences the performance of off-road vehicles on soft soil, as the tire is the only force transmitting element between the off-road vehicles and soil during the vehicle operation. One aspect of the tire performance over soft soil is the tire tractive performance on soft soil, and it attracts the attention of vehicle and geotechnical engineers. The vehicle engineer is interested in the tire tractive performance on soft soil because it is related to vehicle mobility and energy efficiency; the geotechnical engineer is concerned about the soil compaction, brought about by the tire traffic, which accompanies the tire tractive performance on soft soil. In order to improve the vehicle mobility and energy efficiency over soft soil and mitigate the soil compaction, it's essential to develop an in-depth understanding of tire tractive performance on soft soil. This study has enhanced the understanding of tire tractive performance on soft soil and promoted the development of terramechanics and tire model parameterization method through experimental tests. The experimental tests consisted of static tire deflection tests, static tire-soil tests, soil properties tests, and dynamic tire-soil tests. The series of tests (test program) presented herein produced parameterization and validation data that can be used in tire off-road traction dynamics modeling and terramechanics modeling. The 225/60R16 97S Uniroyal (Michelin) Standard Reference Test Tire (SRTT) and loamy sand were chosen to be studied in the test program. The tests included the quantification or/and measurement of soil properties of the test soil, pre-traffic soil condition, the pressure distribution in the tire contact patch, tire off-road tractive performance, and post-traffic soil compaction. The influence of operational parameters, e.g., tire inflation pressure, tire normal load, tire slip ratio, initial soil compaction, or the number of passes, on the measurement data of tire performance parameters or soil response parameters was also analyzed. New methods of the rolling radius estimation for a tire on soft soil and of the 3-D rut reconstruction were developed. A multi-pass effect phenomenon, different from any previously observed phenomenon in the available existing literature, was discovered. The test data was fed into optimization programs for the parameterization of the Bekker's model, a modified Bekker's model, the Magic Formula tire model, and a bulk density estimation model. The modified Bekker's model accounts for the slip sinkage effect which the original Bekker's pressure-sinkage model doesn't. The Magic Formula tire model was adapted to account for the combined influence of tire inflation pressure and initial soil compaction on the tire tractive performance and validated by the test data. The parameterization methods presented herein are new effective terramechanics model parameterization methods, can capture tire-soil interaction which the conventional parameterization methods such as the plate-sinkage test and shear test (not using a tire as the shear tool) cannot sufficiently, and hence can be used to develop tire off-road dynamics models that are heavily based on terramechanics models. This study has been partially supported by the U.S. Army Engineer Research and Development Center (ERDC) and by the Terramechanics, Multibody, and Vehicle (TMVS) Laboratory at Virginia Tech.
Doctor of Philosophy
Big differences exist between a tire moving in on-road conditions, such as asphalt lanes, and a tire moving in off-road conditions, such as soft soil. For example, for passenger cars commonly driven on asphalt lanes, normally, the tire inflation pressure is suggested to be between 30 and 35 psi; very low inflation pressure is also not suggested. By contrast, for off-road vehicles operated on soft soil, low inflation pressure is recommended for their tires; the inflation pressure of a tractor tire can be as low as 12 psi, for the sake of low post-traffic soil compaction and better tire traction. Besides, unlike the research on tire on-road dynamics, the research on off-road dynamics is still immature, while the physics behind the off-road dynamics could be more complex than the on-road dynamics. In this dissertation, experimental tests were completed to study the factors influencing tire tractive performance and soil behavior, and model parameterization methods were developed for a better prediction of tire off-road dynamics models. Tire or vehicle manufacturers can use the research results or methods presented in this dissertation to offer suggestions for the tire or vehicle operation on soft soil in order to maximize the tractive performance and minimize the post-traffic soil compaction.

Ce projet porte sur la production et la caractérisation de composites hybrides basés sur un polymère thermoplastique (polyéthylène linéaire de basse densité, LLDPE) avec des fibres de polyester de pneus recyclés (RTF) mélangées avec le caoutchouc des pneus usés (GTR) avec et sans styrène-éthylène-butylène-styrène greffé d’anhydride maléique (SEBS-g-MA) comme compatibilisant. L'étude vise à améliorer les propriétés du LLDPE avec le RTF, GTR et SEBS-g-MA. La première étape de l'étude est composée de deux parties principales. La première partie porte sur la caractérisation des RTF par spectroscopie infrarouge à transformée de Fourier (FTIR), spectroscopie des photoélectrons X (XPS), analyse thermogravimétrique (TGA), calorimétrie différentielle à balayage (DSC), microscopie électronique (SEM) et densité; tandis que la deuxième partie rapporte la morphologie des composites fabriqués à partir de différentes conditions. En particulier, l'effet de la concentration de RTF (10, 25 et 50% en poids) avec et sans 10% poids de SEBS-g-MA à différentes vitesses de vis (110, 180 et 250 rpm) en-dessous (LT) et au-dessus (HT) de la température de fusion du RTF (253°C) est étudié par extrusion double-vis suivie du moulage par injection. Les résultats montrent une meilleure distribution des particules GTR (intégrées au RTF) dans la matrice (LLDPE) avec l'augmentation du contenu en RTF dans les mélanges compatibilisés. En outre, l’augmentation de la vitesse des vis entraîne une réduction de la longueur des RTF et de la taille des GTR. Cependant, un profil HT mène à la dégradation de la matrice et du GTR. Dans la deuxième étape du travail, une série complète de caractérisation physique (densité et dureté) et mécanique (tension, flexion et impact) des échantillons produits dans la première partie est présentée. Malgré la diminution des modules et des contraintes maximales, la résistance au choc Charpy augmente de 50% avec 50% de FTR compatibilisées et une amélioration supplémentaire de 56% à haute vitesse de rotation des vis (250 rpm). Cependant, le profil HT diminue toutes les propriétés physico-mécaniques des mélanges. Finalement, les propriétés rhéologiques des échantillons produits lors de la première partie ont été rhéologiquement caractérisés à l’état fondu (cisaillement oscillatoire de faible amplitude, SAOS) et solide (analyse mécanique dynamique, DMA) afin de déterminer les relations entre la mise en œuvre, la morphologie et les propriétés macroscopiques. Les résultats montrent une augmentation de l'élasticité des mélanges avec l’augmentation du contenu en RTF en présence de SEBS-g-MA surtout à des vitesses de vis élevées. Néanmoins, le profil HT présente une diminution de l'élasticité à l’état fondu, tandis que la DMA montre une augmentation de l’élasticité pour le profil LT.
This project focuses on the production and characterization of hybrid composites based on a thermoplastic polymer (linear low-density polyethylene, LLDPE) and polyester recycled tire fibers (RTF) mixed with ground tire rubber (GTR) with and without styrene-ethylenebutylene-styrene grafted maleic anhydride (SEBS-g-MA) as a compatibilizer. The study aims at improving the properties of LLDPE using RTF, GTR and SEBS-g-MA. The first step is composed of two main parts. The first part is the characterization of RTF via Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and density; while the second part is to report on the morphology from different processing parameters. In particular, the effect of RTF concentration (10, 25 and 50 wt.%) with and without 10 wt.% SEBS-g-MA at different screw speeds (110, 180 and 250 rpm) processed below (LT) and above (HT) the RTF melting temperature (253°C) are investigated for samples produced via twin-screw extrusion followed by injection molding. The results show better GTR particles distribution (imbedded in RTF) in the matrix (LLDPE) with increasing RTF content in the compatibilized compounds. Also, increasing the screw speed leads to a reduction of RTF length and GTR sizes. However, HT profiles produced degradation of the matrix and GTR particles. In the second step, a complete series of physical (density and hardness) and mechanical (tension, flexion and impact) characterization was performed on the samples produced in the first step. Despite lower moduli and strength, Charpy impact strength increases by 50% for compatibilized 50% RTF compounds with an additional 56% improvement at higher screw speed (250 rpm). However, HT profiles decrease all physico-mechanical properties of the samples. Finally, the rheological properties of the samples produced in the first step are investigated in both the melt (small amplitude oscillatory shear, SAOS) and solid (dynamic mechanical analysis, DMA) states to understand the relations between processing, morphology and macroscopic properties. The results show increased elasticity with increasing RTF content with SEBS-g-MA, especially at higher extrusion screw speeds. HT profiles lead to lower elasticity in the melt state, while DMA results show higher elasticity for LT profiles.

