Thèses sur le sujet « Essais à haute température »
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Assire, Aimery. « Amorçage et propagation de la fissuration dans les jonctions soudées à haute température ». Aix-Marseille 2, 2000. http://www.theses.fr/2000AIX22109.
Texte intégralRobert, Fabienne. « Comportement des bétons sous haute température et en cas d’incendie : caractérisation multi-échelle ». Cachan, Ecole normale supérieure, 2008. http://www.theses.fr/2008DENS0046.
Texte intégralThe full understanding of concrete structure behavior submitted to fire requires to study the phenomena at different scale, from micro scale to macro scale. The aim of this work is to understand the links between the phenomena observed at different scale. This study investigates the chemical phases’ transformation at high temperature thanks to different means of characterization of the microstructure (XRD, DSC, Environmental SEM …). It has been demonstrated that the increase in compressive strength at 200°C may be due to the formation of Katoite or Jaffeite. Moreover, the major part played by the stress state of the concrete elements on the spalling behaviour, between intermediate and full scale, has been put forward. The full scale tests have been done with Promethee Laboratory, new and innovative testing facility which allows to take into account the interactions during a fire between the tested element and the surrounding cold building. The tested element is as a result in a real mechanical and thermal stress state. This approach is based on a substructuring system. The hydraulic jacks forces will be time dependent and calculated taking into account both the deflected shape and the stiffness matrix of the cold surrounding building
Gaweska, Izabela. « Comportement à haute température des bétons à haute performance évolution des principales propriétés mécaniques ». Phd thesis, Ecole des Ponts ParisTech, 2004. http://pastel.archives-ouvertes.fr/pastel-00001147.
Texte intégralTestu, Sébastien. « Déformation à haute température d'un nitrure de silicium à haute performance : relaxation, fluage et essais à vitesse de déformation imposée ». Limoges, 1999. http://www.theses.fr/1999LIMO0018.
Texte intégralZiani, Abdelouahab. « Caractérisation d'alliages légers Al-Cr-Fe pour applications à haute température élaborés par solidification rapide ». Vandoeuvre-les-Nancy, INPL, 1992. http://www.theses.fr/1992INPL035N.
Texte intégralMey, Sébastien. « Absorbeur solaire volumique haute température à propriétés optiques contrôlées ». Thesis, Perpignan, 2016. http://www.theses.fr/2016PERP0014/document.
Texte intégralSolar-to-electricity power plants appear to be the most promises way for large electricity production in the future, in terms of costs as well as environmental impacts. Thus, reaching the required technology level still requires research and innovations in order to implement such power plants at large scale.In this context, volumetric solar receivers/absorbers could allow us to reach higher temperatures in comparison to surface receivers (actual concentrating solar power technology used in solar towers), leading to high efficiency thermodynamical cycles such as Brayton cycles. With the ANR-OPTISOL project, this thesis tends to give new answers on volumetric solar absorbers using ceramic foams:- Experimental studies of open pores ceramic foams used as high temperature volumetric solar absorber have been conducted at CNRS-PROMES laboratory (UPR 8521), with designed of a dedicated experiment for 5cm diameter samples operating under quasi-1D conditions submitted to concentrated solar power at the focal point of a vertical axis solar furnace;- A numerical code has been developed in order to solve coupled heat transfers in porous medium using the “equivalent homogeneous medium” hypothesis, then validated on the experimental campaigns;- Finally, an optimization algorithm has been used (“particle swarm optimization”) aiming the identification of the optimal geometrical characteristics maximizing the solar-to-thermal efficiency of ceramic foams
Colin, Christian. « Etude du fluage du dioxyde d'uranium : caractérisation par essais de fluxion et modélisation mécanique ». Paris, ENMP, 2003. https://pastel.archives-ouvertes.fr/tel-00005741.
Texte intégralQuémard, Ludovic. « Corrosion à haute température et à haute pression de composites thermostructuraux à matrice séquencée SiCf/[Si, C, B]m et Cf/[Si, C, B]m pour applications aéronautiques ». Bordeaux 1, 2005. http://www.theses.fr/2005BOR13019.
Texte intégralMasri, Moustafa. « Étude expérimentale et modélisation numérique du comportement thermomécanique à haute température de l’argilite de Tournemire ». Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10079/document.
Texte intégralWe proposed, in this work, an experimental and numerical study of mechanical behavior of shale rocks subjected to mechanical and thermal loads.In the petroleum industry, during the production of heavy oil with the technique of steam water injection at high temperature, the cap rocks are subjected to coupled thermal and hydro-mechanical solicitations. The challenge is to study the hydro-mechanical behavior of these materials subject to large variations in temperature in order to assess the mechanical stability of the reservoir. The experimental study includes the modifications in a triaxial cell in ordre to support a high temperature (250° C). These modifications are very important for hydrostatic, uniaxial and triaxial tests, all these tests are used to obtain an experimental data base characterizing the thermal effect on the mechanical behavior of shale rocks.The modeling framework is proposed at first to describe the mechanical behavior of shale rock in isotropic case. After a detailed analysis of experimental data obtained in the experimental section, a specific coupled elastoplastic-damage model has been developed to describe the mechanical behavior of these shale materials. The effect of temperature is taken into account and a comparison between numerical simulations and experimental data have shown the ability of the proposed model for the description of thermo mechanical coupling. To describe the behavior of anisotropic rocks, we have proposed an extension of the fabric tensor model to present the initial anisotropy of shale rock. This formulation is expressed in terms of invariant stress tensor coupled with loading orientation. Laboratory tests under different stress paths were modeled, the proposed model seems able to describe correctly the main mechanical responses of shale materials
Bouchard, Sébastien. « Étude de l'effet du courant et de la température sur la dégradation des diodes électroluminescentes blanches à haute intensité ». Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/27759/27759.pdf.
