Tesis sobre el tema "Optimisation multi-Matériaux"
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Montoya, Maxime. "Optimisation du perçage de multi-matériaux CFRP/Titane et/ou Aluminium". Thesis, Paris, ENSAM, 2013. http://www.theses.fr/2013ENAM0019/document.
The proposed research topic is a preliminary study to minimize costs of drilling operation in multi-materials stacks as CFRP/Al and CFRP/Ti. In order to minimize these costs, it is initially necessary to understand the cutting tools wear mechanisms and the phenomenon leading to the non-conformity of the drilled hole. In this way, drilling tests were carried out. The instrumentation of this tests allow to access to the cutting forces and to the temperature achieved during the cutting process.In association, analyses devices were used to monitored the holes quality. The cutting tools wear mechanisms were observed through scanning electron microscope. The access of the cutting edge profile, by the measures achieved on a numerical microscope, allows quantifying the tool wear.The temperature fields near the tool/chip interface influence significantly the tool life. They are difficult to reach by experimentation, but can be obtained using numerical simulation of the workpiece thermal solicitations. The model developed allow, by inverse method, to reach the hole wall temperature using the temperature reach at 4mm of it. The temperature field was obtained and the tendencies observed experimentally were confirmed by this model
Azina, Clio. "Optimisation de multi-matériaux à base de diamant pour la gestion thermique". Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0767/document.
Today, the microelectronics industry uses higher functioning frequencies in commercialized components. These frequencies result in higher functioning temperatures and, therefore, limit a component’s integrity and lifetime. Until now, heat-sink materials were composed of metals which exhibit high thermal conductivities (TC). However, these metals often induce large coefficient of thermal expansion (CTE) mismatches between the heat sink and the nonmetallic components of the device. Such differences in CTEs cause thermomechanical stresses at the interfaces and result in component failure after several on/off cycles.To overcome this issue, we suggest replacing the metallic heat sink materials with a heat-spreader (diamond film) deposited on metal matrix composites (MMCs), specifically, carbon-reinforced copper matrices (Cu/C) which exhibit optimized thermomechanical properties. However, proper transfer of properties in MMCs is often compromised by the absence of effective interfaces, especially in nonreactive systems such as Cu/C. Therefore, the creation of a chemical bond is ever more relevant. The goal of this research was to combine the exceptional properties of diamond by means of a thin film and the adaptive thermomechanical properties of MMCs. Carbon-reinforced copper matrix composites were synthesized using an innovative solid-liquid coexistent phase process to achieve designed composition gradients and optimized matrix/reinforcement interface properties. In addition, the lack of chemical affinitybetween Cu and C results in poor thermal efficiency of the composites. Therefore, alloying elements were inserted into the material to form carbide interphases at the Cu/C interface. Their addition enabled the composite’s integrity to be optimized in order to obtain thermally efficient assemblies. The diamond, in the form of a thin layer, was obtained by laser-assisted chemical vapor deposition. This process allowed action on the film’s phase purity and adhesion to the substrate material. Of particular importance was the influence of the interfaces on thermal properties both within the composite material (matrix-reinforcement interface) and within the diamond film-MMC assembly. This work was carried out within the framework of a Franco-American agreement between the Institute of Condensed Matter Chemistry of the University of Bordeaux in France and the Department of Electrical Engineering at the University of Nebraska-Lincoln, in the United States. Funding, in France, was provided by the Direction Générale de l’Armement (DGA), and by the American equivalent in the United States
Jallageas, Jérémy. "Optimisation du perçage de multi-matériaux sur unité de perçage automatique (UPA)". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00982328.
Djourachkovitch, Tristan. "Conception de matériaux micro-architecturés innovants : Application à l'optimisation topologique multi-échelle". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI086.
The design on innovative micro-architectured materials is a key issue of modern material science. One can find many examples of this kind of materials such as composites materials, foams, and even micro-architectured materials (materials which come along with some periodicity properties at the small scale). A common criterion for these materials is their ratio between weight and stiffness. Topology optimization is well suited for the design of this kind of material since the criterion that is subject to improvement is directly integrated in the formulation of the minimization problem. In this context, we propose some methods for the design of micro-architectured materials using topology optimization and for several criteria. We afterwards illustrate the benefits of these materials thought multi-scale simulations based on the theory of the first gradient and the scale separability assumption in the homogenization framework.A coupled macro/micro optimization method is presented for the concurrent optimization of the these two interdependent scales. The development of a numerical demonstrator has allowed to illustrated those various methods and to test several optimization criteria, mechanical models etcetera. In order to reduce the computational costs that might become exorbitant especially for multi-scale problems since the number of design variables increases significantly, a database approach is proposed. A broad range of micro-architectured materials is stored (and enhanced) for several criteria (weight, stiffness, original behaviour). This database is then consulted throughout the coupled optimization
Rey, Pierre-André. "Caractérisation et optimisation du perçage orbital du Ti6Al4V et d'empilages CFRP/Ti6Al4V". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30113/document.
