Tesi sul tema "Énergie de déformation élastique"
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Shi, Hailong. "Recrystallization of 2D dimensioned Copper (Cu) foils and graphene nanosheets (GNSs) reinforced Cu matrix laminated composites". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0096.
Recrystallization is the intrinsic process of cold-deformed metallic materials that occurs inevitably during the thermal treatment. The produced recrystallization texture contributes to the anisotropy of the mechanical and physical properties. Motivated by the minimization of modern products, 2D materials and laminated composites are increasingly demanded by many applications. Thus, for both scientific and engineering purposes, investigations on the recrystallization of such materials are needed to understand the underlying mechanisms. In this work, Cu foils and graphene nanosheets (GNSs) reinforced Cu matrix laminated composites with Cu foil thicknesses of 10 μm and 30 μm were fabricated, and the recrystallization features were thoroughly investigated from microscale to macroscale by means of SEM-EBSD for microstructure observation, neutron and synchrotron radiation for texture analysis and in-situ synchrotron radiation for lattice strain evaluation. The obtained data were analyzed in the frame of crystallography combined with crystal elasticity and surface energy. The results showed that the recrystallization behavior of the Cu foils were greatly affected by the Cu foil thickness and the addition of the GNSs. For the 10 μm thick Cu foils without GNS, they underwent a transition from the cold-rolling texture to a recrystallization texture dominated by RD-rotated Cube and φ_2-rotated Copper components. The transition was screened by both intrinsic microstructural and extrinsic sample geometrical factors. The orientations of the nuclei were mainly inherited from the deformation orientations. Those with low Taylor factors (Cube, Goss and Brass) demonstrated size preference. The post-nucleation growth was affected by the biaxial thermal elastic constraint and surface energy. Due to their opposite effects, the orientations having moderate biaxial moduli and surface energy density (S, Copper, Brass and recrystallization components) survived, resulting in a mixed texture at the completion of recrystallization. The coherent Σ3 boundaries between the new components stabilized their growth through consuming the other oriented crystals separated by random high-angle boundaries. When sintered into bulk, the texture of the Cu was dominated by the orientations of the abnormally grown grains. The effects of GNSs on the recrystallization of Cu foils were also Cu foil thickness dependent. For the 10 μm thick foils, the effect of the GNSs manifested after the samples were sintered to high temperatures (> 700 ℃). Instead of creating much constraint to the expansion of the adjacent Cu foils, the GNSs worked as a barrier preventing the penetration of the grown Cu grains, resulting in the stabilization of the recrystallization texture represented by the two rotated components. For the Cu/GNS composite with Cu foil thickness of 30 μm, the results evidenced that a strong Cube orientation was produced in the Cu/GNS composite instead of the individual non-Cube orientations in the pure Cu stack without GNSs. Detailed strain-state analysis of the Cu foils in the Cu/GNS composite revealed that the anisotropic expansion behavior of the GNS that is incompatible with that of the Cu foils imposed multiple elastic constraints to the foils, resulting in a biaxial isostrain state in the surface layers and a uniaxial compressive strain state in the central layer. The elastic anisotropy of Cu favors the growth of the Cube oriented grains to minimize the total strain energy. The results of the present work provide quantitative and detailed information on recrystallization of thin Cu foils and laminated composite, which contributes to deepening the understanding of recrystallization behaviour of 2D materials. The mechanisms revealed are useful for analysing abnormal grain growth in elastically strained materials and can also be applied to fabrication process for texturization or even monocrystallization
Quennouz, Nawal. "Déformation et transport d'un filament élastique dans un écoulement cellulaire visqueux". Paris 6, 2013. http://www.theses.fr/2013PA066183.
We study the deformation and transport of an elastic filament in a viscous cellular flow. We used a simple experimental model system consisting of a one centimeter long elastic filament with controlled geometry and elasticity and a viscous flow formed by a lattice of stagnation points. First, we characterized the buckling instability of the filament approaching a stagnation point. We have shown that this instability is controlled by the elasto-viscous number Sp which compares the relative intensity of the viscous forces deforming the filament and the elastic forces resisting the deformation. Then, we showed that the parameters related to the dynamics of the fiber transported are crucial in the prediction of the buckling probability. In parallel to the experimental analysis, numerical simulations were performed in collaboration with Michael Shelley. The characterization of the dynamical parameters and their influence on the buckling instability allows the prediction of a buckling event as a function of the elasto-viscous number Sp and the dynamical parameters linked to the transport of filament accros the lattice. Finally, we investigated how the deformation and the size of the filament affect its transport properties
Aïssani, Amel. "Sur la déformation d'un fil élastique et sur l'étude d'une équation intégro-différentielle". Metz, 2000. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2000/Aissani.Amel.SMZ0036.pdf.
Fouad, Saïd. "Sur quelques problèmes relatifs à la déformation d'une membrane élastique par des boules rigides". Metz, 1999. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1999/Fouad.Said.SMZ9947.pdf.
Quinson, Renaud. "Caractérisation et modélisation de la déformation non élastique des polymères amorphes à l'état solide". Lyon, INSA, 1995. http://www.theses.fr/1995ISAL0107.
[This study deals with the non elastic deformation of amorphous polymers in the glassy state. Two components of the non elastic deformation are clearly identified through the study amorphous polymers deformation recovery. For classical experimental times, the anelastic component recovers below the glass transition temperature whereas the plastic component recovers above this temperature only. During a constant strain rate test, it is observed that the anelastic component of the applied strain can be very important. Moreover, the increase of molecular mobility, energy and density observed on deformed samples appears to be due to this anelastic component of the deformation only. The hydrostatic pressure on the stress which corresponds to the appearance of plastic deformation has been studied through several mechanical tests. Besicles, the mechanical activation of molecular motions which are responsible of the non elastic deformation bas been observed with an anti-stress relaxation test. Our various results allow us to specify and extend the description and the modelisation of the non elastic deformation which has been previously proposed by Perez et al. . This physical model simulates the non elastic behaviour of three amorphous polymers correctly, and, in particular, the amplitude and the kinetics of the activation and recovery of the anelastic deformation. This study should bring better knowledge of the behaviour laws of those polymers. ]
Porzucek, Kathy. "Approche métallurgique de la déformation non élastique de mélanges à base polypropylène renforcés élastomère". Lille 1, 1988. http://www.theses.fr/1988LIL10084.