Vehicle pull is an issue that occurs when the driver has to exert a discerniblesteering torque (pull) for the vehicle to run straight, otherwisea lateral drift takes place. This thesis deals with the straight motion ofroad vehicles, with particular focus on the role played by tire characteristics,road cross slope and interactions between tires and vehicle.A thorough theoretical approach has been adopted, adjusting thePacejka’s formulation for effective axle characteristics and extendingthe linear handling diagram theory. This has allowed to obtain innovativeanalytical expressions, describing the straight-driving slip anglesand steering torque offsets.The analytical expressions have been validated, together with asingle-track model, by means of quasi-static and dynamic simulationsof a full-vehicle model. Moreover, a relationship between tire characteristicsand on-center handling has been described, that relates objectivemetrics with subjective feedback.The obtained analytical expressions can be used by vehicle OriginalEquipment Manufacturers (OEMs) or Tire Suppliers for productdevelopment.
Däckinducerad fordonsavdrift är ett problem som medför att förarenmåste utöva ett märkbart-styrmoment för att fordonet ska köra rakt.Detta examensarbete handlar om bilens avdrift vid körning rakt fram,med särskild fokus på inverkan av däckegenskaper, vägens lateralalutning och samverkan mellan däck och fordon.Ett grundligt teoretiskt tillvägagångssätt har valts: Pacejkas formuleringav effektiva axelegenskaper har anpassats, och den linjära handlingdiagram teorin har expanderats. Detta har gjort det möjligt att erhållainnovativa analytiska ekvationer som beskriver de avdriftsvinklaroch styrmoment som krävs för att fordonet ska färdas rakt fram.De analytiska ekvationerna har validerats, med hjälp av en cykelmodellsamt med kvasi-statiska och dynamiska simuleringar av enhelfordonsmodell. Dessutom har ett samband mellan däckegenskaperoch kursstabilitet tagits fram, som relaterar objektiva parametrar medsubjektiv feedback.De erhållna analytiska ekvationerna kan användas av fordonstillverkareoch däckleverantörer för produktutveckling.

In any automotive system, the tires play a very crucial role in defining both the safety and performance of the vehicle. The interaction between the tire and the road surface determines the vehicle's ability to accelerate, decelerate and steer. Having information about this interaction in real-time can be very valuable for the on-board advanced active safety systems to mitigate the risks ahead of time and keep the vehicle stable. The crucial information which can be obtained from the tire includes but are not limited to tire-road friction, tire forces (longitudinal, lateral), normal load, road surface characteristics and tire pressure. This information can be acquired through indirect vehicle dynamics based estimation algorithms or through direct measurements using sensors inside the tire. However, the indirect estimations fail to give an accurate measure of the vehicle state in certain conditions (e.g. side winds, road banking, surface change) and require ABS or VSC activation before the estimation begins. Therefore, to improve the performance of these active stability systems, direct measurement based approaches must be explored. This research expands the applications of Intelligent tire and focuses on using the sensor based measurement approach to develop estimation algorithms relating to tire force measurement. A tri-axial accelerometer is attached to the inner liner of the tire (Intelligent Tire) and two of such tires are placed on an instrumented (MSW, VBox, IMU, Encoders) VW Jetta. Different controlled tests are carried out on the instrumented vehicle and the Intelligent tire signal is analyzed to extract features related to the tire forces and pressure. Due to unavailability of direct force measurements at the wheel, a VW Jetta simulation model is developed in CarSim and the extracted features are validated with a good correlation.
Master of Science

Tire-Pavement Interaction Noise (TPIN) becomes the main noise source contributor for passenger vehicles traveling at speeds above 40 kph. Therefore, it represents one of the main contributors to noise environmental pollution in residential areas nearby highways. TPIN has been subject of exhaustive studies since the 1970s. Still, almost 50 years later, there is still not an accurate way to model it. This is a consequence of a large number of noise generation mechanisms involved in this phenomenon, and their high complexity nature. It is acknowledged that the main noise mechanisms involve tire vibration, and air pumping within the tire tread and pavement surface. Moreover, TPIN represents the only vehicle noise source strongly affected by an external factor such as pavement roughness. For the last decade, new machine learning algorithms to model TPIN have been implemented. However, their development relay on experimental data, and do not provide strong physical insight into the problem. This research studied the correct configuration of such tools. More specifically, Artificial Neural Network (ANN) configurations were studied. Their implementation was based on the problem requirements (acoustic sound pressure prediction). Moreover, a customized neuron configuration showed improvements on the ANN TPIN prediction capabilities. During the second stage of this thesis, tire noise test was undertaken for different tires at different pavements surfaces on the Virginia Tech SMART road. The experimental data was used to develop an approach to account for the pavement profile when predicting TPIN. Finally, the new ANN configuration, along with the approach to account for pavement roughness were complemented using previous work to obtain what is the first reasonable accurate and complete tool to predict tire noise. This tool uses as inputs: 1) tire parameters, 2) pavement parameters, and 3) vehicle speed. Tire noise narrowband spectra for a frequency range of 400-1600 Hz is obtained as a result.
Master of Science
Tire-Pavement Interaction Noise (TPIN) becomes the main noise source contributor for passenger vehicles traveling at speeds above 40 kph. Therefore, it represents one of the main contributors to noise environmental pollution in residential areas nearby highways. TPIN has been subject of exhaustive studies since the 1970s. Still, almost 50 years later, there is still not an accurate way to model it. This is a consequence of a large number of noise generation mechanisms involved in this phenomenon, and their high complexity nature. It is acknowledged that the main noise mechanisms involve tire vibration, and air pumping within the tire tread and pavement surface. Moreover, TPIN represents the only vehicle noise source strongly affected by an external factor such as pavement roughness. For the last decade, machine learning algorithms, based on the human brain structure, have been implemented to model TPIN. However, their development relay on experimental data, and do not provide strong physical insight into the problem. This research focused on the study of the correct configuration of such machine learning algorithms applied to the very specific task of TPIN prediction. Moreover, a customized configuration showed improvements on the TPIN prediction capabilities of these algorithms. During the second stage of this thesis, tire noise test was undertaken for different tires at different pavements surfaces on the Virginia Tech SMART road. The experimental data was used to develop an approach to account for the pavement roughness when predicting TPIN. Finally, the new machine learning algorithm configuration, along with the approach to account for pavement roughness were complemented using previous work to obtain what is the first reasonable accurate and complete computational tool to predict tire noise. This tool uses as inputs: 1) tire parameters, 2) pavement parameters, and 3) vehicle speed.