The study presented in this thesis deals with the orbital drilling of Ti6Al4V titanium alloy and CFRP carbon fiber composite. This case study is taken from an industrial problem, from the Airbus company wishing to incorporate parts CFRP to reduce its mass. But the combination of these two materials with antagonistic properties poses many problems for drilling. This is why new alternatives to conventional drilling have been sought. Among these alternatives, orbital drilling with micro-lubrication showed interesting prospects. That is why it was chosen in this industrial application. But this process is still relatively unexplored and there is little feedback and many developments to achieve. Orbital drilling process is very different from the conventional axial bore. The bore is machined with a smaller diameter tool than the hole, which describes a helical path in the material. All work presented focus on the characterization for the optimization of the orbital drilling process. To achieve this, several aspects were discussed. First, a geometric modeling and kinematics of operation has been developed. The inclusion of the exact geometry of the tool and cutting conditions helped to define the geometry of the chip at every moment. This knowledge is important for understanding the achieved material removal mechanism, it allows to estimate the loading of the tool and the conditions in which machining is performed. From this first geometric modeling, modeling of cutting forces was established. For this, a model of mechanistic type of effort was used. Its application was adapted to orbital drilling in order to best represent the operation. The thus modeled efforts were compared to those observed experimentally in order to validate the proposed model. This allowed to consider the use of this model for a better understanding of this material removal process. The influence of model inputs, namely the cutting conditions and tool geometry was studied. Another contribution of this work is the characterization of the orbital drilling of CFRP stacks / Ti6Al4V. Indeed, many tests were developed to characterize the orbital drilling process. Experimental procedures have therefore been put in place. First of all, the instrumented test means had to be characterized so that it better corresponds to the means used by the manufacturer and above all it allows to carry out reliable and repeatable testing. The experimental design implemented subsequently helped to define the influence of cutting parameters on the efforts and realized diameters. In this phase of characterization, the bore in errors have also been studied. Thus, the trends have been observed. The results obtained in this work in the meeting helped to consider the process optimization of routes, through the control of advances, the drilling strategy, but also the geometry of the tool. Tracks have been proposed and are subject to further study. modeling implementation and the identification of phenomena occurring during the operation have also laid the foundation for process monitoring. This can be considered passively, to monitor the smooth running of the operation, but also actively to act in real time to the control of the process, based on identified phenomena, to ensure the desired quality
Sofi, Khadija. "Optimisation du générateur d'impulsions magnétiques et adaptation énergétique des machines pour les besoins d'assemblage innovants multi-matériaux". Electronic Thesis or Diss., Amiens, 2021. https://theses.hal.science/tel-03856084.
Magnetic pulse generators are being used more and more in multi-material forming and welding applications and produce a precise forming of metal parts. This PhD. thesis aims to calculate, using analytical methods, the magnetic field, the magnetic pressure, and the Lorentz force generated during electromagnetic forming of a metal tube. First, we propose to analyze the generator operation using a massive coil in interaction with a magnetic field shaper. Then, we develop the 3D models of these components using FEM and BEM methods in order to determine the evolution of the current and the temperature distributions. In this research work, we experimentally study the impact of the field shaper on the current pulse and then using a thermal camera we measure the temperature distribution in the massive coil. Afterwards, we calculate analytically the distribution of the magnetic field created around the coil based on the mutual inductance of two circular and coaxial coils. Finally, we develop an analytical and numerical study of a tube crimping by magnetic pulses. The used analytical method is based on the calculation of the self-inductance and the mutual inductance of the coil and the tube in 3D order to determine the Lorentz force and the magnetic pressure applied on the tube
Faure, Alexis. "Optimisation de forme de matériaux et structures architecturés par la méthode des lignes de niveaux avec prise en compte des interfaces graduées". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI047/document.
