Dissertations / Theses on the topic 'Mécanisme Flexible'
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Wu, Ke. "Conception, Modélisation, Optimisation et Commande de Mécanisme Flexible." Electronic Thesis or Diss., Centrale Lille Institut, 2023. http://www.theses.fr/2023CLIL0008.
According to the literature, it is clearly found out that in the field of compliant mechanisms (CMs),there is no existing results on how to geometrically define random-shape initially curved beams(ICBs) and efficiently modeling large deflection of these slender structures under complex loading conditions. In particular, efficiently modeling nonlinear buckling and post-bucking to serve the design of CMs has not been achieved to the best of our knowledge. Besides, there is also few results for model-based design (optimization) and model-based control of CMs. If the mentionedproblems are not solved, researchers may still suffer from the time-consuming trial-and-errordesign process and be stuck with global-enumeration-based design framework or purelyempirical design methods
Beets, Eric. "Modélisation des systèmes mécaniques articulés flexibles par utilisation des coordonnées naturelles et des équations de Kane : expérimentation et validation numérique." Valenciennes, 1997. http://www.theses.fr/1997VALE0039.
The simulation of multibody dynamics has known an important expand since the 60's. Until the end of the 70's, bodies were considered as rigid in the most of software packages. Results are excellent as long as deformations remain weak. However, the simulation of large sizes or high-speed revolving mechanisms, as well as the optimization of masses, needs to take structural flexibilities into account. During the development of a flexible multibody formalism, it is necessary to choose the descriptive coordinates systems allowing to position the moving reference frame and the type of the motion equations. The former affects directly the facility of the mechanism description as well as the operative cost. We have therefore chosen to develop a method based on Kane’s equations in natural coordinates. These last lead to a simple and “natural” description of the mechanism and to a limited number of descriptive coordinates. Kane’s equation generate besides a minimal number of motion equations. The finite element method is here employed to introduce the elastic coordinates and the component mode s used in order to reduce the number of degrees of freedom. It is also possible to increase the step of the numerical integration method. A software based on this method has therefore been developed. Two benchmarks allow us to conclude that, for similar results, CPU times are inferior to classical methods based on the one hand on Lagrange’s equations in absolute coordinates and on the other hand on Lagrange’s equation in natural coordinates. Moreover, the realization of an experimental flexible four bars mechanism allows showing that the method gives results close to effective working conditions
Bruyas, Arnaud. "Apport de la fabrication additive multi-matériaux pour la conception robotique." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAD045/document.
Percutaneous interventional radiology permits the diagnosis or the treatment of cancer tissues thanks to the use of needles and imaging devices. Being minimally invasive, such procedures are beneficial for the patient, but for the radiologist, they are highly complex. In order to assist the physician and remotely control the needle, we propose in this work the design and the manufacturing of multi-material compliant devices by taking advantage of multi-material additive manufacturing. To perform the design of such device, we propose several solutions in terms of kinematics, actuation and sensing. In particular, we developed a new compliant joint, the HSC joint, as well as a new pneumatic actuator for needle insertion. In the end, we demonstrate in the thesis the contributions of multi-material additive manufacturing for medical robotics, by combining all those solutions into a single device that remotely controls both the orientation and the insertion of the needle
Gomes, Sebastião Cícero Pinheiro. "Précision de la transmission du couple par un moto-réducteur électrique : modélisation et commande d'un bras rigide ou flexible avec compensation du frottement." Toulouse, ENSAE, 1992. http://www.theses.fr/1992ESAE0020.
Gagarina, Tatiana. "Modèle pseudo-rigide pour la simulation dynamique des mécanismes flexibles." Paris 6, 1999. http://www.theses.fr/1999PA066607.
De, Greef Aline. "Towards medical flexible instruments: a contribution to the study of flexible fluidic actuators." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210073.
• A literature review of these actuators has been established. It has allowed to identify the different types of motion that these actuators can develop as well as the design principles underlying. This review can help to develop flexible instruments based on flexible fluidic actuators.
• A test bench has been developed to characterize the flexible fluidic actuators.
• A interesting measuring concept has been implemented and experimentally validated on a specific flexible fluidic actuator (the "Pneumatic Balloon Actuator", PBA). Ac- cording to this principle, the measurements of the pressure and of the volume of fluid supplied to the actuator allow to determine the displacement of the actuator and the force it develops. This means being able to determine the displacement of a flexible fluidic actuator and the force it develops without using a displacement sensor or a force sensor. This principle is interesting for medical applications inside the human body, for which measuring the force applied by the organs to the surgical tools remains a problem.
The study of this principle paves the way for a lot of future works such as the implemen- tation and the testing of this principle on more complex structures or in a control loop in order to control the displacement of the actuator (or the force it develops) without using a displacement or a force sensor.
• A 2D-model of the PBA has been established and has helped to better understand the physics underlying the behaviour of this actuator.
• A miniaturization work has been performed on a particular kind of flexible fluidic actu- ator: the Pleated Pneumatic Artificial Muscle (PPAM). This miniaturization study has been made on this type of actuator because, according to theoretical models, minia- turized PPAMs, whose dimensions are small enough to be inserted into MIS medical instruments, could be able to develop the forces required to allow the instruments to perform most surgical actions. The achieved miniaturized muscles have a design similar to that of the third generation PPAMs developed at the VUB and present a total length of about 90 mm and an outer diameter at rest of about 15 mm. One of the developed miniaturized PPAMs has been pressurized at p = 1 bar and it was able to develop a pulling force F = 100 N while producing a contraction of 4 %.
Propositions have been made regarding a further miniaturization of the muscles.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Lachance, Denis. "Analyse mécanique de chaussées flexibles dans un contexte climatique nordique." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0006/MQ44703.pdf.
Petlova-Marinova, Svetlana. "Modélisation et simulation du comportement mécanique des composites textiles flexibles." Paris 6, 2003. http://www.theses.fr/2003PA066473.