Ouedraogo, Théodore. "La déformation élastique artérielle au cours de la flexion articulaire : aspects biomécaniques et approche physiologique". Reims, 2003. http://www.theses.fr/2003REIMM201.
Akrout, Mohsen. "Contribution à l'étude par éléments finis du retour élastique des tôles en emboutissage et déformation plane". Lyon, INSA, 1994. http://www.theses.fr/1994ISAL0082.
This work has consisted to develop a software using a finite element formulation to simulate the sheet plane strain deep drawing and to obtain its springback. The updated Lagrangian formulation is used with shell finite elements in plane strain and transverse shearing. The efficiency of this element with independent degrees of freedom (two translational displacements and one rotation) has been shown. The numerical unloading problem was cleared up by introducing the plastic reversibility concept in the behaviour law integration expressed in a co-rotational reference. The tools action is introduced by an incremental penalization method coherent with the Coulomb friction law. This software was validated with experimental tests carried out in the laboratory and others in industrial factories. It allows a study of different parameters that have an effect on sheet springback after deep drawing
El, Khouzai El Mostapha. "Ecoulements transitoires en conduite élastique et viscoélastique : Influence relative de la déformation longitudinale de la paroi". Lyon, INSA, 1993. http://www.theses.fr/1993ISAL0051.
The study concerns the analysis of the influence on transient flows of a real pipe deformation of thin walled tubes, with longitudinal displacement in perfect and viscous fluids, A general treatment already has been developed which allows to account on one side, for the flexure and shear deformation, and on other side for the inertia of the pipe and the longitudinal deformation which will be neglected in the previous studies. The asymptotic development has been established in order to facilitate the direct analysis of flows singularities (primary wave front, diffusion front) in relation to different cases considered (Newtonian or perfect fluid, elastic or viscoelastic pipe), The general case has been treated numerically, by direct numerical inversion of the system of equations Expressed in the space transform LAPLACE-CARSON. A t ypical case has been treated concerning semi-infinite pipe fixed at the origin
Sin, Ousphea. "Étude en deux dimensions de l'effet du taux de déformation sur la limite élastique de l'acier structural". Mémoire, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11237.
Chow, Wang. "Développement d'une méthode in situ pour mesurer les champs de déformation élastique et totale à l'échelle du grain". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC003/document.
Micromechanical modelling was widely developed during the past 20 years as they enable ones to make direct links between the actual microstructure of a material and its macroscopic properties such as mechanical, thermal, electrical, etc. Crystal plasticity models aim at predicting local and macroscopic behaviours and/or changes of the microstructure during thermomechanical loading. However, the parameters of these models are difficult to identify, because the mechanisms they describe are at a small scale and are thus complicated to measure. For this reason, the crystalline model identification requires the use of experimental data at the grain scale. The objective of the study presented here is to develop a robust procedure to obtain at least two distinct local mechanical responses of a material at the grain scale.The total and elastic strain fields have been chosen to be characterised referring to the research interest and the adaptability of experimental methodologies. When samples were subjected to simple tensile loadings and unloadings, strain fields were measured on the sample surface simultaneously at each successive level. Total strain fields were determined by the Digital Image Correlation technique (DIC) while elastic strain fields were calculated from the X-ray diffraction (XRD) measurements. Two oligo-crystalline samples of an aluminium alloy (5052) has been prepared and used in this study. The experimental device and methodology was designed and developped to perform DIC, XRD and tensile tests in-situ in an X-ray diffractometer. The total and elastic strain fields of two samples through in situ tension experiments were obtained. Besides results and analysis, the corresponding uncertainties during each measurement were quantified as well
Ouali, Nourdine. "Etude de la déformation non élastique (faible et forte contrainte) de polymères amorphes monophases et polyphases base PMMA". Lyon, INSA, 1992. http://www.theses.fr/1992ISAL0044.
PMMA and PMMA- based blends samples have be en studied by dynamic mechanical spectrometry and high stress mechanical tests. Concerning PMMA, experimental results obtained from dynamic mechanical spectrometry (linear dependence of "Stress vs Strain"), were interpreted in the frame of the physical model of PEREZ et al. In order to interpret experimental results in the plasticity domain (the « Stress-Strain » relation is no more linear), an extension of this model, with the notion of « thermo mechanical activation » is proposed. A unitary description of non elastic strain in amorphous polymers, for all stress then becomes possible. In the case of PMMA-based blends, faced which the enability of the models of mechanical behaviour of composite systems available in the literature to give a precise interpretation of experimental results, we have been lead to develop a very original analysis of the mechanical coupling of the two phases constituting these materials. This enabled us to describe the variations of the static modulus as well as the plastic flow stress, as function of inclusion ratio. Thus, it was possible for us to confirm the morphological characteristics of the blends studied, to show evidence of an interphase terpolymer, between inclusions and matrix, and to evaluate its composition and width
Khavandi, Alireza. "Etude de la déformation non élastique de composites unidirectionnel verre-résine époxyde : prévision du comportement mécanique (module dynamique, fluage)". Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0004.