Shape optimization methods are promising methods and are gradually becoming industrialized. They provide the ability to automatically design structures with optimal behavior. They are outstanding tools for exploration and design of new materials.We use these methods to generate architectured multi-phased materials with prescribed thermoelastic properties. We first propose several solutions and we classify them by the mechanisms they rely on in order to control the effective properties. We also propose to evaluate the influence of an interface with a gradient of properties on the obtained architectures.Eventually we focus on the plausible manufacturing solution to produce our architectured materials. In this context, additive manufacturing methods (often considered as the support of an incoming industrial revolution) is our main option. We introduce several strategies to circumvent some limitations and side effects of these manufacturing methods during optimization process. We particularly focus on Fiber Deposition Molding, which induce an important mechanical anisotropy in processed parts. Then we consider the problem of overhangings features in design and propose a way to handle them prior to additive manufacturing using a mechanical criteria.Finally we take into account geometrical non linearities in optimization process. We highlight the pros and cons of this new modeling by presenting several applications of non linear actuators design
Alby, Delhia. "Matériaux innovants pour la rétention sélective de césium et de strontium à partir de solutions aqueuses multi-composants : synthèse, optimisation et évaluation des performances". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT168.
This work focuses on the synthesis and characterization of new nanostructured materials that can be potentially proposed as alternatives in the field of nuclear decontamination. The first part is devoted to the state of the art on the use of inorganic materials for decontamination purposes, with the emphasis placed on their sorption capacity and selectivity. The layer materials are considered as offering potential for such applications. In consequence, the main efforts in this work have been focused on manganate and vanadate nanostructures.Solvothermal synthesis of these materials was developed on the basis of micro-wave oven procedures to control the materials structuring, thus leading to vanadate nanotubes and manganate nanoflowers. The optimization of vanadates was carried out by taking into account the effect of various factors (e.g., duration of maturation and heating stages, nature and mass of the template) on both the structural and textural properties of the resulting substrates. It was demonstrated that the scrolling of the layers was strongly influenced by the amount of amine and its chemical structure. Indeed, only the amine templates possessing long chains allowed homogeneous nanotubes to be achieved. More information about the structuring process was inferred when coupling experimental and simulation approaches.The sorption performance of the resulting solid materials in terms of sorption capacity and selectivity was assessed in model and simulated systems obtained by using either ultrapure or river water with an adequate composition as solvent to prepare aqueous solutions of strontium or/and cesium. The results of sorption experiments clearly indicated strong selectivity of the vanadate structures toward Cs+ and that of the manganate ones toward Sr2+, even under conditions of competition among various ionic species.Direct calorimetry measurements of heat effects accompanying sorption were correlated with the results of molecular simulation studies to shed more light on the origin of the improved sorption selectivity
Da, Daicong. "Topological optimization of complex heterogeneous materials". Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1102/document.
Mechanical and physical properties of complex heterogeneous materials are determined on one hand by the composition of their constituents, but can on the other hand be drastically modified by their microstructural geometrical shape. Topology optimization aims at defining the optimal structural or material geometry with regards to specific objectives under mechanical constraints like equilibrium and boundary conditions. Recently, the development of 3D printing techniques and other additive manufacturing processes have made possible to manufacture directly the designed materials from a numerical file, opening routes for totally new designs. The main objectives of this thesis are to develop modeling and numerical tools to design new materials using topology optimization. More specifically, the following aspects are investigated. First, topology optimization in mono-scale structures is developed. We primarily present a new evolutionary topology optimization method for design of continuum structures with smoothed boundary representation and high robustness. In addition, we propose two topology optimization frameworks in design of material microstructures for extreme effective elastic modulus or negative Poisson's ratio. Next, multiscale topology optimization of heterogeneous materials is investigated. We firstly present a concurrent topological design framework of 2D and 3D macroscopic structures and the underlying three or more phases material microstructures. Then, multiscale topology optimization procedures are conducted not only for heterogeneous materials but also for mesoscopic structures in the context of non-separated scales. A filter-based nonlocal homogenization framework is adopted to take into account strain gradient. Finally, we investigate the use of topology optimization in the context of fracture resistance of heterogeneous structures and materials. We propose a first attempt for the extension of the phase field method to viscoelastic materials. In addition, Phase field methods for fracture able to take into account initiation, propagation and interactions of complex both matrix and interfacial micro cracks networks are adopted to optimally design the microstructures to improve the fracture resistance
Glé, Philippe. "Acoustique des Matériaux du Bâtiment à base de Fibres et Particules Végétales - Outils de Caractérisation, Modélisation et Optimisation". Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00923665.
