Дисертації з теми "Étanchéités"
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Nguyen, Manh Hung. "Analyse des étanchéités annulaires à bague flottante." Poitiers, 2011. http://www.theses.fr/2011POIT2255.
Повний текст джерелаThe annular floating ring seals can significantly reduce the leakage in rotating machines operating with gas or cryogenic fluids. Their integration into the machine is not simple because the floating ring must be able to follow the vibrations of the rotor. The presented work has two parts. The first part consists of the analysis of static and dynamic behavior of the annular seal which forms the primary seal. The model developed is based on the theory of thin lubrication films dominated by inertia effects together with a total enthalpy form of the energy equation. This model can handle the phase change in cryogenic fluids. The dynamic response of the annular seal is expressed as the linear dynamic coefficients (derived for small perturbations). The dynamic coefficients vary with the operating regime of the seal ring (eccentricity, upstream / downstream pressure, rotation speed) but do not depend on the excitation frequency. The second part is dedicated to the development of a dynamic model. The floating ring is subject to forces generated by the fluid flow in the annular (primary) seal, the mixed friction forces between its nose and the stator (the secondary seal is similar to a mechanical face seal) and the inertia forces caused by its own weight. The rotor acts as an external excitation. A suitable model is developed for each of these forces. Two dynamic models are proposed. The first model is based on the assumption that the floating ring follows the rotor according to a periodic precession motion. This model allows a simple and fast quasi-analytical solution but is limited by the fact that the dynamic response of the ring may be more complex. The second model is fully nonlinear and takes into account the possible impacts between the rotor and the ring and between the ring and the anti-rotation pins. The model shows that under certain conditions the trajectory of the ring can be quasi-periodic or chaotic. Overall, the results of the second part underline design rules for properly integrating annular floating ring seals into a rotating machine
Rouillon, Mathieu. "Modélisation et caractérisation expérimentale des étanchéités faciales hydrodynamiques." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2267/document.
Повний текст джерелаThe main objective of this thesis is to study, through a numerical model and experimentations, the performance and behaviour of different spiral groove face seals, usually used for gas applications, in the case of liquid lubrication. The aim of this work will be to evaluate the eventuality to replace smooth mechanical face seals used in liquid cryogenic turbopumps space rocket applications by spiral groove face seals.The literature presents different theoretical and experimental studies on surface texturing, two-phase flow and turbulence. These last two points may appear when sealing a cryogenic fluid. A numerical model has been developped in finite elements. It solves the Reynolds equation and the energy equation into the fluid film. This equation is expressed using the enthalpy and can thus be used in case of homogeneous fluid phase change. Fluid/structure coupling is considered to obtain thermoelastic deformations of the solids. The next part of this study is dedicated to experiments with water lubricated spiral groove face seals with different groove depths. A comparison with smooth face seals has been done showing that the friction torque of the spiral groove face seals is lower than the smooth face seals one. On the other hand, the spiral groove flow rate is higher. Sharp changes in behaviour such as, laminar to turbulent transition from a Reynolds number equals to 1500, or two-phase flow at low pressure, high angular speed and supplying temperature of the fluid, are observed. The last part compares the thermoelastohydrodynamic theoretical model to experimental results in laminar flow, for one-phase and two-phase flow. The model is able to capture the experimental findings. Even if some convergence difficulties are encountered in two-phase flow, the model can be used for seal design in industrial applications
Minet, Christophe. "Lubrification mixte dans les étanchéités dynamiques : application aux garnitures mécaniques d'étanchéité." Poitiers, 2009. http://theses.edel.univ-poitiers.fr/theses/2009/Minet-Christophe/2009-Minet-Christophe-These.pdf.
Повний текст джерелаMechanical face seals are commonly used in industrial applications. The main purpose of these components is to insure the sealing of rotating shafts. A mechanical seal is basically a set of two rings whose contact is lubricated by the sealed fluid. The optimal point of operation is reached by minimizing both leakage and wear. The average film thickness is then about one micrometer and the seal is operating in mixed lubrication conditions. In this case, the faces are not completely separated by the fluid film and asperity contact occurs. The choice of a deterministic approach was justified from a detailed bibliographical analysis. An accurate description of the surfaces roughness was required, as well as the development of a numerical modelling tool able to simulate it. A metrological study was realised on samples of mechanical seal surfaces at several stages of operation. The statistical parameters obtained from the surfaces roughness could thus be evaluated and used in a numerical model enabling the generation of non Gaussian surfaces. A deterministic flow model for mixed lubrication in mechanical seals is then presented. It takes the cavitation effects and normal hertzian asperity contact into account. The equation of flow rate conservation in the contact was solved using finite volume method. A parametric study was carried out on four statistically equivalent simulated surfaces. The model highlights the increase in load capacity due to the roughness, although the mean surfaces are flat and parallel. Stribeck curves have been obtained for each studied case. The standard deviation of the roughness is the major parameter influencing the coefficient of friction. Furthermore, the development of microcavitation, which mostly depends on the roughness distribution, influences the results to a great extent
Touze-Foltz, Nathalie. "Modélisation des transferts advectifs dans les étanchéités composites de centres de stockage de déchets." Paris, ENMP, 2001. http://www.theses.fr/2001ENMP1038.
Повний текст джерелаGeomembranes of composite liners often exhibit holes representing preferential advective flow paths for leachate. Various authors have developed mathematical models and empirical equations in order to interpret flow rates due to advective transfers obtained in the laboratory and extrapolate them to field conditions, for steady-state flow, unifrom interface transmissivity, and saturated soils and interfaces. Limits of validity of these mathematical models and empirical equations were determined for a uniform interface transmissivity. But the transmissivity proves to be non-uniform. The work performed thus consisted in studying the influence of this non-uniformity on flow rates thanks to analytical equations and experimental devices. The influence of the respective location of the hole in the geomembrane as well as the spatial repartition of transmissivity. For this latestt point two methods were used during the PhD in order to describe geomembrane and compacted soil surfaces topography
Touze-Foltz, Nathalie. "Modélisation des transferts advectifs dans les étanchéités composites de centres de stockage de déchets." Paris, ENMP, 2001. http://www.theses.fr/2001ENMPA001.
