In response to a call for more advanced and more inclusive models for measuring difficulty of international expansion, the resistance index (RI) was created and is advanced in this paper. The RI includes several factors that contribute (detract) to the success (failure) of firms regarding cross border expansion. The RI features variables that represent country specific advantages (CSA), firm specific advantages (FSA), and government specific advantages (GSA). These three areas are represented by a diverse set of data obtained from such widely recognized agencies as the World Bank and Thomson Reuters. Taking data from different sources, may render better predictability for firms than using the popular cultural distance index. Therefore, it is proposed that the RI may be a more relevant tool for firms to use when they are considering international expansion into a particular country, or for researchers to employ in undertaking success or failure in international expansion.

The tyre is an essential part of a road vehicle. It is in the contact between road and tyre that the forces that create the possibility for the driver to control the vehicle are generated. Tyres, however, wear down, which leads to both unhealthy wear particles and disposal of old tyres, both of which are harmful to the environment. If one could learn more about what causes wear, it might be possible to reduce tyre wear, which would be beneficial from both an economic and an ecological point of view. The aim of this thesis work is to develop a tyre model that can simulate tyre wear and take temperature, pressure and vehicle settings into account. Based on tyre brush theory, a tyre wear model has been developed which includes a thermal model, a pressure model and a friction model. Simulations and analysis of different cases has been performed. From the results, one can conclude the following: the tyre temperature and inflation pressure change with the distance the vehicle travels at the beginning and later become steady; higher external temperature will decrease tyre wear rate since the inflation pressure increases with the external temperature and the sliding friction decreases; higher vehicle speed leads to a higher tyre wear rate; the tyre temperature increases with increasing vehicle speed; the amount of tyre wear increases linearly with the normal load on the tyre; the tyre wear increases with the slip ratio exponentially due to both the siding distance and the sliding friction increasing with the slip ratio; the tyre wear increases exponentially with the slip angle. The complete model can estimate the tyre wear with different vehicle settings and external factors. More experiments are needed in the future to validate the complete model. In addition, since the heat transfer coefficient is changeable with temperature, the thermal model can be improved by introducing dynamic heat transfer coefficients. The Savkoor friction model used in the report can also be improved by tuning its parameters using more experimental data.

For internal combustion engines used in heavy-duty vehicles, increased engine efficiency and consequently reduced CO2 emissions can be obtained if the engine speed can be kept within an optimal speed range. This requires swift and frequent gear shifts where the dry friction clutch is utilized. Enhanced dry clutch simulation models and a better understanding of the involved phenomena can assist the development towards swifter gear shifts and help reduce CO2 emissions. The work presented in this thesis focuses on the modelling of dry clutch systems for heavy-duty applications and their effect on the torsional response of the driveline during transient events such as clutch engagement and disengagement. During these events it is primarily the first vibration mode of the driveline that is active and consequently it is possible to greatly reduce theof degrees of freedom (DOFs) of the powertrain model and still capture the relevant dynamics of the powertrain. The reduced set of differential equationsdescribe the torsional motion of the powertrain and the equations of motion are solved numerically in the time-domain. From a mathematical point ofview, the equations of motion turn "stiff" when the clutch is locked. This issue is resolved by utilizing numerical solution techniques suitable for stiff differential equations. In the simulations it was observed that no engine torque fluctuations were transferred through the slipping clutch. Consequently the response of the driveline is purely modal during sliding. If the gradient of the coefficient of friction is negative the modal response is possibly unstable with exponentially growing vibration amplitudes as an effect. Moreover, the way in which the clamp load evolves during clutch engagement is found to severely effect the excitation of transient vibrations during clutch synchronization. It can be shown that reducing the gradient of the evolving clamp load at the onset of sliding will reduce the amplitude of the friction induced vibrations. Reducing the torsional vibration amplitudes will help avoid the jerky motion of the vehicle during launch and increase comfort for driver and passengers. / Reduced transmission vibrations - reduced energy consumption and environmental impacts together with an increased competitiveness. Swedish Energy Agency (project No. 42100-1)