The growth of the automobile Industry in the past 50 years is radical. The development of chassis control systems have grown drastically due to the demand for safer, faster and more comfortable vehicles. For example, the invention of Anti-lock Braking System (ABS) has resulted in saving more than a million lives since its adaptation while also allowing the vehicles to commute faster. As we move into the autonomous vehicles era, demand for additional information about tire-road interaction to improve the performance of the onboard chassis control systems, is high. This is due to the fact that the interaction between the tire and the road surface determines the stability boundary limits of the vehicles. In this research, a real-time system to classify the road surface into five major categories was developed. The five surfaces include Dry Asphalt, Wet Asphalt, Snow, and Ice and dry Concrete. tri-axial accelerometers were placed on the inner liner of the tires. An advanced signal processing technique was utilized along with a machine learning model to classify the road surfaces. The instrumented Volkswagen Jetta with intelligent tires was retrofitted with new instrumentation for collecting data and evaluating the performance of the developed real-time system. A comprehensive study on road surface classification was performed in order to determine the features of the classification algorithm. Performance of the real-time system is discussed in details and compared with offline results.
Master of Science

The evolution of vehicle safety systems, from the earliest brakes to today's accident avoidance systems, has led vehicles to have very high passenger safety. Driving on ice, though, still happens to be one of the driving conditions of low safety. A multitude of factors were identified by various studies to contribute to the complex frictional mechanism at the tire-ice interface. The tire is only force transmitting element of the vehicle, to the surface. Thus it is very essential to have in depth understanding of the contact phenomena at the tire-ice interface, to improve vehicle safety on icy roads. This study has led to understanding of the contact phenomena at the tire-ice contact through experimental studies and a semi-empirical based tire-ice contact model. Experimental studies included both indoor testing and outdoor testing, indoor testing was conducted using the Terramechanics Rig at the Advanced Vehicle Dynamics in Virginia Tech and field tests were conducted at the Keweenaw Research Center in Michigan Tech. The simulation results of the tire-ice model were validated against the findings of the indoor test program. The P225/60R16 97S Standard Reference Test Tire was the candidate tire for this study. The effects of operational parameters, were studied when in driving traction by comparison of the friction - slip ratio curves. The two tests procedures were performed to understand how each test method influences the test results. A comparison of the laboratory and field test method are also presented, with reasons for the differences in the measured values presented. The experimental study also led to development of a modular structured tire-ice model (TIM). The model computes the temperature rise in the contact patch based on the pressure distribution in the contact patch, thermal properties of the tread compound and of the ice surface. The contact patch is then classified into wet and dry regions based on the ice surface temperature and temperature rise simulations. The principle of thermal balance is then applied to compute the friction level in the contact patch. The tire-ice contact model is validated for two parameters: temperature rise and friction levels. Temperature rise from simulations are validated against temperature measurements at the leading and trailing edge of the contact patch. Friction levels at different conditions of load, inflation pressure, and ice temperatures have been simulated using the tire-ice contact model and compared to the experimental findings.
Ph. D.

The disposal of used tires represents an environmental and health hazard, especially when large stockpiles of tires start on fire. This study focuses on ambient particulate matter samples collected during the Iowa City landfill tire fire and laboratory emissions of tire combustion. Levels of elemental (EC) and organic carbon (OC), metals, polycyclic aromatic hydrocarbons (PAH), azaarenes and oxygenated PAH (oxy-PAH) were determined by thermo-optical analysis, high precision mass, inductively-coupled plasma mass spectrometry and gas chromatography mass spectrometry. Results demonstrate that tire combustion emissions are enriched in elemental carbon and PAH. Levels of hazardous metals, such as lead and zinc, are not enhanced in particulate emissions 4.2 km from the fire. In addition, fresh tire combustion emissions have increased amounts of lower molecular weight PAH in the particle phase when compared to diluted real world emissions. This is due to gas phase partitioning of lower molecular weight PAH in plume transport. To build on the prior, qualitative understanding of organic compounds in tire emissions, 15 total azaarenes and oxy-PAH were identified, including four azaarenes and three oxy-PAH that were identified in tire combustion emission for the first time. The combustion of tires has significant health implications, particularly when open burning occurs near populations. This study serves to characterize the major chemical components of tire smoke and to quantify emissions of select chemicals with known carcinogenic, mutagenic, and toxic effects.

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 primary goal of this work is to design and implement a clutch and brake system on the single tire Terramechanics rig of Advanced Vehicle Dynamics Laboratory (AVDL) at Virginia Tech. This test rig was designed and built to study the performance of tires in off-road conditions on surfaces such as soil, sand, and ice. Understanding the braking performance of tires is crucial, especially for terrains like ice, which has a low coefficient of friction. Also, rolling resistance is one of the important aspects affecting the tractive performance of a vehicle and its fuel consumption. Investigating these experimentally will help improve tire models performance. The current configuration of the test rig does not have braking and free rolling capabilities. This study involves modifications on the rig to enable free rolling testing when the clutch is disengaged and to allow braking when the clutch is engaged and the brake applied. The first part of this work involves the design and fabrication of a clutch system that would not require major changes in the setup of the test rig; this includes selecting the appropriate clutch that would meet the torque requirement, the size that would fit in the space available, and the capability to be remotely operated. The test rig's carriage has to be modified in order to fit a pneumatic clutch, its adapter, a new transmission shaft, and the mounting frame for the clutch system. The components of the actuation system consisting of pneumatic lines, the pressure regulator, valves, etc., have to be installed. Easy operation of the clutch from a remote location is enabled through the installation of a solenoid valve. The second part of this work is to design, fabricate, and install a braking system. The main task is to design a customized braking system that satisfies the various physical and functional constraints of the current configuration of the Terramechanics rig. Some other tasks are the design and fabrication of a customized rotor, selection of a suitable caliper, and design and fabrication of a customized mounting bracket for the caliper. A hydraulic actuation system is selected since it is suitable for this configuration and enables remote operation of the brakes. Finally, the rig is upgraded with the assembly of these two systems onto it.
Master of Science

A brief description  of the multibody system mechanics is given as the first step in this thesis to present the dynamical equations which will be the main tool to analyze the two-body tire model.  After establishing the basic theory about multibody systems to understand the main character in the thesis (the tire)  all the  physical components playing in the tire terrain interaction  will be defined together with some of the developed ways and models to describe the  tire rolling  on non-deformable terrain and the  tyre rolling on the deformable terrain. The two-body tire model definition and general description will be introduced.  Using the tools acquired on the course of the thesis  the  dynamic equations will be solved for the particular case of the two-body tire model rolling on a flat rigid surface. After solving the equation we are going to find out some incongruences with respect to reality and then we are going to have a proposal to adjust the model to agree with  real tires.

COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
A utilização de pneus usados é uma técnica interessante para reforço de solos, sob o aspecto ambiental. Os pneus usados constituem uma matéria-prima abundante e de custo reduzido. A técnica de utilização de pneus em obras geotécnicas vem sendo difundida no Brasil desde meados dos anos 90, com a construção do muro experimental de solopneus da PUC-Rio, em colaboração com a Fundação Geo-Rio e a Universidade de Ottawa (Canadá). O presente trabalho tem por objetivo apresentar a metodologia para avaliação da resistência ao arrancamento de malhas de pneus. Os pneus podem ser dispostos em um plano horizontal e amarrados entre si, formando uma malha de reforço. Podem ser utilizados pneus inteiros ou com uma das bandas laterais cortadas. A sobrecarga atuando no reforço provém do confinamento provocado pela altura do aterro de solo, construído sobre a malha de pneus. Os ensaios de arrancamento dos pneus no campo utilizaram uma estrutura metálica de reação, atirantada, a qual foi desenvolvida especificamente para o programa experimental sobre reforço de solos. Os resultados permitiram idealizar um mecanismo de ruptura envolvido no processo de arrancamento das malhas de pneus, bem como a verificação das características de resistência e deformabilidade deste tipo de reforço.
The use of scrap tires as soil reinforcement is an environmentally interesting technique. Scrap tires are an abundant and low cost waste material. The technique for using tires in geotechnical construction is becoming popular in Brazil since the construction of an experimental gravity wall made with soil and tires in 1995. This wall was part of a research project by carried out by PUC-Rio in collaboration with Geo-Rio and University of Ottawa. The objective of this work is to present a methodology to evaluate the pull-out behaviour of tire meshes. The tires can be placed in a horizontal plane and tied with rope or wire, forming a reinforcement mesh. The surcharge on these meshes comes from the confinement due to the height of a soil embankment built on the mesh. Field pull-out tests were performed on these reinforcement meshes, using a metallic reaction structure, which was developed specifically for this experimental research. The results allowed the idealization of a shearing mechanism based on the pull-out of tire meshes, as well as the verification of the strength and deformability characteristics of the reinforcement.

The annual increase in waste car tires in addition to the enormous amount at present poses a major waste management problem as well as an environmental hazard. However, pyrolysis is emerging as a solution for waste tire management and a viable technology for material recycling and energy recovery that produces high energy liquid and gas products as well as char. The pyrolysis oil that is produced from this technology has the potential to be used as vehicle fuel but contains exceeding levels of sulfur and other impurities. This study investigates the upgrading and desulfurization of waste tire pyrolysis oil by reactive adsorption using a molybdenum modified zeolite and its desilicated form. The experiments were performed at 320 °C and a LHSV of 45-50 h-1 for approximately 45 min, and revealed that both desilication and Mo-modification resulted in the cracking of both gaseous and liquids compounds, reduction of TAN, denitrogenation, and deoxygenation. Desilication increased desulfurization while Mo-modification increased the EHI. The treatment was the most effective in the removal of oxygen, followed by nitrogen and sulfur. In conclusion, the treatment process is promising as a method for direct liquid upgrading but requires further research.

Tires serve as important components of wheeled vehicles and their analytical modeling has drawn the attention of many researches in the past decades. A high-resolution finite element (FE) tire model contains detailed structural and material characteristics of a tire that exhibit degrees-of-freedom (DoF) in the order of 10⁵ or greater. However, such high-resolution models in their full detail are not practically applicable in multibody dynamic analysis of vehicles and a reduction in their order becomes necessary. In this research different formulations to construct condensed FE tire models suitable for multibody simulations are developed and their characteristics are discussed. In addition, two new and novel forms of substructuring are presented that aim at isolating the contact region of a tire without the need for keeping the boundary DoF which otherwise remain in the reduced system in the standard substructuring procedures. The new substructuring methods provide a great tool in constructing condensed FE tire models with much less total number of DoF compared to cases where a standard substructuring is used. In order to increase the computational efficiency of the condensed FE tire models even further, the possibility of model condensation in the contact region is studied. This research also addresses the applicability of available friction models into the condensed FE tire models. Different formulations of a condensed tire model presented in this research are used to construct several computational models. These models are utilized to simulate certain scenarios and the results are discussed.

Induced vibrations due to tire-pavement interaction are one of the main sources of vehicle exterior noise, especially near highways and main roads where traveling speeds are above 50 kph. Its dominant spectral content is approximately within 500-1500 Hz. However, accurate prediction tools within this frequency range are not available. Current methods rely on structural modeling of the complete tire using finite elements and modal expansion approaches that are accurate only at low frequencies. Therefore, alternative physically-based models need to be developed. This work proposes a new approach that incorporates wave behavior along the tire's circumferential direction, while modes are assumed along its transversal direction. The formulation for new infinite plate and cylindrical shell structural models of a tire is presented. These are capable of accounting for orthotropic material properties, different structural parameters between the belt and sidewalls, inflation pressure, and rotation of the tire. In addition, a new contact model between the pavement and the tire is developed presented. The excitation of the tire due to the impact of the tread-pattern blocks in the contact patch region is characterized and coupled to the structure of the tire. Finally, a Boundary Element Method is implemented in order to compute the vibration-induced noise produced by the tire. All the modeling components are combined in a single prediction tool named Wave Pro Tire. Lastly, simulated responses and validation cases are presented in terms of harmonic responses, Frequency Response Functions (FRF), and produced noise.
Doctor of Philosophy
Induced vibrations due to tire-pavement interaction are one of the main sources of vehicle exterior noise, especially near highways and main roads where traveling speeds are above 50 kph. Accurate prediction tools are not currently available. Therefore, new physically based models need to be developed. This work proposes a new approach to model the tire’s structure with a formulation that accounts for multiple physical phenomena. In addition, a model that simulates the contact between the pavement and the tire’s tread is presented. Finally, the vibrations are coupled to the produced noise in a single prediction tool named Wave Pro Tire. This work also includes simulated responses and validation cases.

