La modélisation du système musculo-squelettique est un outil permettant l'amélioration des connaissances du fonctionnement biomécanique des structures ostéo-articulaires et musculo- tendineuses. Nos travaux de recherche portent sur le développement d'une méthodologie de modélisation personnalisée, volumique, déformable et à capacité contractile du système musculo- squelettique du membre inférieur, intégrant l'ensemble des outils, le plus possible automatisés, de construction (basée sur l'imagerie médicale), de simulation (en couplage avec un modèle multi-corps dynamique) et d'analyse (comme la cartographie des raideurs locales dans le muscle) nécessaires à leur mise en œuvre dans le cadre d'études orthopédiques / Musculo-skeletal modeling can update our knowledge concerning the biomechanical behavior of the osteoarticular and musculotendinous structures. This research work is focus on the development of methodology and tools for the generation of a personalized model of the lower limb musculoskeletal system, taking account of the deformable and contractile behavior of the muscles. This workflow automatically builds the model dataset (from medical imagery), performs the simulations (coupled with a multibody dynamic model), and offers specific analysis tools (as local stiffness mapping in the active muscle) required for various orthopedic studies

<div>There is an increasing interest in future space missions devoted to the exploration of key moons in the Solar system. These many different missions may involve libration point orbits as well as trajectories that satisfy different endgames in the vicinities of the moons. To this end, an efficient design strategy to produce low-energy transfers between the vicinities of adjacent moons of a planetary system is introduced that leverages the dynamics in these multi-body systems. Such a design strategy is denoted as the moon-to-moon analytical transfer (MMAT) method. It consists of a general methodology for transfer design between the vicinities of the moons in any given system within the context of the circular restricted three-body problem, useful regardless of the orbital planes in which the moons reside. A simplified model enables analytical constraints to efficiently determine the feasibility of a transfer between two different moons moving in the vicinity of a common planet. Subsequently, the strategy builds moon-to-moon transfers based on invariant manifold and transit orbits exploiting some analytical techniques. The strategy is applicable for direct as well as indirect transfers that satisfy the analytical constraints. The transition of the transfers into higher-fidelity ephemeris models confirms the validity of the MMAT method as a fast tool to provide possible transfer options between two consecutive moons. </div><div> </div><div>The current work includes sample applications of transfers between different orbits and planetary systems. The method is efficient and identifies optimal solutions. However, for certain orbital geometries, the direct transfer cannot be constructed because the invariant manifolds do not intersect (due to their mutual inclination, distance, and/or orbital phase). To overcome this difficulty, specific strategies are proposed that introduce intermediate Keplerian arcs and additional impulsive maneuvers to bridge the gaps between trajectories that connect any two moons. The updated techniques are based on the same analytical methods as the original MMAT concept. Therefore, they preserve the optimality of the previous methodology. The basic strategy and the significant additions are demonstrated through a number of applications for transfer scenarios of different types in the Galilean, Uranian, Saturnian and Martian systems. Results are compared with the traditional Lambert arcs. The propellant and time-performance for the transfers are also illustrated and discussed. As far as the exploration of Phobos and Deimos is concerned, a specific design framework that generates transfer trajectories between the Martian moons while leveraging resonant orbits is also introduced. Mars-Deimos resonant orbits that offer repeated flybys of Deimos and arrive at Mars-Phobos libration point orbits are investigated, and a nominal mission scenario with transfer trajectories connecting the two is presented. The MMAT method is used to select the appropriate resonant orbits, and the associated impulsive transfer costs are analyzed. The trajectory concepts are also validated in a higher-fidelity ephemeris model.</div><div> </div><div>Finally, an efficient and general design strategy for transfers between planetary moons that fulfill specific requirements is also included. In particular, the strategy leverages Finite-Time Lyapunov Exponent (FTLE) maps within the context of the MMAT scheme. Incorporating these two techniques enables direct transfers between moons that offer a wide variety of trajectory patterns and endgames designed in the circular restricted three-body problem, such as temporary captures, transits, takeoffs and landings. The technique is applicable to several mission scenarios. Additionally, an efficient strategy that aids in the design of tour missions that involve impulsive transfers between three moons located in their true orbital planes is also included. The result is a computationally efficient technique that allows three-moon tours designed within the context of the circular restricted three-body problem. The method is demonstrated for a Ganymede->Europa->Io tour.</div>