Le, Druillennec Marie. "Etude des mécanismes d'endommagement de films minces métalliques déposés sur substrats souples pour l'électronique flexible." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI108/document.
Over the past 20 years, new improvements in materials and processes led to the development of printed flexible electronics. Flexible electronics devices subjected to bending, twisting, or stretching during their lifetime, the development of device with high reliability is therefore of great importance for the efficiency of electrical connection. This work investigates the mechanical reliability of inkjet or screen-printed Ag thin films on polyimide substrates dedicated to the electrical interconnection of active components. Expected mechanical failure modes are film cracking and buckling delamination.First of all, in order to characterized the two mechanisms, tensile tests are performed under an optical microscope to follow cracks and under an optical interferometer to follow buckles. In order to obtain crack spacing evolution during deformation, an image processing is realized. Two types of cracks are observed: long and straight cracking for thick films and small and zigzag shape cracking for thin films. The evolution of buckles shape with imposed tensile deformation is characterized.In a second time, in order to understand experimental observations, mechanical failure modes are analysed with finite elements models. The origin of the two types of cracking are explained by a geometrical effect of film thickness. A elastoplastic shear lag bidimensional model gives upper and lower bonds of crack spacing during deformation. A three-dimensional model allows identification of cohesive zone model parameters at film/substrate interface, from experimental buckle shape. An adhesion energy of 2 J.m-2 , a critical strength of 20 MPa and a mode mixity parameter of 0.4 are determined. These values are in good agreement with literature
Dufour, Régis. "Influence d'un couple axial sur le comportement dynamique des rotors flexibles." Lyon 1, 1985. http://www.theses.fr/1985LYO19011.
Mikchevitch, Alexei. "Méthodologie de simulation d'assemblage/ désassemblage de composants flexibles : Application à la simulation de pièces de type « poutres flexibles » dans un environnement de réalité virtuelle." Phd thesis, Grenoble INPG, 2004. http://tel.archives-ouvertes.fr/tel-00011292.
Janfaoui, Sabri. "Électronique CMOS en silicium microcristallin sur substrat flexible transparent." Rennes 1, 2012. http://www.theses.fr/2012REN1S119.
The aim of this thesis is to fabricate both types of microcrystalline silicon TFTs N and P (Thin Film Transistors) on flexible and transparent substrate. The microcrystalline silicon technology was optimized in our laboratory at low temperature <180°C. The flexible and transparent chosen substrate is PEN Q65FA (Polyethylene naphthalate) produced by DuPont Teijin Film. N-type microcrystalline silicon top-gate TFTs are successfully fabricated on PEN. These N-TFTs are fairly uniform and replicable. Likewise, N-TFTs are stable under gate bias stress of +15V, the VTH shift was only 12% during four hours. Furthermore, P-TFTs are demonstrated on PEN, the characteristics of these P-TFTs are adequate and they need further work. Both types of these TFTs are mechanically solicited. Tensile and compressive strains were applied by bending TFTs with different curvature radius varying between infinite (flat) and 0. 5 cm. Electron mobility increases (40%) with tensile strain and decreases with compressive one. In contrast, hole mobility decreases with tensile strain and increases (27%) with compressive one. This behaviour is mainly due to the variation of silicon properties. TFTs work until a radius of 1 cm and fail after. Failure occurs mainly from the cracking of silicon nitride that is used as encapsulation layer of the substrate and as gate insulator. Also, it occurred by cracking of the microcrystalline silicon that is used as an active layer. This can be avoided by reducing the thickness of the active layer to 50 nm
Taghbalout, Meryem. "Programmation et commande d’un robot à deux bras pour la manipulation et l’assemblage de pièces flexibles par des tâches collaboratives." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0165.
The main objective of this thesis is to develop a control law to control a two arm robot in order to achieve the manipulation tasks and to ensure the safety aspects for the human and the robot. To accomplish this, we presented an overview of the studies that have been conducted in this context. Thereafter, we proceeded to the kinematic and dynamic robot modeling. In order to calculate its dynamic model, we used the SYMORO+ software. After giving a detailed presentation of the method for identifying the parameters of manipulator robots, we applied it in a concrete way on our own robot. This allowed us to obtain a vector of parameters able to ensure a positive defined inertia matrix for any robot joint configuration, as well as a good quality of torque reconstruction for both constant and variable joint speeds. Thanks to this dynamic identification, we were able to realize an accurate simulator of the robot on Matlab/Simulink. The external forces of the robot have been estimated from the identified dynamic modulus and an experimental validation has been described. To apply control laws on an industrial robot, it was necessary to think about an external communication on the robot. The adopted approach was presented as well as its realization on the robot. The latter allowed us to program in python all our problems to be implemented on the robot. After having validated all the steps previously mentioned we moved on to the implementation of the control on the robot. The main task we adopted is the stripping of the cables. For this purpose, we chose to implement a hybrid force/position control in which the external forces are controlled in order to guarantee the absence of damage on the cables to be stripped. The robot used to perform all the experiments is the IRB14000 YuMi robot from Abb. All the experiments performed in this project have been described and presented. This thesis work was carried out within the framework of the Robotix Academy project financed by the European regional development fund INTERREG V-A Grande Région
Dong, Hanpeng. "Microcrystalline silicon based thin film transistors fabricated on flexible substrate." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S173/document.