Lack of drivers knowledge about the abrupt changes in pavement friction and poor performance of the vehicle stability, traction and ABS controllers on the low friction surfaces are the most important factors affecting car crashes. Due to its direct relation to vehicle stability, accurate estimation of tire-road characteristics is of interest to all vehicle and tire companies. Many studies have been conducted in this field and researchers have used different tools and have proposed different algorithms. One such concept is the Intelligent Tire. The application of intelligent tire in tire-road characterization is investigated in this study. Three different test setups were used in this research to study the application of the intelligent tires to improve mobility; first, a wheeled ground robot was designed and built. A Fuzzy Logic algorithm was developed and validated using the robot for classifying different road surfaces such as asphalt, concrete, grass, and soil. The second test setup is a portable tire testing trailer, which is a quarter car test rig installed in a trailer and towed by a truck. The trailer was equipped with different sensors including an accelerometer attached to the center of the tire inner-liner. Using the trailer, acceleration data was collected under varying conditions and a Neural Network (NN) algorithm was developed and trained to estimate the contact patch length, effective tire rolling radius and tire normal load. The third test setup developed for this study was an instrumented Volkswagen Jetta. Different sensors were installed to measure vehicle dynamic response. Additionally, one front and one rear tire was instrumented with an accelerometer attached to their inner-liner. Two intelligent tire based algorithms, a tire pressure estimation algorithm and a road condition monitoring algorithm, were developed and trained using the experimental data from the instrumented VW Jetta. The two-step pressure monitoring algorithm uses the acceleration signal from the intelligent tire and the wheel angular velocity to monitor the tire pressure. Also, wet and dry surfaces are distinguished using the acceleration signal from the intelligent tire and the wheel angular velocity through the surface monitoring algorithm. Some of the model based tire-road friction estimation algorithms, which are widely used for tire-road friction estimation, were also introduced in this study and the performance of each algorithm was evaluated in high slip and low slip maneuvers. Finally a new friction estimation algorithm was developed, which is a combination of experiment based and vehicle dynamic based approaches and its performance was also investigated.
PHD

Information about dynamic tire properties has always been important for drivers of wheel driven vehicles. With the increasing amount of systems in modern vehicles designed to measure and control the behavior of the vehicle information regarding dynamic tire properties has grown even more important.

In this thesis a number of methods for modeling and estimating dynamic tire properties have been implemented and evaluated. The more general issue of estimating model parameters in linear and non-linear vehicle models is also addressed.

We conclude that the slope of the tire slip curve seems to dependent on the stiffness of the road surface and introduce the term combined stiffness. We also show that it is possible to estimate both longitudinal and lateral combined stiffness using only standard vehicle sensors.

The heavy duty vehicle industry has today no requirement to providea tire pressure monitoring system by law. This has created issues sur-rounding unknown tire pressure and thread depth during active service.There is also no standardization for these kind of systems which meansthat different manufacturers and third party solutions work after theirown principles and it can be hard to know what works for a given vehicletype. National Highway Traffic Safety Administration (NHTSA) put out a new study that determined that underinflated tires of 25% or less are 3 times more likely to be involved in a crash related to tire issues versus vehicles with properly inflated tires. The objective for this thesis is to create an indirect tire monitoring system that can generalize a method that detect both incorrect tire pressure and thread depth for different type of vehicles within a fleet without the need for additional physical sensors or vehicle specific parameters. Drivec Bridge hardware interprets existing sensors from the vehicle. By using supervised machine learning a classifier was created for each axle where the main focus was the front axle which had the most issues.The classifier will classify the vehicles tires condition. The classifier will be implemented in Drivecs cloud service and use data to classify  the tires condition. The resulting classifier of the project is a random forest implemented in Python. The result from the front axle with a dataset consisting of 9767 samples of buses with correct tire condition and 1909 samples of buses with incorrect tire condition it has an accuracy of90.54% (±0.96%). The data sets are created from 34 unique measurements from buses between January and May 2017. The developed solution is called Indirect Tire Monitoring System (ITMS) and is seen as a process. The project group has verified with high accuracy that a vehicle has been classified as bad and then been reclassified as good over a time span of 16 days. At the first day offboard measurements were performed and it showed that the tires of the front axle were underinflated. The classifier indicated that the vehicle had bad classifications until day 14. At this day an offboard measurement was performed and it was concluded that they were no longer underinflated and the classifier indicated this as well. To verify the result the workshop was contacted and verified that the vehicle had changed tires of the front axle at day 14. This has verified that the classifier is able to detect change and stay consistent in the results over a longer time period.

This dissertation is concerned with experimental and analytical studies of the mechanics of interaction where a pneumatic tire is loaded vertically on a supporting ground, i.e., rigid base, clay and sand.
The numerous experiments were conducted under various conditions to characterized the interactions in terms of the experimental results, e.g. axle displacement, contact area, contact pressure, etc. The results of pressure distribution indicate that recognizing a tire as a pneumatic body is crucial in establishing a rational theory for tire-supporting ground interaction problems. The pressure distribution and contact area obtained in the experiments are also utilized in validating an analytical approach (i.e. First Analytical Approach) established in the dissertation.
A hypothetical description of the progress of tire deformation is discussed based on the experimental results. The discussion helps in providing a better understanding of the mechanics of the interaction, and for selecting basic analytical and/or numerical tools in establishing the present analytical methods.
In the analytical work, the two distinct analytical approaches (i.e. First and Second Analytical Approaches) are established under the plane strain condition in predicting contact length and pressure. However, the first analytical approach is emphasized in this dissertation, while the second one is rather a complementary work.
In the first analytical approach, the real contact profile is taken into account, while the existing contact theories (by Hertz, Muskhelishvili, etc.) essentially ignore the real kinematics of contact surfaces on which the pattern of pressure distribution greatly depends. In this first analytical approach, the following steps are taken: (1) transform a tire-supporting ground interaction problem into an equivalent free boundary (-value) problem of the deformed supporting ground; this is done so that the complex factors inherent to pneumatic tires are not directly taken into the analytical formulation; (2) determine the modulus of elasticity of the deformed supporting ground by taking into account the contact profile; (3) find the contact length and pressure by means of the complex variable method.
The contact length and pressure analytically obtained are in close agreement with those obtained through experimentation. An attempt has also been made to solve the sliding interaction problems.
The second analytical approach, which is an iterative technique combining the incremental finite element method and the complex variable method, is established fundamentally to solve an interaction problem between an elastic solid and a nonlinear elastic half-plane. Two different types of interaction problems are solved, i.e. tire-clay and rigid wheel-snowpack interactions. Numerical results on contact length for both problems showed acceptable agreement with the experimental results, while those on sinkage obtained for the rigid wheel did not.