Those last years, mechanical properties of composite materials have led technologists to substitute them to metallic materials in many applications. Industrial materials are however linked to the best knowledge of their behaviour in service. This implies the conservation of functional characteristics of composite structures when submitted to mechanical solicitations and various environments. This work is a contribution to study of the thermomechanical behaviour of unidirectional glass epoxy composites. The main experimental techniques involve viscoelastic properties. Mechanical spectrometry reveals the existence of several mechanical relaxation. The α relaxation associated to the glass-rubber transition appears as a good indicator of the molecular mobility and microstructure of polymer. The influence of the reinforcement on the dynamic behaviour of the composite has been studied. Tests of creep have been carried out on the matrix and composite with deviated directions in respect to the orientation of the fibers. Nonlinear character of the viscoelasticity behaviour is also observed with the composite. A physical model previously developed on molecular basis has been used to describe the viscoelasticity behaviour of the matrix. The non-homogeneous dispersion of fibers in the composite material is carried out using the self-consistent model with three phases repeated in three stages which the purpose to take into account the particular morphology of the system. In torsion the model correctly predicts the dynamic mechanical response. However such as approaches overestimates the creep under transverse traction solicitation. The hypothesis of existence of an interface with specific properties as used in this description has been specified with the nano indentation technique and supported by finite elements calculations. To sum, the viscoelastic behaviour of unidirectional glass-epoxy resin composites is clearly analysed through mechanical spectrometry and creep tests by taking into account the morphology. This approach is tentatively improved to consider the high stress nonlinear regime as well
Dinh, Anh Tuan. "Comportement élastique linéaire et non-linéaire du bois en relation avec sa structure". Phd thesis, AgroParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00720245.
Demonchy, Charles-Edouard. "Etude de réactions et d'états isobariques analogues dans le système 8He+p à basse énergie à l'aide de la cible active MAYA". Caen, 2003. http://www.theses.fr/2003CAEN2071.
Loevenbruck, Anne. "Déformation active du domaine Nord Luzon, Philippines, et de Taiwan". Paris 11, 2003. http://www.theses.fr/2003PA112099.
This thesis aims to study the mechanisms and tectonic processes involved in long and short terms active deformation of two mountain ranges, the Central Cordillera of Luzon and the Central Range of Taiwan, both along the Manila subduction zone. The Central Cordillera of Luzon, built along the related volcanic arc, extends at the northern extremity of the left-lateral Philippine fault. This study of this chain aims to characterize the present permanent deformation and the involved tectonic processes. GPS data are first used to define a kinematic model which quantitatively describes the complex tectonic system of Luzon. The interpretation of SAR images and the analysis of field data then show that the relief of the Central Cordillera is built by a thrusting system, now reactivated with a left-lateral component in the northern extension of the Philippine fault. This study suggests that the shortening structures are related to the subduction of the oceanic Scarborough ridge. The Central Range of Taiwan is the accretionary wedge built as the Manila subduction zone leads the continental China margin to converge toward the volcanic arc. Transient deformations of the seismic cycle are examined along the western thrust front, broken in 1999 during the Chi-Chi earthquake. The coseismic slip distribution is first calculated by inversion of the surface displacements measured by GPS and SPOT images correlation. The analysis of the whole seismic cycle transient deformations allows then to examine the implications of this coseismic slip distribution and to propose a tectonic model for Taiwan. The coseismic slip heterogeneities are finally explained by the variations of the interseismic locking, suggesting that the coupling along the western thrust front of Taiwan increases toward north and toward surface, that is globally in the plate motion direction
Zasada, Ilona. "Théorie de la rétrodiffusion élastique incohérente d'électrons lents par un complexe adsorbat-substrat partiellement ordonné". Lyon 1, 1990. http://www.theses.fr/1990LYO10251.
Benoit, Jean-Pierre. "Étude expérimentale et théorique d'une turbulence homogène soumise à des effets couplés de rotation et de déformation plane". Ecully, Ecole centrale de Lyon, 1992. http://www.theses.fr/1992ECDL0026.
Belhadj, Ahmed Abdelwahed. "Contribution à l’amélioration de la rectitude dans l’obtention de produits longs : application aux abouts de rails". Thesis, Paris, ENSAM, 2013. http://www.theses.fr/2013ENAM0066/document.
Long workpieces are characterized by one dimension, usually length is larger than the height and width, for example, railway rails. These products are obtained by hot rolling and then cooling. During manufacturing process, heterogeneity of cooling and plastic deformation induced straightness error. In order to correct this geometrical error, cold straightening process is necessary. Usually, straightening machines are used to correct the straightness of the workpiece center however; the ends' sides were still not straightened. Based on the optical measurement profile, these ends are straightened by mechanical press. The measuring/straightening closed loop is repeated until the straightness of the product is conformed. The process time depends on the knowledge of key parameters related to geometry and material of workpiece. The objective of this research work is to optimize straightening process of the ends of long workpieces. As a first step, the elastic deformation generated during the measurement of long workpiece has been filtered. Then, a coupled analysis of measurement was used to separate error of machine measurement from workpiece measurement, which allowed a better assessment of workpiece straightness profile. Furthermore, based on straightness profile, a semi-automatic straightening methodology has been developed. It is essentially based on an interaction between metrology and mechanics and it is a contribution to the automation of straightening process for ends parts of long workpieces
Solle, Julien. "Contribution à la caractérisation expérimentale et à la modélisation des champs de pression, de deformations et de contraintes induits par un contact élastique entre composants mécaniques". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4133/document.
The aim of this thesis is to evaluate pressure, strain and stress fields induced by a localized contact between mechanical parts. As the different methods have been explored, it appeared that all existent methods just measure physical quantities only indirectly related to the data of interest. By searching a more direct method, the idea of characterizing the deformation of the surface of contact between parts allowed to find a way of measurement: chromatic confocal microscopy. Thus, measuring this surface by transparency and using Boussinesq and Cerrutti potential theory allows first to calculate the pressure field at the contact between the parts but also to evaluate the other associated elastic fields. This approach also helped to develop an original and highly simulation method of localized contact applying to any contact geometry
Bernard, Denis. "La mesure de la partie réelle de l’amplitude nucléaire élastique proton-antiproton à une énergie dans le centre de masse de 546 GeV". Paris 11, 1987. http://www.theses.fr/1987PA112165.
