Дисертації з теми "Modélisations analytiques"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Modélisations analytiques".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Bouley, Simon. "Modélisations analytiques du bruit tonal d'interaction rotor/ stator par la technique de raccordement modal." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC007/document.
The rotor-stator wake-interaction tonal noise, generated by the impingement of rotor wakes onoutlet guide vanes, plays a crucial role in the aerodynamic noise of axial-flow ducted fan stages. Thelatter are widely used in most aeronautic propulsion and air-conditioning systems. The noise predictionby means of numerical simulations remains expensive, especially at the preliminary design stage whennumerous configurations must be tested. In this respect, the analytical approach chosen in this thesisprovides a well suited alternative. The analytical modeling based on an isolated-airfoil response functioncan not reproduce the cascade effect introduced by the large number of stator vanes. Conversely, drasticapproximations are required to extend the current cascade response functions to three-dimensionalconfigurations. The proposed modeling based on the mode-matching technique simply introduces thecascade effect in an annular rotor-stator stage. A rectilinear cascade response function is firstly presentedto account for the acoustic transmission through the stator along with the wake-interaction noise.In this context, a linearized and non-viscous analysis is carried out, in which the acoustic and vorticalmodes of a gas are coupled at rigid physical boundaries. The velocity perturbations issued from thewakes are written as a sum of convected gusts. Their impingement on the cascade of vanes generatesacoustic waves propagating upstream, downstream of the cascade, as well as inside the inter-vane channelsof the stator, seen as a periodic array of bifurcated waveguides. The duct cross sections at theleading-edge and the trailing-edge of the vanes are seen as interfaces on which the continuity of thefluctuating pressure, axial velocity and vorticity is fulfilled. A system of linear equations is obtained,then solved by means of modal projections and matrix inversions. The acoustic field is then uniformlycalculated in the whole domain. Comparisons with rectilinear cascade response functions show a verygood agreement with predictions based on the Wiener-Hopf technique. The configuration of an annularcascade is addressed by introducing the Bessel functions as radial shape functions, expressing threedimensionaleffects. Finally, a procedure is presented to account for the heterogeneity of the statorvanes, typical of modern fan architectures. This approach is based on the combinaison of the leadingedgedipole principle and the cascade response function derived from the mode-matching technique.The edge-dipole principle identifies Amiet’s solution for the unsteady loading and the radiation of adipole approached very close to the edge of a half plane. The predictions provided by this modeling,applied in a two-dimensional configuration, are finaly compared to measurements performed in the testcampaign of the SEMAFOR project
Rabat, Amélie. "Modélisations analytiques ILCM d'enceintes résonantes munies d'ouvertures de formes complexes. Application au couplage avec des lignes de transmission." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC092.
This PhD work is dedicated to shielding boxes modeling. Those shielding enclosure usually contains apertures, that are essential for cable cross or, for ventilation. They are commonly used to protect sensitive equipment from external radiated disruptions. Then, the capacity of a metallic shield to correctly limit parasitic interference and coupling is crucial to know for EMC designers. This coupling problem is particularly widespread in EMC domain that engineers have to anticipate. Several simulation tools are available to compute and analyze these electromagnetic problems. However, full wave numerical methods remains computationally intensive and take several hours to reach a solution. Analytical formulations may provide an attractive alternative using a far smaller computation time with a great accuracy, as ILCM models. Based on the transmission line theory, this technique is able to reproduce the electromagnetic cavity behavior and its apertures by means of a circuital approach. In fact, ILCM models considerably simplify the original problem by providing a simple equivalent circuit représentation of the electromagnetic problem. Our analysis deals with a fast, reliable and simple analytical formulation, in order to develop an helpful tool for shielding boxes design. In this document, we describe four improvements of the original model. These improvements have been made to renforce the initial formulation of Martin Paul Robinson, the method's pioneer, giving a more realistic description of the problem. However, our models focus predominantly on empty electromagnetic cavities containing apertures. Then, they constitutes an interesting intermediate step to model realistic shielding enclosures. The analytical ILCM approach has been validated for several configurations exemples, demonstrating the method potential
Druon, Yann. "Etude de la propagation guidée et du rayonnement acoustiques par les conduits d'éjection de turboréacteur : Modélisations analytiques et numériques." Ecully, Ecole centrale de Lyon, 2006. http://www.theses.fr/2006ECDL0002.