This work deals with the development of microcrystalline silicon thin film transistors (TFTs) fabricated on flexible substrate at low temperature (T=180 °C). The first step of this work consists in studying the electrical stability of TFTs. The N-type TFTs fabricated on glass substrate are electrically stable under gate bias stress VGStress= +50V at T=50 °C. The threshold voltage shift (ΔVTH) was only 1.2 V during 4 hours. This electrical instability of TFTs is mainly due to carrier trapping inside the silicon nitride gate insulator. The second step of this work lies in the study of the mechanical behavior of the TFTs. Both tensile and compressive strains were applied on TFTs. The minimum curvature radius is r=1.5 mm for both tension and compression. The main limitation of TFTs comes from the mechanical strain εlimit of silicon nitride used as gate insulator of TFTs. Also, these TFTs are mechanically reliable: the variation of ION current was only 1% after 200 cycles mechanical bending. These results obtained open the way to the development of flexible electronics that can be folded in half.Finally, TFTs have been fabricated using different gate insulators in order to improve the mobility. Unfortunately, all the gate insulators used couldn’t improve mobility without sacrificing electrical stability of TFT. More detailed studies and complementary optimization of these gate insulators are necessary
Argoud, Maxime. "Mécanismes de collage et de transfert de films monocristallins dans des structures à couches de polymères." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00848111.
Monnier, Philippe. "Conception et optimisation de transducteurs colocalisés pour l'amortissement actif de structures flexibles." Besançon, 2005. http://www.theses.fr/2005BESA2082.
This work is focused on the active damping of flexible structures. It is divided into four parts dealing with the design, the optimisation, the simulation and the implementation of the control system. In the first part, the stability and robustness of different control strategies are investigated. Collocated active damping is preferred for being the only stable and robust method. The characteristics of the collocated Integral Force Feedback control strategy are studied in a second part. The mechanical parameters that characterize the efficiency of this non-optimal dissipation strategy are identified through a sensitivity analysis. A criterion is proposed to optimize the mechanical power transfer between the structure and the transducers. Its relevance is then proved by numerical and experimental studies. Thus, the third part describes the active vibration control of a plate. Different plate systems are considered to emphasize the effect of mechanical impedances on the control implementation. The agreement of the numerical and experimental results validates the theoretical concepts while underlining the importance of the relative impedance of the transducers with respect to that of the system. The last part is devoted to the vibration control of an automotive windscreen. The efficiency of several control laws is investigated, and their efficiency evaluated by holographic measurements. This final case has revealed the difficulties encountered by controlling highly damped structures
Yin, Binbin. "Contribution au pilotage réactif des sytèmes flexibles d'assemblage : méthode d'équilibrage dynamique." Besançon, 1995. http://www.theses.fr/1995BESA2035.
Bettaieb, Mohamed Nizar. "Modélisation du comportement mécanique d'engrenages : couplages entre engrènements et éléments de structures flexibles." Lyon, INSA, 2006. http://theses.insa-lyon.fr/publication/2006ISAL0030/these.pdf.
The present work is aimed at predicting the static and dynamic behavior of geared transmissions comprising flexible components. The proposed model adopts a hybrid approach, combining classical beam elements, elastic foundations for the simulation of tooth contacts, and sub-structures derived from 3D finite element grids for flexible parts. The pinion shaft and body are modeled via beam elements which simulate bending, torsion and traction. Tooth contact deflections are described using time-varying elastic foundations (Pasternak foundations) connected by independent contact stiffness. In order to account for thin-rimmed gears, a 3D finite element model of the gear (excluding teeth) is set up and a pseudo-modal reduction technique is used prior to solving the equations of motion. Depending on the gear structure, the results reveal a potentially significant influence of thin rims on both quasi-static and dynamic behavior, i. E. , load distributions and dynamic factors
Nguyen, Van Lan Rémi. "Etude numérique de l'interation entre une couche limite turbulente et une paroi flexible." Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX22099.
Meunier, Michel-Bernard. "Éléments méthodologiques pour la conception de systèmes flexibles d'assemblage." Besançon, 1989. http://www.theses.fr/1989BESA2057.
Pujol, Thomas. "Étude mécanique des gels d'actine branchés." Phd thesis, Université Paris-Diderot - Paris VII, 2012. http://pastel.archives-ouvertes.fr/pastel-00874094.
Abousleiman, Vincent. "Comportement dynamique des trains planétaires et épicycloïdaux : conditions de contact instantanées et influence de sous-ensembles flexibles." Lyon, INSA, 2004. http://www.theses.fr/2004ISAL0054.
This work in co-operation with Hispano-Suiza is aimed at improving the prediction of the dynamic behaviour of planetary/epicyclic geared trains, especially for systems with very flexible parts. The proposed hybrid models combine classical lumped parameter representations (sun gear, planets) and three-dimensional finite elements models used for the most flexible components (ring gear, carrier). The large FE substructure models are reduced by means of a modal approach (ring gear) or a constraint mode method for planet carrier. Gear meshes are taken into account through specific gear elements based on time-dependent non-linear mesh stiffnesses. Shape deviations and some usual manufacturing and mounting errors have been introduced in the model. A time integration Newmark scheme is coupled with a normal contact algorithm which verifies instantaneous contact conditions on all gear flanks. The main results show that modelling ring gear and planet carrier as deformable bodies has a significant influence on static and dynamic behaviour of planetary gear sets
Le, Scornec Julien. "Micro-générateurs aéroélectriques flexibles pour l’auto-alimentation de capteurs communicants." Thesis, Nantes, 2020. http://www.theses.fr/2020NANT4039.
The advent of the Internet of Things has rendered the ambient energy harvesting a major issue for powering communicating microsystems. In this context, this work focuses on the development of a flexible piezoelectric micro-generator able to convert the mechanical energy from low airflows. The objective is to develop autonomous microsystems, or at least to extend their lifespan with energy harvesting. To harvest ambient energy, the flexible micro-generators are made of 3 μm-thick lead zirconate titanate (PZT) thin films encapsulated between polyethylene terephthalate (PET) films. The manufacturing process of the micro-generators has been optimized in order to increase their energy efficiency. Both the optimization of the electrode structure and the geometry of the generator made the maximum harvested power increase by a factor of 625. In this work, to characterize the energy harvesting, the micro-generators were excited with different systems (shaker, traction/compression system and wind tunnel). Thus, wind tunnel tests have shown that it was possible to harvest a power of 38 μW at 10 Hz when the generator was subjected to a low airflow (6 m/s). This generator allowed to power a communicating temperature sensor during several measurement/data transmission cycles
Grouthier, Clément. "Récupération d'énergie et vibrations induites par vortex de structures flexibles." Phd thesis, Ecole Polytechnique X, 2013. http://pastel.archives-ouvertes.fr/pastel-00875763.