Considering the more and more concerned climate change issues to which the greenhouse gas emission may contribute the most, as well as the diminishing fossil fuel resource, the automotive industry is paying more and more attention to vehicle concepts with full electric or partly electric propulsion systems. Limited by the current battery technology, most electrified vehicles on the roads today are hybrid electric vehicles (HEV). Though fully electrified systems are not common at the moment, the introduction of electric power sources enables more advanced motion control systems, such as active suspension systems and individual wheel steering, due to electrification of vehicle actuators. Various chassis and suspension control strategies can thus be developed so that the vehicles can be fully utilized. Consequently, future vehicles can be more optimized with respect to active safety and performance. Active camber control is a method that assigns the camber angle of each wheel to generate desired longitudinal and lateral forces and consequently the desired vehicle dynamic behavior. The aim of this study is to explore how the camber angle will affect the tire force generation and how the camber control strategy can be designed so that the safety and performance of a vehicle can be improved. As the link between the vehicle and the road, the tire ultimately determines the dynamic characteristics of the vehicle. Researchers in the automotive industry have developed various tire models to describe the force and torque generation of a tire. The semi-empirical Magic Formula tire model and the simple physical brush tire model are two common and widely used tire models. In this study, a quick review of the Magic Formula tire model and the brush tire model is firstly presented. Bearing the advantages and disadvantages of the two models in mind, a new multi-line brush tire model, which places its focus on camber effect on longitudinal and lateral force generation, is developed according to the brush model theory. The newly developed multi-line brush tire model describes longitudinal and lateral force generation at different camber angles accurately and provides some essential information of the effect of camber angle. However, the multi-line brush tire model consumes huge amount of computational effort thus it is not suitable for real time vehicle level simulations. In order to explore how the camber control strategy can be designed, a simple magic formula model is developed by curve fitting to the multi-line brush tire model. The simple magic formula model takes much less computational effort but represents the force generation at different camber angles quite well as the multi-line brush tire model does. With the help of the simple magic formula model, real time vehicle level simulations are conducted to find the optimal camber control strategies with respect to safety and performance.

Cut-to-length logging is a mechanized method for delimbing trees and cutting them to length. It is a two-machine operation; taken care by a harvester and a forwarder. The forwarder can cause soil rutting, soil compaction and other detrimental after effects. Therefore it has become vital to protect the forest floor from destructive effects of heavy machines. This initiated the study to delve more into the interaction between the loaded forwarder wheel and the soil. Various WES based rut depth models has been compared to validate its effectiveness in predicting the rut depths. New models have been developed to estimate the rut depth produced by the multipass effect of wheels. Models that could predict the contact pressure between the tire and soil as well as the tire soil contact area has been studied. Various relations to determine the mobility parameters have also been studied. The ones that are suitable to predict mobility parameters have been identified. Roots play a major role in reinforcing the soil and protecting them. This extra reinforcement provided by roots has been taken into account in the thesis work. Lab test with pine tree roots have been carried out to determine the extra reinforcement supplied. Models that are capable of predicting the reinforcement effects due to roots have also been looked into. An initial step towards connecting WES and Bekker models have been done; available models correlating both WES and Bekker models have been analysed and finally a set of relations connecting both have been derived. The effect of slip on sinkage has been studied with the help of both WES and Bekker based models. Multibody simulation software MSC Adams has been used to simulate the forwarder model to determine its suitability for rut depth prediction. Adams has been employed to study the effect of tire inflation pressure and velocity on rut depth.
Kortvirkesmetoden är en mekaniserad för skogsavverkning. Det är en två-maskinsprocess, som utförs av en skördare och en skotare. Skotaren kan orsaka skador på marken, som exempelvis spårbildning och markpackning. Det har blivit allt viktigare att skydda skogen från de marskador orsakade av tunga maskiner. Detta är en initiell studie av samspelet mellan mark och hjul på en lastad skotare. Olika WES-baserade spårdjupsmodeller har jämförts för att värdera deras förmåga att prediktera spårdjupen. Nya modeller har också utvecklats för att uppskatta relationen mellan spårdjup och flera hjulpassager. Modeller som kan prediktera kontakttrycket mellan däcket och marken, samt däckets markkontaktarea har studerats. Olika relationer för att bestämma mobilitetsparametrarna har också studerats. Rötter spelar en viktig roll för att öka markens bärighet och att skydda den. Rötternas effekt på markens bärighet har behandlats i examensarbetet. Labbtester med tallrötter har genomförts för att bestämma deras armeringseffekt. Modeller som kan användas för att prediktera rötternas effekter har också studerats. Ett första steg för att kunna kombinera WES- och Bekker-modeller har utförts, tillgängliga modeller som korrelerar WES- och Bekker-modeller har behandlats och en uppsättning relationer som relaterar de båda modellerna har härletts. Effekten av halka i samband med nedsjunkning har studerats med hjälp av både WES- och Bekkerbaserade modeller. Dynamiksimuleringsprogramet MSC Adams har använts för att simulera skotarmodellen för att bestämma dess lämplighet för spårdjupsförutsägelse. Adams har använts för att studera vilken effekt olika däcktryck och hastighet har på spårdjupet.

Mestrado em Finanças
O trabalho elaborado consiste numa avaliação do preço por ação da Goodyear Tire and Rubber Co. para o fim do ano de 2019, tendo por base pressupostos de performance para os próximos cinco anos, bem como os dados históricos dos últimos cinco anos. A decisão de avaliar a Goodyear baseia-se no desejo de proceder a uma análise de uma empresa que se enquadre na indústria dos pneus e borracha. O relatório baseia-se no formato do CFA Institute e tem como inicio a descrição da empresa, a qual contém um breve resumo dos acontecimentos marcantes da sua história até a data.
The following work consists on an Equity Research of Goodyear Tire and Rubber for the year ending 2019F, based on assumptions considered to be viable for the next five years, as well as, in the historical performance of the last five years. The decision to evaluate a company such as Goodyear Tire and Rubber came from a personal preference to further develop an analysis of a Tire and Rubber industry company. The research report follows the CFA Institute format and begins with the company overview, which contains a brief history that summarizes the main events up to date.
info:eu-repo/semantics/publishedVersion

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

Recent experimental results have shown that the vibration induced by the tire air cavity resonance is transmitted into the vehicle cabin and may be responsible for significant interior noise. The tire acoustic cavity is excited by the road surface through the contact patch on the rotating tire. The effect of the cavity resonance is that results in significant forces developed at the vehicle's spindle, which in turn drives the vehicle's interior acoustic field. This tire-cavity interaction phenomenon is analytically investigated by modeling the fully coupled tire-cavity systems. The tire is modeled as an annular shell structure in contact with the road surface. The rotating contact patch is used as a forcing function in the coupled tire-cavity governing equation of motion. The contact patch is defined as a prescribed deformation that in turn is expanded in its Fourier components. The response of the tire is then separated into static (i.e. static deformation induced by the contact patch) and dynamic components due to inertial effects. The coupled system of equations is solved analytically in order to obtain the tire acoustic and structural responses. The model provides valuable physical insight into the patch-tire-acoustic interaction phenomenon. The influence of the acoustic cavity resonance on the spindles forces is shown to be very important. Therefore, the tire cavity resonance effect must be reduced in order to control the tire contribution to the vehicle interior. The analysis and modeling of two feasible approaches to control the tire acoustic cavity resonances are proposed and investigated. The first approach is the incorporation of secondary acoustic cavities to detune and damp out the main tire cavity resonance. The second approach is the addition of damping directly into the tire cavity. The techniques presented in this dissertation to suppress the adverse effects of the acoustic cavity in the tire response, i.e. forces at the spindle, show to be very effective and can be easily applied in practice.
Ph. D.