This work deals with the modeling of the acoustic propagation inside turbofan exhaust ducts and the corresponding radiation to the outside. The main objectives are, first, to develop analytical methods, enabling fast and flexible simulations of the problem, and second, to assess the relevance of different numerical methods, now indispensable to account for more realistic geometries and aerodynamic conditions. The study is performed following a progressive process, beginning with simplified configurations to integrate the elements of physical complexity one by one (presence of acoustic liners, realistic geometry, uniform and non-uniform mean flows…). At each stage, the results of the different methods are compared and the influence of the principal parameters is analyzed. The reference solution is given here by an analytical method based on the modal theory for annular ducts with constant cross section. The far field radiation is calculated, in the case of a hub truncated at the exit plane, using the flanged duct approximation, and for an infinite hub, with the aid of the Wiener-Hopf technique. In this last model, the possibility of vortex shedding from the duct trailing edge is included by application (or not) of a Kutta condition. At low frequency, and in the absence of mean flow, the Boundary and the Finite Element Methods (BEM and FEM) give the same results. The comparisons with measurements are also very good, confirming the relevance of the theoretical models. In the presence of a uniform mean flow, the BEM and the FEM respectively tend to the analytical solutions obtained with and without the Kutta condition imposed at the edge. The particular behavior associated to each method is thought to be related to the acoustic variable considered in the codes, i. E. Acoustic pressure or potential. At high frequency, the results of the Gaussian Beam Summation approach are found to be unsatisfactory, probably because of the absence of any diffraction model in the current code formulation. Several geometrical factors influence the acoustic propagation in the secondary exhaust duct (By-Pass). The most critical point lies in the presence of two bifurcations that induce modal redistributions increasing with the rotation of the incident wave inside the duct. An analytical model for sound propagation in a bifurcated duct is presented and validated by comparison with BEM results. Outside the ducts, the influence of the pylon and the after-body real geometry on the radiation to the ground seems to be more limited. Conversely, the effect of shear layers generated at the duct trailing edges is significant. In spite of theoretical restrictions, the waves refraction due to flow mismatches across a vortex sheet (Munt’s model) seems to be relatively well predicted by the FEM potential formulation. The impact of density or temperature gradients, however, is not well reproduced
Antoinat, Léonard. "Contribution à la caractérisation de la déformation et de la rupture dynamique de structures sous impact : Modélisations et approche expérimentale." Thesis, Paris, ENSAM, 2014. http://www.theses.fr/2014ENAM0037/document.
The objective of this work is to propose approaches to model and to assess experimentally the structural impact on different media. A variety of analytic models and numerical simulations are developed comparing to experimental results. The first part of this work presents a discussion on the similitude between a water impact and an impact on a deformable solid structure. Water impact simulations of a deformable cylinder (without rupture) are performed by finite elements (FE, Coupled Eulerian Lagrangian) and SPH analysis. An analytical model of water impact is proposed for the prediction of peak force evolution. The analysis of results permits to design an impact programmer reproducing this peak force. FE longitudinal impact simulations on cylindrical tubes, with an adapted geometry, are performed and compared with some experiments. The “dynamic buckling” of tubes under impact (due to the material inelastic behavior and to strain waves) is observed. The second part deals with the low velocity perforation (< 10 m/s, strain rate < 1000 s-1) of thin plates. Some experiments on an instrumented drop test (force, displacement, plate shape, crack propagation) are analyzed. Shell FE simulations, with a damage rupture criteria implemented are performed. Parameters are identified by inverse method with the help of Charpy tests made on 2024 T3 aluminum alloy. An analysis of the peak force, during impact, leads to a good understanding of the perforation mechanism. In parallel, a new analytical model, based on an energetic approach of the perforation, is proposed and compared with FE simulations. The numerical perforation study is extended to high velocities and high strain rates (100 - 1000m/s, strain rate < 100 000 s-1) in order to identify different well-known transitions of perforation (Petalisation, petals' fragmentation, total plate's fragmentation)
Amado, Toni. "Modélisation d'un système dynamique à jeu du groupe moto-propulseur." Ecully, Ecole centrale de Lyon, 2006. http://www.theses.fr/2006ECDL0007.
In this document, we have studied the diesel engine vacuum pump drive non linear dynamics. The involved double-sided contact is represented by a classical torsion stiffness and a viscous torsion damping. The piecewise linear motion equation obtained is solved by a semi analytical method. A continuation technique, based on a semi analytical shooting method, is used to describe periodic orbits and their bifurcations. The chaotic behaviour is revealed by the computed Lyaopunov exponents and Poincaré applications. Finally, an experiment idealizing the vacuum pump system has been performed. Experimental and computed results will be confronted to validate the model and the analysis procedure
Allard, Antoine. "Percolation sur graphes aléatoires - modélisation et description analytique -." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30822/30822.pdf.
Graphs are abstract mathematical objects used to model the interactions between the elements of complex systems. Their use is motivated by the fact that there exists a fundamental relationship between the structure of these interactions and the macroscopic properties of these systems. The structure of these graphs is analyzed within the paradigm of percolation theory whose tools and concepts contribute to a better understanding of the conditions for which these emergent properties appear. The underlying interactions of a wide variety of complex systems share many universal structural properties, and including these properties in a unified theoretical framework is one of the main challenges of the science of complex systems. Capitalizing on a multitype approach, a simple yet powerful idea, we have unified the models of percolation on random graphs published to this day in a single framework, hence yielding the most general and realistic framework to date. More than a mere compilation, this framework significantly increases the structural complexity of the graphs that can now be mathematically handled, and, as such, opens the way to many new research opportunities. We illustrate this assertion by using our framework to validate hypotheses hinted at by empirical results. First, we investigate how the network structure of some complex systems (e.g., power grids, social networks) enhances our ability to monitor them, and ultimately to control them. Second, we test the hypothesis that the “k-core” decomposition can act as an effective structure of graphs extracted from real complex systems. Third, we use our framework to identify the conditions for which a new immunization strategy against infectious diseases is optimal.
Kibbou, El Mehdi. "Contribution à la modélisation thermomécanique des vibrations en coupe oblique et à l'établissement d'un plan optimal de maintenance intégré à la production tenant compte des conditions d'usinage." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0234.