Bazalgette, Loïc. "Relations plissement / fracturation multi échelle dans les multicouches sédimentaires du domaine élastique / fragile : accommodation discontinue de la courbure par la fracturation de petite échelle et par les articulations : Possibles implications dynamiques dans les écoulements des réservoirs". Montpellier 2, 2004. http://www.theses.fr/2004MON20142.
Bénard, Michel. "CComparaison élastique de courbes à l'aide de distances bâties sur des modèles stichastiques et déterministes". Cachan, Ecole normale supérieure, 1997. http://www.theses.fr/1997DENS0009.
Eslami, Javad. "Étude de l'endommagement à court et long terme d'une roche poreuse". Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL006N/document.
Among the different phenomena responsible for the short and long term deformation of porous rocks, we have studied in this work the damage of an oolithic limestone in the semi-brittle regime and under different hydrous conditions. For this purpose, we have developed an experimental device allowing the simultaneous and continuous measurement of strains and elastic wave velocities, as well as acoustic emissions, on the same sample under mechanical loading and under different hydrous conditions. Particularly, the experimental setup allows simultaneous and continuous measurement of the five elastic wave velocities in 3 different directions of propagation (axial, lateral and off-axis) and 3 different directions of polarization (P and 2 perpendicular S), this almost instantaneously. These velocity measurements allow to assess the acoustic tensor at any time and thus to continuously monitor the evolution of the damage of the rock. The short and long term damage behavior of the limestone is modelled thanks to a phenomenological model which is based on a macroscopic generalization of the microscopic mechanisms highlighted by the experimental study (sliding-opening of existing cracks, nucleation of new cracks, propagation and coalescence of cracks). The short-term model reproduces very well the instantaneous behavior (stress-strain curves and evolution of elastic moduli). The long-term model, whose formulation is uncoupled from the short-term model, allows reproducing qualitatively the experimental creep curves
Haddag, Badis. "Contribution à la modélisation de la mise en forme des tôles métalliques : application au retour élastique et à la localisation". Phd thesis, Paris, ENSAM, 2007. http://pastel.archives-ouvertes.fr/pastel-00002780.
Leiva, Daniel Rodrigo. "Étude de l'élaboration de nanocomposites à base de magnésium pour le stockage d'hydrogène par broyage à haute énergie et déformation plastique sévère". Grenoble 1, 2009. http://www.theses.fr/2009GRE10040.
Mg-based nanocrystalline alloys or nanocomposites are promising materials for hydrogen storage in the solid state, being more effective and safe storing media than pressurized or liquefied hydrogen. In this work, the synthesis and processing of theses materials by high-energy ball milling (HEBM) and severe plastic deformation (SPD) were studied. MgH2- and Mg2FeH6- based nanocomposites were prepared by reactive milling under hydrogen atmosphere using different conditions in order to clarify the effects of several processing parameters in the hydride synthesis. Beside this, the use of the SPD techniques of high-pressure torsion (HPT) and equal-channel angular extrusion (ECAP) was explored to compose processing routes for Mg-based reactive mixtures for hydrogen storage. The materials prepared by the different methods were characterized by structural analysis techniques as, among others, X-ray diffraction, optical microscopy, scanning and transmission electron microscopy. The desorption behavior was studied by differential scanning calorimetry and selected samples were submitted to H-sorption cycles for kinetic measurements. The correlation of the results for the different Mg-based systems has promoted a better control of the synthesis of the nanocomposites by reactive milling and also a better knowledge of the potential of use of the SPD techniques in the composition of processing routes aiming hydrogen storage applications
El, Housseini Hiam. "Modélisation du comportement d'un bicouche (élastique - viscoélastique) sous l'effet du retrait dans la couche viscoélastique". Phd thesis, Ecole Nationale des Ponts et Chaussées, 1994. http://tel.archives-ouvertes.fr/tel-00523173.
Daghbouj, Nabil. "Implantation ionique d'hydrogène et d'hélium à basse énergie dans le silicium monocristallin". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30018/document.
The high dose hydrogen ion implantation is used in the Smart Cut (tm) process to transfer relatively thick (i.e. >200 nm) Si layers from a donor substrate onto a host material. Hydrogen and helium co-implantation at low energies for a much lower total fluence opens the way for transferring extremely thinner (i.e. <50 nm) layers. However, the phenomena and the mechanisms responsible for the interaction, close to a wafer surface, between H, He, silicon interstitials and vacancies they generate remain poorly understood. First, we studied the effect of reducing the ion energies during both H and He implantations onto the formation and the development of blisters during annealing. Blisters were formed from the micro-cracks since a stiffener was not bonded to the implanted wafer. An approach, based on the comparison between experimentally obtained size characteristics of blisters with the finite element method simulations, allowed us to deduce the pressure inside blister cavities and the fraction of the implanted fluences used to pressurize them. We showed that even when implanted at very low energy, H and He atoms do not exo-diffuse out of the implanted region during annealing. We were able to identify, and then relate the efficiency of blister coalescence to a variation in the elastic energy of blisters as a function of their depth position. In a second part, we studied the role of the damage, produced by He and H coimplantation, on the formation and the thermal evolution of the microstructure of the implanted silicon. These investigations were realized as a function of either the order of co-implantation, or the nominal position of the He profile with respect to the H one, or the ratio between He and H fluences. We showed that the H depth distribution was never affected by He co-implantation. Helium was always trapped at the depth where the damage was maximum. When the damage was highest within the H profile, He diffused and was trapped there in the nano-bubbles and /or the blister cavities. However, when the damage was higher within the He profile than within the H one, He remained trapped in the nano-bubbles outside the H profile. Helium contained in the nano-bubbles, whatever their depth distribution, did not contribute to a pressurization of blister cavities that slowed down their coalescence. Finally, we have proposed various scenarios accounting for the similarities and the differences evidenced both before and after annealing at low or higher temperatures depending on the type of realized implantation
BELHADJ, AHMED Abdelwahed. "Contribution à l'amélioration de la rectitude dans l'obtention de produits longs : application aux abouts de rails". Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2013. http://pastel.archives-ouvertes.fr/pastel-00973531.