In order to provide data for non-rolling tire models that are used in computer simulations of vehicle dynamics, a tire test rig is designed and manufactured which attaches to an MTS kinematics and compliance machine. This test rig is developed for the purpose of characterizing the loaded radius, overturning moment, and displacement of multiple tires in the vertical, lateral, and longitudinal test axes. Equations are developed and used to fit these parameters for the purpose of representing them in non-rolling vehicle simulation models.
Master of Science

Accurate and efficient tire models for deformable terrain operations are essential for performing vehicle simulations. Assessment of the forces and moments that occur at the tire-terrain interface, and the effect of the tire motion on properties of the terrain are crucial in understanding the performance of a vehicle. In order to model the dynamic behavior of the tire on different terrains, a lumped mass discretized tire model using Kelvin-Voigt elements is developed. To optimize the computational time of the code, different techniques were used in memory allocation, parameter initialization, code sequence, and multi-processing. This has resulted in significant improvements in efficiency of the code that can now run close to real time and therefore it is suitable for use by commercially available vehicle simulation packages. Model parameters are obtained using a validated finite element tire model, modal analysis, and other experimental test procedures. Experimental tests were performed on the Terramechanics rig at Virginia Tech. The tests were performed on different terrains; tire forces and moments, soil sinkage, and tire deformation data were collected for various case studies based on a design of experiment matrix. This data, in addition to modal analysis data were used to validate the tire model. Furthermore, to study the validity of the tire model, simulations at conditions similar to the test conditions were performed on a quarter car model. The results have indicated the superiority of this model as compared to other lumped parameter models currently available.
Ph. D.

Recently Michelin has been developing a new airless, integrated tire and wheel combination called the Tweel. The Tweel promises performance levels beyond those possible with conventional pneumatic technology because of its shear band design, added suspension, and decreased rolling resistance. However, many questions remain as to what kind of environmental impact this radical new design will have. The environmental impact of the Tweel will be compared to a current radial tire used on BMWs, but because of the complexity in manufacturing, using, and disposing these tires it is somewhat difficult to compare environmental problems. Currently there are environmental issues all throughout a tire's lifespan from rubber manufacturing emissions to tire disposal, and the rapidly growing method to evaluate all of these points is Life Cycle Analysis (LCA). LCA is the essential tool required by businesses in order to understand the total environmental impact of their products - cradle-to-grave. By considering the entire life cycle of a Tweel from manufacturing, through use and disposal, and comparing it to knowledge of current tires, an accurate assessment of the entire environmental impact of the Tweel will be made. Since the Tweel is currently still in the research phase and is not currently manufactured and used however, there are uncertainties with respect to end-of-life scenarios and rolling resistance estimates that will affect the LCA. Thus, it will be important to consider a range of options to determine which one will have the most environmental benefits while still keeping the strengths of the Tweel design intact.

Considering the more and more important issues concerning the climate changes and the global warming, the automotive industry is paying more and more attention to vehicle concepts with full electric or partly electric propulsion systems. The introduction of electric power sources allow the designers to implement more advanced motion control systems in vehicle, such as active suspensions. An example of this concept is the Autonomous corner module (ACM), designed by S. Zetterström. The ACM is a modular based suspension system that includes all features of wheel control, such as control of steering, wheel torque and camber individually, using electric actuators. With a good control strategy it is believed that is it possible to reduce the fuel consumption and/or increase the handling properties of the vehicle. In particular, camber angle has a significant effect on vehicle handling. However, very few efforts have been done in order to analyse its effects on tire dissipated energy. The aim of this study is to develop a new tire model, having as starting point the simple Brush Tire model, in order to analyse the tire behaviour, in terms of forces generated and energy dissipated, for different dynamic situations. In order to reach this scope, the characteristic equations of the rubber material are implemented in a 3D Multi-Line brush tire model. In this way the energy dissipated, thus the rolling resistance force, can be studied and analysed, considering also the tire geometry. From the results of this work it is possible to assert that the angular parameters (e.g. camber angle) affect the power losses in rolling tires, as well as the tire geometry influences their rolling resistance. Thus, using a good control strategy, it is possible to reduce the power losses in tires.

A proof-of-concept indirect tire-pressure monitoring system is developed using neural net- works to identify the tire pressure of a vehicle tire. A quarter-car model was developed with Matlab and Simulink to generate simulated accelerometer output data. Simulation data are used to train and evaluate a recurrent neural network with long short-term memory blocks (RNN-LSTM) and a convolutional neural network (CNN) developed in Python with Tensorflow. Bayesian Optimization via SigOpt was used to optimize training and model parameters. The predictive accuracy and training speed of the two models with various parameters are compared. Finally, future work and improvements are discussed.

The tire is one of the most important components of the vehicle. It has many functions, such as supporting the load of the vehicle, transmitting the forces which drive, brake and guide the vehicle, and acting as the secondary suspension to absorb the effect of road irregularities before transmitting the forces to the vehicle suspension. A tire is a complex reinforced rubber composite air container. The structure of the tire is very complex. It consists of several layers of synthetic polymer, many flexible filaments of high modulus cord, and glass fiber, which are bonded to a matrix of low modulus polymeric material. As the tire is the only component of the vehicle which makes contact with the road surface, almost all forces and moments acting on the vehicle must be transferred by the tire. To predict the dynamics of the vehicle, we need to know these forces and moments generated at the tire contact patch. Therefore, tire models that accurately describe this dynamic behavior are needed for vehicle dynamic simulation. Many researchers developed tire models for vehicle dynamic simulations; however, most of the development in tire modeling has been limited to deterministic steady-state on-road tire models. The research conducted in this study is concerned with the development of semi-empirical transient tire models for on-road and off-road vehicle simulations. The semi-empirical transient tire model is developed based on existed tire models, analytical tire structure mechanics analysis, and experimental data collected by various researchers. The tire models were developed for vehicle traction, handling and ride analysis. The theoretical mechanics analysis of the tire model focused on the determination of tire and terrain deformation. Then, the results are used together with empirical data to calculate the force response and the moment response. Moreover, the influence of parametric uncertainties in tire parameters on the tire-terrain interaction is investigated. The parametric uncertainties are quantified and propagated through the tire models using a polynomial chaos theory with a collocation approach. To illustrate the capabilities of the tire models developed, both deterministic and stochastic tire models are simulated for various scenarios and maneuvers. Numerically simulated results are analyzed from the perspective of vehicle dynamics. Such an analysis can be used in tire and vehicle development and design.
Ph. D.