In this study, we are interested in a machining production system which is one of the manufacturing processes most adopted by the various mechanical industries (automotive, aviation…etc.). The objective of this multidisciplinary thesis (Mechanics and Industrial Engineering) is double: (1) the development of a new thermomechanical model of oblique cutting in dry machining and (2) the maximization of profit in order to establish a strategy production and a preventive maintenance plan.The coupling between the machining operation and the part "simultaneous optimization of production and maintenance costs" is done by considering the effect of cutting conditions on the generated surface quality and on the tool wear. In the proposed approach, wear is taken into account through Taylor's empirical law and the machined surface quality is predicted via a new model of vibrations in oblique cutting.The first objective of this work concerns the development of a new thermomechanical model of the oblique cutting with vibration. In this analytical cutting model, the vibratory system is assimilated to a system with a single degree of freedom in the tool feed direction. We take into account the coupling between tool oscillations, the thermomechanical process of chip formation as well as the regenerative effect. The latter results from the variation in the material quantity to be machined between two successive passes. The coupling between all of these mechanisms makes the problem to be solved strongly nonlinear. A resolution algorithm making it possible to reduce the computation time has been implemented.The second objective of the thesis is achieved through the development of an analytical model where the optimization consists in maximizing a profit integrating selling price of finished product, production and maintenance costs. We note the originality of this part consists in considering the impact of the machining conditions, especially the cutting speed, on the production durations and costs, the quality of the machined parts as well as the degradation of the production system. The impact of machining conditions on three fundamental aspects is therefore considered simultaneously for the "simultaneous optimization of production and maintenance costs" part. The first concerns the impact of machining conditions on production time and costs. The second concerns the impact on the degradation of the machining system and therefore on the optimal maintenance plan to be adopted. The third concerns the impact on the quality of the output product which directly affects the selling costs and more specifically the total profit. These interactions are taken into account through the development of an analytical model to establish an optimal integrated production maintenance plan for the machining system, illustrated by the optimal switching date for changing cutting speed and the optimal numbers of batches to produce before every preventive maintenance action for every production phase. Every production phase is characterized by a cutting speed
Hallal, Ali. "Modélisation analytique généralisée des propriétés élastiques des composites textiles." Versailles-St Quentin en Yvelines, 2013. http://www.theses.fr/2013VERS0004.
The use of textile composites has increased recently in advanced industries to replace traditional composites and laminates. The prediction of elastic properties of textile composites presents an important step to understand the mechanical behavior of these materials. The objective of this thesis is to propose a reliable analytical model benefits from analytical methods advantageous against numerical methods. The proposed generalized model has been applied to all kinds of textile composites, where it yields very good results especially for the Young's modulus and shear plane. The thesis consists is a thesis by articles/publications. The thesis consists of eight chapters: Coordinating chapter, six chapters correspond to six publications and a general conclusion
Kabagire, K. Daddy. "Modélisation expérimentale et analytique des propriétés rhéologiques des bétons autoplaçants." Thèse, Université de Sherbrooke, 2018. http://hdl.handle.net/11143/11635.
Ghoreishi, Seyed. "Modélisation analytique et caractérisation expérimentale du comportement de câbles synthétiques." Nantes, 2005. http://www.theses.fr/2005NANT2048.
Avevor, Yao Venunye. "Effets thermomécaniques en usinage à sec : une modélisation analytique-numérique." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0112/document.
In dry machining, the thermomechanical process of chip formation, the tool wear and the surface integrity depend strongly on the tribological conditions along the tool rake face. Besides, the friction conditions at the tool-chip interface and along the round cutting edge are very complex. It should be noted that to understand the friction effects in machining, we have to analyse the inherent relationship among, the cutting conditions (cutting and feed velocities, tool geometry), the workpiece material behaviour, the thermomechanical characteristics of the tool material, the frictional heat partition in the sliding zone and the friction conditions at the tool-chip and tool-workpiece interfaces. Due to the problem complexity, it appears that despite many works on machining, the understanding of the effect of friction conditions requires further investigations. In the present work, to identify the interaction between the thermomechanical phenomena at the tool-chip interface and the material flow in the primary shear zone; an analytical model has been coupled with a finite element approach. For the tool rake face, a new pressure model was developed. The transient nonlinear thermal problem in the workpiece-tool-chip system has been solved by using a FE model based on the Petrov-Galerkin formulation. The coupling between the primary shear zone (PSZ) (chip formation), the secondary shear zone (SSZ) (sticking zone) and the frictional heat at the sliding zone has been taking into account. The model allows to determine in a fast and simple way several significant machining parameters as: (i) the cutting forces, (ii) the temperature distribution in the tool-chip-workpiece system, (iii) the heat flux from the PSZ to the workpiece, (iv) the tool-chip contact length, (v) the frictional heat partition and (vi) the apparent friction coefficient. The proposed model allows to analyze different industrial machining processes such as drilling and milling
Lassoued, Rachid. "Modélisation analytique des structures unidimensionnelles et bidimensionnelles sous charges mobiles." Marne-la-Vallée, 2007. http://www.theses.fr/2007MARN0328.
El, Bouami Souhail. "Contribution à l'optimisation du perçage des multi-matériaux CFRP/Al2198 et CFRP/Ti6Al4V." Thesis, Amiens, 2017. http://www.theses.fr/2017AMIE0040/document.
The manufacturing of hybrid structures composite and metal parts aims to combine resistance to multiple stresses and to limit overall weight, particularly in the aviation industry. The significant differences in mechanical behavior that exist between the two types of materials must be taken into account in drilling operations of a hybrid structure. The objective of this thesis is to develop, based on the experimentation, tools and an associated drilling strategy for the CFRP/Al2198 and CFRP/Ti6Al4V hybrid structures. A study of the impact of the morphology of the tool and the machining strategy revealed a link between the morphology of the drill used and the cutting conditions, on the one hand, and the quality of the hole drilled and the thrust force, on the other hand. The tools proposed, at the first step, combine different existing morphologies (twist, square and step drill). In a second step, a tool meeting the requirements was developed and associated with a new machining strategy comprising three phases (roughing, ½ finishing and finishing). Finally, delamination at the exit of the hole remains a major concern when drilling carbon composites, an analytical model allowing the calculation of the critical force before delamination has been proposed. This work is part of Industrilab project financed by the Hauts de France Region and led by STELIA
St-Amand, Olivier. "Modélisation semi-analytique dynamique d'un actionneur THUNDER utilisé en isolation vibratoire." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28744/28744.pdf.
