Дисертації з теми "Déformation résiduelles"
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Lê, Minh-Bao. "Propagation de fissure par fatigue en présence d'une pré-déformation et de contraintes résiduelles." Palaiseau, Ecole polytechnique, 2013. http://www.theses.fr/2013EPXX0032.
Повний текст джерелаKombate, N'Yimanne. "Modélisation numérique et optimisation des micro et nano connecteurs twist-pin." Thesis, Reims, 2018. http://www.theses.fr/2018REIMS027.
Повний текст джерелаThis PhD thesis is part of the FUI "MicroConnect" project, carried out by Axon'Cable Group, whose main objective is the design and development of an automated forming process to manufacture a new type of innovative and high-performance twist-pin connectors. These connectors are used in many fields such as aeronautical electronics, avionics, military systems because of their strength and their hability to be used in very demanding environments... An essential element of the connectors is the contact, as it makes the transfer of the electric current from a system to another. Each connector can have tens or even hundreds.Due to the sequence of the processes used to produce these contacts, their initial properties can be modified. The use of numerical simulation is therefore essential to master the influence of these processes on the final product. The approach adopted in this work consisted in modelling the different steps of the contact fabrication (bending, laser welding and crimping) on the Abaqus software in order to determine the residual stresses resulting from these operations. These models are validated by comparing them with experimental investigations carried out. Finally, an optimization of the crimping is done to highlight the geometrical configurations of the tools allowing the developed product to respond to the tearing tests provided by the validation standards
Taro, Mandikizinoyou. "Modélisation et simulation des procédés de mise en compression des surfaces à très grandes vitesses de déformation par méthode semi-analytique." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0105/document.
Повний текст джерелаThe failure of the mechanical parts is very often initiated by a surface defects. Consequently, the generation of compressive residual stresses on mechanical parts by introducing a heterogeneous plastic strain improves the resistance to fatigue and increases the lifetime of the parts. Among the processes making it possible to introduce residual stresses into the parts, the laser shock peening is more interesting for several reasons. On the one hand, it makes it possible to produce pressures on the surface of material of about 1 to 6 going GPa over short pulse times from 3 to 30 nanoseconds. In addition, he gives the opportunity of introducing residual stresses of compression on a certain depth while preserving the initial state of the treated part. The numerical simulation becomes necessary to determine the best physical phenomena involved. Thus, the semi-analytical method offers a lot of advantages, in particular the simplicity of the models and the computation times saving. This method was never extended to the dynamic problems. In this thesis the semi-analytical method was extended to the dynamic problems and the model implemented is applied for the simulation of the Laser process of shock
Mammadi, Younes. "Métrologie optique à petite échelle sous Microscope Électronique à Balayage : mesures de champs cinématiques en présence de discontinuités, par couplage FIB-MEB-CIN." Electronic Thesis or Diss., Poitiers, 2020. http://www.theses.fr/2020POIT2288.
Повний текст джерелаThis work is divided into three main parts. Initially, in order to order to carry out our studies at smaller scales such as micrometric scale, we must not only use a more complex means of observation, for example, scanning electron microscope "MEB-FEG" to obtain images usable in metrology optical, but also have to mark (speckle) on these scales. More recently, digital image correlation is the most widely used kinematic field measurement technique to study the mechanical behavior of materials and structures over an area of interest ranging from the meter scale to the millimeter one. This can be obtained by using a dual-focused ion beam technique. Furthermore, we have adopted a scientific approach by first developing an artificial speckle, with an engraving depth of the order of 100 nanometers. We also relied on statistical tools such as the range of gray levels, autocorrelation, the number of passes and the variation of magnification, which were necessary to validate the marking and to generate better results.In the second part, we coupled the DIC by utilizing the scanning electron microscope and the focused ion beam as the labelling techniques. In order to build a controlled and reliable metrological solution to observe and quantify the movements and deformations of matter at these scales. Several tests have been carried out on two metals ; Steel 304l and Inconel 718, toensure the repeatability and reproducibility of the procedure. In these tests, we proposed to calculate the horizontal and vertical displacements as well as the error related to these displacements.We demonstrate the same approach on the deformation fields. Different results have been obtained depending on the variation of the standard deviation found in the acquired data making it possible to quantify measurement errors as well as repeatability and drift over time.The last part of the proposed work is about the adaptation of measurement methods to the particular mechanisms of deformation at different scales, such as the location of fractures and damage. To study mechanical behavior and taking into account local fractures, we extract the deformations of a fractured material using a displacement field measurement method. The proposed approach consists of extracting the residual deformations of the first local gradients of H-DIC, the least disturbed by the fractures. Various tests have been carried out to assess the validity of this proposed new approach. An application to study the mechanical behavior of a metallic composite (Al / ω -Al-Cu-Fe) is proposed. Particular exploitation of all the fields lies in the good separation of the deformation fields and the cracked part. A discussion on the comparison between a conventional DIC analysis and its extension is presented on the zones without and with fractures
Panicaud, Benoît. "Contraintes « de croissance » et cinétiques d'oxydation dans des couches d'oxydes thermiques de Fer et de Nickel ;Etude in-situ par Diffraction des Rayons X et modélisation." Phd thesis, Université de La Rochelle, 2004. http://tel.archives-ouvertes.fr/tel-00169180.