Duran-Venegas, Eduardo. "Modélisation et optimisation d'un rotor à pales flexibles." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0195.
Rotors have been historically developed for harvesting and propulsion. For wind turbines and helicopters, decades of research have been done to optimize their design. For recent applications, such as drones, no such a research effort has been made. The high flexibility of the rotor and the different operational conditions still constitute challenging issues for their design. In this work, a coupled fluid-structure model is proposed, taking into account the flexibility of the blades in non-conventional operational conditions.The model is sufficiently simple and robust to permit extensive parameter studies. It includes a model for the wake, a model for the flexible rotor structure and the coupling. Two different wake models are considered: a classical Joukowski model, where two vortices are emitted per blade, one at the tip and one at the axis, and a generalized Joukowski model where the axial vortex is replaced by a hub vortex emitted away from the center. A stability analysis of the solutions derived with the classical Joukowski model is performed. The convective/absolute nature of the instability is analysed for various operational conditions.Stationary wake solutions are used to calculate the flow in the rotor plane. Kutta-Joukowski law and Blade Element Theory are applied to obtain the aerodynamic loads exerted on the blades. The full coupling of the rotor with its wake is first implemented for a rigid configuration. Coupled solutions are obtained for different rotors and compared to experimental and numerical data published in the literature. Finally, blade flexibility is considered using a rod model for the blade
Paraz, Florine. "Oscillation d'une plaque flexible dans un écoulement." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4327/document.
The physics of the swimming with a flexible caudal fin is studied experimentally by the means of an elastic plate immersed in a uniform water flow. The leading edge of the plate is forced into a harmonic motion, while its trailing edge responds passively to this actuation. A resonance response in amplitude is demonstrated, revealing a strong interaction between the natural frequencies of the plate and the forcing frequencies. Experimental results suggest a non-trivial role of the forcing amplitude, emphasizing the role of non linearities in this problem. To gain better insight into the origin of these non linearities, a weakly non linear model is developed. We model a quasi two-dimensional plate of zero thickness immersed in a potential flow and subject to a resistive drag-like force. The plate deflection is then decomposed into a forcing heaving mode and natural flexural modes. Predictions of the response in amplitude and frequency to a heave forcing system are then calculated. The frequencies of the resonances, as well as the shapes of the deflection, match the experimental results. The performance of the system measured through the generated thrust, is well predicted by the modelling. The experimental and modelling results presented here show (very) good agreement with the literature. Finally, an analytical optimization is undertaken and potential applications to bio-robotic are suggested
Brunet, Serge. "Réduction du bruit dans une cavité parallélépipédique supportant une plaque flexible, comparison entre les contrôles actifs mécanique et acoustique." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1995. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq21725.pdf.
Brunet, Serge. "Réduction du bruit dans une cavité parallélépipédique supportant une plaque flexible : comparaison entre les contrôles actifs mécanique et acoustique." Mémoire, Université de Sherbrooke, 1995. http://savoirs.usherbrooke.ca/handle/11143/977.
Karajani, Pirro. "Équilibrage modal de rotors flexibles : application à une machine." Compiègne, 1995. http://www.theses.fr/1995COMPD795.
Anglada, Alexis. "Introduction de mécanisme de flexibilité dans la programmation par contraintes sur les domaines continus." Paris 6, 2005. http://www.theses.fr/2005PA066261.
Lecavelier, des Etangs-Levallois Aurélien. "Report de technologie SOI-CMOS sur substrat flexible : une approche convergente vers les hautes fréquences et la stabilité des performances sous déformation mécanique." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10058/document.
The ability to realize flexible circuits integrating sensing, signal processing, and communicating capabilities is of central importance for the development of numerous nomadic applications requiring foldable, stretchable and large area electronics. A large number of these applications currently rely on organic electronics, or integrate high mobility active films on plastic foils to provide higher performance. A key challenge is however to combine high electrical performance (i.e. millimeter wave, low noise electronics), with the mechanical flexibility required to conform to curvilinear surfaces, in addition to high stability of these electrical performance upon deformation. In this work, a solution has been developed, based on thinning and transfer onto plastic foil of high frequency (HF) CMOS devices initially processed on conventional silicon-on-insulator (SOI) wafers. This transfer process first enables the fabrication of high performance electronics on plastic, with n-MOSFETs featuring characteristic frequencies fT/fmax as high as 150/160GHz in addition to low noise potentialities: NFmin/Ga of 0.57/17.8dB. Secondly, by locating the neutral plane of the flexible system in its active layer, the relative variation of these high frequency figures-of-merit can be limited to 5% even after aggressive bending, demonstrating flexibility, high performance and stability
Windal, Timothée. "Etude en laboratoire du gonflement des sols : mise au point d'un oedomètre flexible et étude du gonflement tridimensionnel." Lille 1, 2001. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2001/50376-2001-291-292.pdf.
Martin, Maverick. "Structures spatiales déployables constituées de mètres rubans : analyse et implémentation de modèles de poutre à section flexible." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0571/document.
Due to their lightness, compactness, their autonomous deployment and their ability to self-locking while deployed, tape-springs are considered to deploy structures. These slender and cylindrical structures highlight a complex behaviour because of the formation of localised folds. Tape-springs are then difficult to model but a rod model with flexible cross-section (RFleXS) has been developed in order to characterise the tape-spring behaviour.The purpose of this PhD was to develop numerical tools dedicated to design structures deployed by tape-spings. A dimensionless form of the RFleXS model dedicated to shallow tape spring has been developed and links with a regularised Ericksen's bar have been made. These links help to explain folds creation and to determine characteristics of the three constitutive areas of a fold. Analysis of the dimensionless model leads to determine the finite number and the position of bifurcation points for the pure bending of a tape-spring. The cross-section kinematic is enriched; simulations of bending tests then show a good correlation with shell models. A new implementation of RFleXS models is introduced, leading to the creation of two numerical tools: a full finite element software and a one-dimensional element with two nodes incorporated in Abaqus. Some bending experiments have been performed in order to compare simulations with measured data. Even if discrepancies are observed, these comparisons show that the tape-spring overall behaviour is well predicted by rod models with flexible cross-section
Richelot, Julien. "Contrôle actif de structures flexibles par commande prédictive généralisée." Toulouse 3, 2006. http://www.theses.fr/2006TOU30020.