Texte intégralParrens, Coralie. « Cyclage thermomécanique d'un acier inoxydable austénitique à haute température : influence sur le vieillissement et le comportement mécanique. Caractérisations expérimentales et modélisations ». Thesis, Toulouse, INPT, 2017. http://www.theses.fr/2017INPT0015/document.
Texte intégralAustenitic stainless steels are widely used in industrial applications. 310S stainless steel has high chromium and nickel contents, providing a competitive mechanical behavior for high temperature utilizations. Nevertheless, lifetime prediction is difficult to assess under coupled mechanical and thermal solicitations. Many data are available on aging and isothermal creep of austenitic stainless steels, but few consider the coupled effect of multiple solicitations. These data are insufficient to explain industrial macroscopic observations. The aim of this study was thus to explore the involved mechanisms in such a case. 310S stainless steel aging was investigated under various thermal cycling solicitations at 870°C. The obtained microstructures were characterized by numerous experimental means. The effect of thermal cycling on nucleation and growth of sigma phase precipitates was quantified. The results of the present work revealed enhanced sigma phase nucleation in these non-isothermal conditions. In addition, mechanical tests were carried out at 20, 650, 780 and 870°C under a large range of stresses. The results highlight a noticeable influence of microstructural evolution on elastic and creep properties of this alloy. Simultaneous increases of Young modulus, rupture stress and creep rates were evidenced. It was thus evidenced that lifetime prediction of components under thermomechanical cycling must take into account the microstructure change during lifetime. Finally, two models were proposed in order to assess microstructural changes and creep behavior that apply to isothermal and thermomechanical cycling conditions mimicking in service conditions of industrial components
Croizet, Didier. « Etude experimentale et numérique du comportement à haute température d'un nitrure de silicium ». Paris, ENMP, 1992. http://www.theses.fr/1992ENMP0516.
Texte intégralBernadet, Lucile. « Étude de l'effet de la pression sur l'électrolyse de H2O et la co-électrolyse de H2O et CO2 à haute température ». Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0312/document.
Texte intégralThis thesis work investigates the behavior of a solid oxide cell operating under pressure in high temperature steam electrolysis and co-electrolysis mode (H2O and CO2). The experimental study of single cell associated with the development of multi-physical models have been set up. The experiments, carried out using an original test bench developed by the CEA-Grenoble on two types of cells between 1 and 10 bar and 700 to 800 °C, allowed to identify in both operating modes that the pressure has a positive or negative effect on performance depending on the cell operating point (current, voltage). In addition, gas analyzes performed in co-electrolysis led to detect in situ CH4 production under pressure. These pressure effects were simulated by models calibrated at atmospheric pressure. Simulations analysis helped identify the pressure dependent mechanisms and propose operating conditions thanks to the establishment of operating maps
Menigault, Jean. « Influence de la vitesse de déformation sur le comportement cyclique à haute température d'un superalliage à base de nickel ». Compiègne, 1988. http://www.theses.fr/1988COMPD122.
Texte intégralColin, Christian. « Etude du fluage du dioxyde d'uranium : caractérisation par essais de flexion et modélisation mécanique ». Phd thesis, École Nationale Supérieure des Mines de Paris, 2003. http://tel.archives-ouvertes.fr/tel-00005741.
Texte intégraltransitoires de puissance de centrale nucléaire. Nous nous sommes intéressés aux résultats disponibles dans la littérature sur le comportement mécanique du dioxyde d'uranium UO2. Ce sont essentiellement des essais de compression qui ont permis de caractériser le fluage de la céramique nucléaire, et qui ont prouvé que le fluage du dioxyde d'uranium est caractérisé par deux types comportement, en fonction du niveau de contraintes appliqué.
Pour évaluer les sollicitations dans la pastille combustible, EDF ou CEA ont développé des codes de calcul spécifiques, dit globaux. Partant dun de ces calculs lors des transitoires de puissance, nous avons dégagé les ordres de grandeur des sollicitations vues par le combustible (température, gradients thermiques, déformations, vitesses de déformations,). Le calcul des contraintes lors de
transitoires de puissance nécessite lidentification de lois de comportement capables de décrire le comportement de la céramique pour de faibles taux de déformation e,t notamment, sous des contraintes de traction. Partant de ce constat nous avons choisi de caractériser le comportement du
dioxyde duranium en flexion. Le cahier des charges de cette étude imposant de prélever les échantillons directement dans les pastilles, ceci dans un souci de représentativité, lentraxe de sollicitation a été fixé à 10 mm. Pour cette étude nous avons donc développé un dispositif spécifique de flexion trois points pouvant atteindre 2000°C sous atmosphère contrôlée (Ar + 5%H2). Une attention particulière a été portée sur la mesure de la flèche ; elle est assurée par un extensomètre à ombrage laser dédié, d'une résolution de ± 2 µm à haute température.