Jrad, Mohamad. "Modélisation du perçage à grande vitesse : approches analytique, numérique et expérimentale." Thesis, Metz, 2007. http://www.theses.fr/2007METZ037S/document.
The determination of the cutting forces generated during the drilling operation is an essential step in the drilling optimisation. This information is crucial for the cutting conditions determination and the tool definition. The aim of this work is to propose a predictive thermo mechanical model for the drilling process. This model is based ont the thermo mechanical oblique cutting model developed and validated in the LPMM laboratory. The parameters used in this model are the cutting angles, the cutting conditions, the behaviour of the workpiece materials and the friction conditions on tool-chip interface. After the determination of the cutting angles from the CAD definition of the drill using a mathematical geometrical model developed in this work, the cutting edges are decomposed into a series of linear oblique cutting edges. A modified version of the thermo mechanical model is then apllied on each elemental cutting edge in order to calculate the elemental cutting forces, and then the global thrust and torque are determined. Experimental dry drilling tests were performed in order to validate the presented model. The calculated and measured global torque and thrust were compared, a good agreement was obtained. In the last section a numerical model using the finite element method with two commercial codes are presented. 2D orthogonal cutting and 3D drilling simulations were carried out. Numerical simulation provides interesting information on the chip formation and on the temperature and stress distributions but the calculations are time consuming. The two proposed methods may be used as complementary approaches to optimize cutting conditions and drill geometry
Chappuis, Johanna. "Modélisation des éffets d'installation sur le rayonnement de turboréacteurs : Méthodes analytiques et numériques." Ecully, Ecole centrale de Lyon, 2007. http://bibli.ec-lyon.fr/exl-doc/TH_T2089_jchappuis.pdf.
Engine noise reduction has been achieved thanks to the use of high bypass ratio engines and to inlet and axhaust duct treatments made of adapted acoustical absorbing materials. However, facing more and more stringent requirements, noise prediction models have to be more and more accurate and it is nor possible anymore to neglect the interactions between acoustic waves and airplane surfaces due to engine installation effect. This work deals with modeling of these installation effects and theassessment of the effect of the plane on the acoustic raiation by turbofan inlet and exhaust ducts. The main objective is the development of prediction tools involve analytical methods based on simplified geometries and aerodynamic conditions. Analytically, the contributions wing and the fuselage have been separated, physics being different in both cases. The first analytical method is dedicated to the modeling of difraction by flat screens and calculates an exact solution of the wave equation associated with boundary conditions on rigid half-plane with no thicckness. In the presence of uniform flow, the theory of diffraction to calculate the diffracting effect of a cylinder under the high-frequency assumption. The considered numerical approach for installation effect stuy implying large size domains, it is base on a domain decomposition and a weak coupling principle. The method accuracy is demonstrated bu comparision with test campaign resukts leading to a good overall agreement with numerical predictions. In addition, a new source model is proposed to reproduce the behaviour of given mode (m,n) at the exit duct section by an association of monopoles: this considerably improves the installation effect prediction by analytical methods
Thomas, Jean-Christophe. "Etude expérimentale et modélisations analytique et numérique de poutres gonflables à haute pression." Nantes, 2002. http://www.theses.fr/2002NANT2010.
The recent evolutions of technical textile properties allow the use of high pressure in inflated structures, increasing their stiffness. One may built carrying structures. Some experiments have been done on prototypes showing the behaviour of panels (two parallel-coated woven fabrics connected by yarns) and tubes (high frequency welded coated fabrics), for pressure varying from 50 kPa to 300 kPa
Guerfi, Fayçal. "Modélisation et approche analytique des systèmes d'écoulements triphasiques compressibles en milieu poreux." Pau, 1989. http://www.theses.fr/1989PAUU3004.
Ferrier, Marlène. "Modélisation analytique du transport balistique et quasi-balistique dans les MOSFETs avancés." Grenoble INPG, 2007. http://www.theses.fr/2007INPG0016.
With the integration of new undoped MOSFETs architectures allowing very short channellengths, the emergence of ballistic transport in next generations' devices become more and more probable. Ballistic MOSFETs are expected to exhibit higher drain currents compared to the predictions of conventional approaches. This work presents the physics and the modeling of ballistic and quasi-ballistic transport in advanced MOSFETs. The impact of the conventional technological parameters on injection velocity, a figure of merit of ballistic transport, has been discussed. Moreover, original analytical models for quantization, allowing subband engineering have been proposed for bulk, SOI and DG-MOSFETs. These models can effectively replace time consuming Poisson-Schrôdinger simulations needed for an accurate evaluation of ballistic currents. Finally, a new approach for the extraction of the backscattering factor has been presented and applied to fully depleted SOI MOSFETs
Vo, Thi Dong. "Modélisation numérique et analytique de la fissuration de séchage des sols argileux." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1214/document.