Houdellier, Florent. "Contribution au développement du CBED et de l'holographie HREM pour l'analyse des déformations de couches épitaxiées". Toulouse, INSA, 2006. http://www.theses.fr/2006ISAT0014.
Epitaxial thin layers undergo an elastic strain, related to the difference in lattice parameters, accompanied or not by chemical segregation. These various effects influence directly the properties of the epitaxial thin layers (emission in quantum wells, transport and magnetic anisotropy. . . ). They interest both fundamental research and applications aiming at adjusting the properties of epitaxial layers through the control of their state of strain. Most of the experimental techniques used to determine the lattice parameters in epitaxial layers only provide information averaged over the whole layer or its surface. On the contrary, Transmission electron microscopy (TEM) makes it possible to precisely select the studied zones, which is a considerable advantage in the presence of heterogeneities. In particular very accurate measurements can be obtained by convergent beam electron diffraction (CBED). This work aims at developing reliable methods to measure the strain in thin layers with a spatial resolution of the order of a nanometer. The selected systems for this study were SiGe=Si and GaInAs=GaAs epitaxial thin layers. CBED patterns obtained on cross-sectional specimens reveal a very heavy deformation in the layer and we observe, in the substrate, a strong evolution of the HOLZ line profile as a function of the distance between the studied zone and the interface. We showed that this evolution results from a free surface relaxation effect occurring in thin foils of strained specimens. This effect depends on many parameters, such as the thickness of the sample, the misfit and the distance between the studied zone and the interface. In order to retrieve the strain in the specimen, we developed a new method based on the combination of finite elements calculations and dynamical simulations obtained using an original formalism developed during this work and referred as TDDT (Time-Dependent Dynamical Theory). Elastic relaxation could also be observed in samples prepared in plan-view. The state of strain was thus determined in the various specimens through the comparison of simulated and experimental line profiles : remarkable agreements have been reached. These various measurements were compared with studies carried out by electron holography in HREM configuration making it possible to combine structural and chemical characterizations at an atomic scale. This works benefited from the use of a TEM-FEG instrument fitted with both a spherical aberration corrector and an energy filter
Pelloux-Gervais, David. "Caractérisation par méthodes nucléaires avancées de boîtes quantiques d'In(Ga)As épitaxiées sur silicium". Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00838787.
Aït, Hocine Nourredine. "Approche globale de la mécanique de la rupture appliquée aux élastomères : validation expérimentale et numérique d'une expression de l'intégrale J sous une forme multiplicative d'une fonction de la densité d'énergie de déformation et d'une fonction de géométrie". Lille 1, 1996. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1996/50376-1996-192.pdf.
Deux types de matériaux caoutchoutiques sont testés : l'e. P. D. M. Et le polybutadiène. Le paramètre énergétique j expérimental est déterminé par l'application d'une méthode originale (critère de séparation) développé antérieurement au laboratoire. La simulation numérique est réalisée à l'aide du code d'éléments finis ansys v 5. 0, en élasticité non linéaire et en grandes déformations. Les résultats ont mis en évidence l'influence des dimensions finies de l'éprouvette sur le paramètre j. Nous avons particulièrement vérifié la validité de la méthode de séparation et celle de l'expression de j mis sous une forme multiplicative d'une fonction de géométrie et d'une fonction tenant compte uniquement de la non linéarité du comportement. La valeur critique j#c de j régit bien, a priori, la rupture des matériaux étudiés
Compagnon, Didier. "Deux points de physiologie des arcades dentaires humaines : perception buccale de la dureté pour des produits à déformation élastique; mesure de l'egression de la première molaire supérieure humaine, en l'absence de dent antagoniste". Clermont-Ferrand 1, 1991. http://www.theses.fr/1991CLF1DD01.
Bassa, Bruno. "Contribution à l'étude d'éléments finis de type coque sans degrés de liberté en rotation ou à formulation solide pour des simulations numériques de l'emboutissage et du retour élastique". Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00716446.
Lechartier, Audrey. "Influence de la transformation martensitique induite par la déformation sur le comportement mécanique d’aciers inoxydables duplex". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI107/document.
Duplex stainless steels offer an attractive combination of high mechanical properties, low thermalconductivity and a relatively low cost. They are increasingly used as structural materials such as inthe construction sector as concrete reinforcement bars, where both high strength (Rm > 900 MPa)and high elongation to failure (A% > 15 %) are required. This thesis aims at improving the strength/ elongation compromise by developing new duplex stainless steel compositions experiencing a wellcontrolledmartensitic transformation induced by plasticity (TRIP effect). The optimisation of thiscompromise has required a good understanding of the transformation mechanisms and of plasticdeformation associated with each phase : ferrite (BCC), austenite (FCC) and martensite (BCC).The influence of martensitic transformation on mechanical behavior has been studied in four duplexgrades of variable austenite stability as a function of their chemical composition. The influence ofmultiphase microstructure on martensitic transformation kinetics has been determined by makingthree alloys respectively representative of a duplex grade and its two constituents (austenite andferrite). Using multiple characterization techniques at different scales has allowed determiningboth the transformation mechanisms and its kinetics as a function of strain, giving thus accessto the influence of transformation on the mechanical behavior. The study of kinematic fields hashighlighted the impact of the martensitic phase on the distribution of deformations. Finally, theuse of a mechanical model taking explicitly into account the phase transformation has allowed theduplication of the mechanical behavior of a duplex stainless steel
Tampon, Benjamin. "Qualification expérimentale de la μTPC LNE-IRSN-MIMAC comme instrument de référence pour les mesures en énergie et en fluence de champs neutronique entre 27keV et 6,5 MeV". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY083/document.