Повний текст джерелаBlaizot, Jérôme. "Etude de l'influence des procédés de fabrication sur les propriétés mécaniques des alliages de nickel." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI024/document.
Повний текст джерелаMechanical behavior of nickel alloy 690 (NY690) is characterized from 25°C to 1100°C and for a strain rate ranging from 10-4 to 5×10-3s-1. The effects of chromium carbides and grain size (50-150 µm) on the tensile properties of NY690, were studied at 25°C and 750°C. Chromium carbides have negligible influence on the yield stress and on the strain hardening whereas the grain size slightly decreases the yield stress and the hardening rate at room temperature. The grain size has little influence on the strain-hardening but increases the steady-state stress. The dislocation density is the major microstructural parameter governing the mechanical behavior of the alloy for the studied experimental conditions. The Kocks-Mecking-Estrin formalism is adapted to a wide range of temperature and strain rate to predict the mechanical behavior
Berchi, Tarek. "Comportement micromécanique des alliages de zirconium en grandes déformations." Nantes, 2006. http://www.theses.fr/2006NANT2067.
Повний текст джерелаZirconium and its alloys are hexagonal close packed materials which present high plastic anisotropy and a variety of active deformation modes. As a consequence of these properties, second-order strains (and stresses) are generated during a plastic forming process between the grains having different crystallographic orientation. The mechanical behaviour of these alloys has been studied in the large strain framework for two cases: cold rolled Zy-4 plates and cold pilgering M5 zirconium alloy cladding tubes. Using X-ray diffraction technique, we have determined the residual stresses and crystallographic texture evolutions for different total strains. The elastoplastic self-consistent model was used to predict the mechanical state at the different scales. This model was developed to large deformations. A new formulation of the crystal plasticity has been proposed. The influence and the role of elastoplastic anisotropy have also been studied and explained in this work. A good agreement has been found between experimental and predicted crystallographic textures. The contribution and the magnitude of the first as well as the second-order residual stresses have been correctly evaluated from the measured strain. The prismatic slip is the most active deformation mode in these alloys at large strains
Depouhon, Pierre. "Contribution à la modélisation des déformations et des contraintes résiduelles induites par la nitruration des pièces mécaniques." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4015.
Повний текст джерелаNitriding of steel is a thermo-chemical treatment well known to improve the mechanical properties of the material. It is based on the diffusion of nitrogen into the surface of treated parts. Complex phenomena are then involved and generate residual stresses and distortions. Depending on their geometry, parts can be distorted up to several millimeters and be subject to significant internal tensile-compression stresses. The aim of this work is to provide a multi-physical model of the nitriding in order to predict, for any part geometry, their residual stresses and distortions after treatment. These informations, precious for engineers, will allow to optimize the design and the manufacturing processes of nitrided parts
Ghfiri, Rachid. "Etude du retard à l'amorçage et à la propagation d'une fissure de fatigue après perçage d'un trou avec et sans expansion." Lille 1, 2000. http://www.theses.fr/2000LIL10146.