Chibane, Hicham. "Contribution à l'optimisation multi-objectif des paramètres de coupe en usinage et apport de l 'analyse vibratoire : application aux matériaux métalliques et composites". Thesis, Tours, 2013. http://www.theses.fr/2013TOUR4053/document.
Manufacturing processes of mechanical parts by removal of material (turning, milling, drilling ...) have extensive use in aeronautic and automobile industry. The components obtained using these methods must satisfy geometric properties, metallurgical and quality characteristics. To meet these requirements, several experimental tests based on the selection of cutting conditions are often necessary before manufacturing. Currently, these empirical methods based on the experience of manufacturers and users of cutting tools (charts, diagrams with experimental findings, ...) are often very lengthy and costly. However, the high cost of a trial limits the number of experiments, so to have a deserted component with an acceptable cost is a difficult task. The importance of cutting conditions monitored by limitations is related to the type of material to be machined, since it determines the behavior of the machining
Vo, Dong Phuong Anh. "Multi-objective optimization for ecodesign of aerospace CFRP waste supply chains". Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19911/1/VODONG_PhuongAnh.pdf.
Cherrière, Théodore. "Élaboration de méthodes et d'outils logiciels pour l'optimisation topologique magnéto-mécanique de machines électriques tournantes". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST159.
In the context of energy transition and the electrification of applications, improving the performance of electromagnetic actuators inevitably involves dimensioning optimization processes. Such methodologies have already been implemented but focus mainly on previously parameterized geometries, which limits the space of possibilities. This thesis aims to develop an efficient topological optimization methodology capable of optimizing the distribution of materials (iron, air, conductors, magnets) required to generate a synchronous machine in its entirety without parameterizing its geometry. To this end, a multi-material density topological optimization methodology has been developed. Its application to optimizing a three-phase stator highlights the importance of penalization, filtering, and control processes in the optimization algorithm. The procedure is then extended to the design of an entire machine: although efficient, the best structures obtained include flux barriers with no mechanical strength. After incorporating rotor stiffness constraints, the method produces high-performance, related structures in a reasonable computation time, demonstrating the relevance of this type of approach to the design of electromagnetic actuators. Eventually, integrating all the physics involved in specifications right from the preliminary phases will save time and money in designing innovative electrical machines
Pinson, Sébastien. "Matériaux architecturés pour refroidissement par transpiration : application aux chambres de combustion". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI089/document.
In order to cool aero-engine combustion chambers as efficiently as possible, there is today a special interest given to transpiration cooling technology. The cooling air flows through a porous liner in which a large amount of heat can be exchanged by convection. The air injection could then take benefit of the pore distribution to form a more homogeneous protective boundary layer.Partially sintered metallic materials are potential candidates to form these porous liners. The present work focuses on internal heat transfers. It aims to develop a methodology capable of highlighting the most adapted partially sintered architectures to this kind of application.During transpiration cooling, flows and heat transfers are governed by some effective material properties which depends on the porous architecture: the effective solid phase thermal conductivity, the volumetric heat transfer coefficient and the permeability properties. Thanks to experimental works and numerical studies on samples digitized by X-ray tomography, simple relationships are first developed between the effective material properties of partially sintered materials and their architectural parameters. The porosity, the specific surface area and the powder type are selected to predict the effective properties.These relationships are finally integrated into a heat transfer model predicting the thermal performance of a design at working engine conditions. A multi-objective optimization and an analysis of the optimal designs highlight some architectures as being potentially interesting for transpiration cooling. Materials with a low porosity and made of large irregular powders seem to ensure the best trade-off among the different criteria taken into consideration
Ma, Xiaoyan. "Expérience et étude numérique sur la dynamique de transfert d'humidité dans les matériaux cimentaires poreux à plusieurs échelles". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASN025.