Повний текст джерелаBerger, Sébastien. "Etude du comportement dynamique non linéaire d'un rotor monté sur éléments fluides : caractérisation des étanchéités ; influence de la butée." Poitiers, 1999. https://tel.archives-ouvertes.fr/tel-00204946.
Повний текст джерелаjolly, pascal. "Contribution à l'étude du changement de phase liquide-vapeur dans des capillaires micrométriques en vue des applications aux étanchéités statiques." Phd thesis, Université de Poitiers, 2004. http://tel.archives-ouvertes.fr/tel-00008547.
Повний текст джерелаJolly, Pascal. "Contribution à l'étude du changement de phase liquide-vapeur dans des capillaires micrométriques en vue des applications aux étanchéités statiques." Poitiers, 2004. http://www.theses.fr/2004POIT2274.
Повний текст джерелаThe matter of this work is the comprehension of liquid-vapor phase change phenomenology in micrometric paths that remain from the contact of two rough surfaces in a static gasket. The main objective is to evaluate the consequences of boiling on flow rate value. The leakage path is supposed to be a capillary tube, of micrometric diameter. Inlet and outlet pressures correspond respectively to liquid phase and vapor phase. Boiling occur when the local pressure falls below the saturation pressure during the liquid flow. Besides, no heat is carried out to the fluid. Conservation and interfacial equations are written in a non dimensional form in order to identify, by a phenomenological analysis, the preponderant mechanisms of boiling of R134a in confined space. It is shown that phase change occurs by heterogeneous nucleation and that the growth of the resulting vapor bubble is controlled by thermal phenomena. An experimental facility is designed for the visualization of boiling in glass capillary tubes of circular cross section whose diameter is comprised in the range 20 to 100 æm. Experimentations are ruled by a protocol that includes three steps. The steps 2 and 3 correspond to a situation of phase change, but with different initial conditions. During the second step, evolution of the vapor phase is measured, with a webcam or a fast cam. This enables to estimate the repercussion of boiling on leakage flow rate. During the third step, despite the fact that the outlet pressure is much smaller than the saturation pressure, no boiling bubbles are observed in the capillary
Bannour, Hajer. "Evalution des transferts advectifs à travers les étanchéités composites géomenbranes-géosynthétiques bentonitiques des barrières de fonds d'installations de stockage de déchets." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU048/document.
Повний текст джерелаGeomembrane (GM)-geosynthetic clay liner placed in bottom landfill barriers could be faced to advective transfers caused by the appearance of GM defects. Leachate could percolate naturally through the GCL; penetrate the soil and the ground water which could result in environmental damage. It's therefore important to understand leakage transfer mechanism though GM-GCL composite liners and quantify them in order to be aware, to master and to minimize advective transfer impact through the barrier to the environment. However, the GM is not accessible in bottom land fill liner which makes it harder to correctly estimate leakage through the composite liner. The present work used to evaluate advective transfer through GM-GCL composite liner via an experimental and numerical approach. This work used also to ameliorate the comprehension of leakage transfer mechanisms as a function of external solicitations compared to the literature. The purpose of this study was thus to properly identify advective transfer problem through composite liner by highlighting the main parameters affecting advective transfers through composite liners (confining stress, heterogeneity of the GCL composition, contact quality at the GM-GCL interface, chemical and physical alteration during its service life). Those parameters influence the whole barrier performances and material characteristics evolution were studied. Experimental program was dealing with acquiring water retention data of GCL by introducing state surface concept under the confining stress generated by the waste. It has been found that confining stress used to reduce GCL swelling facilities while hydrated and consequently lead to the decrease of the saturated hydraulic conductivity. This result emphasizes on landfill conception recommendations based on rapidly covering the GCL in in order to acquiring its watertightness capabilities. This experimental study was reinforced by a numerical computation study dealing with water transfer through composite liner due to a GM defect and a hydraulic head with considering the heterogeneity of the GCL. This numerical study highlighted new phenomena regulating flow rate through composite liners consisting of geotextile deaturation due to high suction performed by the bentonite as part of the GCL. Indeed, in addition to containing the bentonite and providing tensile shear stresses, the geotextile contribute to reduce the flow rate through composite liner thanks to its high hydraulic conductivity while desaturated. Interface transmissivity tests were also carried for different composite liners combinations. Measurements concluded that neither external solicitations resulting from chemical and physical alteration conducting to the increase of the hydraulic conductivity of the GCL nor the quality of the GM (in relation with its roughness, rigidity and thickness) significantly affect advective transfer through composite liners at the steady state. However an effect was highlighted during transient state. A synthetic approach was thus given to summarize composite liners transfers mechanism and anticipate environmental impact of its leakage. It was later confirmed that the bentonite swelling contributes also to flow rate reduction through composite liner regardless of the bentonite nature and granulometry. In addition, it has been concluded that the transient state within which flow rate reduction though has been observed must be taken into consideration to realistically predict flow rate leakage through composite liners
Minet, Christophe. "Lubrification Mixte des Etanchéités dynamiques : application aux garnitures mécaniques d'étanchéité." Phd thesis, Université de Poitiers, 2009. http://tel.archives-ouvertes.fr/tel-00441030.
Повний текст джерелаAl, Nassar Mohammad. "Performances des discontinuités présentes dans les dispositifs d'étanchéité par géosynthétiques bentonitiques : étude des perforations et recouvrements." Lyon, INSA, 2002. http://www.theses.fr/2002ISAL0008.