Повний текст джерелаDans ce travail, trois degres d'expansion ont ete analyses (de = 1. 7%, 3. 4% et 4. 3%). L'expansion du trou ameliore considerablement la duree de vie qui augmente avec le degre d'expansion. Par ailleurs, l'effet du chargement sur le nombre de cycles a l'amorcage est etudie. Ce dernier augmente quand l'amplitude du facteur d'intensite de contrainte diminue. L'analyse des facies de rupture par microscope electronique a balayage montre une zone comprimee au bord du trou et une absence des microfissures. Par contre, loin de cette zone des microfissures orientees dans tous les sens ont ete observees. Une modelisation numerique par elements finis est realisee afin de quantifier les contraintes residuelles de compression ainsi que la zone affectee par l'expansion au bord du trou
Lu, Jian. "Mesure de la distribution des contraintes résiduelles par la méthode du trou incrémentale." Compiègne, 1986. http://www.theses.fr/1986COMPD045.
Повний текст джерелаHassini, Sami. "Qualification multi-critères des gammes d'usinage : application aux pièces de structure aéronautique en alliage Airware®." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22587/document.
Повний текст джерелаThe optimization of machining sequences is not easy because it suffers from two major shortcomings. The first focuses on the adaptability of existing ranges to current production facilities and their evolution over the years to respond to technological developments. The second point concerns the lack of consideration in the mechanical behavior of the part during the development of machining sequence. This thesis addresses these in relation to the FUI OFELIA project. At first, they study the influence of the machining parameters on the deformation of the workpiece. The aim is to predict the mechanical behavior of the part to identify recommendations with minimal distortion. The second issue deals with multi-criteria evaluation of manufacturing ranges. The criteria take into account are the deformation of the workpiece, productivity through a quick estimate of machining time and recyclability of chips produced during machining. On the other hand, we propose a geometric model of the intermediate states of the workpiece during machining in order to both assess the manufacturing recommendations and to drive the simulation calculations of the deformation of the workpiece during machining
Krier, Joël. "Influences des hétérogénéité élastoplastiques sur les contraintes du deuxième ordre dans les polycristaux métalliques mono- et biphasés : calculs autocohérents - mesures par diffraction X." Metz, 1993. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1993/Krier.Joel.SMZ9305.pdf.
Повний текст джерелаThe aim of this work is to study influences of elastoplastic heterogeneities on microscopic stress and strain fields in one - and two phased polycrystals. Local stresses and strains are calculated owing to the self consistant scheme of cinematic integral equation linking local and global strains. Elastic strain calculations allow to show second order stresses and to simulate perfectly X-ray diffraction experiments on isotropic materials and materials with crystallographic and morphologic texture. Parallel calculations and diffraction experiments after tensile plastic déformations show that the model is able to predict residual stresses and their evolution during plastic straining, and their influences on X-ray diffraction experiments. The simple model based on the problem of an inclusion in a matrix allows to explain qualitatively the splitting of X-ray diffraction curves after surface machining in multiphased materials, and to link it to the morphology of the constituents for global homogeneous strains
Veaux, Michaël. "Étude expérimentale et prévisions par le calcul des cinétiques de transformation de phases, des contraintes résiduelles et des déformations lors de la transformation bainitique." Vandoeuvre-les-Nancy, INPL, 2003. http://www.theses.fr/2003INPL050N.
Повний текст джерелаA fully bainitic microstructure is required for some mechanical steel parts. The simulation of the dedicated heat treatment process is necessary to optimise the parts in terms of final microstructures (i. E. Mechanical properties), residual stresses and distortions. The first part of the work deals with the experimental study of the bainitic transformation kinetics, the thermomechanical behaviour of the formed microstructures and the effect of an applied stress on the bainitic transformation (transformation plasticity and kinetic effect) for a middle alloyed steel. Different models for the prediction of phase transformation kinetics and thermomechanical behaviour (macroscopic and microscopic cnes) have been used at the scale of specimen without gradients. The. Experimental validations at that scale have allowed to move to the scale of massive specimen (with high gradients) for whlch the dlfferent coupllngs between thermal, metallurglcal and mechanlcal phenomena have been taken into account in finite element simulations. The influence of phase transformations on the development of internai stresses and deformations during cooling have been analysed in details. Moreover, quenching experiments with in-situ temperature measurements have allowed to validate the numerical simulations. It has been pointed out that it is necessary to take into account the effect of internai stresses on bainitic transformation kinetics to predict final microstructure and hardness distributions
Roland, Thierry. "Génération de nanostructures par traitement de nanocritallisation superficielle SMAT sur matériaux métalliques et étude des propriétés mécaniques associées." Troyes, 2006. http://www.theses.fr/2006TROY0011.