Climate change in the last decades is hugely influenced by humans activities including the emission of greenhouse gases. In the construction field, cement production contributes to about eight percent of the world's carbon dioxide emissions, due to the fact that concrete is the most widely used manufactured material in existence. Therefore, the sustainability of concrete and the durability of their structures have significant concerns about global energy consumption and worldwide environmental impact. Research results showed that the structural behavior of concrete is closely related to the variation of water level in concretes and the loss of free water may induce a modification of its elastic properties, strengths, shrinkage, or creep deformations. Thus, the knowledge of the hydric state of concrete is of utmost importance regarding the mechanical behavior and durability potential of concrete structures. From a microstructure perspective, the property of moisture transfer is a manifestation of the internal pore structures. Therefore, it is also important to acquire the knowledge of the pore networks and the pore size distribution over a large range of the material. In this thesis work, we focus on the moisture-transferring mechanisms in concrete, by the combination of the experimental and numerical approach. From the perspective of the drying model and the multi-scale structure of the concrete, we performed the test of drying, imbibition, and drying-imbibition cycling in different geometries of concrete for over 200 days, obtaining the global mass variation and local inner humidity data. The moisture-transferring model contains two major mechanisms: liquid water permeation and water vapor diffusion. Based on the present model and the experimental results obtained, the simulation results of mass loss and relative humidity is calculated in CAST3M, and identification produce of parameters in the model is performed in an optimization program coupled with Matlab. A numerical-experiment-identification coupling method is adopted to simulate drying phenomenon, and the results provide a practical approach in following the moisture transfer process of concrete. Following the parameters optimization, the hypothesis in the moisture-transferring model are discussed as well. The analysis includes the assumptions that are proposed in the model; a simplified analytic solution with the hypothesis of linear coefficient; and the moisture transfer pattern in the model, namely if the two phases (liquid and vapor) of water interact in a parallel, series or combination style, how this influences the humidity profile and mass evolution. The last part of the work is multiple approaches to investigate the inner structure of concrete material, including mercury intrusion porosimetry method (MIP), computational X-Ray tomography, and focused ion beam scanning electron microscope (FIB-SEM). By adopting these three techniques, we obtain the pore size distribution that covers a large range from tens of nanometers to few millimeters. In addition, the 3D volumetric bubble visualization is reconstructed from of X-Rray tomography results
Tonnelier, Gilles. "Contribution à la conception et à l'optimisation multi-physique de batterie mécaniques pour les applications mobiles". Thesis, Besançon, 2011. http://www.theses.fr/2011BESA2048.
To improve its tram offer, ALSTOM Transport has decided to develop a mechanical batterythat provides energy of a vehicle between two stations. But even if the flywheels are essentiallydevelopped since the 1950s for mobile applications, none of them is designed to ensure 100%of energy for mobile applications. The battery must be light, weigh as little as possible, besafe and respect the specifications.Following a bibliographic data analysis, we undertook to develop a method of pre-sizingmechanical battery by taking into account interactions between different major organs, whereaspreviously, methods were concentrated on developing mechanical batteries part by part.For this, we developed an integrated design tool that takes into account the energy (energyand power), mechanic (strength of materials, rotor dynamics), electromagnetic (electric motor)and geometric (template integration, creation of volumes). We also develop a method forselecting the right materials for flywheels, from which we have compiled a list of relevantmaterials.We have shown that the integrated design is more efficient in terms of integration andbalance between the mechanical and electromagnetic.We also showed that composite materialsare not necessarily the best design choices and materials such as high performance steels areexcellent candidates according to the study area of interest (the threshold being the criticalrotational speed 30000 rpm). We have shown that it is possible to achieve stable areas ofoperation, although it will probably be inevitable to pass critical speeds at startup. The designmethod we developed ensures that the only modes excited are the dynamic modes of bearings,which can be treaten quite easily. It can also represent the system configuration, make a staticstress analysis, study the dynamic phenomena of a mechanical battery, and finally, this methodallows an overall system optimization by the Kohonen method.The results are significant because the systematic method we developed can be applied toevery cases. It helps to know what materials to choose, the configuration you want, presentsgraphically the results of behavioral systems studied and brings a knowledge of the systemunder development. This allows us to anticipate potential changes in design. It is therefore atool for understanding and making during the design process.The scientific path that we have taken is the one advocated by Professor Giancarlo Genta,Italian specialist in the field, at the end of his own studies. This evolutionary approach hasled to increased knowledge of batteries and better mechanical design.Keywords
Guenfoud, Nassardin. "On the multi-scale vibroacoustic behavior of multi-layer core topology systems". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEC010.