This work focuses on the analysis of desiccation cracking by numerical and analytical approaches. The initiation and the propagation of cracks are investigated by using a finite element code including cohesive joints elements. Coupling between the hydraulic and the mechanical processes in the presence of discontinuities is considered. The cohesive crack’s law is applied to simulate the initiation and the propagation of cracks.Results of a laboratory experiments performed on slurry clay soil are first used to evaluate the proposed numerical modelling method. The results show that the method is able to reproduce the main trends of desiccation process. The importance of boundary conditions are also discussed. Second, an energy approach is proposed to study the initiation of cracks. The energies before and after crack initiation are estimated by both numerical and analytical solutions. The energy released by cracking is then compared to the crack energy to discuss crack initiation conditions. The analysis shows that the energy criterion is reached before the stress criterion, and this can explain unstable crack propagation at the beginning. Third, the development and the geometry of desiccation cracks are studied by numerical simulation with several cohesive joints. The numerical results show that cracking occurs sequentially to form different cracks families with a dichotomy process (the subsequent cracks appear at the middle of two existing neighboring ones). The cracks in each family appear simultaneously and reach an identical ultimate depth. From the numerical results and additional analytical analysis, empirical correlations are proposed to predict the spacing and crack depth. Finally, some preliminary studies are performed showing that the proposed numerical method can be used to predict the desiccation crack phenomena observed on geotechnical earth structures
Besri, Abdelhadi. "Modélisation analytique et outils pour l'optimisation des transformateurs de puissance haute fréquence planars." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00612344.
Brochard, Kévin. "Modélisation analytique de la réponse d’un cylindre immergé à une explosion sous-marine." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0019/document.
The design of a hull of submarine is crucial for its operability and the safety of the crew, but also complex. Indeed, the engineers have to take into account at the same time lightness, acoustic discretion and resistance of the hull to immersion pressure and to environmental attacks. Underwater explosions represent a first-rate threat to the integrity of the hull, whose behavior needs to be properly analyzed. The works presented in this thesis concern the development of a simplified method, based on analytical formulations, to study the mechanical behavior of a cylinder deeply immersed subjected to an underwater explosion. The purpose of this method is to give engineers a fast estimation of the damage undergone by the cylindrical shell, allowing them to compute a large number of scenarios of explosion.In the scope of this thesis, the model of the plastic string on plastic foundation is picked up and adapted to the study of an immersed cylinder subjected to an explosive load, for which the effects of immersion pressure and fluid-structure interaction are to be taken into account. This simplified model of the fluid structure interaction is coupled with the model of a plastic string resting on plastic foundation, by considering on one hand the effects of the immersion pressure and on the other hand the circumferential stiffening of the cylinder. Analytical expressions are derived in order to calculate the final deflection of the shell as well as its energy of plastic deformation. The obtained results are compared with results obtained with numerical simulations, which allows to validate gradually the simplified method, but also to highlight its limitations
Oulmane, Mohamed. "Transport dans les composants en présence de centres profonds : modélisation numérique et analytique." Montpellier 2, 1999. http://www.theses.fr/1999MON20210.
Raoux, Jean-Jacques. "Modélisation non-linéaire des composants électroniques : du modèle analytique au modèle tabulaire paramétrique." Limoges, 1995. http://www.theses.fr/1995LIMO0006.
Gintrand, Antoine. "Modélisation analytique et numérique de l'évolution des restes de supernova en phase radiative." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEO012.
At the end of a massive (typically more than 5 to 6 solar masses) star life, the star becomes a supernova. After the explosion, the strong shock begins to propagate with the ejecta of the star in the circumstellar medium and later in the interstellar medium (ISM). This object is called a supernova remnant (SNR). During its expansion, the SNR accumulates matter behind the shock front to form a shell. Theory describes three stages of the SNR. The first stage corresponds to a ballistic expansion with a radius R of the SNR proportional to its age t. In the second stage, called the Sedov-Taylor (ST) regime, the evolution is adiabatic (energy conservation) and R increases like R(t) ∝ t^2⁄5 . In this PhD thesis, we present an analytical and numerical modeling of the SNR evolution in its third stage (radiative late stage) where the energy is not anymore conserved. The remnant loses its energy by radiative emission processes or by ionisation of the ISM. In this last stage, the radius is given by R(t) ∝ t^n where the exponant n satisfies 1/4 < n < 2/5. First, we study the structure of the shock which ionizes the ISM and show that the compression ratio can become high (of the order of 40 compared to 4 for a adiabatic shock in a monoatomic gas). Indeed, a portion of the shock energy is used to ionize the gas and is no longer available to heat the postshock medium, so the gas will be compressed. Then, we apply this property to the modeling of a SNR in late stage and show that the SNR shell can become dense and thin. In a second part, we perform the self-similar analysis of a SNR where energy losses are described by a spatially uniform cooling function. This study demonstrates that there are two types of hydrodynamic solutions : ST-type solutions which are smooth up to the center of the remnant and shell-type solutions where the shell is bounded by a contact discontinuity that separates it from the hot and rarefied interior (bubble) of the SNR. Also, we show that the shell becomes dense and thin when the energy loss is strong enough. Finally, we complete the study of the transition to the radiative stage of the SNR for more realistic radiative losses using the numerical simulation. We show that although the formation process of the thin and dense shell is complex (catastrophic cooling of Falle and secondary shocks), the evolution of SNR in the radiative stage shares common properties for a wide variety of cooling functions. In particular, we show that in almost every cases the SNR radius follows the law R(t) ∝ t^n where n is close to 2/7. This behavior is constistent with theory, because this value has been found previously by other autors and we highlight it also in our self-similar analysis
Sidi, Ali Kamel. "Contribution à la modélisation analytique et numérique des écoulements stratifiés en conduite horizontale." Paris 6, 2009. http://www.theses.fr/2009PA066694.