En utilisant ce dispositif, nous avons testé en fluage des éprouvettes dépaisseur 0,5 à 1 mm. Dans nos conditions d'essai, le fluage stationnaire a pu être décrit à laide d'une loi de Norton avec un exposant de contrainte de 1,73 et une énergie d'activation de 540 kJ.mole-1. Nous avons ensuite modélisé le comportement mécanique du combustible : lintroduction de variables internes dans une loi à écrouissage cinématique a permis de représenter l'ensemble des courbes de fluage et les phénomènes de recouvrance de la déformation présentés lors de déchargements partiels. Lidentification a été réalisée par méthode inverse, couplant optimisation des paramètres et calcul par éléments finis des déformations de l'éprouvette de flexion. L'application de cette loi dans un calcul de transitoire de
puissance démontre que les capacités de relaxation du matériau ne permettent pas de prévenir une rupture radiale du combustible en fin de montée de puissance. Lors du maintien à puissance élevée, la température élevée à coeur autorise une diminution des contraintes, notamment près des évidements. Il en résulte un écoulement de matière principalement axial, clairement confirmé par l'observation de pastilles usagées. L'application finale de notre dispositif expérimental a été de tester des éprouvettes implantées aux ions, sur une profondeur de 50µm. La faible épaisseur de nos échantillons a permis de mettre en
évidence leffet de lirradiation sur le fluage de UO2.
Tran, Nhu Cuong. « Développement d'un modèle d'interface acier-béton à haute température : modélisation des structures en béton exposées au feu ». Phd thesis, Université Paris-Est, 2011. http://pastel.archives-ouvertes.fr/pastel-00657207.
Texte intégralEl, sabbagh Alexandre. « Caractérisation du mécanisme de glissement aux joints de grains dans l’aluminium à haute température par mesures de champs in situ MEB ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX098/document.
Texte intégralIn many industrial applications, polycrystalline materials are subjected to high temperatures at which grain boundary sliding (GBS) plays an essential part. It is however strongly coupled with intracrystalline plasticity, but very few models account for this coupling. GBS is not well understood and poorly quantified experimentally. To do so we have developed a set-up to perform in-situ compression experiments inside a scanning electron microscope, with a contactless temperature measurement. The tests have been done with large grained aluminium samples (0.1 % wt Mn) at several temperatures between 25°C and 400°C and a low strain rate. The kinematic fields measured by digital image correlation (DIC) have allowed the analysis of the start and development of plasticity mechanisms during deformation and their evolution with temperature. We have shown a strong coupling between intragranular plasticity and GBS. At higher temperature, the deformation is more concentrated at the grain boundaries while intragranular slip gets more complex, involving more glide systems. A DIC method has been used to measure the discontinuities at the grain boundaries and thus quantify the part of GBS with respect to the total plastic deformation at 200°C. Despite a large grain size, GBS contributes significantly to the deformation. GBS appears from the start of the deformation process, then reaches a limit. A local approach has been developed to quantify the local amplitude of GBS. This has allowed to weigh the influence of some geometrical parameters, such as grain misorientation, a coefficient which measures the transfer of intragranular sliding across the grain boundary and the orientation of the grain boundary with respect to the direction of solicitation. This last parameter seems to be the most relevant, but does not suffice to characterize the amplitude of the slip. The local properties of the microstructure cannot be neglected
Sasaki, Layla. « Influence du vieillissement sur la résistance à la fissuration par fatigue à haute température d'alliages de titane pour mâts-réacteurs ». Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2018. http://www.theses.fr/2018ESMA0006/document.
Texte intégralThe conception of more efficient aircraft engines induces increased stress and temperature levels on the titanium alloys constitutive of the engine pylon. On the one hand, these materials have to be qualified in terms of damage tolerance. On the other hand, the long term high temperature exposure of these titanium alloys gives also rise to the question of thermal aging and metallurgical stability. Hence, the dimensioning as well as the maintenance of such aerostructures need to be considered in the light of both these critical issues.In the present work, the cyclic behavior as well as the fatigue crack resistance of different titanium alloys (TA6V, Ti 6242 et Ti 17), with various microstructures were studied after different aging conditions. Aging induces mainly an increase in crack growth rates at high values of the stress intensity factor, at room temperature. Subsequently, a thorough characterization procedure of this phenomenon was undertaken,including various types of loadings, at different scales and associated with fractographic analyses. The results allowed to suggest a damage scenario before and after aging, in the case of the alloy most affected by aging: theTi 17 alloy. This scenario shows the occurrence of a « static » mode of failure, which is linked to a damage process associated with intralamellar fracture and decohesion, without noticeable changes in the cyclic behavior. Finally, a time-temperature equivalency approach was developed to describe the kinetics of degradation of the mechanical properties induced by aging
Monfared, Mohammad. « Couplages température-endommagement-perméabilité dans les sols et les roches argileux ». Phd thesis, Université Paris-Est, 2011. http://pastel.archives-ouvertes.fr/pastel-00657206.
