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Die Kontaktverhältnisse zwischen Reifen und Fahrbahn bestimmen die maximal übertragbaren Beschleunigungs-, Brems- und Seitenkräfte des Fahrzeugs und sind daher für die Fahrsicherheit von großer Bedeutung. In dieser Arbeit wird ein Modell zur numerisch effizienten Simulation der hochfrequenten Dynamik einzelner Reifenprofilblöcke entwickelt. Der vorgestellte Modellansatz nutzt einerseits die Vorteile der Finite-Elemente-Methode, welche die Bauteilstruktur detailliert auflösen kann, bei der jedoch lange Rechenzeiten in Kauf genommen werden. Andererseits profitiert der vorgestellte Modellansatz von den Vorteilen stark vereinfachter Mehrkörpersysteme, welche die Berechnung der hochfrequenten Dynamik und akustischer Phänomene erlauben, jedoch strukturdynamische Effekte und das Kontaktverhalten in der Bodenaufstandsfläche des Reifens nur begrenzt abbilden können. Das hier vorgestellte Modell berücksichtigt in einem modularen Ansatz die Effekte der Strukturdynamik, der lokalen Reibwertcharakteristik, der nichtlinearen Wechselwirkungen durch den Kontakt mit der rauen Fahrbahnoberfläche und des lokalen Verschleißes. Die erforderlichen Modellparameter werden durch geeignete Experimente bestimmt. Ein Schwerpunkt der Arbeit liegt in der Untersuchung reibungsselbsterregter Profilblockschwingungen bei Variation der Modell- und Prozessparameter. Zur realistischen Betrachtung des Reifenprofilblockverhaltens erfolgt eine Erweiterung des Modells um eine Abrollkinematik, die tiefere Einblicke in die dynamischen Vorgänge in der Bodenaufstandsfläche des Reifens ermöglicht. Diese Simulationen lassen eine Zuordnung der aus der Literatur bekannten zeitlichen Abfolge von Einlaufphase, Haftphase, Gleitphase und Ausschnappphase zu. Es zeigen sich bei bestimmten Kombinationen aus Fahrzeuggeschwindigkeit und Schlupfwert ausgeprägte Stick-Slip-Schwingungen im akustisch relevanten Frequenzbereich. Das Modell erlaubt die Untersuchung des Einflusses der Profilblockgeometrie, der Materialparameter, der Fahrbahneigenschaften sowie der Betriebszustände auf den resultierenden Reibwert, auf das lokale Verschleißverhalten sowie auf das Auftreten hochfrequenter reibungsselbsterregter Schwingungen. Somit ermöglicht das Modell ein vertieftes Verständnis der Vorgänge im Reifen-Fahrbahn-Kontakt und der auftretenden Wechselwirkungen zwischen Struktur- und Kontaktmechanik. Es kann eine Basis für zukünftige Optimierungen des Profilblocks zur Verbesserung wesentlicher Reifeneigenschaften wie Kraftschlussverhalten, Verschleiß und Akustik bilden. / The contact conditions between tyre and road are responsible for the maximum acceleration, braking and side forces of a vehicle. Therefore, they have a large impact on the driving safety. Within this work a numerically efficient model for the simulation of the high-frequency dynamics of single tyre tread blocks is developed. The presented modelling approach benefits the advantage of the finite element method to resolve the component structure in detail. However, a long computation time is accepted for these finite element models. Moreover, the presented modelling approach makes use of the advantage of simplified multibody systems to calculate the high-frequency dynamics and acoustic phenomena. However, structural effects and the contact behaviour in the tyre contact patch can be covered only to a minor degree. The model treated here considers the effects of structural dynamics, the local friction characteristic, the non-linear interaction due to the contact with the rough road surface and local wear. The required model parameters are determined by appropriate experiments. One focus of this work is the investigation of self-excited tread block vibrations under variation of the model and process parameters. In order to realistically investigate the tread block behaviour the model is extended with regard to rolling kinematics which provides a deeper insight into the dynamic processes in the tyre contact patch. The corresponding simulations allow the allocation of the run-in phase, sticking phase, sliding phase and snap-out which is reported in the literature. For certain combinations of vehicle velocity and slip value pronounced stick-slip vibrations occur within the acoustically relevant frequency range. The model enables to study the influence of the tread block geometry, the material properties, the road surface characteristics and the operating conditions on the resulting tread block friction coefficient, local tread block wear and the occurrence of high-frequency self-excited vibrations. The simulation results provide a distinct understanding of the processes in the tyre/road contact and the interactions between structural mechanics and contact mechanics. They can be a basis for future tread block optimisations with respect to essential tyre properties such as traction, wear and acoustic phenomena.