Повний текст джерелаGeosynthetic Clay Liners (G. C. L) are often used more and more for sealing of hydraulic structures or intended for the environment protection. The G. C. L are the unique sealing products that having the capacity to seal or limit a punctual leakage through an accidental defect. According to the environmental conditions, it is appropriate to estimate the limits of this self-healing potential. On the other hand, the installation of the G. C. L obligatorily requires overlap zones between the panels. These zones are potential weak points to which particular attention has to be given if we want to guarantee the sealing continuity. The research work presented in this rapport is situated in this context, which has two experimentally objectives : To examine the self-healing capacity of G. C. L in site and in laboratory as well; Original apparatus were designed and realized. Tests carried out in site on a capping landfill and in laboratory as well intend to quantify, qualify and visualise self-healing of several types of G. C. L. To study the hydraulic behavior at the level of the G. C. L’s overlap. An original apparatus of tank type was designed and realized to study the overlap’s zones of G. C. L, it allows to carry out tests of characterization and performance. A radial permeameter was also used in order to qualify another interfaces no woven or woven G. C. L’s Geotextile/Géomembrane. Nine tests of long duration were devoted to study the hydraulic performances of the G. C. L at the level of the overlap and in the plein section. Different types of zone’s overlap treatment were studied. Gas flow through the G. C. L’s overlap was studied by the realization of tests concerning four types of G. C. L’s overlap. Finally, an overlap non treated and an interface zone G. C. L/rough surface were modelled in the hydraulic point view by a flow software “eau-sol”
Pichon, Vincent. "Contributions théoriques et expérimentales à l’étude d'une étanchéité pneumatique : application aux distributeurs." Lyon, INSA, 1993. http://www.theses.fr/1993ISAL0077.
Повний текст джерелаThis work presents a study on pneumatic valve performances. Satisfactory valve operation is directly on a compromise between sealing, friction and life of 0-Ring. Both theoretical and experimental approaches have been performed ta study this compromise. An F. E. M program has been developed to determine the 0-Ring deformation its groove under pressure. An hybrid element,based on Hellinger-Reissner formulation in small and finite strains, has been developed to calculate the elastomeric response. A frictional contact algorithm has been adapted to obtain the contact area between the seal and its groove. By using experimental design method to analyse numerical results, an optimization of this compromise has been realized in static. Ex experimental work has been made bath to allow numerical results validation and to study the dynamic evolution of this compromise,when grease lubrication is present. Results an grease feeding conditions, film thickness and life have been established. Analysis of both numerical and experimental results have been made to improve this compromise
Amyot, Olivier. "Contribution à l'étude des écoulements diphasiques à travers un contact rugueux." Poitiers, 2004. http://www.theses.fr/2004POIT2283.
Повний текст джерелаZaouter, Tony. "Etude des écoulements à l'interface joint-rugosité pour des applications de haute étanchéité." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0116/document.
Повний текст джерелаSome industrial applications require exceptional sealing levels to maintain ultra-high vacuumconditions or for radiological safety concerns for example. Such high performance static sealingconditions on mechanical assemblies are reached using entirely metallic gaskets. The resultingleak-rate is only due to the persistence of an aperture field at the seal-flange interface,consequence of a non-ideal contact between the two rough surfaces. This aperture field can beviewed as a rough and heterogeneous fracture, of multi-scale nature, and can be obtained by aprior contact mechanics computation. In this work, we are interested on the rarefied flow of a gasin this fracture, drawing our attention to the slip regime. For such moderately rarefied regime, theflow is described by the slightly compressible Reynolds equation with a first-order slip-flowcorrection at the walls, which we develop. Using the method of volume averaging, an upscalingprocedure is performed to derive the macroscopic flow model at the scale of a representativeelement, and where the mass flow rate is related to the pressure gradient by the transmissivitytensor. This latter is characteristic of the representative fracture element and is obtained by solvingan auxiliary closure problem which depends on the micro-structure as well as the representativemean free path on the element. To compute the flow in the whole fracture, heterogeneous at thisscale, it is subdivided in tiles on which a transmissivity tensor is locally computed by theaforementioned method. Then, the flow problem in this tensor field is solved using a boundaryelement method, leading to the apparent slip-corrected transmissivity of the entire aperture field.This two-scale approach is a conception tool which reduces the overall complexity with respect toa direct numerical simulation, allowing a more efficient analysis of the behavior of a sealingassembly. To validate the use of slip models at the macroscopic level and to eliminate theuncertainties of the contact mechanics computation, nanofluidic chips composed ofheterogeneous network of straight channels are fabricated using a grayscale photolithographytechnique. Experimental measurements of the leak-rate are performed on these idealizedgeometries that mimic a seal assembly. They are realized by applying a strong helium pressuredifference on the chip using a mass spectrometer to measure the leak, which produces a nearvacuum condition at the outlet. Depending of the chip, the rarefaction regime ranges from slip tofree-molecular. The measured leak-rate is greater than predicted by the first order model, thoughbeing of the same order of magnitude whatever the regime
Pelte, Thierry. "Etude théorique et expérimentale de la fonction étanchéité et du comportement thermique des géomembranes." Grenoble 1, 1993. http://www.theses.fr/1993GRE10172.
Повний текст джерелаBeautru, Yannick. "Inflence des films d'eau très minces sur le frottement pneu/chaussée." Ecole centrale de Nantes, 2012. https://tel.archives-ouvertes.fr/tel-00851330.