Texte intégralBattegay, Gilles. « Étude comparative de la déformation plastique à haute température d'olivines monocristallines à divers cations : essai de détermination du volume d'activation ». Paris 11, 1986. http://www.theses.fr/1986PA112192.
Texte intégralOuaida, Rémy. « Vieillissement et mécanismes de dégradation sur des composants de puissance en carbure de silicium (SIC) pour des applications haute température ». Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10228/document.
Texte intégralSince 2000, Silicon Carbide (SiC) power devices have been available on the market offering tremendous performances. This leads to really high efficiency power systems, and allows achieving significative improvements in terms of volume and weight, i.e. a better integration. Moreover, SiC devices could be used at high temperature (>200°C). However, the SiCmarket share is limited by the lack of reliability studies. This problem has yet to be solved and this is the objective of this study : aging and failure mechanisms on power devices for high temperature applications. Aging tests have been realized on SiC MOSFETs. Due to its simple drive requirement and the advantage of safe normally-Off operation, SiCMOSFET is becoming a very promising device. However, the gate oxide remains one of the major weakness of this device. Thus, in this study, the threshold voltage shift has been measured and its instability has been explained. Results demonstrate good lifetime and stable operation regarding the threshold voltage below a 300°C temperature reached using a suitable packaging. Understanding SiC MOSFET reliability issues under realistic switching conditions remains a challenge that requires investigations. A specific aging test has been developed to monitor the electrical parameters of the device. This allows to estimate the health state and predict the remaining lifetime.Moreover, the defects in the failed device have been observed by using FIB and SEM imagery. The gate leakage current appears to reflect the state of health of the component with a runaway just before the failure. This hypothesis has been validated with micrographs showing cracks in the gate. Eventually, a comparative study has been realized with the new generations of SiCMOSFET
Masson, Isabelle. « Détermination des propriétés mécaniques en fluage a haute température et étude des microstructures de déformation de céramiques a base de nitrure d'aluminium ». Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL136N.
Texte intégralLiang, Yue. « Comportement du béton sous sollicitations multiaxiales en fonction de la saturation et de la température ». Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10198/document.
Texte intégralStudies of this paper are focused on the experimental characterization of concrete durability for Andra (National Agency for Radioactive Waste Management), and notably in order to study the feasibility of radioactive waste storage in deep geological rocks. In that context, the concretes are subjected to coupled mechanisms: stress variation due to cavity excavation, change of water saturation degree due to ventilation and gas pressure, variation of temperature due to exothermic waste… Therefore, it is necessary to acquire new experimental data for an adequate characterization of short and long-term thermo-hydro-mechanical couplings. Researches are carried out on Andra reference concretes made from cement CEM I and CEM V/A. In the short term, various tests highlight the evolution of multiaxial mechanical behaviour of concrete as a function of saturation and temperature. In a long-term view, creep tests (uniaxial and multiaxial) are performed to study the delayed effects of mechanical behaviour under temperature or during drying by small controlled steps in relative humidity
Abdallah, Rafik. « Comportement au feu des briques de terre comprimée ». Thesis, Pau, 2021. http://www.theses.fr/2021PAUU3065.
Texte intégralThe present PhD thesis addresses the high temperature behavior of a compacted raw earth material and a cement stabilized earth material, both of which are likely to be used in fire-prone buildings.A complete campaign of laboratory tests was carried out on the two materials. Residual tests, which included mechanical, thermal and permeability tests were performed after slowly heating at a rate of 2 °C.min-1 using an electric furnace to attain temperatures of 80 °C, 120 °C, 200 °C, 350 °C, 450 °C and 600 °C. Then, fire tests were performed, which allowed for the exposure of these materials' bricks to a high heating rate using a mobile gas furnace designed to follow an ISO 834-1 fire curve in order to simulate a real-life fire accident in a building.Besides the effect of the material composition on the high temperature behavior, the effect of the water content on this behavior was also studied after subjecting the samples of the two materials to different relative humidities (RH): dry condition, 50 % RH, 75 % RH and 100 % RH, at an ambient temperature of 23 °C. As a result, the behavior of these materials is better characterized, allowing for a better understanding of real-world applications in a variety of environments.The material's composition and water content influence significantly its behavior at high temperatures. Following the fire tests, the samples were classified into two categories based on their composition and water state: thermally stable and unstable. The observed differences in behaviors have been ascribed to thermomechanical phenomena. They are caused, on the one hand, by the formed thermal gradients induced as a result of the consequent thermal stresses, which decrease as the water content increases, and, on the other hand, by the intrinsic mechanical properties of the materials (which decrease with the water content). These factors were subsequently demonstrated to play a major role in the material's fire behavior and load-bearing capacity at high temperatures, as assessed by mechanical loading of the samples during fire tests
Thieurmel, Ronan. « Identification des conditions de rupture fragile des gainages combustibles en alliage de zirconium oxydés sous vapeur d’eau à haute température et trempés sous charge axiale ». Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM022/document.