Cette thèse vise à évaluer le potentiel d'un nouveau couple cathode / électrolyte pour une application en IT-SOFC (700°C), par le biais de l’élaboration et du test de cellules à anode support de configuration planaire. Les matériaux concernés sont l'électrolyte BaIn0.3Ti0.7O2.85 (BIT07), de structure perovskite, et les nickelates de terres rares Ln2-xNiO4+ (LnN, Ln = La, Nd, Pr) en tant que cathodes ; ces matériaux ont montré des propriétés prometteuses dans des travaux préliminaires effectués à l'IMN et l'ICMCB. La première partie de cette thèse porte sur la mise en place d'un protocole d'élaboration de cellules complètes utilisant des techniques bas coûts et industrialisables (cellules de taille 3 x 3 cm2) : l’anode Ni / BIT07 a été élaborée par coulage en bande, l'électrolyte BIT07 par vacuum slip casting et les cathodes par sérigraphie. Les mesures électrochimiques réalisées sur une première génération de cellules ont mis en évidence la nécessité d'ajouter une couche barrière de GDC entre les cathodes LnN et l'électrolyte BIT07. Les meilleures performances ont été obtenues pour une cellule BIT07 / Ni | BIT07 | GDC | PrN, avec une densité de puissance à 700°C et 0.7 V de 176 mW cm-2 pour une faible résistance de polarisation de 0. 29 Ω cm2. La principale limitation des performances a été identifiée comme étant la résistance interne du banc de test, donnant lieu à des valeurs de résistances séries anormalement élevées. Cette cellule a été opérée avec succès durant plus de 500 heures sous courant, avec néanmoins une vitesse de dégradation extrapolée élevée de l’ordre de 27% / kh. / This thesis aimed at assessing the potential of a novel cathode / electrolyte couple for IT-SOFC applications (700°C), through the elaboration and testing of planar anode-supported cells. The materials involved were the perovskite-structured BaIn0.3Ti0.7O2.85 (BIT07) electrolyte and the rare earth nickelate Ln2-xNiO4+ (LnN, Ln = La, Nd, Pr) cathodes, both materials having shown promising properties in preliminary work done at the IMN and the ICMCB. The first part of this thesis concerned the implementation of a cell elaboration protocol using low-cost and scalable shaping techniques (cell size 3 x 3 cm2); namely, the Ni / BIT07 anodes were elaborated by tape casting, the BIT07 electrolyte by vacuum slip casting and the cathodes by screen printing. Comparison of electrochemical results for a first and second generation of cells highlighted the usefulness of adding a GDC buffer layer in between the LnN cathodes and the BIT07 electrolyte. The best performance has been obtained for a cell BIT07 / Ni | BIT07 | GDC | PrN, with a power density at 700°C and 0.7 V of 176 mW cm-2 for a competitive polarisation resistance of 0.29 Ω cm2. The main limitation of the performance has been determined to be related to the internal resistance of the test setup, giving anomalously high series resistances. This cell has been successfully operated beyond 500 hours under current, although with a fairly high extrapolated degradation rate of 27% / kh.

[pt] Sistemas rotativos atuados através de um eixo flexível apresentam um grande desafio para estratégias de controle, uma vez que o atuador não está conectado diretamente ao sistema principal, causando efeitos de propagação de ondas e acúmulos e dissipações de energia no eixo. Este trabalho apresenta um estudo sobre uma das mais notórias aplicações deste problema, sistemas de perfuração de petróleo. Habitualmente, o sistema de perfuração é composto por um motor de topo conectado à broca através de milhares de metros de tubos de aço que transmitem o toque. Diversos tipos de vibrações podem ser observadas: Axiais, de flexão e torcionais, estas últimas ligadas ao fenomeno stick-slip. Para um completo conhecimento do problema, é necessário conhecer cada uma delas. Esta tese trata especificamente das vibrações torsionais através de uma análise com dois diferentes modelos, um primeiro mais simples de fois graus de liberdade (inércia, mola torcional, amortecedor), e um segundo mais completo discretizado em 20 graus de liberdade capaz de considerar a masssa do eixo e efeitos de propagação de ondas mecânicas no eixo. Este trabalho inclui aidna a construção de uma bancada em escala reduzida para observar os fenômenos associados as vibraçoes torcionais. São apresentados ainda estudos numéricos e experimentais de técnicas de controle de minimizar os efeitos do atrito na dinâmica torcional do sistema. Duas estrututas de controle são estudadas nesta tese a fim de reduzir vibrações torcionais em colunas de perfuração. A primeira é um controle simples, de malha aberta, baseado no comportamento do sistema. A segunda é o controle adaptativo L1, que faz uso de um modelo de refeência do sistema em sua estrutura. / [en] Systems actuated trough a highly flexible shaft poses a big challenge to control strategies as the actuator is not connected directly to the end effector, causing propagation effects as well as an energy accumulation and dissipation in the shaft. This thesis focuses the study of one of the most investigated application of this type, the top driven drilling system used in the oil and gas industry. Usually, the drilling system is composed by a top drive linked to the drill bit trough hundreds or even thousands of meters of steel pipes. All kind of vibrations will be found: longitudinal deformations will be associated to the bit bouncing, flexional with rubbing, and torsional with stick-slip effects. A better understanding is only possible when each of these situations is carefully investigated. This thesis focuses on the torsional deformation of the highly flexible string and presents two different models for the drill string, the first is the most common single spring single damper model. The second one is a 20 DOF Lumped parameters that has the advantage of being able to consider the mass of the drill string and propagation of torsional waves in the shaft. The investigation includes the development of a test rig adequate for torsional vibrations under damping that may induce stick-slip in the system. Two control techniques are studied to reduce the torsional vibrations in drill strings with numerical and experimental results presented. The first is a behavior based open loop scheme control, which is very simple and effective to reduce stick-slip oscillations. The second one is the L1 adaptive control that uses a reference model on its structure.