Повний текст джерелаThis thesis aims at understanding better how skid resistance is altered by a very thin water film (thickness less than 1 mm) on the road surface. This wetting can cause viscoplaning which is the source of accidents during drizzles or after rainfalls. The final goal of the thesis is to suggest criteria to define conditions for the onset of viscoplaning. Laboratory tests are performed on different types of samples : asphalt concrete but also mosaics composed of sandblasted coarse aggregates which allow studying the influence of microtexture, an essential parameter for the evacuation of thin water films. Tests on actual roads (test tracks) are also performed to validate the representativeness of laboratory tests. Specific tests protocols are developed to monitor the evolution of the friction coefficient from a dry state to a complete wetting of the surface. The curve representing the variation of the friction coefficient with water depth is similar to the Stribeck curve which highlights three lubrication regimes : boundary, mixed and hydrodynamic. The influence of some parameters (speed, microtexture, macrotexture) on this variation is studied. A?critical ? water depth, transition between the boundary lubrication regime (value of the friction coefficient close to the value on dry surface) and the mixed lubrication regime (collapse of the friction coefficient), is defined. Relationship between critical water depth, microtexture and speed is analyzed. The relative influence of contact parameters is quantified. A physical model is developed. The theorical friction coefficient results from three contributions (deformation of rubber, adhesion and hydrodynamic effects). Contact parameters such as vertical load and speed are also considered. The model is applied to texture profiles measured by a high resolution laser sensor. A method of profile analysis is developed to detect profile asperities on which deformation and adhesion calculations are made. Comparison between model and measurement is satisfactory, justifying the hypotheses of the model. The model has especially highlighted the importance of the water film at the top of the road asperities. A model from the literature was used, as a first attempt, to estimate the thickness of this water film. Applications of the results of the thesis are mentioned : they contribute to a better understanding of the presence of thin water films on skid resistance but also to the determination of the onset of viscoplaning
Zaghzi, Nacira. "Etude théorique et expérimentale de l'adhésion instantanée élastomère-métal à l'aide d'une méthode de roulement." Mulhouse, 1986. http://www.theses.fr/1986MULH0017.
Повний текст джерелаShekarchi, Zadeh Mohammad. "Etude du comportement thermo-hydrique d'une paroi en béton a hautes performances : application au cas des enceintes de confinement en situations accidentelles." Lyon, INSA, 1999. http://www.theses.fr/1999ISAL0014.
Повний текст джерелаThe interest of use of High Performance Concrete in the construction of the containment wall of the nuclear power plant of Civaux (in France) has been confined by the satisfactory level of leak tightness integrity of this type of concrete under leakage test at 0. 5 MPa in dry air at room temperature. The aim of this work is to study the hygrothermal behaviour of the used concrete exposed to accidental conditions leading to high temperatures and high steam pressures (200°C and 15 bars). In order to obtain the representative measurements, during heat and mass transfer in the concrete under accidental conditions, the tests have been carried out in the cylindrical specimens having the same height as the thickness of containment wall of nuclear power plant (1. 3 m). The design and fabrication of test equipment allowing to accidental simulations were the first phases of this work. The temperature, pressure and moisture distributions have been measured and the leak tightness integrity of concrete has been analysed during testing. In order to obtain the moisture propagations in the concrete exposed to high temperature, it was necessary to design a moisture meter in autoclaved mortar, using a resistive electrical method. The main parameters affecting the hygrothennal behaviour of concrete under accidental situations have been identified and it is shown that the thickness of wall which is touched by accident (i. E. Temperature higher than 1 00°C, vapor water penetration and pressure induced) is about 25% of wall thickness. It is also observed that leak tightness integrity of wall has been improved during testing by the wetting due to vapor water penetration. Besides, the test results of mercury porosimetry of concrete confirms that accidental conditions by heating at high steam pressure (similar to autoclaving process), increase the density of pore network of testing concrete. That means, at least the microstructure of material is not damaged by testing. Numerical investigation consists in adapting a heat and mass transfer mode (TEMPOR. 2), to high performance concrete, which has been intended for ordinary concrete. To do so, the test results of concrete characterization obtained during this work have been employed. The analysis of numerical results shows that a modified model could be used in the case of high performance concrete. Finally, theoretical results associated with experimental obtained permit to describe more clearly the difference between concrete behaviour under heating (temperature) or under accidental conditions (temperature and steam pressure)
Durin, Leïla. "Transfert d'eau et de contaminants organiques dans les structures d'étanchéité synthétiques et minérales des centres de stockage de déchets ménagers." Paris 11, 1999. http://www.theses.fr/1999PA112111.
Повний текст джерелаKoutroulis, Vaios. "Les relations entre le jus contra bellum et le jus in bello: étanchéité absolue ou vases communicants ?" Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209966.
Повний текст джерелаDans la première partie, nous avons procédé à l’étude du principe de l’égalité des belligérants. Ce principe constitue la pierre angulaire de l’application des règles du DIH et proscrit toute invocation du jus contra bellum pour influencer l’application du jus in bello. Cela n’est pas évidemment sans poser de problèmes dans un ordre juridique dont une des règles fondamentales interdit le recours à la force. Ainsi, le principe de l’égalité des belligérants a fait l’objet de théories visant à remettre en cause son caractère absolu. Notre étude a montré qu’il n’en était rien. Le principe de l’égalité des belligérants est de nature coutumière et ne souffre pas d’exception. Ainsi, il incarne, dans sa forme la plus absolue, l’indépendance qui existe entre le jus contra bellum et le jus in bello.
La seconde partie de notre étude a eu pour objet de vérifier si cette indépendance pouvait également caractériser d’autres aspects des relations entre ces deux corps de règles, ou si on contraire, l’étanchéité entre ces deux branches du droit international n’était pas absolue. Ont été analysés, d’une part, les champs d’application ratione materiae et personae de ces corps de règles et, d’autre part, deux notions de fond qui sont considérées comme formant des « ponts » entre le jus contra bellum et le jus in bello :la nécessité et la proportionnalité. Ici encore, notre analyse confirme que l’indépendance constitue la caractéristique principale des relations entre le jus contra bellum et le jus in bello.
Doctorat en Sciences juridiques
info:eu-repo/semantics/nonPublished
Karnaeva, Ekaterina. "Amorçage et propagation des réseaux de fractures dans le contexte du stockage de CO2 : étanchéité des couvertures." Paris 6, 2012. http://www.theses.fr/2012PA066513.