The objective of this study is to develop a high-fidelity physics-based flexible tire model that can be fully integrated into multibody dynamics computer algorithms for use in on-road and off-road vehicle dynamics simulation without ad-hoc co-simulation techniques. Despite the fact detailed finite element tire models using explicit finite element software have been widely utilized for structural design of tires by tire manufactures, it is recognized in the tire industry that existing state-of-the-art explicit finite element tire models are not capable of predicting the transient tire force characteristics accurately under severe vehicle maneuvering conditions due to the numerical instability that is essentially inevitable for explicit finite element procedures for severe loading scenarios and the lack of transient (dynamic) tire friction model suited for FE tire models. Furthermore, to integrate the deformable tire models into multibody full vehicle simulation, co-simulation technique could be an option for commercial software. However, there exist various challenges in co-simulation for the transient vehicle maneuvering simulation in terms of numerical stability and computational efficiency. The transient tire dynamics involves rapid changes in contact forces due to the abrupt braking and steering input, thus use of co-simulation requires very small step size to ensure the numerical stability and energy balance between two separate simulation using different solvers. In order to address these essential and challenging issues on the high-fidelity flexible tire model suited for multibody vehicle dynamics simulation, a physics-based tire model using the flexible multibody dynamics approach is proposed in this study. To this end, a continuum mechanics based shear deformable laminated composite shell element is developed based on the finite element absolute nodal coordinate formulation for modeling the complex fiber reinforced rubber tire structure. The assumed natural strain (ANS) and enhanced assumed strain (EAS) approaches are introduced for alleviating element lockings exhibited in the element. Use of the concept of the absolute nodal coordinate formulation leads to various advantages for tire dynamics simulation in that (1) constant mass matrix can be obtained for fully nonlinear dynamics simulation; (2) exact modeling of rigid body motion is ensured when strains are zero; and (3) non-incremental solution procedure utilized in the general multibody dynamics computer algorithm can be directly applied without specialized updating schemes for finite rotations. Using the proposed shear deformable laminated composite shell element, a physics-based flexible tire model is developed. To account for the transient tire friction characteristics including the friction-induced hysteresis that appears in severe maneuvering conditions, the distributed parameter LuGre tire friction model is integrated into the flexible tire model. To this end, the contact patch predicted by the structural tire model is discretized into small strips across the tire width, and then each strip is further discretized into small elements to convert the partial differential equations of the LuGre tire friction model to the set of first-order ordinary differential equations. By doing so, the structural deformation of the flexible tire model and the LuGre tire friction force model are dynamically coupled in the final form of the equations, and these equations are integrated simultaneously forward in time at every time step. Furthermore, a systematic and automated procedure for parameter identification of LuGre tire friction model is developed. Since several fitting parameters are introduced to account for the nonlinear friction characteristics, the correlation of the model parameters with physical quantities are not clear, making the parameter identification of the LuGre tire friction model difficult. In the procedure developed in this study, friction parameters in terms of slip-dependent friction characteristics and adhesion parameter are estimated separately, and then all the parameters are identified using the nonlinear least squares fitting. Furthermore, the modified friction characteristic curve function is proposed for wet road conditions, in which the linear decay in friction is exhibited in the large slip velocity range. It is shown that use of the proposed numerical procedure leads to an accurate prediction of the LuGre model parameters for measured tire force characteristics under various loading and speed conditions. Furthermore, the fundamental tire properties including the load-deflection curve, the contact patch lengths, contact pressure distributions, and natural frequencies are validated against the test data. Several numerical examples for hard braking and cornering simulation are presented to demonstrate capabilities of the physics-based flexible tire model developed in this study. Finally, the physics-based flexible tire model is further extended for application to off-road mobility simulation. To this end, a locking-free 9-node brick element with the curvature coordinates at the center node is developed and justified for use in modeling a continuum soil with the capped Drucker-Prager failure criterion. Multiplicative finite strain plasticity theory is utilized to consider the large soil deformation exhibited in the tire/soil interaction simulation. In order to identify soil parameters including cohesion and friction angle, the triaxial soil test is conducted. Using the soil parameters identified including the plastic hardening parameters by the compression soil test, the continuum soil model developed is validated against the test data. Use of the high-fidelity physics-based tire/soil simulation model in off-road mobility simulation, however, leads to a very large computational model to consider a wide area of terrains. Thus, the computational cost dramatically increases as the size of the soil model increases. To address this issue, the component soil model is proposed such that soil elements far behind the tire can be removed from the equations of motion sequentially, and then new soil elements are added to the portion that the tire is heading to. That is, the soil behavior only in the vicinity of the rolling tire is solved in order to reduce the overall model dimensionality associated with the finite element soil model. It is shown that use of the component soil model leads to a significant reduction in computational time while ensuring the accuracy, making the use of the physics-based deformable tire/soil simulation capability feasible in off-road mobility simulation.