This thesis focuses on the development of a health monitoring system for gearbox transmissions. This was accomplished by developing and understanding a two-stage gearbox computer model that emulates an actual gearbox test rig. The computer model contains actual gearbox geometry, flexible shafts, bearings, gear contact forces, input motor torque, output brake torque, and realistic gearbox imbalance. The gear contact force of each gear stage and the input bearing translational acceleration were the main outputs compared between a healthy gearbox and damaged gearbox computer model. The damage of focus was a fatigue crack on the input pinion gear. A sideband energy ratio comparison yielded the computer simulation accurately modeled the difference between a healthy and damaged gearbox. The next step in this study involved the development of a repeatable procedure to initiate and propagate a fatigue crack at the tooth root in an actual spur gear. A damaged spur gear allows for a future comparison of an actual healthy and damaged gearbox system in the lab. A custom fatigue fixture was designed and manufactured for a Martin S1224BS 1 spur gear. The fatigue crack was initiated by position control fatigue testing which deflects the gear tooth a set amplitude for a number of cycles. Over the length of the test, the load that the tooth can withstand in bending decreases as damage begins to occur. Once the max load on the gear has dropped by a significant percentage (5-15%) a crack has initiated and begun to propagate across the tooth face. The use of a scanning electron microscope confirmed the presence a fatigue crack.

The aim of this thesis is an analysis of the construction of a trailer used for transporting concrete pillars. The main part of the thesis is focused on frame construction. For the calculation of load states a multi body system was used, whereby a simulation of transport in terrain was performed. The results from these calculations will be used as limiting conditions for strength control. The method of solution is the finite element method. All acquired results will be analysed and according to them changes will be made to the frame construction. In addition to this, the thesis contains drawings documenting the above-mentioned changes.

Die Arbeit befasst sich mit der Entwicklung automatischer Lenkungen, die die von Schienenfahrzeugen bekannte Spurtreue auf n-gliedrige, mehrachsgelenkte Straßenfahrzeuge übertragen. Spurtreu bedeutet folglich, dass die Lenkachsmittelpunkte keinen seitlichen Versatz zueinander aufweisen. Dafür wird ein modellbasiertes automatisches Lenkverfahren systematisch konzipiert, entworfen und erprobt, das sowohl eine vollautomatische Spurführung als auch eine halbautomatische Nachführung erlaubt. Die modellbasierten automatischen Lenkungen unterliegen keinen praktisch relevanten Einschränkungen. Das wird durch die Verwendung einer Steuerungsstruktur mit zwei Freiheitsgraden erreicht, die aus einer modellbasierten Vorsteuerung und einem Rückführregler besteht. In der Vorsteuerung werden die Lenkwinkel aller Achsen berechnet, mit denen der Sollweg theoretisch spurtreu befahren wird. Durch den Einsatz eines speziell angepassten, modularen Mehrkörpermodells gelingt diese Berechnung allgemein für eine Klasse n-gliedriger Fahrzeuge. Zum Ausgleich von nicht vermeidbaren Modellunbestimmtheiten und nicht gemessenen Störungen werden ein nichtlinearer Mehrgrößenregler sowie achs-individuelle lineare Eingrößenregler entworfen und miteinander verglichen. Simulationen und Fahrversuche zeigen, dass das entwickelte Verfahren in einem weiten Geschwindigkeitsbereich robust gegenüber typischen Einflussgrößen wie Fahrbahn- und Beladungszustand ist.