Повний текст джерелаOne way to reduce the amount of greenhouse gas emission in the atmosphere is to inject CO2 in deep geological formations. The long term safety of the storage site is ensured by the impermeable multilayered caprock that covers the porous reservoir, it prevents migration of the injected CO2. However, due to the injection, the inner pressure increases and the caprock may be fractured because of displacements or compressions of inside fluids. These may promote a hydraulic intrusive fracture located at the bottom of the caprock to penetrate into the next layer or to deflect at the interface between the beds. The goal is to determine the optimal injection conditions and quantify maximal CO2 injection pressure in order to avoid the risk of fracture initiation and propagation. This study aims at establishing the conditions that control the behaviour of a dyke-type fracture near the bedding contact during CO2 injection. The analysis is based on the theory of brittle fracture mechanics and carried out in the framework of the coupled energy-stress failure criterion proposed by Leguillon. In this work the original energy-stress criterion was extended by taking into account the overburden load and the fluid pressure inside the fracture. Thanks to the coupled energy-stress criterion we have the right tool to study the effect: (i) of the contrasts between elastic properties of materials (Young’s moduli, toughness and tensile strength), (ii) of the loads (overburden load and fluid pressure), on the behaviour of a dyke-type fracture near the bedding contact. This approach allows testing a large range of parameters and drawing maps of the crack behaviour
Sriti, Mohammed. "Comportement statique et dynamique des joints labyrinthe." Lille 1, 1994. http://www.theses.fr/1994LIL10075.
Повний текст джерелаEl, Gamal Ahmed. "Effet de l’irradiation laser sur les couronnes céramiques usinées en CFAO : propriétés chimiques et mécaniques et étanchéité bactérienne." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4121.
Повний текст джерелаThe purpose is to study the physical and chemical properties of CAD/CAM ceramics irradiated with CO2 and Nd:YAP lasers and to evaluate surface adhesion of ceramic crowns by microleakage test with a mono bacterial biofilm and a FISH technique. Methods : Evaluations tests were: Micro hardness, roughness, surface wettability, shear bond strength and EDS. 60 samples Two ceramics used: lithium disilicate and zirconia ceramics were prepared for different test. For microleakage test:Six ceramics crowns of different ceramics were contaminated with a Streptococcus salivarius biofilm for 10 d. Fluorescence in situ hybridization technique was applied samples were examined with confocal laser microscope. Results: Shear bond test showed significant difference between irradiated and non irradiated (p. value= 0,014 S). Partial superficial wettability was observed for the two ceramics. In micro hardness test, CO2 at 5 W increased micro hardness of lithium disilicate ceramics with significant value (6,32 GPa). SEM showed rough surface in all groups. EDS did not modify the chemical composition of tested ceramics. No significant rise in temperature could be recorded on both types of ceramic.The micro leakage test of a mono-bacterial biofilm was positive at the crown / tooth cervical junction. Conclusion: CO2 and Nd: YAP lasers modify CAD/CAM ceramic surfaces without chemical composition modifications. CO2 irradiation increase shear bond strength, surface roughness, micro hardness and made CAD/CAM ceramics hydrophilic. Irradiation with CO2 laser seems to improve surface adhesion and decrease bacterial microleakage
Behin, Pascal. "Les composites postérieurs et les composites prothétiques : étude structurale et mécanique appliquée à leur usure et à leur étanchéité." Paris 5, 1988. http://www.theses.fr/1988PA05M096.
Повний текст джерелаFourt, Erwan. "Étude de joints radiaux en carbone graphite avec application aéronautique." Electronic Thesis or Diss., Poitiers, 2021. http://www.theses.fr/2021POIT2292.
Повний текст джерелаThe main goal of this thesis is the experimental study of several technologies of radial segmented seals. First of all, an introduction presents the context of the study by detailing the most commonly used seals technologies in aero engines.Firstly, three different technologies of radial segmented seals have been studied: without pocket, with pocket and without pocket and inclined grooves on the rotor. The performance of each technologies has been investigated and compared. In complement, the wear of the pocket-free technology has been study. The work highlights the fragility of this kind of seals. It is why the performance and the wear of faulty seals have been investigated.This second study shows that despite the failure, the seals do not show more serious complications.Then, the impact of roughness on a gas flow was investigate to highlight the lift effect of the segments. For this, a multiscale method was developed. It was shown that this method works well to study such a problem with a very low computational effort in comparison with two other existent methods
Comeaga, Loretta. "Dispositifs d'étanchéité par geoéynthétiques bentonitiques dans les centres de stockage de déchets." Lyon, INSA, 1997. http://www.theses.fr/1997ISALO115.
Повний текст джерелаGeosynthetic Clay Liners (GCL) are factory manufactured hydraulic barriers consisting of bentonite supported by geosynthetics (geotextiles or geomembranes). The last few years Geosynthetic Clay Liners are more and more often used as liners or in capping systems of landfills, as a single or part of a multilayer barrier, with traditional materials ( compacted clay or geomembrane). At the present, in most countries, tests on GCLs are performed using standards for geotextiles and low permeable soils, which are not always easy to adapt to GCLs. In this context, the aim of the presented work is to elaborate adapted devices and testing procedures and to study various GCL products (needlepunched, stitched, containing granular or powder bentonite) in real conditions and in similar manner. Original devices were developed in order to study the Geosynthetic Clay Liners hydraulic behaviour in simulated landfill conditions. They allow performing characterisation and performance tests, as well as to study the chemical compatibility with the leachate. The experimental part is focused on the study of the hydraulic performances of 4 products currently available on the market, in various situations: - in contact with smooth surfaces or granular materials; - in contact with a synthetic leachate, the GCL being dry, partially hydrated or saturated with • water. Tests performed on samples with defects allowed to verify the GCL's selfhealing capacity. The chemical compatibility of bentonite to synthetic leachate are analysed as a function of the degree of initial water saturation and of the type of GCL
Hernandez, Pascal. "Modélisation du comportement d'un dispositif d'étanchéité dynamique." Toulouse 3, 1994. http://www.theses.fr/1994TOU30214.
Повний текст джерелаMarie, Christophe. "Fuite monophasique au travers d'un contact rugueux : contribution à l'étude de l'étanchéité statique." Bordeaux 1, 2002. http://www.theses.fr/2002BOR12548.
Повний текст джерелаBarast, Gilles. "Etude de la continuité des états liquides et solides pour les géomatériaux traités constituants les barrières d’étanchéité hydraulique." Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0117/these.pdf.