Dans ce travail de thèse, le microscope à force atomique (AFM) a été utilisé comme outil de manipulation de haute précision pour construire des nanostructures plasmoniques avec des géométries définies et un réglage précis de la distance interparticulaire et également comme technique de spectroscopie d'absorption. Différentes études concernant les phénomènes pertinents pour la manipulation des nanoparticules et émergeant à l'interface substrat-nanoparticules, ont été réalisées. Des expériences de frottement menées sur diverses surfaces d'oxydes ont révélé un nouveau mécanisme de frottement à l’échelle nanométrique, expliqué par un modèle de potentiel d'interaction de type Lennard-Jones modifié. Les propriétés de frottement et d'adhésion de CTAB adsorbé sur silice sont également présentées. Des nano-bâtonnets d'or fonctionnalisés par du CTAB ont été manipulés par AFM afin de construire des nanostructures plasmoniques. La dernière partie de la thèse présente les efforts expérimentaux et théoriques pour démontrer la faisabilité de l'utilisation d'un AFM comme une technique de spectroscopie optoélectronique à base de force. / In this thesis work the atomic force microscope (AFM) was employed first as a high precision manipulation tool for building plasmonic nanostructures with defined geometries and precise tuning of interparticle distance and second as an absorption spectroscopy technique. Different studies regarding phenomena emerging at sample nanoparticle interface relevant for nanoparticle manipulation were performed. Friction experiments conducted on various oxide surfaces revealed a novel nanoscale stick slip friction mechanism, explained by a modified Lennard-Jones-like interaction potential model. Frictional and adhesion properties of CTAB adsorbed on silica are also reported. CTAB functionalized gold nanorods were used for building specific plasmonic particulate nanostructures. The final part of the thesis presents experimental and theoretical efforts to demonstrate the feasibility of using an AFM as a force-based optoelectronic spectroscopy technique.

O fenômeno de stick-slip, no processo de perfuração de poços de petróleo, é propiciado pela interação entre broca e formação rochosa e pode dar origem a grandes oscilações na velocidade angular podendo provocar danos irreparáveis ao processo. Neste trabalho, analisa-se o desempenho de leis de controle aplicadas à mesa rotativa (responsável por movimentar a coluna de perfuração), visando à redução de stick-slip e de oscilações da velocidade angular da broca. As leis de controle implementadas são do tipo PI (Proporcional-Integral), com parcelas de torque aplicado à mesa rotativa, proporcional e integral à velocidade da mesa, podendo ser com peso na broca constante ou variável. Para a coluna de perfuração, foi proposto um modelo em elementos finitos com função de forma linear. O torque na broca foi modelado segundo atrito de Coulomb pela forma não regularizada, curva esta ajustada pelos dados empíricos conforme propostas da literatura. Diversos critérios de desempenho foram analisados e foi observado que a minimização do desvio médio da velocidade angular em relação à referência propicia melhores condições de operação. Análises paramétricas dos ganhos de controle proporcional e integral foram realizadas, dando origem a curvas de nível para o desvio médio de velocidade angular na broca. A partir destas curvas, foram definidas regiões de estabilidade nas quais o desvio é aceitável. Estas regiões foram observadas serem maiores para menores pesos na broca e maiores velocidades angulares de referência e vice-versa. A adição do controle do peso na broca permitiu uma redução global dos níveis de desvio médio de velocidade angular, dando origem a um aumento das regiões de estabilidade do processo de perfuração. / The stick-slip phenomenon, in the process of drilling oil wells, due to the interaction between drill and rock formation can lead to large fluctuations in drill-bit angular velocity and, thus, cause irreparable damage to the process. In this work, the performance of control laws applied to the rotary table (responsible for moving the drill string) is analyzed, in order to reduce stick-slip and drill-bit angular velocity oscillations. The control laws implemented are based on a PI (Proportional-Integral) controller, for which the torque applied to the rotating table has components proportional and integral to table angular velocity with constant or variable WOB (Weight On Bit). For the drillstring, a finite element model with a linear interpolation was proposed. The torque on the drill-bit was modeled by a non-regularized Coulomb friction model, with parameters that were adjusted using empirical data proposed in literature. Several performance criteria were analyzed and it was observed that the minimization of the mean deviation of the drill-bit angular velocity relative to the target one would provide the best operating condition. Parametric analyses of proportional and integral control gains were performed, yielding level curves for the mean deviation of drill-bit angular velocity. From these curves, stability regions were defined in which the deviation is acceptable. These regions were observed to be wider for smaller values of WOB and higher values of target angular velocity and vice-versa. The inclusion of a controlled dynamic WOB reduced the levels of mean deviation of angular velocity, leading to improved stability regions for the drilling process.