In this last decades, honeycomb sandwich panels have been the subject of intensive researches. Indeed, their high mechanical performances combined to a low stiffness to weight ratio result in a reduced acoustic efficiency. Therefore, many designs are usually proposed to overcome this issue. Besides, different methods are developed to model more complex structures using the periodic structure theory to study the wave propagation allowing to investigate the vibroacoustic parameters. The main purpose of this thesis is to investigate the vibroacoustic multi-scale behavior of multi-layer core topology systems which consist on stacking layers of honeycomb cores leading to an impedance mismatch between layers. In addition, such structures allow to increase the design space up to now limited to standard sandwich panels made of a single honeycomb core. Therefore, it is possible to obtain many configurations keeping the mass constant with simple shifting process between layers. A parametric model is proposed allowing to extract the unit cell through the thickness of the panel and to apply the periodic structure theory. Modelling multi-layer core topology systems has been performed using the wave finite element method, and an extended method has been proposed to solve the acoustic transmission problem. The study is focused on transition frequencies, the sound transmission loss as well as veering effects and internal resonances, to finally optimize the geometrical parameters and to analyze their influence on the acoustical and mechanical performances of the structure. Although the out-of-plane compression properties of multi-layer core topology systems are reduced, it is possible to strongly improve the in-plane compression properties. These later are studied by comparing a multi-layer hexagonal core and a standard single hexagonal core. Finally, using multi-layer core topology systems and a perforated upper skin, it is possible to increase the energy dissipation occurring inside the core and thus, improve the sound absorption coefficient. Therefore, the thermo-viscous effect is considered. The acoustic behavior is similar to porous media and the Johnson-Champoux-Allard parameters are retrieved to characterize the acoustic fluid flow.An improvement of the sound transmission loss and the sound absorption coefficient is obtained in a broadband frequency and the obtained resonance frequencies can be modified. However, this leads to lower mechanical properties especially the compression modulus and the dynamic rigidity
Akiki, Paul. "Conception multi-physique de machines électriques à flux radial et axial pour des applications à entraînement direct". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC055/document.
The work presented in this thesis deals with the modeling and optimization of electrical machines for direct drive applications. The objective is to reduce the use of rare earth permanent magnets along with the improvement of the motor’s efficiency. A state of the art of electrical machines is realized. It focused on radial and axial flow structures for high torque and low speed applications. A classification is established to identify interesting and innovative structures. Firstly, the radial machine is studied. The choice of the structure is made after a finite element comparison of different machines resulting from the literature. This led to an original structure with concentrated winding and multi-V shape barriers. Then, a multi-physics analytical modeling of the structure is detailed in order to calculate the performances with a reduced calculation time. A preliminary design led to the definition of a prototype which was used to experimentally validate the multi-physics model. An optimization design approach is adopted to obtain optimal machines meeting industrial specifications. Secondly, a novel axial flux structure is studied. It is a machine with double rotor and single stator with several barriers per pole. A finite element study is carried out in order to validate the transition from a three dimensional to a two-dimensional model. The analysis of iron losses made it possible to choose the materials used in the stator and the rotors. Then, the development of a multi-physics analytical model for the axial machine is proposed. It is used to optimize the structure according to the same specifications defined for the radial machine. Finally, a comparison between the radial and axial structures is performed in order to evaluate the advantages in terms of torque density
Ejday, Mohsen. "Optimisation multi-objectifs à base de métamodèle pour les procédés de mise en forme". Paris, ENMP, 2011. http://pastel.archives-ouvertes.fr/pastel-00583805.
Cost saving and product improvement have always been important goals in the metal forming industry. To achieve them, metal forming processes need to be optimized, which consequently requires solving optimization problems. Usually these problems have multiple objectives; they aim at minimizing several objective functions in the presence of several explicit and implicit constraints. Each function evaluation is quite time consuming. To solve this type of problems, a robust and efficient algorithm is developed. It consists in coupling an evolutionary algorithm (a multi-objective genetic algorithm) with a metamodel (an approximation of the problem functions). Then, the number of expensive function evaluations can be significantly reduced by partly replacing exact evaluations with fast approximates of the objective functions. In this report, we first present the multi-objective optimization problem, multi-objective optimization (evolutionary) algorithms and the most commonly used metamodels (Chapter I). We select the elitist non-dominated sorting genetic algorithm (NSGA-II) to be coupled with the metamodel based on the meshless finite difference method. This metamodel, which is presented and enhanced within this thesis, is presented in Chapter II. In Chapter III, different coupling strategies between NSGA-II and the metamodel are investigated, C-Constant, C-Actualise, C-Updated-H1 and C-Updated-MC. The different studied methods differ in the choice of master points (the exact evaluations of the objective functions), the evolution of the metamodel, and the utilized approximation error. They are studied and compared on several analytical functions, mono-objective functions, multi-objective functions and constrained functions. The best method, C-Updated-MC, is then used to optimize metal forming processes in Chapter IV. The obtained results show the efficiency of our method
Devos, Guillaume. "Approche multi-physique pour l’optimisation du dimensionnement des composants passifs dans les convertisseurs électroniques de puissance aéronautiques". Thesis, université Paris-Saclay, 2022. http://www.theses.fr/2022UPAST031.