Повний текст джерелаTo comply with waste containment liners regulatory requirements, bentonite (moisture-reactive clay) based hydraulic sealing systems may be required, possibly enhanced using innovative polymer reinforcement. Due to the low hydraulic conductivity, the testing lime for characterisation in the laboratory is long, which makes it difficult for rapid engineering design. Pioneering investigations, as weil as new quick hydraulic indexes, are called for. Accordingly, experimental studies were undertaken on the geomaterials in their higher hydraulic conductivity liquid state, based on rheology and filtration. Liquid state rheological parameters were experimentally transposed into solid state soli mechanics parameters (specifically hydraulic conductivity). This methodology was based on test results for various bentonites, fluids (including water and CaCI2) two polymers and sand, for compacted sand-bentonite-polymer mixtures. Observations from HMC investigations, from the literature, and from rheology and. Filtration testing, showed compatibility for bentonite polymer-fluid mixtures over a range of states. Dynamic rheology testing was found to provide the most appropriate parameters to formulate a hydraulic performance index. Two approaches were adopted (gel and swelling), linking the hydraulic conductivity with rheological parameters. Linear correlations were observed, dependent on the fluid chemistry and polymer addition, manifesting the mixing affect and the significance of a liquid-solid continuum
Patron, Elisabeth. "Poromécanique des joints en graphite expansé matricé." Marne-la-Vallée, ENPC, 1999. http://www.theses.fr/1999ENPC9936.
Повний текст джерелаA strict leaktightness of bolted assemblies, which connect valves to pipes, is essential to ensure the safety of conventional or nuclear power plant. This is among others the function of ring-shaped gaskets inserted between the connecting flanges. Improving the tightness of bolted assemblies, · which is a crucial point for Electricité de France, requires a modeling of this particular component behavior. This thesis specially studies porous expanded graphite gaskets, which fit high pressure and high temperature steam-water systems. Service fluid is water or steam, but qualification tests use helium. We then considered gaseous single-phase interstitial flows (of helium) and two-phase interstitial flows (of water and steam). Two hydraulic test devices have been defined to determine the permeability tensor of expanded graphite rings. The proposed theoretical flow models permits a good simulation of experimental leak rates. A third experimental rig has been adjusted to identify expanded graphite poromechanical behavior. Obtained results show that, although elaborated to represent clay behavior, the CamClay model is interestingly suited to expanded graphite. The behavior and the tightness of a bolted assembly subject to high temperature transients have been simulated by introducing the gasket poromechanical modeling into the assembly numerical model. The so-defined numerical model correctly reproduces the various behavior phases that have been experimentally observed. Besides, calculations give information on the leak rate allowed by the assembly in operation. This work thus results in a numerical tool for bolted assemblies design
Sousa, David. "Etude des émissions de fluides frigorigènes des joints tournants de compresseurs de climatisation automobile." Paris, ENMP, 2008. http://pastel.paristech.org/5057/01/Sousa_Thesis.pdf.
Повний текст джерелаThe air-conditioning system is today a worldwide standard equipment in the automotive industry improving not only the thermal comfort but also the safety of passengers. This refrigerant system uses HFC-134a, a hydro-fluorocarbon refrigerant, whose emissions contribute to global warming. Among the mobile air conditioning components, the compressor has been identified as the most leak prone component representing 50 to 60% of the system emissions. The most emissive component of the compressor is the shaft seal that represents up to 50% of the compressor emissions, as demonstrated in this dissertation. The objectives of this thesis are to study the physical principles and to analyze the experimental results of gas emissions in order to contribute to the knowledge of the fundamental mechanisms and the influence parameters of the compressor shaft seal gas emissions. Two original experimental setups have been developed to study the shaft seal gas emissions in standing mode as well as in running mode. The same test benches have also been used to investigate the seal performances during the compressor aging. This new approach has allowed identifying the shaft sealing mechanism at rest and in running mode. Results obtained have been used to demonstrate the relation between the shaft seal emissions and its lubrication regime, as well as the oil transitory effect when the shaft is at rest. This study has also underlined the significant deterioration process of the shaft seal emissions with wear, which explains the high demand of refrigerant for servicing and the increase in the number of system recharges as the vehicle gets old
Roque, António José Pereira Mendes. "Transfert advectif et diffusif de polluants inorganiques dans les barrières d'étanchéité minérales présentes dans les centres de stockage de déchets." Lyon, INSA, 2001. http://www.theses.fr/2001ISAL0034.
Повний текст джерелаThis work is intended to contribute to understand better the hydro-geochemical performance of fine-grained soils with geotechnical properties similar to those of soils that are currently used in the construction of compacted clay liners existing in the landfills. Therefore, the work is expected to contribute to improve the design and dimensioning of confinement systems based on the determination of the hydraulic conductivity, the effective diffusion coefficient and the capacity of retention of fine-grained soils. We begin by studying of the phenomenology of soil-water-electrolyte interactions, with a view to contribute to understand better the operation of the soil-leachate system. Subsequently, we describe the main physical, chemical and biological processes of retention of inorganic pollutants in the soils, and we present for some inorganic pollutants the mechanisms of retention that are responsible for their retardation in the soils. In addition, we indicate the main processes of pollutant transport through compacted clay liners, as well as the corresponding mathematical formulation. W e also refer to the fundamental principles of permeability and diffusion in the soils as well as the methods used in laboratory for measuring the hydraulic conductivity and the effective diffusion coefficient. W e present the characteristics of leachates produced in municipal solid landfills, as well as a data base concerning the chemical composition of these leachates. These data were used as supporting basis to the selection of inorganic chemical species and of chemical concentrations representative of the chemical composition of real leachates, with a view to prepare both acid and neutral to moderately alkaline leachates. We present the methodology that has led to collecting thirty samples from the main Portuguese clayey formations and we characterise the soils. The results obtained in the tests are analysed and we perform their statistical processing using linear regression and multivariate analysis methods, in order to select representative samples of the overall sampling. W e carry out permeability tests in laboratory with equipment and apparatuses that were specifically designed for: i) determining the hydraulic conductivity of specimens; ii) determining the time of advective transport of inorganic chemical species through the sampling soils; iii) studying the effects of both ac id and neutral to moderately alkaline leachates on the long-term integrity of soils. We carry out, other than the study on the advective transport of chemical species, a study on the diffusive transport of inorganic chemical species through the sampling soils. For the purpose, we designed equipment and apparatuses that were specifically intended to study the transport of pollutants by pure diffusion
Liu, Guo Hui. "Mécanismes de frottement et d'avaries à haute température des revêtements céramiques pures ou additionnées de lubrifiants solides." Paris, ENSAM, 1991. http://www.theses.fr/1991ENAM0020.