The transmission line (TL) tower is an important component in electrical network system. These towers consist of members (angle sections) and connections (bolted connections) plus foundation, which act together to resist externally applied loads. The latticed towers are used to support conductors in transmission network for transmission and distribution of electricity. These towers are constructed in large numbers all over the world. The connections in electric TL classical latticed towers are peculiar compared to other types of bolted connections in buildings and bridges because (i) the angle members are connected directly or through gusset plates with bolts, (ii) the eccentric application of load due to the non-coincidence of centroid axes of angle members near the connection and (iii) members are designed as beam column element to sustain tensile or compressive forces. Bearing type bolts are used in TL towers in preference to friction type bolts, because they (i) connect thin walled angle members, (ii) are easy to use for erection at all heights, (iii) can be galvanized, (iv)erosion of galvanizing can be remedied and (v) do not require skilled personnel for installation. However, these connections are subjected to reversal of stresses due to wind load. Damage in the bolted connections generally occur due to loosening of bolts due to stress reversals (Feenstra et al. (2005) [23). The damage induced after extreme wind and earthquake may lead to collapse of the whole tower. The failure of a TL tower results in power shut down, which has huge impact on national economy. Hence, the structural safety and reliable performance of these towers are extremely important. The design of TL tower is based on minimum weight philosophy. The TL towers are highly repetitive and therefore, their designs need to be commercially competitive. The TL tower design has the following deficiencies such as misappropriate design assumptions, deficit detailing, defects in material, errors in fabrication, force fitting of members during erection, variation in grade of bolts, improper gusset plate detailing, notch cutting of member, vocalization of bolt holes, etc. Hence, to check the design and detailing aspects of members along with bolted connections and to study the behavior of tower under complex loading conditions, the prototype testing of tower is made mandatory requirement in many countries throughout the world. The structural behavior of TL tower is determined from its deflection response. Thus, the full scale testing of the towers is the only way that one can counteract the un conservatism due to structural analysis. The premature failure of TL towers occurs during prototype testing due to deficiencies in joint detailing, uncertainties in framing eccentricity, force fitting of members, unequal force distribution in bolts and gusset plate connections, etc. To have better structural response of TL tower to be tested, there is need to develop reliable model for bolted connections in TL towers. The bolted connection model plays an important role in determining the deflection response and predicting the premature member buckling failure of TL towers. The issues related to prototype testing of full scale TL towers such as fabrication errors, force fitting and notch cutting of members, application of loads, joint and crossarm detailing are discussed. The need to develop bolt slip model to simulate the actual behaviour of bolted connection in TL towers is also discussed. The bolted connections in TL towers play an important role in determining its structural behavior. The angle members used in TL towers are subjected to bi-axial bending in addition to axial load. The slip will occur in the bolted connections, due to the provision 1.5 mm bolt hole clearance. In the conventional Finite Element Analysis (FEA), the bolted connections are modeled as pin joint assuming the axial load transfer. The deflection predicted from pin joint analysis in TL towers generally does not match with experimental results. The analytical and experimental deflection value varies in the range of 30 to 50%. Hence, there is need to develop model to account bolt slip for accurate deflection and dynamic characteristic prediction of TL towers. Experimental and analytical investigations have been carried out to develop and validate bolt slip model for bolted connections in TL towers. All six degrees of freedom (both translational and rotational) have been considered to simulate the exact behaviour of bolted connections in TL towers. The model is developed based on experimental results of Ungkurapinan’s bolt slip model for axial stiffness. The rotational stiffness is formulated based on the component level experiment conducted on lap joint made of steel angle with single and double bolt subjected to tensile loading. The axial and rotational stiffness for different stages of bolt tightening is also formulated based on component level experimental investigation on lap joint. The proposed model is validated by comparing with experimental results at sub-structural level on full scale king post truss subjected to tensile loading. Further the bolt slip model is validated for different bolt tightening and failure prediction of TL tower sub panel subjected to tensile loading. Finally the proposed model is also validated for full scale TL tower for deflection prediction. NE NASTRAN, a nonlinear finite element analysis (FEA) software is used for analytical simulation and the load-deflection predictions, which are compared with the corresponding experimental results. The experimental and analytical results are in good agreement with each other. The steel pole structures are replacing the conventional lattice towers, because they have smaller plan dimension and occupy less space, when compared to lattice towers. The steel pole structures are dynamically sensitive structures and the determination of their natural frequency is extremely important. For the calculation of wind load through gust factor method, the preliminary estimation of natural frequency is required. Hence, the primary step involved in dynamic analysis is the evaluation of its natural frequency. Hence, a simplified model is proposed based on model order reduction technique for the evaluation of natural frequency of TL towers and steel pole structures. For the development of base line model to detect damage in TL towers, the natural frequency has to be updated. A semi empirical approach is proposed based on the deflection by using the proposed bolt slip model. The proposed approach of updating natural frequency is validated for different cases of member damage in TL tower sub panel, such as removal of tension, compression and hip bracing members. The transmission pole structures accumulate damage during their service life. Damage in these structures will cause a change in stiffness of the system and the physical properties of these structures, such as modal frequencies and mode shapes. Hence in the present study, the damage localization study based on modified modal strain energy approach is carried out for steel pole structures and the location of damage is identified correctly. To prevent premature failure of towers during its service life testing and failure analysis of TL towers is a mandatory requirement. In the present study, forensic failure investigation of a full scale TL tower due to deficient design of a redundant member is emphasized and the remedial measures are explained in detail. The stub failure of TL tower due to reduction in cross sectional area due to unfilled bolt hole is also discussed. To investigate the effect of unfilled bolt holes on the compression capacity of leg member, detailed FEA is carried out and compared with experimental results. The reason for failure of 9 m roof top communication tower due to redundant member deficiency is also discussed. The importance of guyed tower accessories in the guy rope design of 7 m roof top guyed pole structure is also investigated. Finally, failure investigation of compression bracing member, which has failed during testing of TL tower sub panel has been investigated. The failure load is predicted by using the proposed bolt slip model in the analysis. Thus the overall research contributions emerging from this thesis are, i) development of bolt slip model accounting for rotational stiffness, ii) development of direct method of damage detection for steel pole structures based on modified modal strain energy approach, iii) development of simplified model for prediction of natural frequency of TL tower and steel pole structures, iv) development of model updating technique through natural frequency based on semi-empirical approach and v) prediction of failure load for TL tower panel using the proposed bolt slip model.