The aim of this study is to perform the active damping of a sloshing structure, i. E. A free-clamped beam with a tank. The first step is to model and DIMENSION the structure. Because of its complexity, a Finite Elements software has been used, to compute the electromechanical parameters from which the model is deducted. Then comes the choice of the control law, which must handle a multimode and MIMO context and must be robust, the fluid/structure interactions and the several filling configurations of the tank being seen as uncertainties around a nominal model. Generalized Predictive Control has been chosen. The use of GPC to perform the active damping of the flexible structure is interesting. The controller is efficient and compact; moreover the results show the same global behaviour for the looped system, from one filling configuration of the tank to another
Yang, Ke. "Etude de la dynamique des matériaux poreux hybrides de type MOFs sous l'effet de la pression mécanique." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20092.
Metal Organic Framework (MOF) materials have been the focus of intense research activities over the past 10 years, with the emergence of a wide range of novel architectures, constructed from inorganic clusters linked by organic moieties. In order to maintain their useful functionalities and high performances in the different fields explored so far (gas storage/separation, catalysis, sensors and many others), besides high chemical and thermal stabilities, MOFs must be also stable enough to resist to different mechanical constraints in both processing and applications. Indeed, there is nowadays a growing interest to characterize the mechanical behaviours of this class of materials under moderate and high applied pressure. This work first aimed to probe the pressure dependence of the structural behaviour of the highly flexible MIL-53 system [MIL stands for Materials of Institut Lavoisier] as a function of the nature of (i) the metal center (Al,Cr) and (ii) the functional group grafted on the organic linker (-H,-Cl,-CH3) using a combination of high-pressure x-ray/neutron diffraction and molecular simulations. The same methodology was further applied to probe how the presence of guest molecules affects the structural transition of this class of hybrid porous solids. Finally, the mechanical stability and the compressibility of two families of rigid MOFs, the MIL-125(Ti) and the UiO-66(Zr) [UiO stands for University of Oslo] up to high pressure (P~5 GPa) have been investigated and their properties in terms of bulk modulus were compared with the most resilient MOFs reported so far
Algarra, Nicolas Pierre. "Pénétration d'une fibre flexible dans un milieu granulaire dense." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066500/document.
We study experimentally a fluid/structure interaction between an elastic fiber and a dense granular medium near the jamming transition. In our horizontal setup, a bidimensionnal and dense random packing is interacting with a clamped elastic fiber. The clamped end of the fiber is in translation relative to the the grains while the free end faces initially the grain flux in a penetration geometry before being deflected by grain/fiber interactions. The control parameters of our system are the packing fraction of the medium, the length and the rigidity of the fiber. Our setup allows us to measure the deflected shape of the fiber, the forces exerted by the grains on the fiber (including the drag force) and to follow the reorganizations of the granular medium. Under some experimental conditions, we observed that this system exhibits several regimes of evolution. For low and large fiber deflections, the system evolves stochastically as a consequence of the random nature of the granular medium : respectively small fluctuations of the fiber around its equilibrium position and sudden events of unlozding of the fiber in flexion associated to granular avalanches. The transition between those two regimes is associated with a symmetry breaking that affects the granular medium as well as the fiber. In a first part, we study how the fiber deflection is influenced by the control parameters, particularly by the distance to jamming. In a second part, we show that a packing fraction asymmetry appears in the granular medium when the fiber is deflected enough. In a third part, we try to understand the evolution of the measured forces using numerical simulations of the Elastica on a constrained beam. Finally, we propose a model of compaction of the grains by the fiber that is in a good aggreement with the experimental evolution of the system. An application of this thesis is the understanding of the mechanisms involved in the penetration of a root or a beam in a granular soil
Zaidani, Mouna. "Modélisation numérique de la mise en oeuvre des matériaux composites par les procédés d'infusion sous membrane flexible." Le Havre, 2012. http://www.theses.fr/2012LEHA0018.
In the infusion process, it is important to take into account the reinforcement deformation as well as the resin flow. Moreover, the analysis of the process physics clearly shows the existence of a hydro-mechanical coupling between two phenomena. In this work , a numerical tool to model the hydro-mechanical coupling of unsaturated deformable fibrous medium, considering a void formation and compression/tow saturation model is presented. The case study of two phase defromable medium requires an analyse of the pore scale phenomena and an up-scaling method on a Representative Volume (REV) of the local mass conservation equations, the reinforcement compressibility and the resin flow occur simultaneously ans there is thus a mutula influence between the two solid and liquid phases. It is important to simulate the infusion process by calculating the maximum height infused by the resin, the final height of the part, the infusion time and the content and entrapped air un the final part. In the simulation code, a void formation model is integrated considering two different flows in the macropore and the micropore, respectively, the viscous flow ans the capillary wicking. The influence of fibrous medium deformation on the fiber tow saturation and void formation during infusion is presented too
Rial, Djihad. "Modélisation tridimensionnelle des flexibles hydroformés et tressés en statique et en fatigue." Electronic Thesis or Diss., Compiègne, 2015. http://www.theses.fr/2015COMP2184.