Повний текст джерелаThis work aims to study a recently developed process for the generation of a nanocrystalline surface layer on metallic materials. Based on a concept, close to which of ultrasonic shot peening, this process, known as “surface mechanical attrition treatment (SMAT)” is based on a gain refinement mechanism down to the nanometer scale obtained by severe plastic deformations. In this way, the material to be treated is impacted by shot, in general, perfectly spherical balls, launch with random directions at the surface of the sample. Consequently, a nanocrystalline surface layer with a thickness of several tens of micrometers is formed. Because of the very small grain size, nanocrystalline materials are structurally characterized by a large volume fraction of grain boundaries, which may significantly after their physical, chemical and mechanical properties in comparison with conventional coarse-grained polycrystalline materials and which have grain sizes usually in the range of 10-300um. Thus, it may be suggested that the transformation of the surface layer of metals into surface nanocrystalline layer may enhance their overall properties
Aubry, Agnès. "Mesure, par diffraction des rayons X, des contraintes résiduelles dans les couches d'oxyde : application au système Ni/NiO." Compiègne, 1985. http://www.theses.fr/1985COMPI193.
Повний текст джерелаHoblos, Jazzar. "Évaluation des contraintes résiduelles par méthode ultrasonore avec prise en compte des effets de la microstructure : application au cas du soudage." Lille 1, 2004. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2004/50376-2004-318.pdf.
Повний текст джерелаKassegne, Komlan Assogba. "Analyse par diffraction X en trois dimensions des déformations/contraintes dans des matériaux cristallins à réseaux très déformés." Vandoeuvre-les-Nancy, INPL, 1992. http://docnum.univ-lorraine.fr/public/INPL_T_1992_KASSEGNE_K_A.pdf.
Повний текст джерелаTraore, Yeli. "Influence de la plasticité dans la mesure des contraintes résiduelles par la méthode du contour." Thesis, Reims, 2014. http://www.theses.fr/2014REIMS027.
Повний текст джерелаThe contour method has emerged as a promising technique for residual stress measurement in relatively large, thick and complex engineering components. The method involves making a cut in the sample of interest, measuring the subsequent relaxed deformation of the cut face and using this profile to back-calculate the original residual stress field by FE modelling. The method is based on the theory of elasticity in that the stress relaxation during test specimen cutting is assumed to be entirely elastic. However, when measuring residual stresses close to the material yield stress, plasticity can occur and affect the measurements.The main aim of this thesis was to develop methods of mitigating and estimating plasticity-induced errors in the contour method. The outcomes of this research provide a valuable insight into how accumulation of plasticity affects the performance of the contour method. A novel cutting strategy that aims at mitigating the plasticity-induced errors has been developed. Furthermore, procedures are developed to estimate the plasticity-induced errors. Finally guidelines are proposed and applied to a case study for mitigating the plasticity-induced errors in the contour method
Liu, Shibo. "Numerical and experimental study on residual stresses in laser beam welding of dual phase DP600 steel plates." Thesis, Rennes, INSA, 2017. http://www.theses.fr/2017ISAR0003/document.
Повний текст джерелаLaser welding process is widely used in assembly work of automobi le industry. DP600 dual phase steeis a high strength steel to reduce automobile weight. Residual stresses are produced during laser weldingDP600. Continuum mechanics is used for analyzing res idual stresses by finite element simulation.Based on experimental tensile tests, the DP600 steel constitutive model are identified. The hardening termaccording to Ludwik law, Voce law and a proposed synthesis model are studied. The temperature sensitivityof Johnson-Cook, Khan, Chen and a proposed temperature sensitivity model are investigated. The strain ratesensitivity model proposed by A. Gavrus and planar anisotropy defined by Hi ll theory are also used.Cellul ar Automaton (CA) 20 method are programed for the simulation of solidification microstructureevolution during laser welding process. The temperature field of CA are imported from finite element analysimodel. The analysis function of nucleation, solid fraction, interface concentration, surface tension an isotropy,diffusion, interface growth ve locity and conservation equations are presented in detail. By comparing thesimulation and experimental results, good accordances are found.Modelling by a finite element method of laser welding process are presented. Geometry of specimen, heatsource, boundary conditions, DP600 dual phase steel material properties such as conductivity, density, specifiheat, expansion, elasticity and plasticity are introduced. Models analyzing hardening term, strain ratesensitivity, temperature sensitivity, plastic an isotropy and elastic an isotropy are simulated.The numerical results of laser welding DP600 steel process are presented. The influence of hardening term,strain rate sensitivity, temperature sensitivity and anisotropy on residual stresses are analyzed. Comparisonwith experimental data show good numerical accuracy.Keywords: Laser Welding, DP600, Residual Stress, Cellular Automaton, Hardening, Temperature sensitivity,Strain Rate Sensitivity, Anisotropy, Mixture dual phase law
Chevre, Pascal. "Modélisation magnéto-thermique, métallurgique et mécanique et validation expérimentale de traitement par induction des engrenages à dentures hélicoïdales." Paris, ENSAM, 2000. http://www.theses.fr/2000ENAM0009.