In France, the references associated to the neutron fluence and the deriva-ted dosimetric quantities are under the responsability of the micro-irradiation and neutronmetrology and dosimetry laboratory (LMDN)of IRSN. In order to improve the definition ofreferences in fluence and energy of the monoenergetic neutron fields, produced at AMANDEfacility, a micro-TPC gaseous detector, called LNE-IRSN-MIMAC, is developping in collabo-ration with LPSC.In a previous work, the detector was qualified for neutron fields in the energy rangebetween 27 keV and 565 keV. The objective of the present work is to extend the range of theμTPC above 1 MeV. The choice of the gas, the development of an analysis method and thedetector characterization allowed to validate the detector capacity to perform measurements inmonoenergetic neutron fields ranging from 250 keV up to 6,5 MeV with a relative uncertaintyof 3% and 2,5% respectively in energy and fluence
Jiang, Chennan. "Damage accumulation and recovery in Xe implanted 4H-SiC". Thesis, Poitiers, 2018. http://www.theses.fr/2018POIT2251/document.
Silicon carbide is a material that can be considered as a wide band gap semiconductor or as a ceramic according to its applications in microelectronics and in nuclear energy system (fission and fusion). In both fields of application defects or damage induced by ion implantation/ irradiation (doping, material structure) should be controlled. This work is a study of defects induced by noble gas implantation according to the implantation conditions (fluence and temperature). The elastic strain buildup, particularly in the case of xenon implantation, has been studied at elevated temperatures for which the dynamic recombination prevents the amorphization transition. A phenomenological model based on cascade recovery has been proposed to understand the strain evolution with increasing dose and for different noble gases. In addition, with the help of transmission electron microscopy the evolution of defects under subsequent annealing was studied. The formation of nanocavities was observed under severe implantation/annealing conditions. These cavities are of different nature (full of gas or empty) according to the xenon and damage distribution. This study is also linked to swelling properties under irradiation that should be projected in the SiC application fields
Girault, Baptiste. "Étude de l'effet de taille et de structure sur l'élasticité de composites W/Cu nanostructurés en couche mince". Phd thesis, Université de Poitiers, 2008. http://tel.archives-ouvertes.fr/tel-00457334.
Elmay, Wafa. "Développement de nouveaux alliages biocompatibles instables mécaniquement à bas module d'Young". Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2013. http://pastel.archives-ouvertes.fr/pastel-00915166.
BAZALGETTE, LOIC. "Relations plissement/fracturation multi échelle dans les multicouches sédimentaires du domaine élastique/fragile :Accommodation discontinue de la courbure par la fracturation de petite échelle et par les articulations. Possibles implications dynamiques dans les écoulements des réservoirs". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2004. http://tel.archives-ouvertes.fr/tel-00007923.
Les principaux résultats de ce travail sont les suivants :
- Une classification originale des relations entre plis et fractures est établie sur la base d'études comparatives de terrain. La cinématique et les origines mécaniques des différentes associations observées sont discutées, ainsi que de possibles implications au niveau de la dynamique dans les réservoirs plissés fracturés sont proposées.
- Le rôle prédominant de zones de fractures appelées articulations sur l'accommodation de la courbure des plis est démontré par de nombreuses études de terrain. Une typologie de ces zones de fractures est proposée sur la base d'exemples naturels et leur origine mécanique est discutée. L'origine mécanique de ces articulations est précisée dans une étude expérimentale. On utilise des multicouches de paraffine cassante, sollicités dans un dispositif de chargement original. Ce dispositif permet une étude paramétrique des conditions de chargement et de la structure du multicouche, tout en autorisant l'observation en continu de la déformation. Les paramètres les plus importants contrôlant la distribution des articulations et leur évolution géométrique sont la pression de confinement et la friction interfaciale dans le multicouche.
- On présente en outre une étude de cas intégrant l'ensemble des résultats et des concepts. Il s'agit de l'anticlinal de la Montagna della Majella (Italie), qui représente un analogue de réservoir plissé/fracturé.
- Des implications des résultats précédents aux problèmes des écoulements dans les réservoirs sont discutées.
Bassa, Bruno. "Contribution à l’étude d’éléments finis de type coque sans degrés de liberté en rotation ou à formulation solide pour des simulations numériques de l’emboutissage et du retour élastique". Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0113/document.
This thesis presents a methodology for developing under-integrated “solid-shell” finite elements for sheet forming simulations like deep drawing where these elements must offer a bending capability and sheet thinning conditions as well. Starting from 8-node elements endowing three degrees of freedom per node (three displacement components), a ninth node is added at the centre of the element. This extra node has just one degree of freedom: a displacement along the ‘thickness’ direction. Several integration points are distributed along this privileged direction (5 points, generally) but the in-plane reduced integration at the centre of the element decreases CPU costs compared to a full integration. A special care has been taken to control all zero-energy modes due to the reduced integration. This additional node allows a linear distribution of the normal strain. With fully-3D constitutive laws, these new solid-shell elements give similar bending results as those obtained with shell elements and a plane stress state hypothesis. This ninth node acts as an additional parameter for the quadratic interpolation of the displacement in the ‘thickness’ direction. The corresponding degree of freedom has a physical meaning and a force, equivalent to a normal pressure for instance, may be prescribed. In situations of a normal pressure and in the case of contact, the obtained normal stress is physically defined, which is not the case for many solid-shell elements found in the literature. The pinching (or the thinning) of sheets is properly modelled. To validate these elements, an apparatus for U-drawing tests with ironing or thinning on strip sheets has been built in the laboratory. The comparison between numerical and experimental punch force during sheet forming is pretty good as well as the geometry of blank after springback
Ponchel, Arnaud. "Champs de déformation locaux autour d'éléments d'addition en solution solide dans les alliages ordonnés TiAl+X (X=Cr, Mn, Ni, Zr, Nb) : déterminations expérimentales et théoriques : application à l'étude de l'interaction soluté-dislocation". Paris 6, 2001. http://www.theses.fr/2001PA066563.