Elevation axis model of a barrel stabilization system is constructed. The nonlinearities which are considered in the model are orifice flow characteristics, coulomb friction, hard-stop limits, kinematics of the system and unbalance on the barrel. A Simulink&reg / model for the servo valve, actuation system and barrel is constructed. Servo valve identification is made via the actual test data. Compressibility of the hydraulic fluid is taken into consideration while modeling the actuation system. Friction model is simulated for different cases. Controller of the system is constructed by two PIDs, one for each of the velocity and the position loops. Velocity feed forward can reduce the time to make a quick move by the system. The disturbance is evaluated from a given road profile and disturbance feed forward is applied to the system.

No description available.

Nasslaufende Lamellenkupplungen finden im Automobil immer mehr Anwendungen. Im Bezug auf die steigenden Motorleistungen, die Gewichtsoptimierungsmaßnamen und die hohen Ansprüche an Fahrdynamik nimmt die geforderte Leistungsdichte einer nasslaufenden Lamellenkupplung ständig zu. Die Lamellenkupplung wird oft nahe an ihrer Belastungsgrenze ausgelegt. Außerdem wachsen gleichzeitig die Anforderungen an ihre Schaltdynamik, das Komfortverhalten und die Lebensdauer. Schwerpunkt dieser Arbeit ist die Modellierung und Simulation von Reibung und Verschleiß nasslaufender Lamellenkupplungen, insbesondere der mit dem Papierreibbelag. Ein umfassendes Verständnis für die Reibungsvorgänge und Verschleißmechanismen stellt die Grundvoraussetzung für eine optimale Entwicklung der nasslaufenden Lamellenkupplung dar. Zur Lösung der gestellten Aufgabe werden die wichtigsten Einflussgrößen auf das tribolgische System der Lamellenkupplung charakterisiert und die Wirkungen der tribologischen Beanspruchungsgrößen identifiziert. Zudem werden verschiedene Simulationsmodelle mit unterschiedlicher Modellierungstiefe erstellt. Dazu gehören Reibmodelle, Wärmeflussmodelle sowie Lebensdauermodelle, wobei die Reib- und Wärmeflussmodelle für die Lebensdauermodelle benötigt werden. Die hergeleiteten Modelle werden in die Simulationsumgebung implementiert und mit Hilfe eines Prüfstandsversuches verifiziert. Die validierten Modelle können für die Systemoptimierung und die Lebensdauerabsicherung der nasslaufenden Lamellenkupplungen effizient eingesetzt werden. Dies kann eine deutliche Reduktion der Entwicklungszeit sowie der Versuchskosten ermöglichen.

Dans la continuité des travaux de recherches sur les systèmes de transmission mécanique embarqués, l’objectif de cette thèse est double : approfondir les modèles d’estimations des pièces d’un Actionneur Electromécanique (EMA) et étendre la vision transversale de la conception préliminaire aux aspects dynamiques. En effet, cette recherche permet, lors de la conception préliminaire basée sur les modèles, d’adapter les choix d’architectures et de technologies vis-à-vis des performances statiques et dynamiques à atteindre. Les modèles développés à partir des lois d’échelles sont étendus et exploités afin de modéliser les pièces élémentaires de l’EMA et de faire ressortir les règles de « bonnes pratiques » en conception préliminaire. On s’intéresse en particulier au dimensionnement des EMAs dans le domaine aéronautique. Dans un premier temps, nous avons donc créé des modèles d’estimation et des métamodèles des pièces de l’EMA. A cet effet, il est décomposé en carter et pièces élémentaires qu’il intègre.Dans un second temps, nous avons établis des règles de bonne conception et des pistes de dimensionnement de l’actionneur asservi en position. Contrairement aux recherches antérieures, qui se centraient sur le dimensionnement en puissance, nous avons pris en compte la synthèse de la commande pour établir ces règles. A partir de modèles de simulations, nous qualifions et quantifions l’influence des défauts (inertie et saturations, élasticité/jeu, frottement) sur les performances limites de l’EMA. En effet, les structures de commande usuelles et le choix des éléments de contrôle-commande sont intimement liés aux performances dynamiques et à ces défauts. Enfin, afin de se doter de moyens d’essais pour identifier finement un modèle de frottement dans des conditions aéronautiques de température, un banc d'essai sur le réducteur Harmonic Drive a été conçu et mis en œuvre. Il permet également d’amorcer la validation des règles de bonne conception / In the continuity of work of research on embedded systems of mechanical transmission, this these has two objectives: to improve estimation models of Electromechanical Actuator (EMA) pieces and to extend the cross-cutting vision of preliminary design to the dynamic aspects. Indeed, in the preliminary design based on models, this research should allow to adapt the choice of architectures and technologies to static and dynamic performance to achieve. The models developed from the scaling laws will be extended and exploited to modelize elementary pieces of the EMA and to highlight rules of "good practices" in preliminary design. We focus in particular on the design of EMA in aeronautic field. In the first time, we developed estimations models and métamodèles of elementary components of EMA which was decomposed in housing and elementary pieces.In a second time, we established rules of good practices for actuator sizing in control position loop. Contrary to older researches, we take into account control synthesis to create these rules. From simulations models, we quantified the influence of technological defects of components (inertia and saturations, elasticity (backlash), friction) on EMA performances. Indeed, the usual command structures and the choice of the elements of control are intimately linked to the dynamic performance and these defects.Finally, to give test way to identify with accuracy a friction model in aeronautical conditions of temperature, a test bench of Harmonic Drive was create, integrated and implemented. It allows booting the validation of rules of good practices in preliminary design.