<p> </p> <p>In the coming decades, numerous missions plan to exploit multi-body orbits for operations. Given the complex nature of multi-body systems, trajectory designers must possess effective tools that leverage aspects of the dynamical environment to streamline the design process and enable these missions. In this investigation, a particular class of dynamical structures, quasi-periodic orbits, are examined. This work summarizes a computational framework to construct quasi-periodic orbits and a design framework to leverage quasi-periodic motion within the path planning process. First, quasi-periodic orbit computation in the Circular Restricted Three-Body Problem (CR3BP) and the Bicircular Restricted Four-Body Problem (BCR4BP) is summarized. The CR3BP and BCR4BP serve as preliminary models to capture fundamental motion that is leveraged for end-to-end designs. Additionally, the relationship between the Earth-Moon CR3BP and the BCR4BP is explored to provide insight into the effect of solar acceleration on multi-body structures in the lunar vicinity. Characterization of families of quasi-periodic orbits in the CR3BP and BCR4BP is also summarized. Families of quasi-periodic orbits prove to be particularly insightful in the BCR4BP, where periodic orbits only exist as isolated solutions. Computation of three-dimensional quasi-periodic tori is also summarized to demonstrate the extensibility of the computational framework to higher-dimensional quasi-periodic orbits. Lastly, a design framework to incorporate quasi-periodic orbits into the trajectory design process is demonstrated through a series of applications. First, several applications were examined for transfer design in the vicinity of the Moon. The first application leverages a single quasi-periodic trajectory arc as an initial guess to transfer between two periodic orbits. Next, several quasi-periodic arcs are leveraged to construct transfer between a planar periodic orbit and a spatial periodic orbit. Lastly, transfers between two quasi-periodic orbits are demonstrated by leveraging heteroclinic connections between orbits at the same energy. These transfer applications are all constructed in the CR3BP and validated in a higher-fidelity ephemeris model to ensure the geometry persists. Applications to ballistic lunar transfers are also constructed by leveraging quasi-periodic motion in the BCR4BP. Stable manifold trajectories of four-body quasi-periodic orbits supply an initial guess to generate families of ballistic lunar transfers to a single quasi-periodic orbit. Poincare mapping techniques are used to isolate transfer solutions that possess a low time of flight or an outbound lunar flyby. Additionally, impulsive maneuvers are introduced to expand the solution space. This strategy is extended to additional orbits in a single family to demonstrate "corridors" of transfers exist to reach a type of destination motion. To ensure these transfers exist in a higher fidelity model, several solutions are transitioned to a Sun-Earth-Moon ephemeris model using a differential corrections process to show that the geometries persist.</p>

Im Rahmen des Exzellenzclusters MERGE an der TU Chemnitz erfolgt die Entwicklung eines kontinuierlichen großserientauglichen Verfahrens zur Herstellung komplexer geschlossener Strukturbauteile. Hierbei werden vorimprägnierte faserverstärkte thermoplastische Halbzeuge (thermoplastische Tapes) in einem Kombinationsverfahren aus thermoplastischen Tapelegen und Tapewickeln verarbeitet. Für dieses kontinuierliche Orbitalwickelverfahren wurde ein spezieller Technologiedemonstrator entwickelt mit dessen Hilfe Machbarkeitsstudien zur Erbringung des Funktionsnachweises durchgeführt werden. Die oben genannte Versuchsanlage ermöglicht die Erzeugung rotationssymmetrischer Profile, die zudem einen inkonstanten Querschnitt aufweisen können. Für die Anlagenkonzeptionierung wurde ein Beispielprofil eines Strukturbauteils ausgewählt und die Anlagendimensionierung durchgeführt. Basierend auf dem Entwurf werden zur Anlagendimensionierung die Parameter der Einzelantriebe mit Hilfe inverser Kinematik simulativ und analytisch abgeleitet und durch anschließende Simulation in CreoElements/Pro® vervollständigt. Die konstruktive Realisierung erfolgte mittels Solid Works. Die abschließende simulative Validierung wurde wiederum mittels CreoElements/Pro® durchgeführt. Diese Arbeiten entstanden im Rahmen des Bundesexzellenzclusters EXC 1075 "Technologiefusion für multifunktionale Leichtbaustrukturen" und wurde von der Deutschen Forschungsgemeinschaft gefördert. Die Autoren danken für die finanzielle Unterstützung.