The present work deals with the analytical and numerical modelling of stratified flows in a horizontal pipe. The equation set-up is done in the analytical part, while taking into account the discontinuities at the gas-liquid interface. The resolution of the system of differential equations obtained can follow the behaviour of the fluid system. In the second part, a numerical 2D unsteady-state study is done using the CFD code Fluent. The study deals with a two-phase gas-liquid flow with and without gravity. The effect of the absence of gravity is shown and commented. In the third part, the study is done in steady-state and 3D. The study concerns the flow in the gas-interface part. The obtained results are compared to the experiences done by Strand (1993) and to the numerical results of Meknassi et al (2000). The expressions giving the friction factors are deduced and compared to those of Taitel and Dukler (1976)
Dargnat, Frédéric. "Modélisation semi-analytique par approche énergétique du procédé de perçage de matériaux monolithiques." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13216.
Halila, Faycel. "Modélisation analytique et caractérisation expérimentale de l'usure par abrasion des outils de coupe." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0147/document.
Tool wear and tool failure are critical problems in the industrial manufacturing field since they affect the quality of the machined workpiece (unexpected surface finish or dimensional tolerance) and raise the production cost. Improving our knowledge of wear mechanisms and capabilities of wear prediction are therefore of great importance in machining. The three main wear modes usually identified at the tool/chip and the tool/workpiece interfaces are abrasion, adhesion and diffusion. Besides the fact that understanding mechanisms that govern these wear mechanisms are still incomplete, the experimental analysis is very difficult because friction interface features (such as temperature, pressure, particles embedded in the contact …) are not easily measurable. The objective of this research work is to understand the physical mechanisms governing the tool wear by taking into account the sensibilities to scale going from the microscopic scale (microstructure scale) to the macroscopic scale (scale of the manufacturing operation) passing by the mesoscopic scale (tool tip scale). For this purpose, an analytic wear model was developed to describe the abrasive wear and to predict the cutting tool life. The proposed model is based on a tribological approach including a statistical description of the distribution of particles seen as non-metallic inclusions. The latter are assumed embedded at the interface of contact and having a conical shape characterized by two main parameters in the present approach: the corresponding size and apex angle. The volume of the removed material per unit time is chosen in this study as the main parameter to describe the abrasive wear mode. Coupled with literature results, the developed model is able to take into account the nature of the sticking-sliding contact and the effect of the friction coefficient on the rake face of the cutting tool. In order to identify all the material's parameters of the predictive model, a study of non-metallic inclusion considered responsible of the abrasive wear was performed on the 42CD4 steel. The determination of inclusion type and inclusion morphology was assessed qualitatively and quantitatively through microscopic and MEB observations as well as image processing. Finally, the volume removed by abrasion given by the model was compared to the experimental results previously achieved under orthogonal cutting
Ren, Xiaotao. "Modélisation semi-analytique des pertes par courants de Foucault dans les matériaux composites." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS159/document.
Composite materials have been widely used in Electrical Engineering, and they have stimulated a growing number of scientific research, especially when it comes to energy savings. Soft Magnetic Composites (SMC) incorporate the attributes of different constituents. They can be designed to exhibit high permeability and to dissipate low Eddy Current (EC) losses compared to more conventional structures such as laminated steel. Nevertheless, electromagnetic properties of SMC are not easily determined. Numerical tools such as finite element method (FEM) are usually employed to provide a full-field description of SMC. As the microstructure has to be finely meshed, it brings significant numerical burden and instabilities. To overcome this restriction, semi-analytical homogenization methods are adapted and applied here. They consist in developing a complex permeability model. In the complex permeability model for SMC, the static magnetic permeability and EC losses are integrated respectively as the real and imaginary part of the complex permeability. Classical estimates are applied to determine the macroscopic effective magnetic permeability. A correct determination of the effective permeability, i.e. the real part of the complex permeability, is crucial for the estimate of EC losses. EC losses formulas are derived for SMC with periodic microstructure in 2D and 3D cases. Furthermore, different approaches of field averaging are employed to obtain lower and upper bounds on the EC losses in SMC. The complex permeability model is then applied to analyze a transformer structure. The magnetic field and EC losses distribution can be obtained on the equivalent homogenized transformer. The results are compared to the full-field calculations on the heterogeneous transformer. A good consistency is observed. Finally, the effect of mechanical stress on the magnetic permeability and loss property of SMC is studied, which leads to a coupled formula of EC loss density as a function of macroscopic stress and magnetic field
Bujnak, Jan. "Analyse globale de poutres mixtes acier béton : approche analytique et modélisation non-linéaire." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2007. http://tel.archives-ouvertes.fr/tel-00718174.
Bujnak, Jan. "Analyse globale de poutres mixtes acier béton : approche analytique et modélisation non-linéaire." Phd thesis, Clermont-Ferrand 2, 2007. http://www.theses.fr/2007CLF21762.
Quaglia, Michael. "Méthodes de prévision acoustique semi-analytiques pour un doublet d'hélices contrarotatives isolé." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC063/document.
No abstract
Tollet, Edouard. "Formation et évolution des galaxies en cosmologie : modèles semi-analytiques et simulations hydrodynamiques." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC179/document.
