Littérature scientifique sur le sujet « Propriétés mécanique (approche d’homogénéisation) »
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Articles de revues sur le sujet "Propriétés mécanique (approche d’homogénéisation)"
Foucher, Fabrice, Sébastien Lonné, Philippe Dubois, Stéphane Leberre, Pierre Calmon, Michael Enright et Yasin Zaman. « Apports d’une cosimulation “END – Tolérance aux dommages” dans la réduction des risques de rupture ». e-journal of nondestructive testing 28, no 9 (septembre 2023). http://dx.doi.org/10.58286/28527.
Texte intégralThèses sur le sujet "Propriétés mécanique (approche d’homogénéisation)"
Mtibaa, Mohamed. « Οptimisatiοn de cοuplage Ρrοcédé/Ρrοpriétés/Fiabilité des Structures en Μatériaux Cοmpοsites Fοnctiοnnels ». Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH03.
Texte intégralThis research focuses on the challenges and interactions between the manufacturing processes (Resin Transfer Molding ‘RTM’ and Compression Resin Transfer Molding ‘CRTM’), the mechanical properties, and the reliability of composite material structures; more specifically the functional composites. A number of numerical models have been developed for simulating the suspension (resin + particles) impregnation through the fibrous medium (fibers) in the RTM and CRTM processes. These models are validated by comparing their results with experimental, semi-analytical, and analytical ones from the literature. A parametric study is carried out to demonstrate the impact of various process parameters on particles’ distribution in the final composite. Moreover, a comparison between the injection and compression modes is done. The results of this part show that the distribution of particles in the final part depends on the initial concentration, the distance travelled, and the initial fibers’ volume fraction. However, it is independent of the parameters values of injection and compression. It is also observed that the CRTM process with imposed pressure injection and imposed force compression represents the most favorable scenario for producing composite parts.For the purpose of controlling the final particles’ distribution in the composite material, manufactured by the RTM process, two key steps have been identified. The first step consists in a sensitivity analysis that examines three parameters: the temporal evolution of the initial injected particles’ concentration, the injection pressure field and the initial fibers’ porosity. The conclusions indicate a minimal impact of the initial porosity and the injection pressure field; while the evolution of the initial concentration of the injected particles has a dominant effect. In a second step, an optimization algorithm is implemented in the numerical model of the RTM process. It is used to determine the optimal configuration of the initial injected particles’ concentration’s evolution; in order to approximate the particles’ distribution in the final composite to the desired profiles. The obtained results from the genetic algorithm provide a very satisfactory control of this distribution. To complete this section, a model, estimating the mechanical properties of the manufactured part, is developed. It is found that there is a positive correlation between the particles’ fraction and certain mechanical properties, namely the elastic modulus E11 and E22, and the shear modulus G12 and G23. Nevertheless, the Poisson’s ratio (Nu12) is inversely proportional to the particles’ fraction. Also, the shear module G12 is the most significantly influenced by this fraction.Following this, the control of the mechanical properties of the composite parts, manufactured by the CRTM process, is targeted, and compared to the results of the RTM process. The conclusions reveal that the RTM process offers a better control of these properties. Whereas, the CRTM process improves considerably the mechanical properties of the parts due to its compression phase, which increases the fibers’ volume fraction and consequently enhances these properties.Finally, a static analysis is conducted based on the developed numerical model that uses the finite element method (Ansys APDL). This model is combined with those of the CRTM process and the mechanical properties calculation. An optimization algorithm is integrated in our global model to adapt the mechanical properties of the composite part according to the configuration (cantilever or simply supported) and the load distribution. Moreover, it minimizes the composite part’s weight and ensures the respect of the predetermined mechanical constraints such as the maximum deformation limit. The obtained results correspond perfectly to these objectives
Simon, Pierre. « Approche multiéchelle du comportement mécanique du bois dans le plan transverse ». Lyon, INSA, 2009. http://theses.insa-lyon.fr/publication/2009ISAL0049/these.pdf.