Texte intégralDuring hypothetical Loss-Of-Coolant-Accident (LOCA) scenarios, zirconium alloy fuel cladding tubes are subjected to severe thermo- mechanical loading conditions in highly oxidising chemical environments. Pressure and temperature evolution together with cooling water can lead to ballooning and burst followed by steam oxidation and hydrogen uptake at high temperature, and then axial loading during the final reflooding stage.This study focuses on the identification of mechanisms and key parameters which drive cladding fracture during the reflooding stage under axial tensile load.Laboratory-scale semi-integral tests simulating LOCA transients on Zircaloy−4 test rods have been realised. A fracture/no-fracture threshold of oxidation duration at high temperature has been determined. Two fracture locations have been identified: i) the burst zone with maximal oxidation and no hydrogen uptake, and ii) the “secondary hydriding” zone below the burst zone, with substantial hydrogen absorption and lower oxidation levels. Moreover, a scenario of fracture as a function of the reflooding chronology has been identified. Nevertheless, the macroscopic treatment of these tests has not permitted to discriminate these two fracture locations because fracture independently occurs in and out of the burst zone, whatever the applied transient and the balloon and burst morphologies.From systematic microstructural and fractographic characterisation of test specimens, a local approach aiming at identifying a fracture threshold as a function of the microstructural state of the material has been applied. The complex distribution of chemical elements and phases across the cladding thickness has been determined. Phase transformations in the highly-oxidised balloon, leading to a globally brittle microstructure have been explicated. In the secondary hydriding zone, a fracture threshold criterion has been identified by means of layer thickness measurements and hydrogen uptake profile
DUBIEZ-LE, GOFF Sophie. « Comportement et endommagement d'un superalliage élaboré par compression isostatique à chaud ». Ecole nationale supérieure des mines de Paris, 2003. http://www.theses.fr/2003ENMP1352.
Texte intégralPelisson, Bernard. « Vieillissement du polyamide-11 en présence d'huiles brutes et en température ». Rouen, 1986. http://www.theses.fr/1986ROUES021.
Texte intégralCol, Audrey. « Étude de l'oxydation catastrophique de l'acier 304L : mécanismes et effet d'une prédéformation ». Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI072/document.
Texte intégralTo provide good resistance to oxidation at high temperature, the oxide layers formed on stainless steels must stay thin, rich in chromium and adhere to their metallic substrate. When the stainless steels operate at atmospheres or temperatures that are too severe, breakaway oxidation triggers the quick growth of Fe-rich oxide nodules, which are non-protective, instead of the Cr-rich layer. This study focuses on the different mechanisms that lead to the loss of the protective characteristic of the oxide layer, to the growth of the iron oxides, and in the formation of internal oxidation zones. The study of the morphology and composition of the oxides formed, along with Raman spectroscopy and TEM and EBSD mappings, allowed to propose a mechanism for the formation of the internal oxidation zone. This mechanism relies in part on the formation of a "boundary" oxide layer, that forms along the grain boundaries of the underlying metal during oxidation. This study also showed that a deformation prior to oxidation improves the durability of the steels by encouraging the formation of a protective layer during the first stages of the oxidation. When it starts, breakaway oxidation stays localized while with no deformation, a protective regime is never reached at 850 °C for austenitic stainless steel 304L
Lemarchand, Gwénael. « Caractérisation mécanique et simulation numérique d' une anode tournante de rayons X ». Paris, ENMP, 2003. http://www.theses.fr/2003ENMP1176.
Texte intégralHamadouche, Ines. « Mécanismes d'endommagement d'un composite à matrice céramique revêtu d'une barrière environnementale sous sollicitations multiphysiques ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST020.
Texte intégralThis study is part of the development of the next generation of aircraft engines. Ceramic matrix composites (CMC) made from SiC/SiC are today promising materials for use in aircraft engines hot areas. However, the engine extreme environment requires the CMC to be protected by an environmental barrier coating (EBC) against oxidizing species. In this context, this study consisted in characterizing, modeling and understanding the damage mechanisms of the CMC/EBC system under coupled multiphysical loadings (thermal/mechanical and thermal/oxidation) representative of engine conditions. To address this issue, several test configurations were set up at high temperature (>1200°C) under thermal gradients (laser heating) coupled with mechanical loading (4-point bend test) or an oxidizing environment (steam). Thanks to the instrumentation used (damage detection by acoustic emission, measurement of thermal and kinematic fields), post-mortem SEM analysis and finite element simulations, the impact of loading and stress conditions on the coating cracking were studied. The coupling between coating cracking and system oxidation was also investigated
Alexandre, Franck. « Aspects probabilistes et microstructuraux de l'amorçage des fissures de fatigue dans l'alliage Inco 718 ». Phd thesis, École Nationale Supérieure des Mines de Paris, 2004. http://tel.archives-ouvertes.fr/tel-00161472.