Pneumatic tire friction on ice is an under-researched area of tire mechanics. This study covers the design and analysis of a series of pneumatic tire tests on a flat-level ice road surface. The terramechanics rig of the Advanced Vehicle Dynamics Lab (AVDL) is a single-wheel test rig that allows for the experimental analysis of the forces and moments on a tire, providing directly the data for the drawbar pull of said tire, thus supporting the calculation of friction based on this data. This indoor testing apparatus allows for some degree of replication by helping to maintain test conditions and by imposing a desired tire slip; the normal load, camber angle, toe angle, and other testing configurations can also be pre-set, as required. Methods of and issues related to controlling the production of ice and maintaining the conditions of numerous factors for each trial run were also documented. The AVDL terramechanics rig allowed for the collection of data from tests that varied the tire tread, tire inflation pressure, normal load on the wheel, and the slip ratio of the moving tire. This empirical data was then analyzed through the statistical analysis program JMP 8 in order to determine which factors (or combination of factors) significantly influence pneumatic tire friction on ice. The analysis verified that the slip ratio had a significant effect on the observed coefficient of friction, which decreased as the slip ratio increased. The combinations of the slip ratio and inflation pressure and the slip ratio and tire setup also had a significant effect on the observed coefficient of friction. The tests appear to have validated the theory that the drawbar pull and the traction was higher for the tire with tread.
Master of Science

碩士
國立交通大學
電控工程研究所
99
Due to the advances in modern automotive technologies, requirements for driving comfort and being friendly to the environment are ever demanding. Vehicles run on roads with different surface conditions which make tire-road forces, and in turn the vehicle dynamics vary significantly. This study develops an algorithm that uses measurable signals and simple vehicle dynamic models to estimate tire-road friction forces. Then an experimental platform is established to simulate a tire rolling on a road surface such that the validity of the proposed algorithm can be verified experimentally. This thesis establishes a friction force estimation algorithm which uses torque balance equations to obtain longitude friction forces. Lateral friction forces are estimated by introducing the concept of friction circles and switching between a simplified four-wheel model and the bicycle model. The uncertain parameters of the vehicle are also estimated on-line by applying the expectation-maximization algorithm. Finally, simulations are conducted under various driving and road conditions to evaluate the performance of parameter and tire-road force estimation. This study also sets up a quarter-car experimental platform to estimate longitudinal forces. Experimental results exhibit a linear relation between the longitudinal tire force and the slip ratio whenever the latter is low.

As vehicle dynamics research delves deeper into better insights in performance, modeling, and vehicle controls, one area remains of utmost importance: tire and road friction forces. The vehicle???s interaction with the road remains the dominant mean of vehicle control. Ultimately, the tire-road interaction will determine the majority of the vehicle???s capabilities and as the understanding of the interface improves, so too can the performance. With more computationally intensive systems being instrumented into modern vehicle systems, one is able to observe a great deal of important vehicle states directly for the remaining vehicle information; excellent estimation techniques are providing the rest of the insights. This study looks at the possible improvements that can be observed by implementing an adaptive dynamic tire model that is physical and flexible enough to permit time varying tire performance. The tire model selected is the Average Lumped LuGre Friction Tire Model, which was originally developed from physical properties of friction and tire systems. The material presented here examines the possibility of an adaptive tire model, which can be implemented on a real-time vehicle platform. The adaptive tire model is just one section of an entire control strategy that is being developed by General Motors in partnership with the University of Waterloo. The approach allows for estimated and measured vehicle information to provide input excitation for the tire model when driven with real-world conditions that enabling tire estimations. The tire model would then provide the controller information indicating the expected tire capacity and compares it with the instantaneous loading. The adaptive tire model has been tested with flat road experimental cases and the results provided reasonable estimates. The experimentation was performed with a fully instrumented research vehicle that used in-wheel force transducers, and later repeated with a completely different non-instrumented fully electric vehicle. The concepts and investigation presented here has initiated the ground work for a real-time implementation of a full adaptive tire model. Further work is still required to evaluate the influence of a range of operating conditions, tire pressure, and of different tire types. However, the findings indicate that this approach can produce reasonable results for the specified conditions examined.

碩士
國立屏東科技大學
車輛工程系所
103
This study aims to establish a real-time tire-road friction coefficient law. This estimation law uses an iterative process with real time estimated lateral force, slip angle and the vertical force under 2 DoF model and the embedded lateral force curve to estimate the road coefficient of friction. To acquire the lateral force curve, this study proposes an experiment to acquire the lateral force and slip angle pair under a constant vertical force. This experiment features a constant speed and piece wise constant driving wheel angle such that the lateral force and slip angle can be calculated with relative dynamics variables. Furthermore, to validate the friction coefficient estimation law, this study uses CarSim simulation to conduct several cases which include same driving pattern with different friction coefficients in different cases and same friction coefficient with different driving patterns. Results show that the estimation is inaccurate in straight driving and is accurate under a significant driving. This is due to the influence from the lateral force caused by camber. The proposed lateral force can only calculate the total lateral force which is a combination of the lateral forces caused by camber and slip angle but the estimation law requires only the lateral caused by slip angle. The lateral force caused by camber is larger than the lateral force caused by slip angle in straight driving.

碩士
國立政治大學
國際經營管理英語碩士學位學程(IMBA)
107
In year 2018, China tire and rubber industry achieved revenues of more than $81.03 billion, with an annual compound growth rate of 8.2% from 2014 and 2018; China tire consumption reached 580.7 million, with an annual compound growth rate of 6.3% from 2014 and 2018 in year 2018. In year 2018, the entire market value of global tire and rubber industry reached $612 billion, with a year-on-year increase of 4.7%. By 2023, the entire market value of global tire and rubber industry is expected to reach $793.5 billion, with an increase of 29.7% compared with that of 2018. However, the severe regulation for environmental protection, the ADD (Anti-Dumping Duties) and CVD (Countervailing Duty) investigation from EU and US, and the trade war between US and China may put tire business become more volatile and unpredictable. The additional 25% US tariffs, ADD and CVD from DOC (Department of Commerce) make US headquarter decide to reduce GRT production tickets and shift them to the Vietnam JV facility. Curtailment or layoff will be an option for GRT operation!! Just like the Great Purge in TBR tire industry, most large Chinese TBR tire makers set up facilities overseas in succession in order to avoid high tariff and heavy duty or even to circumvent the severe environmental regulation.

碩士
逢甲大學
自動控制工程學系
105
The wireless tire pressure monitoring system (TPMS) can improve the safety of driving. General TPMS system installed in the specific location of the vehicle, the system will be set according to the preset tire location ID value sent to the display shows the current actual tire pressure and temperature. When the tire pressure or temperature anomalies, the monitoring system will take the initiative to alert, and show the value to remind the user. This method must record in advance to identify the ID value in the receiver, in order to identify the wheels of the assembly of the sensor to send the temperature, pressure and other messages. However, when the tire needs to be replaced, the ID code of the tire inner launch module and the ID code originally recorded in the receiver will produce a misjudgment of the actual location of the tire. In this thesis, we work with orange electrons to propose an automatic location technique that can solve the above problems and reduce the inconvenient use of the tire pressure detector. When the car changes the tire location or changes the new sensor, The vehicle is only a short period of time, through the existing Anti-lock Braking System (ABS), with uniaxial gravity sensor, you can automatically complete the ID code update or omit the new sensor required Re-set the operating procedures to complete the automatic judging function, eliminating the cumbersome operation to re-set. It is found that the phenomenon of resonance between the road surface and the body causes the noise problem of the ABS signal when the signal of the real vehicle test is sent and received, resulting in the deviation of the experimental result. This study uses the anti-noise characteristic of the Smith circuit Improve this problem.