Curtet, Émilien. "Évolution microstructurale et compréhension des mécanismes de déformation d'un acier austénitique stabilisé au titane pour les réacteurs de quatrième dimension". Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2293.
The fourth generation of nuclear reactors must meet new requirements for safety, energy efficiency, and integration into the nuclear fuel cycle. The CEA is a primary actor in this field and is developing new concepts for sodium-cooled fast reactors. The fuel cladding material being considered for these reactors is 15-15Ti AIM1 steel (Austenitic Improved Material #1), which is an advanced austenitic stainless steel containing 15-wt% chromium and 15-wt% nickel, Ti-stabilized and slightly cold-worked. This steel exhibits a singular loss of ductility between 20 and 200°C: the uniform and total elongations (UE and TE) are reduced by a factor of 3 in this temperature range. In addition, the effect of thermal aging on the microstructure and mechanical behavior is poorly known in the lowest operating conditions that are between 400 and 600°C. In this context, the objectives of this Ph.D. thesis are: - Increase our knowledge of the deformation mechanisms involved in the singular behavior at 200°C ; - Study the influence of a thermal aging between 400 and 600°C on the microstructural evolutions and on the mechanical behavior, with particular attention on the singularity at 200°C. Examining the relation between the singular behavior at 200°C and the related deformation mechanisms required a multi-scale approach combining techniques such as tensile tests, Electron Backscatter Diffraction (EBSD), and Transmission electron Microscopy (TEM). The analyses revealed: - A coexistence of twinning and perfect slip at 20°C;- An extinction of twinning replaced by a predominance of perfect slip associated with cross-slip at 200°C;- A continuous increase of the Stacking Fault Energy (SFE) from 20 to 200°C. In particular, the measured values are respectively 27 mJ/m² and 46 mJ/m². The evolution of the deformation mechanisms of 15-15Ti AIM can be explained by a competition between twinning and cross-slip for releasing the strain energy of the material. At 20°C, both dislocation glide and twinning are active, and the twinning produces a “Dynamic Hall-Petch Effect”, which produces continual strain hardening of the microstructure even at high strains, which leads to high ductility. On the other hand, the stacking fault energy is high at 200°C, so twinning no longer occurs, but cross-slip becomes active. Thus, little strain hardening occurs at 200°C, which leads to the rapid onset of strain localization and reduced ductility.Samples that were aged between 400 and 600°C for 1000 hours exhibit no evidence of material recovery. However, TEM observations established a new threshold for the precipitation of nanometric titanium carbides after an isothermal treatment at 500°C for 5000 hours. Concerning the tensile properties, the aged states present a gain both in strength (especially in Ultimate Tensile Strength) and in ductility (UE, TE) compared to the initial cold-worked state. This gain in ductility is observed for all of the temperatures tested (between 20 and 400°C) and is accompanied by an increase of the strain hardening rate of the material. One plausible hypothesis to explain this improvement of the mechanical behavior relies on the nanometric titanium carbides formed during the aging process. These precipitates could prevent by pinning the initially present dislocations to recombine or annihilate with the dislocations introduced by the tensile test
Gourragui, Ismail. "Modélisation numérique, optimisation et commande de machines à réluctance variable". Metz, 2006. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2006/Gourragui.Ismail.SMZ0642.pdf.
He aim of this thesis is the study of the numerical modelling of switched reluctance motors, the optimization of their shape and their dynamics at high speed, and finally, the design of their control. The first part of this study is devoted to introduce a new algorithm of electro-magneto-mechanical coupling phenomenon by taking into account the moving mesh and material saturation. The calculation of eddy current losses, flux linkage and magnetic torque are carried out. On the other hand, the calculation of hysteresis losses by using a Preisach model is introduced. The subject of the second part is to design of a SRM 6/2 structure in order to maximize the average magnetic torque and to minimize eddy current losses. The result obtained is a new rotor shape, that we have named rotor with leading teeth. In the third part, this thesis deals with the design of the waveform currents. We suppose two objective costs, to maximize electromechanical energy conversion and to minimize the electrical loss. This problem is formulated into a multiobjective optimization task with certain constraints. Then the Pontryagin’s principle is applied. The optimality system obtained is solved with the shooting technique for numerical solution. However, the implementation of the control laws is difficult. We thus provide an interval observer of the system in presence of load torque by taking into account a nonlinear model of SRM
Charitopoulos, Anastasios. "Computational Fluid Dynamics study of heavily loaded fixed-pad thrust bearings operating under thermoelastohydrodynamic regime". Thesis, Poitiers, 2020. http://www.theses.fr/2020POIT2285.
The present Thesis investigates the effects of thermal deformations on the performance of fixed-pad thrust bearings operating under high loads and temperatures. The presented work consists of two main parts. Firstly, in order to identify the mechanisms of pressure build-up in parallel surface thrust bearings, the different theories proposed in the scientific literature have been evaluated. To this end, a CFD-based thermoelastohydrodynamic (TEHD) model has been generated, accounting for all the physical phenomena of the lubricant, of the solid domains and their interaction, which have been suggested in the literature as phenomena contributing to the pressure build-up mechanism of the parallel thrust bearing. The importance of each theory has been quantified and a final modelling approach has been proposed, for accurately evaluating the performance of a parallel thrust bearing. Furthermore, the generated model has been validated against experimental results of the literature. The second part of the Thesis utilises the previously proposed modelling approach to evaluate contemporary designs of thrust bearings, such as textured, coated, pocket and tapered-land bearings. In conclusion, the thermal deformations of the bearing pad are established as the main pressure build-up mechanism in parallel thrust bearings. Moreover, they contribute significantly to the TEHD performance of textured and coated bearings. Contrariwise, on pocket and tapered-land bearings, the thermal deformations are of negligible importance, even at high loads and operating temperatures
Mlika, Rabii. "Nitsche method for frictional contact and self-contact : Mathematical and numerical study". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI002/document.