The growing electrification of aircrafts required for the development of more electrical aircrafts needs new methodologies for the design of embedded electronic components.This thesis fits into this framework, proposing a new methodology for the optimal design of inductors. Firstly, we defined specifications for a smoothing inductor located at the output of a Buck DC/DC converter. Then we developed a simple presizing process. Using only analytical formulations, it gave us a first bunch of geometries relatively close to the optimal solutions. It allowed us to initialize our optimization algorithm.A differential evolution stochastic algorithm is executed with an analytical model of the inductor. It attempts to reduce both the weight of the component and its losses. The solutions we obtained are used to initialize a second algorithm execution. Two possible meta-models can be used to take into account magnetic and electrical losses. The first one uses a simple model for the characterization of magnetic losses. Electrical losses are determined with finite element analysis. The use of an artificial neural network allows a reduction of the number of needed analysis. Current is supposed to be perfectly triangular. Thus, three networks have been built. The first one is dedicated to the fundamental frequency. The other two are dedicated to the 3rd and 5th harmonic. The second meta-model uses a characterization of ferromagnetic hysteresis. Such a model allows an estimation of both magnetic losses and real shape of the current. Knowing the real current flowing through the inductor, we can estimate more precisely the value of electrical losses.The model for the characterization of ferromagnetic hysteresis does not provide sufficiently precise results. Optimization results obtained with the first meta-model are presented and discussed
Akkaoui, Abdessamad. "Bétons de granulats de bois : étude expérimentale et théorique des propriétés thermo-hydro-mécaniques par des approches multi-échelles". Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1169/document.
Environmentally-friendly concretes, made up of plant-based particles and mineral or organic binder, are solutions worth exploring to reduce the environmental impact of buildings. Mainly used for their thermal performance, these materials have aroused interest of many research organisations and industrial companies. Their widespread use in construction is not possible without resolving some technical problems related to their implementation, certification and durability. This work aims to contribute to characterize these complex materials, in particular to study the mechanical, thermal and hydromechanical behaviors of wood-aggregate concrete. Modeling and experiments have been used to understand the complex mechanisms involved. The Young's modulus and the compressive strength were experimentally measured using digital image correlation. The evolution of these properties depends on the conditions of storage, the drying time and the cement content. Because of the random orientation of the wood aggregates, the material exhibits isotropic behavior. A homogenization model based on a self-consistent scheme was developed to predict the Young's modulus. The results were satisfactory. Measurements show that thermal conductivity remains constant under sealed conditions. The modeling of this property with the self-consistent scheme gives results consistent with experimental measurements. In desiccation conditions, the thermal conductivity depends linearly on the density of concrete. The evolution of the thermal conductivity of the wood aggregates and the cement paste during drying was modeled with the Mori-Tanaka scheme. These evolutions were integrated into the self-consistent model, which yielded satisfactory results, but could be improved if sorption/desorption curves of the phases were available. The macroscopic dimensional variations of the wood-aggregate concretes depended on the storage conditions, but not on the measurement direction, nor on the cement content. A model based on the combination of the strains induced by the desorption of water from the phases and the moisture transfer between them was proposed. It allowed us to capture the trends of the strains of our concrete except at early age. At a local scale, the study showed that the strains of concrete were close to those of the cement paste. The study also shed light on a significant damage of the aggregate/binder interfaces, which would deserve to be taken into account into the modeling
Gobé, Alexis. "Méthodes Galerkin discontinues pour la simulation de problèmes multiéchelles en nanophotonique et applications au piégeage de la lumière dans des cellules solaires". Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4011.
The objective of this thesis is the numerical study of light trapping in nanostructured solar cells. Climate change has become a major issue requiring a short-term energy transition. In this context, solar energy seems to be an ideal energy source. This resource is both globally scalable and environmentally friendly. In order to maximize its penetration, it is needed to increase the amount of light absorbed and reduce the costs associated with cell design. Light trapping is a strategy that achieves both of these objectives. The principle is to use nanometric textures to focus the light in the absorbing semiconductor layers. In this work, the Discontinuous Galerkin Time-Domain (DGTD) method is introduced. Two major methodological developments are presented, allowing to better take into account the characteristics of solar cells. First, the use of a local approximation order is proposed, based on a particular order distribution strategy. The second development is the use of hybrid meshes mixing structured hexahedral and unstructured tetrahedral elements. Realistic cases of solar cells from the literature and collaborations with physicists in the field of photovoltaics illustrate the contribution of these developments. A case of inverse optimization of a diffraction grating in a solar cell is also presented by coupling the numerical solver with a Bayesian optimization algorithm. In addition, an in-depth study of the solver's performance has also been carried out with methodological modifications to counter load balancing problems. Finally, a more prospective method, the Multiscale Hybrid-Mixed method (MHM) specialized in solving very highly multiscale problems is introduced. A multiscale time scheme is presented and its stability is proven
Fontecha, Dulcey Gilberto. "Modèle paramétrique, réduit et multi-échelle pour l’optimisation interactive de structures composites". Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0247/document.