Повний текст джерелаRoman, Adriana. "Méthodes d'indentation normale et transverse appliquées à l'étude des propriétés mécaniques des films et révêtements." Lille 1, 2000. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2000/50376-2000-276.pdf.
Повний текст джерелаWeiller, Sébastien. "Etude de la relation entre porosité et étanchéité à l'ultra-vide de dépôts à base d'aluminium obtenus par projection dynamique par gaz froid ("cold spray")." Thesis, Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLM004.
Повний текст джерелаCold Spray is a thermal spray process, a key advantage of which is its capability to achieve highly-dense coatings. The practical objective of the study is to fully exploit this asset to obtain a metallic coating which exhibit gas-tightness in ultra-high vacuum conditions as requested for the targeted application. The thesis work consists in studying cold spray conditions to result in suitable properties. The study will focus on porosity formation mechanisms when spraying. A major objective is to determine a critical size for porosity above which gas-tightness no more meets the required specifications for the application. For this, relevant characteristics of pores (size, distribution, shape, ... ) will be assessed. More basically, the work aims to correlate, including using numerical simulation, these characteristics with the previously-mentioned formation mechanisms as a function of spraying conditions. The influence of the substrate (a metal or a polymer) onporosity will be studied in particular, through the study of modifications in the coating build-up. Coating-substrate bond strength will be determined, based on the study of adhesion mechanisms since an influence of these on gas-tightness can be expected
Bertrand, Lionel. "Influence d'un MHEC sur les propriétés physiques et mécaniques d'un enduit de rénovation de façade : étude de l'adhérence de l'enduit sur une pierre de Tuffeau." Lyon, INSA, 2004. http://www.theses.fr/2004ISAL0087.
Повний текст джерелаRenovation renders are complex materials. They content many components: cement, lime, aggregates and organic admixtures. One of them, the water retentive, allows to retain the water inside the render when applied on a porous substrate. In this study, the retentive admixture is a cellulose ether (MHEC). Its mode of action and effects on render properties are not well known. The aim of this work is to measure and explain the MHEC influence on the render adhesion when applied on a limestone substrate (tuff). Therefore, we compared Iwo renders, with and without MHEC. However, the adjunction of MHEC demands an addition of water during the render mix to obtain similar render workability. The study of the render adhesion is done thanks to the Wedge Splitting Test. This test allows to control the crack propagation at the render/substrate interface and gives many information (load, stiffness, fracture energy). The characterization of mechanical (elastic modulus) and physical properties (length variations, setting kinetics) of renders completed by the study of water movements (suction, evaporation) helps to understand their adhesive behavior. Also, modifications due to MHEC addition were underlined, separately of the render water content. ESEM observations of the renders hydration and of the renders/substrate fracture surfaces allow to raise assumptions on the MHEC action mode
Nyemeck, André Parfait. "Modélisation de la lubrification mixte et du comportement thermique des garnitures mécaniques." Poitiers, 2011. http://nuxeo.edel.univ-poitiers.fr/nuxeo/site/esupversions/2ece3128-ba75-4399-ac23-1f1d5f66069b.
Повний текст джерелаMechanical seals are sealing components used in rotating shafts. They are basically a set of two rings (the rotor and the stator), separated by a lubricant film that must be impervious. The optimum operation is obtained by minimizing both leakage and wear. This corresponds to a film thickness of approximately one micrometer and to a mixed lubrication regime. The literature review justified the choice of a multiscale approach to model a mixed lubrication process. A part of this literature allowed identifying the thermal models to use. A model of a mixed lubrication in mechanical seals based on a multiscale approach is presented. This uses numerical surface roughness and consists in dividing the studied area into sub-domains. The Reynolds equation, which takes into account the fluid cavitation is solved by mean of finite volumes method, at fine scale of the sub-domains, as the hertzian contact asperities. The macroscale is introduced to connect the boundaries conditions of the sub-domains. Then, the macroscale pressure distribution is obtained insuring the mass conservation law. The model also takes into account, at the macroscale step, the Thermo-Elasto-Hydro-Dynamic (TEHD) behaviour in mechanical seals. The discretization of heat and elasticity equations is performed using the finite element method for axisymmetric geometry. The multiscale model is first validated by comparing in to a deterministic model, and then to the TEHD model previously developed at the Pprime laboratory. The influence of the parameters characterizing the mechanical seal behaviour is analyzed through the parametric study. In this study, the different lubrication regimes are identified. The lubricant film thickness is controlled by the roughness or by the thermoelastic deformation of the faces
Dursun, Élisabeth. "Les ciments verres ionomères modifiés par addition de résine : données actuelles par revues systématiques de la littérature et études in vitro de leurs propriétés précoces et retardées." Paris 13, 2013. http://scbd-sto.univ-paris13.fr/secure/edgalilee_th_2012_dursun.pdf.
Повний текст джерелаDurand, Julian. "Approche multi-échelles des problèmes de contact et d'étanchéité." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00820173.
Повний текст джерелаSousa, David. "Étude des émissions de fluides frigorigènes des joints tournants de compresseurs de climatisation automobile." Phd thesis, École Nationale Supérieure des Mines de Paris, 2008. http://pastel.archives-ouvertes.fr/pastel-00005057.
Повний текст джерелаSaiyouri, Nadia. "Approche microstructurale et modélisation des transferts d'eau et du gonflement dans les argiles non saturées." Châtenay-Malabry, Ecole centrale de Paris, 1996. http://www.theses.fr/1996ECAP0446.