Der Reibkontakt zwischen zwei Körpern hat entscheidende Einflüsse auf die Schwingungsselbsterregung. Da in der Literatur bisher vorwiegend ein Festkörper-Festkörper-Kontakt im Fokus steht, beschäftigt sich diese Arbeit mit einem Partikel-Festkörper-Kontakt. Dabei stehen Partikelsysteme in Form von Schüttgütern im Mittelpunkt. Ein bekanntes Beispiel solcher selbsterregten Schwingungen sind Silovibrationen. Dies sind Stick-Slip-Schwingungen beim Entleerungsvorgang von dünnwandigen Metallsilos. Untersuchungen mittels Fouriertransformation zeigen, dass die hörbaren Schwingungen sich aus einer Grundharmonischen und mehreren Oberwellen zusammensetzen. Diese Frequenzen sind allerdings weit oberhalb der numerisch untersuchten ersten Eigenfrequenzen der Silos. Ein Schwerpunkt der Arbeit liegt in den experimentellen Untersuchungen der Stick-Slip-Frequenz eines Schüttgut-Wand-Systems in einem speziell dafür entwickelten Versuchsstand. Es werden sowohl Systemkenngrößen, wie z.B. Geschwindigkeit, Systemsteifigkeit oder Masse, als auch tribologische Kenngrößen, wie z.B. Kontaktfläche oder -pressung, Materialkombination und Wandbeschaffenheit, auf ihren Einfluss auf die Stick-Slip-Frequenz untersucht. Ergänzend dazu wird die reale Kontaktfläche im statischen Zustand und bei einer äußeren dynamischen Anregung zwischen den Randpartikeln und einem Festkörper untersucht. Des Weiteren wird der tatsächliche Reibwert über der Relativgeschwindigkeit in Form einer Reibhysterese gemessen. In den Simulationsstudien wird ein Modell eines Reibschwingers vorgestellt und untersucht. Hier zeigen sich bereits bei einer stationären Kennlinie große Unterschiede in der Stick-Slip-Neigung und der Frequenz. In einer Modellerweiterung mittels einer zeitabhängigen Reibhysterese werden weiterführende Modellstudien getätigt. Hierbei steht vor allem das zeitabhängige Reibverhalten in der Haft- und Gleitphase im Fokus der Untersuchungen. / The friction contact between two bodies has an important influence on self-excited vibrations. Often the main focus is on a solid-solid contact. Therefore, this thesis focuses on a particle-solid contact, represented as the interaction between a bulk solid and a wall. Silo vibrations are a well known example of this kind of self-excited vibrations. Stick-slip vibrations occure during the discharging of thin walled metal silo. The hearable vibrations consist of a basic harmonic and some higher harmonics. The frequencies can be detected by a Fourier transform. One main focus of this thesis is the experimental investigation of the stick-slip frequency of a bulk solid-wall system. Therefore, a special test rig is designed. The investigation concentrates on system parameters, e.g. velocity, system stiffness or mass, on tribological parameters, e.g. contact area, pressure, material combination and wall surfaces, and their influence on the stick-slip frequency. Additional, the real contact area between particles in wall proximity and the wall itself is investigated in a static situation and during an external dynamic excitation. Furthermore, the real friction coefficient over the relative velocity will be measured. A model of a single mass friction oscillator will be presented and investigated in the simulation studies. Even with stationary friction characteristics this studies show big differences in the stick-slip stability and frequency. Henceforth, an advanced model with friction characteristics dependent on time in the form of a friction hysteresis is presented. There, the main focus is on the time dependent friction behaviour during the stick and slip phase of the oscillation.

La capacité de réaliser des tâches robotiques dextres à l'échelle nanométrique dans un microscope électronique à balayage (MEB) est un enjeu crucial pour les nanotechnologies. Les systèmes nano-robotiques dédiés à des applications sous MEB ont ainsi émergé dans de nombreux laboratoires de robotique. Ils peuvent être composés d'un ou de plusieurs actionneurs intégrés à des plateformes nano-robotiques avec un ou plusieurs effecteurs. L’actionneur Piézoélectrique Stick-Slip (PSS) est l'un des meilleurs candidats pour actionner les systèmes nano-robotiques dédiés à des applications sous MEB car il est capable d'effectuer un positionnement grossier avec une plage de déplacement millimétrique et un positionnement précis avec une plage de déplacement de quelques micromètres. La modélisation des actionneurs PSS est complexe notamment en raison de leur mode de fonctionnement hybride. La commande est également difficile à cause de plusieurs caractéristiques liées aux actionneurs PSS, soient le frottement, l’hystérésis et les vibrations non-amorties, qui dégradent leur performances en termes de précision et de vitesse. Ce travail porte sur la modélisation et la commande d'un système nano-robotique à 3 axes dédié à des applications sous MEB et actionné par des actionneurs piézoélectriques de type stick-slip. Chaque élément et caractéristique des actionneurs PSS ont été analysés et modélisés afin d’établir par la suite un modèle dynamique complet capable de décrire les deux modes de fonctionnement, à savoir le mode balayage et pas à pas. Pour chacun de ces deux modes, des lois de commande ont ainsi été développées pour les actionneurs PSS. Des stratégies de commande robuste ont été synthétisées pour des objectifs de positionnement rapide et à haute résolution en mode balayage. De telles performances sont fondamentales dans plusieurs tâches