In this thesis, we present and study a new formulation of frictional contact between two elastic bodies based on Nitsche’s method. This method aims to treat the interface conditions in a weak sense, thanks to a consistent additional term stabilized with the parameter gamma. At first, we introduce the study carried out in the small strain framwork for an unbiased version of the ethod. The non-distinction between a master surface and a slave one will allow the method to be more generic and directly applicable to the self-contact problem. The restrictive framework of small strain allowed us to obtain theoretical results on the consistency and convergence of the method. Then, we present the extension of the Nitsche method to the large strain case more relevant for industrial applications and situations of self-contact. This Nitsche’s method is formulated for an hyper-elastic material and declines in the two versions: biased and unbiased. We describe a class of methods through a generalisation parameter theta . Particular variants have different properties from a numerical point of view, in terms of accuracy and robustness. To prove the accuracy of the method for large deformations, we provide several academic and industrial tests. We also study the influence of numerical quadrature on the accuarcy and convergence of the method. This study covers a comparison of several integration rules proposed in the literature for other integral methods
Pelloux-Gervais, David. "Caractérisation par méthodes nucléaires avancées de boîtes quantiques d'In(Ga)As épitaxiées sur silicium". Electronic Thesis or Diss., Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0109.
The integration on silicon of direct band gap materials such as some semiconductors from the III-V group is of a rising interest for tomorrow's optoelectronic devices. Although silicon is the raw material for many microelectronic devices, it has a poor light emitting efficiency due to his indirect band gap. Among the III-V family, the In(Ga)As compounds present the advantage of a smaller band gap than silicon, which encourage the confinement of electron-hole pairs. However, the large lattice mismatch between silicon and In(Ga)As is a serious limitation for the epitaxial integration. This PhD work has been focused on the ion beam study of In(Ga)As quantum dots (QDs) grown by epitaxy on silicon and of the QD capping by silicon. Rutherford Backscattering Spectrometry (RBS) has been used to quantify composition of both QDs and cap layer. Exo-diffusion and excess issues of some elements have been pointed out. The epitaxial relation between QDs and substrate have been investigated by ion channelling (RBS-C). Medium Energy Ion Scattering (MEIS) has also been used to obtain high resolution profiles of composition, defects and strain for both the QD plane and the capping layer. Direct space mapping of both crystals has also been achieved by MEIS thanks to the blocking effect
Delannoy, Stéphanie. "Développement d’alliages de titane innovants à gradient de propriétés pour applications implantaires". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066653.
The work carried out concerns the development titanium alloys with elastic gradient. They are part of the development of materials dedicated to dental implantology, in collaboration with the company Biotech Dental. The elastic discontinuity observed at the bone / implant interface has been called into question in the occurrence of bone resorption phenomena which can lead to implant failures. The lowering of the surface modulus could then allow a more appropriate transfer of stresses which would lead to an improvement of the osseointegration. An upstream work, based on the consideration of electronic parameters and biocompatibility elements, made it possible to select alloys which can exhibit a great elastic variability: Ti-13Nb-13Zr (wt.%) and Ti-20Nb-6Zr (at.%). A preliminary study carried out on laminated samples allowed to confirm this variability and to associate the elastic bounds obtained with different microstructural states. On the basis of these observations, we have developed approaches combining sequences of deformation and short heat treatments on massive samples. Thus, on the TNZ, a surface deformation approach by shot peening applied on a β-quenched state made it possible to obtain a gradient of 65 GPa to 85 GPa over 400 μm. And a preferential dissolution approach on the Ti-13-13 has lead to a gradient of 75 GPa to 130 GPa on 100 μm, via the realization of flash thermal treatments on massive samples in the precipitated state previously shot-peened. These results have thus validated the previously designed material - strategy - process combinations. They also allowed a rationalization of the different possible approaches to obtain the elasticity gradient
Flerit, Frédéric Jean-Philippe. "La mécanique de l'extrusion et de l'extension continentale en Anatolie-Egée : comment la mécanique de la fracturation, basée sur des observations tectoniques et géodésiques (GPS), réconcilie la déformation continentale avec la tectonique des plaques". Paris, Institut de physique du globe, 2003. http://www.theses.fr/2003GLOB0010.
Tectonic and geodetic observations (GPS) allow us to model the present-day deformation of the Anatolia-Aegean region and its mechanical evolution. In our approach, the deformation of the lithosphere is localised on known faults, treated as dislocations in elastic half-space. We show that two tectonic processes are superposed at the lithospheric scale : The extension associated with the Hellenic subduction and the extrusion of Anatolia associated with the propagation of the North Anatolian Fault (NAF). Since the NAF entered the Aegean, the two processes interact mechanically. We show that a large process zone forms at the front of the NAF, as the lithosphere relaxes long-term elastic strains. As a result the NAF has become a transform fault for 3/4 of its length. The simple elastic behaviour of the continental lithosphere explains the mechanical balance between the rigid rotation of Anatolia and the deformation of the Aegean
Durinck, Julien. "Modélisation de la plasticité de la forsterite par calculs à l'échelle atomique et par dynamique des dislocations". Lille 1, 2005. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/9fd43a9a-26ef-450b-93e3-5ad8c43033b0.