Hydroformed flexible tubes are essential structures used in several industrial sectors such as the automotive sector, the aviation industry or energy production, such as the production of renewable energy in solar thermal energy farms where the panels must both be supplying fluid along and follow the direction of the sun. These structures serve as connecting parts between the rigid parts different mechanisms, primarily used for damping vibrations and acoustic emissions, and, as their name suggests, they also allow flexibility and pressure expansion, which considerably improves the fatigue strength. The mastery and prediction of the mechanical behavior of these structures are very important from a safety point of view and an economic point of view. Indeed, their accidental breakage can cause very serious consequences due to their use in sensitive areas such as the nuclear industry. In this context, this thesis was launched between Compiegne University of Technology and industrial BOA-group to create digital approaches to behavioral predictions and estimating the life braided hoses that take into account extreme conditions (temperature and pressure) and the forming parameters and properties of the materials used. In terms of use, these products are subject to thermomechanical charge-discharge cycles and vibrations can induce complex deformed piping of wear due to friction and damage by fatigue, The purpose of the study is to develop a numerical approach validated by the experience to certify products and improve the design. This approach will allow to estimate the lifetime of braided wavy taking into account: - the initial state of the product after forming and assembly, - thermomechanical stresses, is defined by the specification, or encountered in specific use cases, - vibrations encountered during use in real cases. The expected results are the life of the products from a calculation model of their behavior using the characteristics of the materials and interaction braid / tube
Kromer, Valérie. "Analyse des forces musculaires au cours de la marche : approche en corps rigide et simulation en mécanismes plans flexibles par éléments finis." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL040N.
Mohd, Zawawi Fazila. "Analyse aéroélastique d'une pale flexible composite : application au microdrone." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0027/document.
L’idée principale du travail rapporté ici est d’étudier les effets de l’intéraction fluide-structure (FSI) de pales laminées flexibles pour les proprotors de micro véhicules aériens(MAV) de type tilt-body dans les configurations de vol stationnaire et en avant. Eneffet, le but est d’exploiter les possibilités offertes par les proprotors à pales flexiblespar rapport aux proprotors à pales rigides pour améliorer leur performance dans cesphases de vol. Le modèle FSI a été développé à cet effet. Ce modèle tient compte desproblèmes spécifiques liés aux proprotors de MAV faits de composite laminé. Il com-bine l’adaptation de modèle aérodynamique par la théorie d’élement de pale (BEM) etl’adaptation de modèle structurel par la théorie des éléments finis de poutre anisotropes(AFEM). Le modèle aérodynamique est développé pour être capable de s’adapter àl’analyse des proprotors à bas nombres de Reynolds. Dans le modèle structural, la paleest modélisée comme une poutre élastique subissant des déviations dans la flexion, latraction et la torsion afin de capturer les effets de couplage de matériaux anisotropes.Il adapte l’analyse structurale des pales du proprotor faites de composite laminé. Lafiabilité du modèle FSI développé est vérifiée à travers une validation par modèles aéro-dynamique et structural, séparément, sur plusieurs proprotors de MAV. Afin de se dirigervers une analyse de pales de proprotors à adaptation passive , une recherche de designoptimal a été effectuée pour des proprotor à adaptation active. Pour cela, un programmepour la conception de pales rigides optimales à un unique point de fonctionnement (soitle vol de croisière soit le vol stationnaire) et à plusieurs points (combinant croisière etvol stationnaire) ont été développés. Les procédures du programme de design optimalemploient les mèthodes de design inverse par itération numérique, sur la base de pertesde poussée induites minimales (MIL). Même si le travail dans cette thèse a été dirigéprincipalement vers le proprotor, la partie moteur du système de propulsion n’a pasété négligée puisque l’efficacité de la propulsion est un facteur crucial pour le succès desMAVs. Une méthode simple et rapide de sélection du meilleur moteur parmi les moteurscommerciaux choisis est élaborée sur la base de la méthode de Taguchi. La sensibilitéde la consommation d’énergie totale à la variation de la valeur de chaque variable deconception du moteur a été étudiée. Le bénéfice de l’utilisation de la charge à la pointe de la pale et l’effet de la flexion sur la torsion induite et sur la dégradation de la poussée respectivement ont aussi été analysés et identifiés. Enfin, les proprotors à pales flexibles conçues systématiquement ont été évalués dans des conditions de fonctionnement stables. Performances en vol stationnaire et performances croisière propulsive, caractérisées par la puissance totale Ptotal ont été comparées entre les proprotors à pales rigides et à pales flexibles. En tant que résultat de la comparaison, les proprotors à pales flexibles s’avère capable d’améliorer légèrement les performances par la réduction de la Ptotal surson optimal proprotors à pales rigides
Caer, Yves. "Contribution à l'étude du comportement mécanique de conteneurs souples." Grenoble INPG, 1993. http://www.theses.fr/1993INPG0110.
Kuhm, David. "Contribution à la modélisation et à l'optimisation d'accumulateurs de bandes flexibles, incluant l'étude du frottement bande/rouleau." Thesis, Mulhouse, 2011. http://www.theses.fr/2011MULH4271.
This study focuses mainly on modeling and optimization of industrial web accumulators. The chapter one presents the nonlinear model of an industrial accumulator including a pneumatic actuated or a motorized carriage. The nonlinear model is then linearized around a working point. This model takes into account nonlinearities of both carriage actuators. The most influent mechanical parameters on the accumulator performances are highlighted and then, classical industrial control strategies are tested on the modeled accumulators. The chapter two concerns the accumulator performances optimization. Firstly, controllers are improved by taking into account the robustness against parameter variations, by using multi-objective controllers optimization or by using new control strategies. All these improvements show drastic performances gain. New accumulator structures including a dancer roll are proposed and improve also the accumulator performances. A performances comparison of the entire presented accumulator is presented at the end of this chapter. The last chapter presents the study of the friction between textile fabric and roll. The friction behavior of a web sliding on a roll is identified. The friction coefficient evolution is experimentally determined for different experimental parameters and kind of webs. These measures have permitted to build a model of a web sliding on a roll. This model, including the friction coefficient and the adherence loss between web and roll highlights the response of the web/roll system against web velocity variation
Philippe, Justine. "Intégration hétérogène de systèmes communicants CMOS-SOI en gamme millimétrique sur substrat flexible." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10178/document.