The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. The transient and steady-state dynamic loading on teeth within a two stage crank-slider mechanism arising from backlash and geometric manufacturing errors is investigated by utilizing a non-linear multi-body dynamics software model. The multi-body model drastically reduces the computation time required by finite element methods to simulate realistic operation. The gears are considered rigid with elastic contact surfaces defined by a penalty based non-linear contact formulation. The third section examines a practical differential planetary transmission which combines two inputs and one output. Planetary gears with only backlash errors are compared to those containing both backlash and tooth defects under different kinematic and loading conditions. Fast Fourier Transform (FFT) analysis shows the appearance of side band modulations and harmonics of the gear mesh frequency. A joint time-frequency analysis (JTFA) during start-up reveals the unique vibration patterns for fixed axis gear train and differential planetary gear, respectively, when the contact forces increase during acceleration.

In this report, the effect of external torque injection of a particular phase and frequency was analyzed using an induction motor assembly consisting of a prototype of an induction motor and a flexible mounting arrangement. The eigenfrequencies of the several components that make up the construction of the induction machine assembly are found out both by analytical and FEM methods. The electromagnetics of the Induction machine is simulated utilizing COMSOL Finite Element Analysis (FEA) software. The single direction coupling is set up to synchronize the parameters between the Rotating Machinery, Magnetic (RMM) and Multi Body Dynamics (MBD) models in COMSOL. / I denna rapport analyserades effekten av extern momentinsprutning av särskild fas och frekvens med hjälp av en induktionsmotor som består av en prototyp av induktionsmotor och ett flexibelt monteringsarrangemang. Egenfrekvenserna för de flera komponenterna som utgör konstruktionen av induktions maskin aggregatet upptäcks både med analytiska metoder och metoder. Induktions maskinens elektromagnetik simuleras med COMSOL FEA programvara. En enkelriktad koppling är konfigurerad för att synkronisera parametrarna mellan RMM och MBD modellerna i COMSOL.