Lors d’une opération de forage, un certain nombre d’événements imprévus par rapport à l’écoulement du fluide de forage dans le puits, peuvent se produire assez rapidement. Des exemples de tels événements sont les afflux de pétrole ("kick") ainsi que les pertes de boue dans la formation. Un "kick" qui augmente en intensité peut entraîner, par ce que l’on nomme, un "blowout" (par exemple l’incident Deepwater Horizon en 2010). Les pertes et les gains sont habituellement détectés en contrôlant l’équilibre de la boue de forage dans le puits, en particulier en contrôlant le débit sortant du puits et en le comparant au débit entrant induit par les pompes. La plupart des méthodes de surveillance, de l’écoulement du puits en cours de forage, est d’utiliser un simple "paddle" (capteur qui mesure la hauteur du fluide de forage avec l’inclinaison d’une pagaie) dans la ligne d’écoulement de retour, ou d’utiliser un débitmètre de Coriolis (débitmètre connu pour sa précision, mais coûteux et nécessite une installation complexe en ajoutant un "by-pass"). Il y a un besoin évident d’un nouveau débitmètre précis, mais facile à installer et peu coûteux. Le canal Venturi a été utilisé comme débitmètre pendant des années dans l’industrie des eaux. Il apparaît comme une solution peu chère mais précise pour mesurer des débits importants. Beaucoup de personnes ont travaillé sur cette solution pour améliorer sa précision et élargir son champ d’application. Ils ont développé des modèles, sur la base d’un processus d’étalonnage, permettant de relier la hauteur en amont au débit. Cela signifie que les modèles actuels, comme ISO NORM 4359 [1], peuvent être uniquement utilisés pour l’écoulement d’eau et pour une géométrie bien spécifique. Comme nous le savons, les boues ont des comportement non- Newtonien, et donc ces modèles établis ne peuvent pas être utilisés avec ce type de fluides. Pour notre application, la forme trapézoïdale apparaît comme un bon compromis entre la précision et la portée des mesures de débit. Ainsi, nous avons développé un modèle capable de calculer le débit en prenant en compte les propriétés du fluide ainsi que les paramètres géométriques du canal. Ce modèle a été simplifié sous forme 1D en utilisant la théorie des eaux peux profondes, et a été complété par un modèle de friction tenant en compte de la variation des propriétés des fluides et de la géométrie du canal. Ce modèle a été validé par une série d’expériences avec les deux types de fluides: Newtonien et non-Newtonien, où nous avons mesuré le débit et la hauteur de l’écoulement à différents endroits le long du canal Venturi. Nous avons également réalisé des simulations 3D, en simulant des écoulements Newtoniens et non- Newtonien le long du canal. Pour généraliser cette étude, cette démarche a été étendue à une autre forme de Venturi plus adapté à un certain design de plate-forme pétrolière. Les corrélations et les modèles développés et validés expérimentalement au cours de cette étude peuvent être utilisés pour étendre l’utilisation des canaux Venturi à tous les fluides Newtonien mais aussi non-Newtonien. Il est maintenant l’occasion pour les industries de proposer une solution, peu chère mais précise pour mesurer les débits dans des canaux ouverts et pour tous types de fluides. / During a drilling operation, a certain number of unexpected events, related to the flow of drilling fluid in the well, may happen rather quickly. Examples of such events are formation fluid influx (kick) and mud loss to the formation. An uncontrolled kick that increases in intensity may result in what is known as a blowout (e.g. the Deepwater Horizon incident in 2010). Influxes and kicks are traditionally detected by monitoring the drilling mud balance in the well, in particular, by monitoring the flow out the well and comparing it to the incoming flow induced by the pumps. Most methods of monitoring the flow out of the well while drilling consists in using a simple paddle (sensor that measures the height of drilling fluid with the inclination of a paddle) in the return flow line, or in using a Coriolis flow meter (flow meter known for its accuracy but expensive and requires a complex installation by adding a bypass). There is a clear need of a new accurate flow meter, but easy to install and inexpensive. The Venturi flume has been used as flow meter for years in water industry. It appears as a cheap but accurate solution to measure large flow rates. Many people have worked on this solution to improve its accuracy and to expand its scope. They have developed models, based on a calibration process, to relate the upstream height to the flow rate. This means that current models, as ISO NORM 4359 [1], can be used only for water flow and specific geometry. As known, muds have non-Newtonian behavior and water models cannot be used with this kind of fluids. For our application, trapezoidal shape appears as a good compromise between accuracy and range of flow rate measurements. Thus, we built a model able to compute the flow rate with taking into account fluid properties and geometrical parameters. This model is simplified in 1D form by using the Shallow Water theory, and completed by a friction model taking into account the variation of fluid properties and geometry along the open channel. It have been validated by series of experiments with both Newtonian and non-Newtonian fluids, where we measured the flow rate and heights of the flow at different locations along the trapezoidal Venturi flume. It have been also completed by 3D CFD which has been simulated both Newtonian and non-Newtonian flows along the flume. To generalized this study, the work was extended to another shape of Venturi more suited to some rig design. The correlations and models developed and experimentally validated during this research can be used to extend the use of Venturi flume flow meters for any fluids : Newtonian and non- Newtonian. It is an opportunity for industries to propose a cheap but accurate solution to measure flow rates in open channels with any kind of fluids.