The ability to realize flexible circuits integrating sensing, signal processing, and communicating capabilities is of central importance for the development of numerous nomadic applications requiring foldable, stretchable and large area electronics. A large number of these applications currently rely on organic electronics, but new fabrication methods permitted to realize flexible mechanically and electrically efficient devices. Besides the transfert on flexible substrates offers many advantages (mechanical flexibility, preservation of original properties, possible heterogeneous integration). In this work, a solution has been developed, based on thinning and transfert onto flexible substrate (metal, glass) of high frequency (HF) CMOS devices initially patterned on conventional silicon-on-insulator (SOI) wafers. This transfer process first enables the fabrication of high performance electronics on metal, with n-MOSFETs featuring characteristic frequencies fT/fmax as high as 165/188 GHz. Secondly, the use of materials other than plastic permit to modify the original properties of a device in terms of thermal dissipation or harmonic distorsions for example, demonstrating flexibility, high performance and stability
Babanezhad, Kaveh. "Inspection géométrique des pièces flexibles sans gabarit de conformation." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI023.
In manufacturing, quality control (QC) is an essential phase of a product’s lifecycle management (PLM) as it ensures customers receive parts within permissible tolerance ranges and free from defects. Given that all manufactured parts often have geometrical differences compared to their nominal computer-aided design (CAD) models, performing geometrical inspections becomes critical during the QC phase. Nowadays, actual measurements and defect identification during geometrical inspections have been semi-automated through the use of computer-aided inspection (CAI) software. Such software can simplify the inspection into a data acquisition task (contact-based probing or non-contact scanning of the part) followed by semi-automated procedures in a software environment. Despite their growing popularity and practicality, currently available CAI software assume the input acquired data are from a rigid part. This assumption is a major limitation given that not all manufactured parts are rigid, and in some sectors such as the aeronautical industries a considerable percentage of all manufactured components (35 to 40 percent) possess some nonrigid behavior. In other words, CAI software can only be used when a part maintains its shape in both free-state and state-of-use positions. Free-state shape is that which a part has without inspection fixture support and/or before assembly, whilst state-of-use shape is that which is defined in the nominal CAD. Although free-state and state-of-use positions are the same for rigid parts, some mechanical parts such as sheet metals and skins (thin-wall featured parts) often have significantly large geometric deviations in a free-state position compared to their nominal CAD models due to the effects of gravity and residual stress. Referring to such parts as flexible, the aforementioned deviations force the QC technicians to traditionally use a variety of inspection fixtures and conformation jigs in order to maintain flexible parts in their state-of-use position before using conventional CAI software. Without fixation, the free-state elastic geometric deviation of flexible parts would be mistaken by CAI software as plastic deformations and as a result identified as defects. With fixation, the aforementioned free-state deviations are removed before data acquisition, and whatever deviations remain can be inspected as potential defects. However, multiple disadvantages exist in using fixtures including: time consuming set-up process (e.g. 60+ hours for a skin panel in the aerospace industry), considerable purchase and operating expenses, limitations of standard fixture kits in some scenarios, big errors in CAI analysis if fixation has not been conducted correctly, etc. Such disadvantages have recently led researchers to:1) try to circumvent use of fixtures by digitally deforming (or better called registering) the acquired free-state pointcloud/mesh data of a flexible part until it superimposes onto the part’s corresponding nominal CAD model, thereby elastically deforming the data to obtain an optimal state-of-use shape whilst avoiding neutralization of any existing manufacturing defects2) and to try to introduce dedicated defect identification modules with higher degrees of automation (compared to conventional semi-automated CAI tools)In this thesis the same two goals are pursued. A bi-criterion registration method (and two algorithms/demos based upon it) is proposed to achieve the first goal, thereby enabling defect identification of flexible parts in conventional CAI software without the use of fixtures. This is followed by introducing an automated method for fast approximation of defect amplitudes (and an algorithm/demo based upon it) to achieve the second goal. Validation was conducted against a number of virtual (simulated) and experimental industrial case studies. Obtained satisfactory results reflect the effectiveness and utility of the proposed methods
Guilbert, Bérengère. "Hybrid modular models for the dynamic study of high-speed thin -rimmed/-webbed gears." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI127/document.
The research work presented in this manuscript was conducted in the Contact and Structural Mechanics Laboratory (LaMCoS) at INSA Lyon, in partnership with Safran Helicopter Engines (formerly-Turbomeca). In helicopters, the power from the turboshaft is transmitted to the rotor and the various accessories (pumps, starters etc…) via transmission gearboxes. In the context of high-speed, light-weight aeronautical applications, mechanical parts such as gears have to meet somehow contradictory design requirements in terms of reliability and mass reduction thus justifying precise dynamic simulations. The present work focuses on the definition of modular gear dynamic models, capable of integrating both the local phenomena associated with the instant contact conditions between the tooth flanks and the more global aspects related to shafts, bearings and particularly the contributions of light thin-rimmed /-webbed gear bodies. The proposed models rely on combinations of condensed sub-structures, lumped parameter and beam elements to simulate a pinion-gear pair, shafts, bearings and housing. Mesh elasticity is time-varying, possibly non-linear and is accounted for by Winkler foundations derived from a classic thin-slice model. The contact lines in the base plane are therefore discretised into elemental segments which are all attributed a mesh stiffness function and a normal deviation which are updated depending on the pinion and gear angular positions. The main originality in this PhD consists in inserting condensed finite elements models to simulate flexible gear bodies while keeping the simple and faster rigid-body approach for solid gears. To this end, a specific interface has been developed to connect the discretised tooth contact lines to the continuous finite element gear body models and avoid numerical spikes in the tooth load distributions for example. A number of comparisons with numerical and experimental results show that the proposed modelling is sound and can capture most of the quasi-static and dynamic behaviour of single stage reduction units with thin-webbed gears and/or pinions. The model is then applied to the analysis of academic and industrial gears with the objective of analysing the contributions of thin, flexible bodies. Results are presented which highlight the role of centrifugal effects and tooth shape modifications at high speeds. Finally, the possibility to further improve gear web design with regard to mass reduction is investigated and commented upon
Akue, Ludi. "Un cadriciel pour la vérification en ligne, générique, flexible et évolutive de configurations de systèmes communicants complexes." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2344/.