A galaxy is a complex system since as many phenomena take place at the scale of the interstellar medium, such as supernovae explosions or the activity of supermassive black holes, as interactions between galaxies within groups or clusters, such as tidal or ram pressure stripping, affect and condition the evolution of the galaxy itself as a whole. Because the processes acting in such systems involve a considerable range of times and distances, going from individual stars to entire clusters of galaxies, they modelling constitutes an immense challenge that cannot be met neither by a purely analytical approach nor by solely numerical technics.This thesis, being at the interface between semi-analytical models and the analysis of numerical simulations, focuses on the study of star stripping in satellite galaxies by tidal effects and on the supernovae induced feedback.This manuscript presents, on one hand, an halo occupation model that allows to constrain the stellar mass lost by satellite galaxies since they entered their group or their cluster, and a model of impulsive stripping that predicts the stellar mass ripped out of satellites. The latter is compared, through the halo occupation model, to the observed mass functions of groups and clusters.It exposes, on the other hand, the study of the supernovae feedback implemented in the numerical simulations of the NIHAO project, performed separating the simulated gas into different components and counting the exchanges that take place between them. This allowed for the highlighting of three distinct processes through which supernovae reduce or suppress their star formation
Mouity, Nzoumba Joseph Gildas. "La modélisation des coûts à l'hôpital." Rennes 1, 2010. http://www.theses.fr/2010REN1G009.
Quaglia, Michaël. "Méthodes de prévision acoustique semi-analytiques pour un doublet d'hélices contrarotatives isolé." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11781.
Schwinn, Karno. "Dérivées secondes analytiques de l'énergie QM/MM : étude théorique des vibrations en cryptochrome." Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0605.
This work presents the developments of a QM/MM method that can calculate the entire Hessian matrix of large biomolecules in order to perform a vibrational analysis. Developments have been carried out on the electrostatic potential fitting (ESPF) method to calculate analytic second derivatives of ESPF-QM/MM energy with a Kohn-Sham density functional theory (DFT) description for the electronic ground state of the QM subsystem.The implementation includes a new way of obtaining the density response, that replaces the need of solving the MM CPSCF equations with a set of auxiliary couple-perturbed equations over a number of multipole components representing the QM density.In practice, the calculation of the full ESPF-QM/MM Hessian matrix exhibits a linear scaling behaviour with the size of the MM system.The method has been applied to study the chromophore of the photoreceptor protein cryptochrome in its protein surrounding. The vibrational analysis is used as a basis to calculated various molecular properties such as vibrationally resolved electronic spectra, vibronic couplings and molecular property derivatives that allow the calculation of vibrational IR and Raman spectral intensities at the electrostatic embedding QM/MM level. The results presented in this thesis make the ESPF method a promising candidate for the future modeling of relaxation and dissipation dynamics in proteins
Tran, Le Nhat Hoang. "Modélisation fréquentielle analytique de convertisseurs statiques en vue du dimensionnement de systèmes par optimisation." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT122/document.
For the design of static energy conversion systems from power grids, harmonic standards have to berespected. To characterize them, frequency modeling approaches, either numerical or semi-analytical. Thesecond one is more advisable for the sizing by optimization of systems, where a fast model is required and manyconstraints have to be carried out. However, the main difficulties happen in the analytical modeling of powerelectronics structures, especially those with soft commutations.This thesis proposes a semi-analytical modeling approach where the solving of implicit equations iscarried out by Newton-Raphson or SQP. The convergence difficulties are analyzed in two viewpoints:numerically and according the operating mode of the static converters. Then, alternatives are proposed to solvethem.To illustrate the problematic, applications with diode rectifiers (widely used in railway electrical gridsubstations or airline electrical grid) are used. Especially, the sizing of power channel of « new generation» of anAirbus, is made by optimization, using the proposed modelling approach
Giraud-Audine, Christophe. "Contribution à la modélisation analytique d'actionneurs piézoélectriques en vue de leur conception et dimensionnement." Toulouse, INPT, 1998. http://www.theses.fr/1998INPT044H.
Su, Yishi. "Modélisation analytique et numérique de structure des mousses métalliques MPPCs et du comportement mécanique." Troyes, 2011. http://www.theses.fr/2011TROY0018.
The main objective of this work is analytical and numerical modeling of the static, dynamic and thermal mechanical properties of the innovative materials (metal foam and composites MPPCs). Initially, the negative pressure infiltration technique is applied to manufacture the open-cell aluminum foams and the composites MPPCs. Considering the open-cell arrangements, three analytical models are proposed at the microscopic level to predict and optimize the porosity of the materials. The microstructures are experimentally analyzed to study the mechanical behavior of the composites MPPC. Secondly, we proposed a constitutive model of stress-strain in the case of uniaxial static compression of metal foam. This model is utilized with the finite element to numerically simulate the compressive behavior. Afterwards, the model is once again used in the case of dynamic low-velocity impact of metal foam. These models are verified by the experimental tests. Finally, we study the thermomechanical behavior of the composites MPPCs with the micro-structures of spherical and Kelvin cells. The numerical simulations of thermomechanical properties are carried out with the program ABAQUS
Pegoraro, Paul. "Modélisation analytique de matériaux et de structures composites pour un comportement hygro-thermo-élastique." Paris 6, 1993. http://www.theses.fr/1993PA066737.
Alakian, Alexandre. "Modélisation radiative et caractérisation des panaches d'aérosols en imagerie hyperspectrale." Paris 6, 2008. http://www.theses.fr/2008PA066003.
Ostiguy, Pierre-Claude. "Modélisation pour l'imagerie des composites par ondes guidées." Thèse, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8870.
Ech, Cheikh Fouad. "Modélisations numérique et analytique du comportement mécanique et multiphysique d'une phase haute-tension pour fermes offshores." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0004.