Nasslaufende Lamellenkupplungen finden im Automobil immer mehr Anwendungen. Im Bezug auf die steigenden Motorleistungen, die Gewichtsoptimierungsmaßnamen und die hohen Ansprüche an Fahrdynamik nimmt die geforderte Leistungsdichte einer nasslaufenden Lamellenkupplung ständig zu. Die Lamellenkupplung wird oft nahe an ihrer Belastungsgrenze ausgelegt. Außerdem wachsen gleichzeitig die Anforderungen an ihre Schaltdynamik, das Komfortverhalten und die Lebensdauer. Schwerpunkt dieser Arbeit ist die Modellierung und Simulation von Reibung und Verschleiß nasslaufender Lamellenkupplungen, insbesondere der mit dem Papierreibbelag. Ein umfassendes Verständnis für die Reibungsvorgänge und Verschleißmechanismen stellt die Grundvoraussetzung für eine optimale Entwicklung der nasslaufenden Lamellenkupplung dar. Zur Lösung der gestellten Aufgabe werden die wichtigsten Einflussgrößen auf das tribolgische System der Lamellenkupplung charakterisiert und die Wirkungen der tribologischen Beanspruchungsgrößen identifiziert. Zudem werden verschiedene Simulationsmodelle mit unterschiedlicher Modellierungstiefe erstellt. Dazu gehören Reibmodelle, Wärmeflussmodelle sowie Lebensdauermodelle, wobei die Reib- und Wärmeflussmodelle für die Lebensdauermodelle benötigt werden. Die hergeleiteten Modelle werden in die Simulationsumgebung implementiert und mit Hilfe eines Prüfstandsversuches verifiziert. Die validierten Modelle können für die Systemoptimierung und die Lebensdauerabsicherung der nasslaufenden Lamellenkupplungen effizient eingesetzt werden. Dies kann eine deutliche Reduktion der Entwicklungszeit sowie der Versuchskosten ermöglichen.