Повний текст джерелаSfar, Hedi. "Approches numérique et expérimentale du dudgeonnage en vue d'optimiser les paramètres de mise en œuvre industrielle." Compiègne, 1997. http://www.theses.fr/1997COMP994S.
Повний текст джерелаLukat, Sébastien. "Optimisation de l'adhérence de revêtements d'alumine projetés sur matériaux composites à matrice céramique : application à l'instrumentation extensométrique." Besançon, 2007. http://www.theses.fr/2007BESA2018.
Повний текст джерелаThis study deals with a self-healing multilayer matrix and carbon or silicon carbide fiber-reinforced ceramic matrix composites. Many papers have shown that the adherence of sprayed alumina coatings to such substrates is quite poor. According to a literature survey, two ways were identified to improve the coating bond : enhancing the substrate surface properties, by means of a cumulative laser treatment, and depositing a silicon bond coat, i. E. Implementing a multilayer coating. First the surface modifications of CMC induced by a cumulative laser treatment were studied. Some morphological, elementary and structural analyses of the treated surfaces revealed a microcone morphology and a superficial decarburization, due to laser ablation. The relationships between the surface properties and the adherence of sprayed alumina coatings on CMC were then studied. In the case of alumina deposit after laser treatment, a rather high level of adherence compared to untreated surfaces has been noticed. This might be due to the surface morphology : indeed microcones could favor the mechanical anchorage of the sprayed particles on the substrate. In the case of silicon/alumina multilayer coatings, it was shown that the adherence of silicon coatings prepared by vacuum plasma spraying was higher than that of the coatings prepared by atmospherical plasma spraying. In the former, physico-chemical binds are supposed to develop. Eventually, these results were applied to strain measurement. The feasibility of integrating a free filament strain gage in a sprayed alumina coating on CMC was demonstrated by the preparation of test specimens
Noirrit-Esclassan, Emmanuelle. "Etude de l'interface et de l'étanchéité endocanalaire après collage de tenons fibrés radiculaires." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/497/.
Повний текст джерелаInterfaces and permeability obtained after root bonding of a fiber-reinforced post, using two different adhesive systems coupled with the dual-curing luting composite Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein): a one-bottle system used after application of phosphoric acid, Excite DSC (Ivoclar Vivadent, Schaan, Liechtensenstein) and a self-etch system, AdheSe DC (Ivoclar Vivadent, Schaan, Liechtensenstein), were evaluated in three different ways: - A morphological study of interfaces between adhesive systems and root dentin by SEM - A study of permeability by a fluid filtration method - A study of the molecular interaction between root dentin and a one-bottle bonding system used after etching, by spectrophotometry and microspectrofluorimetry. Root dentin bonding is difficult to achieve in terms of moisture control, polymerization conditions, accessibility, and polymerization shrinkage. Both adhesive systems studied are able to provide good hybridization with a continuous hybrid layer and dense resin tags with numerous lateral branches at the coronal third. In addition, hermeticity of the root treatment is preserved and this bonding can be clinically recommended. Pursuit of the study of intermolecular relations between adhesive system and dentin by spectrofluorimetric methods opens new research perspectives
Mariot, Antoine. "Analyse théorique et expérimentale des joints d'étanchéité à bague flottante et des joints rainurés segmentés." Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2292/document.
Повний текст джерелаThis thesis presents a theoretical and experimental study of floating ring annular seals and radial segmented seals. These seals are designed to prevent leakage inside high-speed rotating machinery used in aeronautics and aerospace applications. Floating ring annular seals were tested on a dedicated test rig inside the Institut Pprime. Various rotation speed and pressure difference configurations were used. The behavior of the floating rings when submitted to rotor vibrations was studied for different excitation amplitudes. Results from this study were confronted to a numerical model based on the equations of motion of the seal. The seal is driven by inertia forces, hydrodynamic forces in the main seal and friction forces on the secondary seal. The friction coefficient on the secondary seal was estimated by Greenwood and Williamson’s model for mixed lubrication. The analysis validates the theoretical model, which reproduces the dynamic behavior of a seal driven by a given rotor excitation. Another model was used to study segmented seals. The flow in each part of such a seal was modeled with various methods. Friction forces were studied with a model similar to that used for floating rings. A parametric study was performed on various geometric and operating parameters
Brunetière, Noël. "Les garnitures mécaniques : Etude théorique et expérimentale." Habilitation à diriger des recherches, Université de Poitiers, 2010. http://tel.archives-ouvertes.fr/tel-00506535.
Повний текст джерелаChristophe, Vallet. "Fuite liquide au travers d'un contact rugueux : application à l'étanchéité interne d'appareils de robinetterie." Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2008. http://tel.archives-ouvertes.fr/tel-00413260.
Повний текст джерелаChaignaud, Stéphanie. "Durabilité des assemblages élastomère/métal en milieu marin." Toulon, 2003. http://www.theses.fr/2003TOUL0012.
Повний текст джерелаImmersed acoustic modules are made of a rubber membrane glued or vulcanised on a metallic housing. When they are submitted to a cathodic protection, they can undergo cathodic delamination. The aims of the study are to develop a test enabling a non-destructive follow-up of the delamination and to understand the formation and the de gradation of rubber to metal joints. Electrochemical Impedance Spectroscopy test is chosen to follow cathodic delamination during the ageing and an equivalent electrical circuit models electrochemical phenomena occurring. Several analyses have also been realised on materials alone, on joints ~ before ageing and on delaminated surfaces after de gradation. Formation and degradation J' mechanisms are then proposed. Finally, a configuration offering an optimum resistance to delamination is defined
Besnault, Catherine. "Influence de la simulation in vitro des conditions environnementales intra-orales sur l'adhésion des restaurations esthétiques, directes et indirectes." Paris 7, 2002. http://www.theses.fr/2002PA077023.
Повний текст джерелаChopinez, Fabrice. "Influence de la formulation de polypropylènes choc injectés sur l'adhérence d'une peinture." Paris, ENMP, 2001. http://www.theses.fr/2001ENMP1077.
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