micro-/nano-robotique tels que le nano-assemblage rapide et précis et la nano-caractérisation des matériaux. Une commande proportionnelle en fréquence et en amplitude est synthétisée pour effectuer un déplacement millimétrique en mode pas à pas. Ceci est motivé par les applications robotiques pour lesquelles une large plage de déplacement est requise, tels que le scan de grandes surfaces et les phases d’approche d’une sonde d’un échantillon à manipuler. Une stratégie de commutation qui combine les modes balayage et pas à pas, est alors proposée pour remédier au manque de précision en mode pas à pas, lors de passage d’un grand à un petit déplacement. Ce travail a donné lieu à des résultats qui ouvrent de nouvelles perspectives pour l'utilisation des actionneurs PSS dans les systèmes nano-robotiques dédiés à des applications sous MEB. / The capability of doing dexterous robotic tasks at the nanometer scale inside a Scanning Electron Microscope (SEM) is a critical issue for nanotechnologies. SEM-integrated nano-robotic systems have consequently emerged in many robotics laboratories. They can be composed of one or more actuators assembled into nano-robotic platforms with one or several effectors. Piezoelectric Stick-Slip (PSS) actuators is one of the best candidate to actuate SEM-integrated nano-robotic systems because it is able to perform coarse positioning with millimeter displacement range and fine positioning with travel range of few micrometers. Modeling of PSS actuators is complex and difficult mainly because of their hybrid operating mode. Furthermore, control is challenging due to several characteristics related to PSS actuators, namely friction, hysteresis and undamped vibrations, which degrade their performance in terms of precision and speed. This work deals with modeling and control of a 3-axes SEM integrated nano-robotic system driven by piezoelectric stick-slip actuators. Each element and characteristic of PSS actuators are analyzed and modeled to thereafter establish a complete dynamic model able to describe the two functioning modes, namely the scanning and the stepping modes. PSS actuators are then controlled in each of these modes. Robust control strategies are developed to achieve high-resolution and fast positioning in scanning mode. Such performance is fundamental in several micro/nano-robotic tasks such as fast and accurate nano-assembly and nano-material characterization. A frequency/amplitude proportional controller is designed to perform millimeter displacement in stepping mode. This is motivated by robotic tasks where large motion is required, such as large surfaces scan and bringing a probe close to a sample to manipulate. A switched strategy, which combines scanning and stepping motion modes, is then proposed to remedy to the lack of precision in stepping motion, when passing from a large to a small displacement. This work has given rise to results which open new perspectives to the use of PSS actuators in SEM integrated nano-robotic systems.

Die Kontaktverhältnisse zwischen Reifen und Fahrbahn bestimmen die maximal übertragbaren Beschleunigungs-, Brems- und Seitenkräfte des Fahrzeugs und sind daher für die Fahrsicherheit von großer Bedeutung. In dieser Arbeit wird ein Modell zur numerisch effizienten Simulation der hochfrequenten Dynamik einzelner Reifenprofilblöcke entwickelt. Der vorgestellte Modellansatz nutzt einerseits die Vorteile der Finite-Elemente-Methode, welche die Bauteilstruktur detailliert auflösen kann, bei der jedoch lange Rechenzeiten in Kauf genommen werden. Andererseits profitiert der vorgestellte Modellansatz von den Vorteilen stark vereinfachter Mehrkörpersysteme, welche die Berechnung der hochfrequenten Dynamik und akustischer Phänomene erlauben, jedoch strukturdynamische Effekte und das Kontaktverhalten in der Bodenaufstandsfläche des Reifens nur begrenzt abbilden können. Das hier vorgestellte Modell berücksichtigt in einem modularen Ansatz die Effekte der Strukturdynamik, der lokalen Reibwertcharakteristik, der nichtlinearen Wechselwirkungen durch den Kontakt mit der rauen Fahrbahnoberfläche und des lokalen Verschleißes. Die erforderlichen Modellparameter werden durch geeignete Experimente bestimmt. Ein Schwerpunkt der Arbeit liegt in der Untersuchung reibungsselbsterregter Profilblockschwingungen bei Variation der Modell- und Prozessparameter. Zur realistischen Betrachtung des Reifenprofilblockverhaltens erfolgt eine Erweiterung des Modells um eine Abrollkinematik, die tiefere Einblicke in die dynamischen Vorgänge in der Bodenaufstandsfläche des Reifens ermöglicht. Diese Simulationen lassen eine Zuordnung der aus der Literatur bekannten zeitlichen Abfolge von Einlaufphase, Haftphase, Gleitphase und Ausschnappphase zu. Es zeigen sich bei bestimmten Kombinationen aus Fahrzeuggeschwindigkeit und Schlupfwert ausgeprägte Stick-Slip-Schwingungen im akustisch relevanten Frequenzbereich. Das Modell erlaubt die Untersuchung des Einflusses der Profilblockgeometrie, der Materialparameter, der Fahrbahneigenschaften sowie der Betriebszustände auf den resultierenden Reibwert, auf das lokale Verschleißverhalten sowie auf das Auftreten hochfrequenter reibungsselbsterregter Schwingungen. Somit ermöglicht das Modell ein vertieftes Verständnis der Vorgänge im Reifen-Fahrbahn-Kontakt und der auftretenden Wechselwirkungen zwischen Struktur- und Kontaktmechanik. Es kann eine Basis für zukünftige Optimierungen des Profilblocks zur Verbesserung wesentlicher Reifeneigenschaften wie Kraftschlussverhalten, Verschleiß und Akustik bilden.:Formelverzeichnis VII Kurzfassung X Abstract XI 1 Einleitung 1 1.1 Zielsetzung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Gliederung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Stand des Wissens 6 2.1 Mechanische Eigenschaften von Elastomeren . . . . . . . . . . . . . . . . . . 