Complex networked systems are a fundamental basis of today's life. They increasingly sup- port critical services and usages, essential both to businesses and the society at large. The evident example is the Internet with all its services and usages in a variety of forms, architectures and media ranging from small mobile devices such as smartphones to large-scale critical systems such as clusters of servers and cloud infrastructures. It is therefore crucial to ensure their effective and continuous operation. A vision to do this consists in the development of autonomous and adaptive management solutions, capable of dynamically and continuously reconfiguring these systems in order to maintain a desired state of operation in the face of unstable and unpredictable operational conditions. A main obstacle to the effective deployment of dynamic reconfiguration solutions is the lack of methods and means to ensure the effectiveness and safety of these dynamic con- figuration changes. The overall contribution of this thesis is to provide concepts, methods and tools to enable an online configuration verification. Our approach to build this framework was first to define a high-level language dedicated to the specification and verification of configurations. Second, we designed a generic flexible and adaptable runtime verification service, able to manipulate the concepts defined in this language. Finally, we defined an architecture of adapters for integrating existing systems and platforms. This allows our framework to support a runtime configuration verification process that starts at design time with a rigorous specification of configuration models and continues at runtime through automatic checking of configurations based on these models. The framework has been implemented in a prototype that has been experienced on a series of experiments from two different application domains: the verification of a messaging middle- ware's configurations in a JMX environment and the verification of virtual machines' configurations in a CIM/WBEM (DMTF standards) environment. The results showed the feasibility of our approach and the framework's ability to support a flexible and adaptable online verification of configurations that can be integrated with existing management solutions
Shi, Jinshan. "Fabrication and characterization of InAlAs/InGaAs High Electron Mobility Transistors on plastic flexible substrate." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10150/document.
The development of future flexible electronics requires combining high electrical performance devices (i.e. millimeter and sub-millimeter wave electronic devices) with mechanical flexiblility and stability. However, a variety of existing technologies such as organic thin film transistors, amorphous silicon, and polycrystalline-silicon are limited by their poor transport properties. High electron mobility transistors (HEMTs) based on III-V materials have been used in the field of ultra-high frequency microwave applications for a long time. This work develops a feasible method for transferring conventional HEMTs onto the flexible substrate. By the means of adhesive bonding technique, 100nm-gate InAlAs/InGaAs HEMTs have been transferred onto polyimide film (Kapton) and electrically characterized in static and dynamic regime. Through the epitaxial layers optimization, finally, the fabricated devices are able to suppress Kink effect and provide high cut-off frequencies (ft=160GHz and fmax=290GHz) in unbent condition. These microwave characteristics are comparable to those obtained on 100nm-gate HEMTs on rigid substrate. Moreover, measured devices for various bending radius and bending directions show no obvious electrical degradation (lower than 15%)
Chajmowicz, Henri. "Modélisation et simulation numérique de structures articulées flexibles." Phd thesis, Marne-la-vallée, ENPC, 1996. http://pastel.archives-ouvertes.fr/pastel-00569038.
Picault, Elia. "Un modèle de poutre à section mince flexible - Application aux pliages 3D de mètres rubans." Phd thesis, Aix-Marseille Université, 2013. http://tel.archives-ouvertes.fr/tel-00921931.
Marone-Hitz, Pernelle. "Modélisation de structures spatiales déployées par des mètres ruban : vers un outil métier basé sur des modèles de poutre à section flexible et la méthode asymptotique numérique." Thesis, Ecole centrale de Marseille, 2014. http://www.theses.fr/2014ECDM0011/document.
Dimensions of spatial satellites tend to grow bigger and bigger, whereas the volume in launchers remains very limited. Deployable structures must be used to meet this contradiction. To expand the offer of possible solutions, the Research Department of Thales Alenia Space is currently studying tape springs as an innovative deployment solution. The first structure to be considered is a telescope that is deployed by the uncoiling of six tape springs that also ensure the positioning of the secondary mirror. Other deployable structures that use the properties of tape springs are under investigation : mast, solar panels,...Specific modeling tools then appear compulsory to model deployment scenarios and multiply the tested configurations. Two previous PhD thesis lead to the development of energetic rod models with flexible cross-sections that account for planar ([Guinot2011])and three dimensional behavior of tape springs ([Picault2014]). This PhD thesis presents several contributions on these rod models with flexible cross-sections. The hypotheses of the model were improved. Re-positioning the reference rod line so that it passes through the sections' centroids leads to results that are closer to experimental scenarios (creation and disappearance of folds in the spring). The hypotheses and equations of the model are now definitively formalized.We have derived the 1D local equations in the three-dimensional behavior case in the most generalist way. Then, the derivation of the equations in simplified cases (restriction to 2D behavior, shallow cross-section) enabled us to obtain several analytic solutions and the equations to implement in the specific modeling tool.We have developed on the continuation software ManLab the first elements towards a home made, efficient modeling tool dedicated to the modeling of tape springs. Two main contributions can be listed :- A generalist tool, efficient in calculus times, to study 1D differential problems (BVP, Boundary Value Problems). The local equations of the rod models with flexible cross sections were implemented in this tool, with a discretization based on polynomial interpolation and orthogonal collocation.- A specific finite element for rods with flexible cross sections and its implementation in ManLab.These elements enabled us to perform several numerical simulations and have a better understanding of the behavior of tape springs thanks to full bifurcation diagrams obtained for significant tests