OTDR-based electrical cable diagnostic methods exist that allow the detection and localization of faults, but the analysis of the measured signals needs to be improved, particularly through the use of models. The link between the physical degradation of the cable and the values of the electrical parameters has, to our knowledge, never yet been realized. As a result, we are not able to know the actual condition of the cable in its natural evolution environment, let alone its residual life. The work carried out in this thesis aims at studying the mechanical behavior in both quasistatic and cyclic fatigue loadings in order to correlate the deformation levels reached to the operating mechanisms of damage and which reflect the proliferation of microstructural defects within the components of the phase (Conductor and insulators). To do this, we propose a numerical modeling using Abaqus. Then, again using numerical modeling, this time using Comsol, we tried to show the impact of mechanical damage on the physical properties (electrical and thermal) of the phase, emphasizing the role of copper. Insulators are playing a key role as well. However, the contour of the thesis had to be well defined in accordance with the time allocated and it seemed to us that a lot of information can be got out of the study of the conductor
Le, Grand Philippe. "Formes curvilinéaires avancées pour la modélisation centrée objet des écoulements souterrains par la méthode des éléments analytiques." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2003. http://tel.archives-ouvertes.fr/tel-00839910.
Tanneau, Olivier. "Modélisation de panneaux d'isolation aéronautiques : couplages poro-élastiques, élastodynamiques et acoustiques par méthodes analytiques, FEM et BEM." Paris 6, 2004. http://www.theses.fr/2004PA066401.
Absi, Rafik. "Contribution à la modélisation analytique des couches limites turbulentes et dispersion de particules en suspension." Habilitation à diriger des recherches, Université de Cergy Pontoise, 2011. http://tel.archives-ouvertes.fr/tel-00770089.
Cournoyer, Benoît. "Modélisation analytique et numérique de plaques multicouches ; application au traitement viscoélastique des disques encastrés - libres." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1995. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq21737.pdf.
Jean, Dit Gautier-Gaudenzi Estelle. "Modélisation du système pelvien de la femme enceinte et simulation d'accouchement : outil analytique et pédagogique." Thesis, Lille 2, 2018. http://www.theses.fr/2018LIL2S019/document.
We aim at developing a complete 3D numerical model of a parturient pelvic system representing all the anatomical structures of the pelvis such as ligament, muscle and organs. Then we generate a parametric FE model that allows simulating normal and dystocic vaginal delivery.We have developed a parturient pelvic numerical model at different gestational ages, 16, 32 and 38 weeks of gestation, (WG) and in postpartum (2months and 1year) from MRI. The different organs, muscles and ligaments of the pelvic system were segmented in order to generate a complete anatomical 3D model. Starting from this numerical model we studied the changes the muscles and ligaments undergo during pregnancy. Then we performed a Finite Element (FE) model that allows simulation and analysis of the deformations of pelvic anatomical structures under the stress induce by normal and dystocic vaginal delivery. In particular, we investigated the influence of the head size, terms and cephalic orientation and flexion. We particularly studied the structures that play an important role in the stability of the pelvic system.ResultsThe analysis during pregnancy of the US ligaments and levator ani muscle (LAM) reveals some geometrical modification, even then at the beginning of the second pregnancy trimester. This 3D anatomical model help to develop a teaching model for manual removing of the placenta, that could be integrated in a simple physic mannequin. The proof of pedagogical interest of this tool was made by different series of tests, underwent by gynaecolog-obstetrician and midwives. Then we worked with FE simulation of the vaginal delivery. The model developed is parametric. Than mean we can then change different maternal and fetal criteria such as gestational age, fetal head size, orientation and flexion. First place we performed normal vaginal delivery to study the impact of the fetal head descent in the pelvic system, and his stress impact on the different anatomical structures. Then we introduce dystocic element. We can evaluate and localize the strain levels and the most injured areas. Posterior cephalic presentation presents higher injury risk than the anterior one. Maternal geometry at different terms brings equivalent results contrary to the fetal head sizes that have an influence on the strain level and the potential damage induced. We developed pressure and trajectories sensors integrated in a forceps. We can then record an ex-vivo forceps extraction and then integrate all the information in the FE model.ConclusionThis multi-parametric investigation allows us to have a customizable and predictive tool evaluating the potential damages on the pelvis during vaginal delivery. We could then explain, understand and maybe predict some maternal and fetal complications that could happen during vaginal delivery. We can in particular try to explain the perinea injuries during, after and long time after vaginal delivery. This tool can be used to teach the complexity of obstetric
Courvoisier, Ludovic. "Modélisation analytique et étude numérique de l'écoulement d'une tôle le long d'un jonc de retenue." Metz, 2001. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2001/Courvoisier.Ludovic.SMZ0101.pdf.
Numerical simulations take a great place in deep drawing processes. But some parts, like drawbeads, are complex and leads to an unacceptable increase in CPU time. The purpose of this work is to develop an analytical model for sheet bending/stretching along drawbead. The geometrical evolution of an elementary length of the sheet is described by the Love-Kirchhoff assumption. The thinning of the sheet is taken into account in the calculation. The assumption of either isotropic or kinematic hardening, and Coulomb's friction is assumed. This model, confirmed by numerical simulations, allowed us to perform a complete parameter analysis, and constitute a tool to choose drawbeads
Faucher, Sébastien. "Modélisation quasi-analytique des composants passifs hybrides planar par la méthode des lignes de transmission." Montpellier 2, 2003. http://www.theses.fr/2003MON20153.