Повний текст джерелаThis work is a part of developpemnt of a new gear box by Research Departement of RENAULT. The aim of this work is to replace a thermo chemical by an induction contour harding. To have a perfect control of the process, the different physical phenomena were modeled. This report falls in 3 parts : the 1er chapter is dedicated to the state of the art of induction contour hardening and more particularly of its simulation. An analysis of physical phenomena is performed. In chapters 2 and 3, the equations and models needed are presented. The difficuty to obtain accurate measures is outlined. Chapters 4 and 5 are the heart of this report. The 2D and 3D simulation allowed the study of the process parameters influence and parameters sensibilities on the results. The difficulty to obtain a correct treatment of the gear because of the helical geometry of teeth is shown. The duration cycle, the strains and stress state in the part were calculated. First experimental results were compared to numerical predictions. In conclusion, numericla simulation has shown its usefulness in analys and understanding of physical phenomena, and appears as an efficient tool to design and optimise the induction heat treatment of helical gears
Dusfour, Gilles. "Contribution à l’étude de la croissance du disque intervertébral et de cartilage de synthèse." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS049/document.
Повний текст джерелаThis thesis aims to contribute to the study of the intervertebral disc growth. It is a part of a global reasearch program which focuses on the development of new predictive tools to improve treatments related to cartilage and fibrocartilage growth phenomenon pathologies. A second objective is to provide elements of understanding that could be useful for the development of innovative tissue engineering technics.The first experimental part of this work consists in the identification of quasi-static mechanical properties of the annulus fibrosus of the intervertebral disk, through an anisotropic hyperelastic constitutive law, as well as a residual strains field present within the annulus fibrosus, through a digital image correlation tool. This double identification makes it possible both to estimate the stress field in vivo of the annulus fibrosus, but also to obtain a historical trace of the growth process which will serve us as a reference in the rest of the study.We note the spatial homogenization of the deformations during physiological loadings when residual strains field is take into account in a numerical model of annulus fibrosus. These results underline the importance of the consideration of residual strains in the estimation of the deformations and stresses undergone by the annulus fibrosus.In addition, a growth scenario of the annulus fibrosus associated with two mechanical growth criterias has also been implemented using the finite element method. The results of this numerical study did not make it possible to reproduce the residual strains field estimated experimentally. Only the growth model using an anisotropic mechanical criterion taking into account the fibers direction present in the annulus fibrosus and in the case of a deliberately omitted load in the vertical direction on the annulus fibrosus has made it possible to qualitatively reproduce the tangential residual strains measured experimentally.In order to complete the understanding of cartilage growth, a biomechanical study of a synthetic in vitro cartilage model revealed the impact of the TGF-beta3 growth factor on the extracellular matrix cartilage stiffness. A strong correlation between the cartilage cell gene expressions and the mechanical properties of the extracellular matrix was found. This strong correlation between cellular activity and the rigidity of the extracellular matrix, coupled with the difficulty of the current growth models based solely on mechanical criteria, opens up interesting prospects for studies on the understanding of the phenomenon of growth under mechanical stimulus. In-depth study of this sample will eventually enrich the growth models to take into account the different physical phenomena present in biological tissues
Stoehr, Michèle. "Epitaxie par MOVPE de ZnSe sur des substrats semiconducteurs et études des contraintes dans ces hétérostructures." Montpellier 2, 1991. http://www.theses.fr/1991MON20301.
Повний текст джерелаXu, Chan. "Étude et simulation numérique d’un procédé de cuisson rapide pour l’élaboration de matériaux composites à matrice thermodurcissable." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14895/document.