Deviations from the design track geometry are called track irregularities, which are a main excitation mechanism in the track–vehicle dynamic system, and very important to monitor and maintain to have trac on a line run safely and comfortably. Especially during vehicle acceptance testing, it is important that a new vehicle behaves close to design predictions and within limit values, thus it is important to be able to describe track irregularities in a consistent way. There are several methods which quantify the eects track irregularities have on a vehicle while running along the track. Most common is analyse standard deviations and percentiles and maximum values over sections with pre-defined length. However, these quantities do not correlate well with the vehicle dynamic response, e.g. two track sections with similar maxima and standard deviations can result in very dierent response of the vehicle. To improve the correlation between track irregularities and vehicle re- sponse measures, it is recommended by past research to use multiple regres- sion analysis to take e.g. vehicle speed and track curvature into account as well. Other methods range from derivatives of track irregularities, via trans- fer functions and vehicle filters to neural networks. Common for all these methods are that there is either still slight inconsistencies in the results or that they are tailored for certain vehicle types on specific lines. As a result, the preferred method to evaluate track irregularities is still to use standard deviations. In this thesis, data from three vehicles in two measurement campaigns is evaluated using a single degree of freedom model as inspiration to break down the path from track to vehicle into several steps. A weak link in these steps is identified, which shows significantly lower correlation coecients than the other steps. The weak link is the step from vertical track irregularity second spatial derivative to vertical axle box acceleration divided by the squared vehicle speed. A variable wavelength range Dx is introduced, as an alternative to the common D1 (3–25 m), D2 (25–70 m) and D3 (70–150 m) wavelength ranges. Its wavelength range corresponds to the vehicle response band-pass filter frequencies and is thus speed dependent. Simulations are also carried out to investigate the weak link and for the possibility to vary parameters that cannot be changed during on-track mea- surements. A multi-body system model of the passenger coach Bim 547.5 is used, together with recorded track data and vehicle speed from the on-track measurements. The varied parameters have rather low sensitivity and aect results to a small extent. Most impact has the randomly varying vertical track stiness which aects the vertical wheel–rail forces and axle box accelerations. In future work, it should be explored if it is possible – and in such case how – to separate the eects of varying track stiness from the track irreg- ularities. This to better understand when a vehicle response is linked more to the track irregularities or to the track flexibility. The weak link identified in the steps from track to vehicle should also be further explored, perhaps by extending the underlying model or evaluate a dierent set of measurements. / Spårlägesfel är avvikelser från den nominella spårgeometrin. De är en vik- tig excitationsmekanism i det dynamiska system som bana och fordon utgör och är viktiga att övervaka och åtgärda för att trafiken ska kunna flyta sä- kert och komfortabelt. Eftersom det vid mätningar för typgodkännande av fordon är viktigt att fordonet beter sig som förväntat och inom gränsvärden, är det viktigt att kunna beskriva spårlägesfel på ett sätt som är konsekvent och motsvarar hur fordonet ”känner av” dem. Det finns ett flertal olika metoder som kvantifierar de eekter spårläges- fel har på ett fordon som rör sig längs ett spår. Vanligast är att använda standardavvikelser, percentiler och maxvärden från spårsektioner med för- definierad längd. Dessa storheter korrelerar dock inte väl med den dynamiska fordonsresponsen, till exempel kan två spårsektioner med liknande maxvärden och standardavvikelse resultera i väldigt olika fordonsrespons. För att förbättra korrelationen mellan storheter för spårlägesfel och for- donsrespons rekommenderar tidigare forskning att använda multipel regres- sionsanalys för att även ta hänsyn till till exempel fordonets hastighet eller spårets kurvatur. Det finns flera alternativa metoder, till exempel derivator av spårlägesfel, överföringsfunktioner och fordonsfilter eller neurala nätverk. Generellt ger dock dessa metoder antingen fortfarande en viss osäkerhet i resultaten, eller så är de anpassade för vissa fordonstyper på enstaka järn- vägslinjer. Sammantaget är resultatet att den metod som föredras för att utvärdera spårlägesfel, fortfarande baseras på standardavvikelser. I den här avhandlingen används en enfrihetsgradsmodell som inspiration för att bryta ner excitationsvägen från spår till fordon i ett antal steg, som sedan undersöks genom att utvärdera mätdata från tre fordon i två forsk- ningsprojekt. En svag länk bland stegen identifieras, vilken visar signifikant lägre korrelationsvärde än övriga steg. Den svaga länken är steget från spatial andraderivata av spårlägesfel till axelboxacceleration dividerat med fordons- hastigheten i kvadrat. Ett variabelt våglängdsområde Dx introduceras som ett alternativ till de vanligt förekommande D1 (3–25 m), D2 (25–70 m) och D3 (70–150 m). Det variabla våglängdsområdet motsvarar de frekvenser som används för utvärdering av fordonsrespons och är därmed hastighetsberoende. Vidare används simuleringar för att undersöka den svaga länken och för möjligheten till parametervariationer. En flerkroppsmodell (MBS-modell) av passagerarvagnen Bim 547.5 används tillsammans med uppmätta data för spår och fordonshastighet. De parametrar som varieras visar sig ha låg käns- lighet och påverkar resultaten i liten utsträckning. Störst inverkan har den slumpmässigt varierande vertikala spårstyvheten, vilken påverkar de vertikala hjul–rälkrafterna och axelboxaccelerationerna. Fortsatt forskning bör undersöka om det är möjligt att – och i så fall hur – separera eekten av varierande spårstyvhet och spårlägesfel. Detta kan ge bättre förståelse för om fordonsrespons kopplar mer till spårlägesfelen eller till spårflexibiliteten. Den svaga länken som identifierats bör också undersö- kas ytterligare, förslagsvis genom att utöka den bakomliggande modellen eller analysera annan mätdata. / <p>QC 20180517</p>