Texte intégralBaril, Catherine. « Filtration réactive à haute température ». Mémoire, Université de Sherbrooke, 2002. http://savoirs.usherbrooke.ca/handle/11143/1146.
Texte intégralPagnoni, Filippo. « Design and Experimental Analysis of a Loop Heat Pipe for Thermal Control of Aircraft Engine Equipment ». Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2019. http://www.theses.fr/2019ESMA0004.
Texte intégralIn this work, the development of a Loop Heat Pipe (LHP) for aircraft nacelle thermal management is presented. The study is focused on engine compartments and integrated equipment applications, according to the upcoming thermal management challenges in the next generation of engines. First, a feasibility study was performed, analyzing the thermal environment, the integration constraints and the identification of suitable working fluid construction material pairs. As for the latter aspect, water and DowthermTM J were identified as most suitable candidates with the lightweight aeronautical alloys considered for this environment. On one hand, the high triple point of water obliged to verify the wick mechanical resistance to repeated freezing cycles when soaked into pure water. On the other hand, compatibility tests were performed between DowthermTM J and the selected alloys, due to the lack of related data. In the former, the sintered titanium wick provided an excellent stiffness and it remained perfectly intact after more than 1500 cycles. In the latter, the thermal tests performed on parallel thermosyphon shave clearly shown the generation of non-condensable gases (NCG) inside all the samples starting from low operating temperatures. As a result, the compatibility of DowthermTM J was considered not fully satisfactory and this fluid was discarded. The next step concerned the design of the titanium/water LHP prototype. Robust numerical tools were developed for the final design validation: a simplified 0D nodal model for the entire device and a coupled 1D and 2D condenser model representation. The LHP prototype was manufactured and tested in different operating conditions. A significant amount of NCG was initially generated inside the device, due top assivation of the internal surfaces. Nonetheless, the experimental results demonstrated the LHP capability to satisfy the thermal requirements, even in presence of NCG, with standing high operating temperatures and pressures. Although the gas generation rate became negligible after several hours of tests, internal inspections performed at the end of the test revealed a deep alteration of the internal surface state, due to the chemical reactions with the working fluid. The results of this work represent an important milestone for the development of a LHP for aircraft nacelle applications. Essential information for the design of future generations of prototypes are provided, toward the validation and certification of LHP for nacelle thermal management
Fiquet, Guillaume. « Propriétés thermodynamiques de minéraux du manteau supérieur. Calorimétrie à Haute Température et Spectroscopie Raman à Haute Pression et Haute Température ». Phd thesis, Université Rennes 1, 1990. http://tel.archives-ouvertes.fr/tel-00626851.
Texte intégralCozonac, Dorin. « Conception d'une machine asynchrone haute température ». Thesis, Artois, 2015. http://www.theses.fr/2015ARTO0209/document.
Texte intégralThe windings that are currently used in electrical machines are mostly insulated based on organic insulation. The temperature limit of these windings is up to 240°C. Increasing the working temperature of electrical motors means, indirectly the increasing of current density on the main conductors. Therefore these new motors may provide a higher mass and volume power as classical machines. Furthermore, the magnetic materials can work up to 800 °C. Indeed, in reality technical limit today is the wire insulation. The objective of thesis is to define a theoretical approach combined with experimental validations for identify the appropriate electrical materials used on high-temperature electrical machines. Design is fixed around the winding, that will implemented by calculating a high-temperature asynchronous machine (400°C of windings). The windings are placed as the base of machine design and will determine the geometrical shape and properties of magnetic core
Riva, Raphaël. « Solution d'interconnexions pour la haute température ». Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0064/document.
Texte intégralSilicon has reached its usage limit in many areas such as aeronautics. One of the challenges is the design of power components operable in high temperature and/or high voltage. The use of wide bandgap materials such as silicon carbide (SiC) provides in part a solution to meet these requirements. The packaging must be adapted to these new types of components and new operating environnement. However, it appears that the planar integration (2D), consisting of wire-bonding and soldered components-attach, can not meet these expectations. This thesis aims to develop a three dimensional power module for the high temperature aeronautics applications. A new original 3D structure made of two silicon carbide dies, silver-sintered die-attaches and an encapsulation by parylene HT has been developed. Its various constituting elements, the reason for their choice, and the pratical realization of the structure are presented in this manuscript. Then, we focus on a failure mode specific to silver-sintered attaches : The silver migration. An experimental study allows to define the triggering conditions of this failure. It is extended and analyzed by numerical simulations
Roske, Laurent. « Packaging de composants grand gap haute température et haute tension ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30049/document.