6 2.2 Elastomerreibung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.1 Modelle zur Beschreibung von Hysteresereibung . . . . . . . . . . . 11 2.2.2 Modelle zur Beschreibung von Adhäsionsreibung . . . . . . . . . . . 12 2.2.3 Phänomenologische Beschreibung von Elastomerreibung . . . . . . 13 2.3 Verschleiß von Profilblöcken . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.4 Entstehung von Stick-Slip-Schwingungen . . . . . . . . . . . . . . . . . . . . 28 2.5 Profilblockmodelle und -simulationen . . . . . . . . . . . . . . . . . . . . . . 31 2.6 Experimentelle Einrichtungen zur Untersuchung von Profilblöcken . . . . . 42 2.6.1 Schwerlasttribometer . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.6.2 IDS-Tribometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 2.6.3 Mini-mue-road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2.6.4 Linear Friction Tester . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2.6.5 Prüfstand für Stollenmessungen . . . . . . . . . . . . . . . . . . . . . 48 2.6.6 Hochgeschwindigkeits-Abrollprüfstand . . . . . . . . . . . . . . . . 49 2.6.7 Hochgeschwindigkeits-Linearprüfstand . . . . . . . . . . . . . . . . 50 2.7 Experimentelle Reibwertbestimmung . . . . . . . . . . . . . . . . . . . . . . 52 3 Profilblockmodell 55 3.1 Modularer Modellansatz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.2 Modul 1: Strukturdynamik . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 3.2.1 Transformations- und Reduktionsverfahren . . . . . . . . . . . . . . 59 3.2.2 Implementierung in das Gesamtmodell . . . . . . . . . . . . . . . . . 72 3.3 Modul 2: Lokale Reibwertcharakteristik . . . . . . . . . . . . . . . . . . . . . 72 3.3.1 Einflussgrößen auf den Reibwert . . . . . . . . . . . . . . . . . . . . 72 3.3.2 Numerische Behandlung der Reibwertberechnung . . . . . . . . . . 73 3.4 Modul 3: Nichtlineare Kontaktsteifigkeit . . . . . . . . . . . . . . . . . . . . 75 3.4.1 Lokale Kontaktbetrachtungen . . . . . . . . . . . . . . . . . . . . . . 76 3.4.2 Kontaktalgorithmus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 3.5 Modul 4: Lokaler Verschleiß . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 3.5.1 Vorgehen zur Verschleißmodellierung . . . . . . . . . . . . . . . . . 81 3.5.2 Implementierung in das Gesamtmodell . . . . . . . . . . . . . . . . . 82 4 Parameterbestimmung 84 4.1 Strukturdynamische Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . 84 4.1.1 Bestimmung des Elastizitätsmoduls und der Dämpfung . . . . . . . 84 4.1.2 Optimierung der Modenanzahl . . . . . . . . . . . . . . . . . . . . . 88 4.2 Bestimmung der Reibcharakteristik . . . . . . . . . . . . . . . . . . . . . . . 90 4.3 Bestimmung der nichtlinearen Kontaktsteifigkeit . . . . . . . . . . . . . . . 92 4.4 Bestimmung der Verschleißparameter . . . . . . . . . . . . . . . . . . . . . . 94 5 Simulationen 100 5.1 Betrachtung eines gleitenden Profilblocks . . . . . . . . . . . . . . . . . . . . 100 5.1.1 Simulationen bei hoher Gleitgeschwindigkeit ohne Verschleiß . . . . 100 5.1.2 Simulationen bei hoher Gleitgeschwindigkeit mit Verschleiß . . . . 103 5.1.3 Profilblockverhalten bei niedriger Gleitgeschwindigkeit . . . . . . . 106 5.1.4 Simulationen mit Normalkraftvorgabe . . . . . . . . . . . . . . . . . 114 5.1.5 Vergleich Experiment-Simulation . . . . . . . . . . . . . . . . . . . . 117 5.1.6 Variation der Profilblockgeometrie . . . . . . . . . . . . . . . . . . . 119 5.2 Betrachtung eines abrollenden Profilblocks . . . . . . . . . . . . . . . . . . . 124 5.2.1 Abrollkinematik . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 5.2.2 Einfluss der Fahrzeuggeschwindigkeit . . . . . . . . . . . . . . . . . 130 5.2.3 Einfluss des Schlupfwerts . . . . . . . . . . . . . . . . . . . . . . . . . 133 5.2.4 Einfluss des Kontaktdrucks . . . . . . . . . . . . . . . . . . . . . . . . 133 5.2.5 Kontaktkraftbetrachtungen . . . . . . . . . . . . . . . . . . . . . . . . 135 6 Zusammenfassung 139 Literatur 143 / The contact conditions between tyre and road are responsible for the maximum acceleration, braking and side forces of a vehicle. Therefore, they have a large impact on the driving safety. Within this work a numerically efficient model for the simulation of the high-frequency dynamics of single tyre tread blocks is developed. The presented modelling approach benefits the advantage of the finite element method to resolve the component structure in detail. However, a long computation time is accepted for these finite element models. Moreover, the presented modelling approach makes use of the advantage of simplified multibody systems to calculate the high-frequency dynamics and acoustic phenomena. However, structural effects and the contact behaviour in the tyre contact patch can be covered only to a minor degree. The model treated here considers the effects of structural dynamics, the local friction characteristic, the non-linear interaction due to the contact with the rough road surface and local wear. The required model parameters are determined by appropriate experiments. One focus of this work is the investigation