Повний текст джерелаThe autoclave polymerization is the bottleneck of the production flux for largepublic parts, hence the speedy polymerization process emerges to improve the productionratio. The objective is to study the possibility of reducing the cycle time of polymerizationfor the production of thin composite laminates using a fast cure process out-of-autoclave.Specific or standard chemical and mechanical characterization tests had been designed inorder to capture the expected characteristics for the model simulation and validate thesimulation results. According to the values obtained, an analysis based on the finiteelement technique is developed to simulate the speedy curing process of epoxy resincomposite. The analysis relates the cure temperature to the thermal, chemical and physicalprocesses occurring in the thin composite part during cure. Included in the analysis are theeffects such as the heat generation due to exothermic chemical reactions. For a specifiedcure cycle, the model could be used to calculate the temperature distribution, the degree ofcure of the resin inside the composite part as well as predict the residual curing stressesand the strains of the cured composite parts.Keywords :
Christelle, Combescure. "Formulation d'un modèle homogénéisé de plaque en béton armé pour des applications sismiques." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00880279.
Повний текст джерелаGuidara, Mohamed. "Tenue en service des joints soudés : influence des paramètres géométriques." Lille 1, 2007. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2007/50376-2007-142.pdf.
Повний текст джерелаKolegain, Komlan. "Correction de trajectoires d'un robot manipulateur utilisé pour le soudage par friction malaxage." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0033/document.
Повний текст джерелаFriction Stir Welding (FSW) is a recent process used for welding metallic parts in aerospace, automotive, and railway industries. Serial industrial robots may be used as FSW welding machines, but because of their lack of stiffness, they undergo elastic deformation under the effect of stresses produced by the process. This causes a welding tool path deviation both in position and orientation, which induces defects in the weld seam. In this work, two path correction methods were developed. The first method is based on the prediction of the position and orientation deviations in the cartesian space from robot models and stiffness model of the links and the joints. The knowledge of tool deviations enabled the synthesis of a path programming approach adapted for robotic FSW. Unlike linear interpolation methods often used, this approach is based on approximations of the adapted path by Bézier or B-splines curves. Experimental validations on a Kuka KR500-2MT robot welding complex paths showed an average residual deviation of 0.3 mm and weld seams without defects. The path accuracy achieved makes it possible to consider an industrial exploitation of the developed solution. The second proposed correction method uses position feedback with a 2D laser profile sensor in the feedback loop for real-time measurement of deviations. Two controllers were designed to correct the deviations. In spite of the external disturbances related to the constraints of the process, experimental results obtained on straight and curvilinear welding paths showed the stability of the feedback loop and a mean residual deviation of 0.1 mm was achieved. The interests and difficulties of deploying this second method were also highlighted
Khan, Inamullah. "Etude expérimentale de la corrosion en béton armé." Thesis, Toulouse, INSA, 2012. http://www.theses.fr/2012ISAT0043/document.
Повний текст джерелаThe thesis aims to study the effect of corrosion on the mechanical properties of reinforced concrete reinforced concrete structures in chloride environment. Experiments were carried out in order to investigate the different mechanical properties such as bending strength, shear strength etc. The experimental work consists of two parts; in the first part small annular cement sand mortar samples were tested in order to observe the effect of cracks on corrosion. Results show that cracks whatever their width allows the corrosion onset at bottom of cracks and along the steel-concrete interface damaged zone caused by the creation of cracks. In the second part an extensive study was carried out on a 26-year-old corroded reinforced concrete beam and a non-corroded of same age in order to better understand the effect of corrosion on reinforced concrete members in flexion and shear. Impact of corrosion on the mechanical properties of steel in reinforced concrete was studied. A new model was proposed for the relationship between corrosion cracks width and loss of steel cross-section
Saadaoui, Mohamed. "Optimisation des circuits passifs micro-ondes suspendus sur membrane diélectrique." Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00011358.
Повний текст джерелаXu, Chan. "Étude et simulation numérique d'un procédé de cuisson rapide pour l'élaboration de matériaux composites à matrice thermodurcissable." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-01064333.
Повний текст джерелаOumarou, Noura. "La caractérisation mécanique de systèmes film-substrat par indentation instrumentée (nanoindentation) en géométrie sphère-plan." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL001N/document.