Texte intégralIn power electronics, one of the main research topics concerns high temperature operation of the components. Under such a constraint, the encapsulation and the passivation of the semiconductors devices in power module appear as physical and technological bottleneck. As a matter of fact, usual polymeric materials are unable to endure the temperature requirements set out in our study (350 °C) without significant loss of their dielectric properties. Therefore, gas insulation is considered and encouraging results have been obtained. The Discharges Inception Voltage is studied for different gases that could be used in high temperature power modules. Thanks to their dielectric properties and their low GWP, two gases have been selected: octafluoropropane (C3F8) and octafluorocyclobutane (c-C4F8), nitrogen (N2) being used as reference in this study. In a first step, the high temperature behaviors of the most widely used substrate materials (ceramics) are studied. A change of the conduction mechanism from a pure capacitive behavior (at low temperature) to a pure resistive one (at high temperature) is observed for both alumina and AlN samples. On the contrary, Si3N4 remains capacitive whatever the temperature. Such a behavior has an impact on the charges located at the surface. They disappear quickly for the two formers while they slowly decrease for the later. The field reinforcement associated to their existence and its impact on the DIV will not be the same. Whatever the gas under study, a local heating leads to a decrease in the DIV with temperature. A decrease of the distance between the two electrodes, leads to a decrease of the DIV changes vs Temperature. These results are compared to the measurements performed when the samples were uniformly heated. The use of gas in power packaging seems to be promising but it still needs a better understanding of the mechanisms involved
Armanni, Thibaut. « Étude de nouveaux alliages de titane pour applications aéronautiques hautes températures ». Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0342.
Texte intégralImproving the high-temperature resistance of titanium alloys is a major challenge for the aerospace industry. Exceeding the current limit of 550°C in aircraft engines requires finding the best compromise between good oxidation resistance and good mechanical properties. Near-alpha alloys consisting mainly of a compact hexagonal phase are the best candidates. Unfortunately, they are sensitive to cold creep-fatigue, known as the dwell effect. In this context, our work aims to achieve two main objectives. Firstly, to contribute to the design of new near-alpha alloys based on machine learning, supported by extensive mechanical testing, at both ambient and high temperatures. Secondly, to gain a better understanding of the effect of chemical composition, particularly silicon content, on the microstructure and mechanical behaviour. Our approach was based on multi-scale microstructure study of selected alloys using a combination of different microscopy techniques. We examined the influence of a variation in silicon content using a combination of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We showed that silicide precipitation occurs above a certain silicon content. We demonstrated the limitations of two-dimensional analysis, and used an alternative technique combining ion beam cutting (FIB) with SEM observation to reconstruct the 3D microstructure. This approach enabled us to analyze and quantify the shapes, sizes and spatial distributions of the silicides. Finally, we carried out tensile tests at different strain rates as well as creep tests under various conditions to better understand how silicon addition improves the behaviour of near-alpha alloys
Weck, Gunnar. « Etude des propriétés de l'oxygène sous haute pression et haute température ». Paris 6, 2001. http://www.theses.fr/2001PA066251.
Texte intégralVery-Alvergnas, Florian. « Capteur acoustique sérigraphié pour application haute température ». Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS151/document.
Texte intégralThe goal of the work presented in this thesis is to develop methods of preparation and characterization of piezoelectric materials for inclusion in acoustic sensors for applications in hostile environments. Measurements aspects in high temperatures and under radiation are of great interest to our partners of the CEA.In this context, the study and the realization of acoustic sensors operating at high temperature provide a wide range of possible application. This work includes research of optimal piezoelectric material, their technologies of implementation as well as the pairing mode of the transducer on a metallic or ceramic wall. In addition to the traditional techniques of solder, another technological way is envisaged through the use of screen printing. Specific test devices have been developed in order to determine the intrinsic characteristics to the materials, and the performances after their integration as sensitive elements of a measurement system. This screen printing as method of material transfer offers undeniable advantages in terms of use, a rapid prototyping and good reproducibility. Piezoelectric ink was developed from piezoelectric powder, glass sintering and organic vehicle ESL400. This ink has been made by screen printing. The realized technology stack consists of two electrodes of silver-Palladium and multilayered piezoelectric ink. As a first step, a deposit of stacking of Lead Zirconate Titanate (PZT) between two electrodes of silver palladium on alumina substrate allowed a lot of tests on the various optimizations potentialities. Layers have been characterized in a systematic way by measuring piezoelectric coefficient d33, relative permittivity and dielectric loss as a direct measurement. The coupling factor kt and frequency constant was determined by fit of the impedance curve from models. These models have been developed to indirectly determine different parameters from the direct measurement. Thick layers of PZT showed potential to be used up to 200 ° C.Finally, piezoelectric materials based on bismuth powders have been synthesized and incorporated in inks for screen printing deposits. Bismuth Titanate (BIT) niobium doped or undoped did not highlight significant macroscopic piezoelectric character because of the polarization difficulties. On the other hand, Sodium Bismuth Titanate (NBT) presents a great potential for future study. In fact in the form of thick layer it presents d33 of 9pC.N-1 and an impedance curve that does not reveal evolution even at temperatures in the range of 350 ° C
Bouhanek, Karima. « Oxydation à haute température de superalliages monocristallins ». Toulouse, INPT, 1997. http://www.theses.fr/1997INPT016G.