The design process of laminated composites faces a major challenge: while an engineer designing a metallic based mechanical product is mainly focusing on the development of a shape that will guarantee a specific behavior, the engineer designing a composite based product must find the best combination of the shape-material structure. Therefore, he must simultaneously create a material and the product topology. The number of design solutions can be huge since the solution space is considerable.Standard CAE systems (CAD, Finite Element Simulation) do not provide an approach to explore these solution spaces efficiently and interactively. A new numerical procedure is proposed to allow engineers to handle each design parameter of a laminated composite structure, each at its relevant scale.First, the Parametric and Reduced Behavior Model (PRBM) is a separated model that enables reasoning based on1- A multiscale approach: the mechanical parameters of the structure are explicitly described as coming from the material quality of each fiber, the matrix, each layer and the topology of the laminate,2- A multiphysical approach: independently the mechanical behavior of each layer and each interface is processed, leading to the behavior of the laminate. Some situations of static and dynamic behavior are studied. In the case of dynamic behavior, the creeping becomes a conceptual issue.Secondly, a method mixing fractional derivatives and the Proper Generalized Decomposition (PGD) method allowed the creation of the PRBM. Integrated into a Parametric Knowledge Model (PKM) with other expert knowledge models, the PRBM makes the basis of an interactive method of design support.The PKM is processed by an evolutionary optimization method. As a result, the designer can interactively explore the design space. To qualify our models and our PRBM, we study two problems of design of laminated composite structures. The solutions determined are qualified versus finite element simulations or according to an empirical approach
El diseño de una estructura compuesta es un desafío mayor, mientras que un ingeniero que diseña un producto mecánico con materiales metálicos se concentra principalmente en el desarrollo de una geometría que garantice un comportamiento específico, el ingeniero que diseña un producto con materiales compuestos debe encontrar la mejor combinación forma – estructura del material. De esta manera, el ingeniero debe diseñar simultáneamente el material y la topología del producto, razón por la que esta combinación se vislumbra compleja, puesto que los espacios de solución son gran tamaño.Las herramientas CAO y de simulación por elementos finitos no ofrecen al diseñador una metodología que permita explorar los espacios de solución de manera interactiva y rápida. Por lo tanto, este trabajo de tesis propone un nuevo enfoque numérico que permite manipular parámetros de diseño que caracterizan la estructura compuesta, cualquiera que sea la escala de pertinencia.Como primera medida, el modelo de comportamiento paramétrico y reducido (Parametric and Reduced Behavior Model, PRBM) es un modelo definido de manera separada que permite:1- Un enfoque multiescala: los parámetros mecánicos se presentan de manera explícita en términos de las propiedades de cada fibra, de la matriz, de cada capa y de la topología del mismo apilamiento.2- Un enfoque multifísico: el comportamiento mecánico de cada capa y cada interface se modela de manera independiente para dar lugar al comportamiento del apilamiento. Se estudian situaciones de casos de comportamiento estático y dinámico. En el caso dinámico en particular, se tiene en cuenta también la característica viscoelástica de las interfaces.Como segunda medida, un método que combina derivadas no enteras y el uso de la descomposición propia generalizada (PGD), permite la realización del PRBM. Este constituye la base de un método interactivo de ayuda al diseño, pues está integrado dentro de un modelo de conocimiento (PKM) que también incorpora mejores prácticas aprendidas por expertos.El PKM es utilizado por un método de optimización evolucionaria. De esta manera, el diseñador puede explorar de manera interactiva los espacios de solución. Para validar nuestros modelos y el PRBM, se estudian dos problemas de diseño de estructuras apiladas. Las soluciones obtenidas se comparan con respecto a simulaciones obtenidas por el método de los elementos finitos y con respecto a resultados experimentales
MONTOYA, Maxime. "Optimisation du perçage de multi-matériaux CFRP/Titane et/ou Aluminium". Phd thesis, 2013. http://pastel.archives-ouvertes.fr/pastel-00936176.