Повний текст джерелаDepth sensing Indentation (nanoindentation) is an experimental technique increasing retained for the assessment of the mechanical properties of materials (hardness H, Young's modulus E) for which common homogeneous mechanical tests can not be performed or are extremely difficult to perform. The mechanical parameters are obtained from the indentation curve (the plot of the load vs penetration depth during both load and unload). Usually, some methodology reported in the literature (Oliver and pharr, Field and Swain, Doener and Nix, Loubet and al.) are used in order to assess E and H. We have performed a number of experiments on homogeneous materials (stainless steel AISI304, AISI316, AISI430; high-speed steel HSS652; glass SiO2) as well as a film-substrate system (TiN/AISI430, TiN/HSS652, TiO2/HSS652). Applying the Oliver and Pharr methodology, E end H vary with the applied load as well as the percentage of used unload curve retained for the analysis, as reported in the literature. Besides, in the case of the film-substrate system, only composite parameters are obtained instead of the in-situ films properties. In order to establish a simple strategy for the determination of the elastic modulus of a hard coating, we have carried out many simulations using a boundary element based numerical tool. Then a number of useful results have been identified. The well known elastic relation [delta]=a2/R between the relative approach [delta], the projected contact radius a and the punch radius R, remain valid in the plastic range for homogeneous as well as film-substrate specimens. This allows data indentation to be represented in term of mean pressure F/[pi]a2 vs indentation strain a/R . The initial slope of the loading part of the latter curve is proportional to the elastic modulus of the film, while the slope of the initial part of the unloading curve is proportional to the substrate elastic modulus. Our indentation procedure anlysis has been validated experimentally on a number of samples (TiN/AISI430, TiN/HSS652, TiO2/HSS652) after having established a relation between the punch displacement and the relative approach [delta]
Hernàndez, Moreno Hilario. "Monitoring de la fabrication de tubes composites réalisés par enroulement filamentaire et comportement mécanique sous pression externe." Toulouse 3, 2006. http://www.theses.fr/2006TOU30090.
Повний текст джерелаEl, Mayas Theet Nathalie. "Modélisation microscopique et macroscopique du comportement d'un composite à matrice métallique." Phd thesis, Ecole Nationale des Ponts et Chaussées, 1994. http://tel.archives-ouvertes.fr/tel-00523623.
Повний текст джерелаDang, Vu Hiep. "Phases d'initiation et de propagation de la corrosion des armatures du béton armé fissuré en environnement carbonique ou salin." Thesis, Toulouse, INSA, 2013. http://www.theses.fr/2013ISAT0039/document.
Повний текст джерелаThis thesis aims to study the reinforcement corrosion embedded in reinforced concrete structures on both initiation and propagation of corrosion and its long-term consequences on the service life of structures. Firstly, a long-term study on the conditions for the initiation and propagation of corrosion in saline environment is presented and the first results confirm the early initiation of corrosion, but shows that the influence of pre-cracks on the propagation of corrosion depends on their conditions of exposure and concrete cover thickness. A study was conducted in carbon dioxide condition with presence of cracks to examine its impact on the initiation and propagation of corrosion. The results showed that whatever the mechanical crack opening, the crack edge and the steel-concrete interface were carbonated. Carbonation of the steel-concrete interface is likely to be due to mechanical damage induced by loading and stress transfer from the steel to mortar when creating cracks. This damage is also caused by the presence of internal micro-cracks around the steel bar. Following exposure to wetting-drying cycles, corrosion develops throughout the reinforcement but with a greater thickness of rust layer on the underside of the reinforcement where the quality of the interface is weaker. The results showed that the corrosion cracking induced by the development of rust layer arises from internal micro-cracks due to mechanical damage. This result is consistent with the development of corrosion cracks observed previously in saline environment. Another part of the thesis is to study the residual mechanical properties of corroded reinforced concrete beams of 26-28 years exposed to a saline environment under bending load. The behavior of single tensile steel corroded extracted from these corroded beams is studied. It is very difficult to know the true stress of tensile steels corroded "naturally" in concrete contaminated by exposure to chlorides. Indeed, the corrosion induced by chlorides leads to create corrosion pits with various geometries that make it difficult to determine accurately the residual steel cross-section. However, it appears that the true yield stress is unaffected, the true ultimate stress is slightly increased by corrosion but the total elongation at failure is drastically reduced by the presence of pitting corrosion. The effect of reinforcement corrosion on flexural behavior is then studied. The corrosion resulted in a change in failure mode, from concrete crushing in compression after yielding of tensile steel to brittle failure of tension reinforcement. The decrease of the load bearing capacity is proportional to the loss of steel section in the mid-span section. The loss of ductility or decrease in deflection at failure of reinforced concrete beams is very important and could be the limiting factor for the service life of corroded RC structures. It appears that the change in ductility of corroded reinforced concrete beam is correlated with the change in ductility of the steel due to corrosion. The effect of corrosion on the shear behavior is then studied. To make this, the short-shear span beams (deep beams) were tested under three point bending until failure. The results showed that corrosion can lead to changes in mechanical behavior but load bearing capacity of deep beams is generally unaffected by corrosion of longitudinal reinforcement and stirrups. These results can be explained by a coupled behavior between arch action and beam action leading to change in load transfer mechanism and failure mode. In addition, the capacity of straight end anchorage of corroded reinforcement appears to be very much higher than expected despite the presence of corrosion cracks. Concrete confinement effect due to the end support reaction and the “natural” corrosion condition which do not lead to a homogeneous damage all around perimeter of re-bars may explain these surprising results
Rial, Djihad. "Modélisation tridimensionnelle des flexibles hydroformés et tressés en statique et en fatigue." Electronic Thesis or Diss., Compiègne, 2015. http://www.theses.fr/2015COMP2184.