Texte intégralRoblin-Semène, Laurence. « Composites "verre-supraconducteur à haute température critique" ». Montpellier 2, 1994. http://www.theses.fr/1994MON20099.
Texte intégralGARREAU, ALEXANDRE. « Conception et élaboration d'absorbants radar haute température ». Université Louis Pasteur (Strasbourg) (1971-2008), 1997. http://www.theses.fr/1997STR13135.
Texte intégralMárquez, Costa Juan Pablo. « Caractérisation et modélisation des interfaces dans les composites organiques stratifiés à haute température : Application à la tenue au feu des structures aéronautiques PhyFire LOT 2 - Développement de modèles de comportement du composite Caractérisation en température de la ténacité en mode II des interfaces des CMO en utilisant l’effet Joule Caractérisation du comportement visqueux des interfaces CMO et influence sur la propagation de délaminage Convention PhyFIRE 2 - LOT 2 : Développement d’un cadre de modélisation pour les matériaux composites Durabilité des matériaux composites en conditions extrêmes : vers la prédiction des propriétés de tenue au feu Durability of Composite Materials under Severe Temperature Conditions : Influence of Moisture Content and Prediction of Thermo- Mechanical Properties During a Fire Towards the Prediction of Sandwich Composites Durability in Severe Condition of Temperature : A New Numerical Model Describing the Influence of Material Water Content during a Fire Scenario ». Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2021. http://www.theses.fr/2021ESMA0004.
Texte intégralWithin the framework of the fire resistance of composite materials, it is necessary to assess the degradation of their thermal and mechanical properties due to mass losses, matrix cracking and/or delamination cracks. Nevertheless, few studies in the literature about the temperature resistance of aeronautical composites concern the mechanical behaviour and the rupture of interfaces before any thermal degradation,subject which is the main topic of this work. Thus, the objective is to propose a failure model concerning both the delamination crack initiation and growth under thermomechanical loads. Much of this work has focused on the characterisation of interface properties using an analysis of mode II crack propagation tests for Joule heated specimens. These numerical analyses show that the ply behaviour does not explain the macroscopic pseudo-ductile response observed experimentally. Thus, a test-calculation dialog method, comparing the kinematic fields measured by digital images correlation and those simulated by finite elements, underlines the importance of the viscous behaviour at the interface scale. By a similar FEMU approach the parameters of a cohesive-type fracture law have been identified in temperature and taking into account the different sources of uncertainty. This work highlights the similarity between plane and out-of-plane shearing, both on behaviour and on failure. In parallel, the analysis of temperature resistance tests by laser impact made it possible to establish a crack initiation criterion by a coupled stress and energy approach. A comparison of this criterion with the parameters of the cohesive zone law previously identified makes it possible to discuss about the modeling scale of the interface
Champallier, Rémi. « Déformation expérimentale à Haute Température et Haute Pression de magmas partiellement cristallisés ». Phd thesis, Université d'Orléans, 2005. http://tel.archives-ouvertes.fr/tel-00008988.
Texte intégralLes travaux entrepris à haute température - haute pression (HT-HP) se proposaient d'étudier ce phénomène ainsi que la rotation des cristaux. Une telle étude nécessite de disposer d'un appareil de déformation des magmas fonctionnant à HT-HP. Ce mémoire présente les tests de deux appareils développés dans cette optique ainsi que ceux réalisés en presse Paterson. Une large place est également consacrée aux artefacts expérimentaux rencontrés et aux moyens mis en œuvre pour les résoudre.
Carrier, Hervé. « Contribution à l'étude thermodynamique de solutions d'électrolytes sous haute pression, haute température ». Pau, 1996. http://www.theses.fr/1996PAUU3018.
Texte intégralBouhifd, Mohammed Ali. « Physique des minéraux et des magmas à haute pression et haute température ». Paris 7, 1995. http://www.theses.fr/1995PA077167.
Texte intégralMunholand, Luke. « Filtration à haute température avec des chandelles céramiques ». Mémoire, Université de Sherbrooke, 2001. http://savoirs.usherbrooke.ca/handle/11143/1170.
Texte intégralAdes, Claude. « Propriétés optiques des verres silicatés à haute température ». Toulouse 3, 1989. http://www.theses.fr/1989TOU30164.
Texte intégralViverge, Pierre-Jean. « Convertisseur de faible puissance pour environnement haute température ». Lyon, INSA, 1993. http://www.theses.fr/1993ISAL0061.
Texte intégralThis complete study covers the analysis from 20°C to l85°C of the realisation bases and behaviour of a low power AC/DC converter. After the choice of he power supply structure, we propose rules, remarks and cautions for such type of converter for low and high temperature electronic as well. The study shows the evolution of t he convert er components and elements versus temperature. The devices are tested alone and inside their environment. In particular, we analyse the bidirectional switch behaviour versus temperature because it can induce problems if we don't apply specific rules of choice about its components. We study the 185°C running of the complete converter (using hundred components ) and we show that it is possible to use a low power converter during 400 hours at l85°C then 100 hours at 200°C