of self-excited tread block vibrations under variation of the model and process parameters. In order to realistically investigate the tread block behaviour the model is extended with regard to rolling kinematics which provides a deeper insight into the dynamic processes in the tyre contact patch. The corresponding simulations allow the allocation of the run-in phase, sticking phase, sliding phase and snap-out which is reported in the literature. For certain combinations of vehicle velocity and slip value pronounced stick-slip vibrations occur within the acoustically relevant frequency range. The model enables to study the influence of the tread block geometry, the material properties, the road surface characteristics and the operating conditions on the resulting tread block friction coefficient, local tread block wear and the occurrence of high-frequency self-excited vibrations. The simulation results provide a distinct understanding of the processes in the tyre/road contact and the interactions between structural mechanics and contact mechanics. They can be a basis for future tread block optimisations with respect to essential tyre properties such as traction, wear and acoustic phenomena.:Formelverzeichnis VII Kurzfassung X Abstract XI 1 Einleitung 1 1.1 Zielsetzung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Gliederung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Stand des Wissens 6 2.1 Mechanische Eigenschaften von Elastomeren . . . . . . . . . . . . . . . . . . 6 2.2 Elastomerreibung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.1 Modelle zur Beschreibung von Hysteresereibung . . . . . . . . . . . 11 2.2.2 Modelle zur Beschreibung von Adhäsionsreibung . . . . . . . . . . . 12 2.2.3 Phänomenologische Beschreibung von Elastomerreibung . . . . . . 13 2.3 Verschleiß von Profilblöcken . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.4 Entstehung von Stick-Slip-Schwingungen . . . . . . . . . . . . . . . . . . . . 28 2.5 Profilblockmodelle und -simulationen . . . . . . . . . . . . . . . . . . . . . . 31 2.6 Experimentelle Einrichtungen zur Untersuchung von Profilblöcken . . . . . 42 2.6.1 Schwerlasttribometer . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.6.2 IDS-Tribometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 2.6.3 Mini-mue-road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2.6.4 Linear Friction Tester . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2.6.5 Prüfstand für Stollenmessungen . . . . . . . . . . . . . . . . . . . . . 48 2.6.6 Hochgeschwindigkeits-Abrollprüfstand . . . . . . . . . . . . . . . . 49 2.6.7 Hochgeschwindigkeits-Linearprüfstand . . . . . . . . . . . . . . . . 50 2.7 Experimentelle Reibwertbestimmung . . . . . . . . . . . . . . . . . . . . . . 52 3 Profilblockmodell 55 3.1 Modularer Modellansatz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.2 Modul 1: Strukturdynamik . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 3.2.1 Transformations- und Reduktionsverfahren . . . . . . . . . . . . . . 59 3.2.2 Implementierung in das Gesamtmodell . . . . . . . . . . . . . . . . . 72 3.3 Modul 2: Lokale Reibwertcharakteristik . . . . . . . . . . . . . . . . . . . . . 72 3.3.1 Einflussgrößen auf den Reibwert . . . . . . . . . . . . . . . . . . . . 72 3.3.2 Numerische Behandlung der Reibwertberechnung . . . . . . . . . . 73 3.4 Modul 3: Nichtlineare Kontaktsteifigkeit . . . . . . . . . . . . . . . . . . . . 75 3.4.1 Lokale Kontaktbetrachtungen . . . . . . . . . . . . . . . . . . . . . . 76 3.4.2 Kontaktalgorithmus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 3.5 Modul 4: Lokaler Verschleiß . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 3.5.1 Vorgehen zur Verschleißmodellierung . . . . . . . . . . . . . . . . . 81 3.5.2 Implementierung in das Gesamtmodell . . . . . . . . . . . . . . . . . 82 4 Parameterbestimmung 84 4.1 Strukturdynamische Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . 84 4.1.1 Bestimmung des Elastizitätsmoduls und der Dämpfung . . . . . . . 84 4.1.2 Optimierung der Modenanzahl . . . . . . . . . . . . . . . . . . . . . 88 4.2 Bestimmung der Reibcharakteristik . . . . . . . . . . . . . . . . . . . . . . . 90 4.3 Bestimmung der nichtlinearen Kontaktsteifigkeit . . . . . . . . . . . . . . . 92 4.4 Bestimmung der Verschleißparameter . . . . . . . . . . . . . . . . . . . . . . 94 5 Simulationen 100 5.1 Betrachtung eines gleitenden Profilblocks . . . . . . . . . . . . . . . . . . . . 100 5.1.1 Simulationen bei hoher Gleitgeschwindigkeit ohne Verschleiß . . . . 100 5.1.2 Simulationen bei hoher Gleitgeschwindigkeit mit Verschleiß . . . . 103 5.1.3 Profilblockverhalten bei niedriger Gleitgeschwindigkeit . . . . . . . 106 5.1.4 Simulationen mit Normalkraftvorgabe . . . . . . . . . . . . . . . . . 114 5.1.5 Vergleich Experiment-Simulation . . . . . . . . . . . . . . . . . . . . 117 5.1.6 Variation der Profilblockgeometrie . . . . . . . . . . . . . . . . . . . 119 5.2 Betrachtung eines abrollenden Profilblocks . . . . . . . . . . . . . . . . . . . 124 5.2.1 Abrollkinematik . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 5.2.2 Einfluss der Fahrzeuggeschwindigkeit . . . . . . . . . . . . . . . . . 130 5.2.3 Einfluss des Schlupfwerts . . . . . . . . . . . . . . . . . . . . . . . . . 133 5.2.4 Einfluss des Kontaktdrucks . . . . . . . . . . . . . . . . . . . . . . . . 133 5.2.5 Kontaktkraftbetrachtungen . . . . . . . . . . . . . . . . . . . . . . . . 135 6 Zusammenfassung 139 Literatur 143