Повний текст джерелаHydroformed flexible tubes are essential structures used in several industrial sectors such as the automotive sector, the aviation industry or energy production, such as the production of renewable energy in solar thermal energy farms where the panels must both be supplying fluid along and follow the direction of the sun. These structures serve as connecting parts between the rigid parts different mechanisms, primarily used for damping vibrations and acoustic emissions, and, as their name suggests, they also allow flexibility and pressure expansion, which considerably improves the fatigue strength. The mastery and prediction of the mechanical behavior of these structures are very important from a safety point of view and an economic point of view. Indeed, their accidental breakage can cause very serious consequences due to their use in sensitive areas such as the nuclear industry. In this context, this thesis was launched between Compiegne University of Technology and industrial BOA-group to create digital approaches to behavioral predictions and estimating the life braided hoses that take into account extreme conditions (temperature and pressure) and the forming parameters and properties of the materials used. In terms of use, these products are subject to thermomechanical charge-discharge cycles and vibrations can induce complex deformed piping of wear due to friction and damage by fatigue, The purpose of the study is to develop a numerical approach validated by the experience to certify products and improve the design. This approach will allow to estimate the lifetime of braided wavy taking into account: - the initial state of the product after forming and assembly, - thermomechanical stresses, is defined by the specification, or encountered in specific use cases, - vibrations encountered during use in real cases. The expected results are the life of the products from a calculation model of their behavior using the characteristics of the materials and interaction braid / tube
Yao, Wei-Zhen. "Analyses thermomécaniques multi-échelles expérimentale et numérique pour des empilements de couches minces en microélectronique." Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4023.
Повний текст джерелаThe aim of this work is to understand and predict the warpage of silicon wafers during the fabrication process of PTIC microelectronic components. The warpages are partially responsible for several productivity problems. This study is done by coupling analytical calculation, finite element modeling and experimentation. The mechanical characterization of thin films constituting the multi-layered stack has been carried out by an experimental method nanoindentation with the help of a finite element model. The intrinsic stress in the thin films has been determined by coupling measurements of the wafer warpage and a finite element model. The obtained Young’s modulus and intrinsic stress are used to feed the database for calculating the wafer warpage by analytical and numerical approaches. The complexity of the structures (thousands of components in the wafer) required the use of homogenized models to calculate the wafer warpage. These results obtained allow the prediction of the wafer-level warpage in order to optimize the fabrication process flow and therefore reduce the risk of the mechanical problem
Lazzarino, Frederic. "Etude et caractérisation des films minces lors du procédé de lithographie par nanoimpression." Phd thesis, 2005. http://tel.archives-ouvertes.fr/tel-00128711.
Повний текст джерелаL'objet de ce travail de thèse est l'étude et le développement de la technique de lithographie par nanoimpression. Ce travail est principalement axé sur l'étude et la caractérisation des films minces de polymère lors du procédé de lithographie par nanoimpression. Nous nous sommes essentiellement intéressés à la caractérisation des propriétés thermique et physico-chimique des films sur leur substrat, à l'uniformité de l'épaisseur résiduelle, aux mécanismes d'impression, aux déformations du moule ainsi qu'à ses conséquences et enfin aux instabilités des films de polymère lors de l'impression