Texte intégral[The elastic behavior of softwoods presents a huge anisotropy in the transverse plane. It is moreover very heterogeneous at some scales. Transverse mechanical properties also seem to be very different between species or from a piece of wood to another. Here is proposed an experimental and theoretical study of this behavior. To explain, it, at least the cellular scale must be observed. Many shapes of cells exist and an adaptative goemetric model of the cells has been constructed. An analytical calculus then gives the mechanical properties associated to this geometric model. Then the behavior of wood at upper scales is deduced from the morphology of cells in the annual rings. The anisotropy and the heterogeneity of spruce are quantified. Experimental data are compared to the theoretical results. The great variability of cellular shapes locally leads to a very important diversity in their stiffness, from 1 to 10 for some types of loads. Macroscopoic orthotropy come from the microscopic anisotropy but also depends on the regular assembly of cells in annual rings. The behavior of annual rings is less random than cell properties, paradoxically thanks to the great cellular variability. And when the transverse behavior of macroscopic wood pieces is measured, its variability decreases with the number of annual rings in the section, and reach only some ten percents. Nevertheless, the mean transverse elastic behavior of structure pieces is quite variable. It largely depends on the orientation and curvature of the annual rings. And the transverse stiffness can vary from 1 to 5 from one beam to another]
Langlade, Cécile. « Approche physico-chimique et mécanique des propriétés lubrifiantes de poudres graphite + additifs ». Ecully, Ecole centrale de Lyon, 1993. http://www.theses.fr/1993ECDL0002.
Texte intégralGueguin, Maxime. « Approche par une méthode d’homogénéisation du comportement des ouvrages en sols renforcés par colonnes ou tranchées ». Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1062/document.
Texte intégralThis work takes place in the context of soil reinforcement techniques, aimed at improving the mechanical performances of poor quality grounds. Among these techniques, the use of soft inclusions taking the form of columns or cross trenches has known important developments. Even if the aspects relative to their construction process are presently well mastered, the design methods of such reinforced soil structures still remain to be greatly improved. The present work advocates the use of the homogenization method for assessing the global behavior of reinforced soil structures, both in the context of linear elasticity (stiffness properties) and in the framework of yield design (strength properties). Taking into account the geometrical periodicity of the various reinforcement configurations, we thus determine the behavior of the reinforced soils first locally and then at the global scale. To assess the strength capacities of reinforced soil structures, the static and kinematic approaches of the yield design theory are performed analytically or numerically depending on the kind of reinforcing material which is used. Adopting innovative numerical formulations dedicated to this theory, we can notably evaluate the macroscopic strength domains of column as well as cross trench reinforced soils which can then be introduced in the yield design of reinforced soil structures. Two illustrative applications of this procedure are performed relating to the bearing capacity problem of a reinforced soil shallow foundation on the one hand, the stability analysis of an embankment on the other hand
Regnet, Jean Baptiste. « Propriétés physiques et comportement mécanique des roches carbonatées microporeuses : Approche intégrée expérimentale et microstructurale ». Thesis, Cergy-Pontoise, 2014. http://www.theses.fr/2014CERG0718/document.
Texte intégralThis integrated study provides significant insight into parameters controlling (1) the acoustic and reservoir properties of microporous limestone and (2) the mechanical behavior of such rocks. This work improves the knowledge of the relationships among rock physic and rock mechanic on one hand, and the microstructural content on the other hand.(1) Petrophysical properties measured from laboratory and logging tools (porosity, permeability, electrical conductivity and acoustic properties) have been coupled with thin section and SEM observations on the EST205 borehole from the Oxfordian limestone aquifer of the Eastern part of the Paris Basin. A major achievement is the establishment of the link between micrite microtexture types (particle morphology and nature of inter-crystal contacts) and the physical response. Fluid-flow properties are enhanced by the progressive augmentation of intercrystalline microporosity and associated pore throat diameter, as the coalescence of micrite particle decreases between relatively coarser tight morphologies and microporous morphologies. The slow increase of P-wave velocity can be seen as a reflection of crystal size and growing contact cementation leading to a more cohesive and stiffer micrite microtexture. By applying poroelasticity theory on our samples, we show that velocity dispersion can be a very useful tool for data discrimination in carbonates. Finally, a possible origin of high porous levels in neritic limestones is a mineralogical dissolution of carbonates through freshwater-related diagenesis during subaerial exposure time.(2) Regarding rock mechanic, conventional triaxial experiments were performed on samples from the Oolithe Blanche formation (Middle Jurassic Limestone, Paris basin) to investigate the effect of different microstructural parameter on the mechanical behavior of microporous carbonate rocks. Type A samples display two different microporosity distributions within the grains (uniform versus rimmed microporosity) and type B samples are based on the presence/absence of an isopachous cement around the ooids. This work is of primary importance since the Oolithe Blanche formation, a deep saline aquifer, is a possible target for CO2 sequestration and geothermal production in the center of the Paris Basin. Experiments were performed under saturated state with respectively two sets of experimental conditions: (1) a 5 MPa pore pressure and a 28 MPa confining pressure with a temperature of 55°C for Type A carbonates to mimic in-situ conditions in the Center of the Paris Basin; and (2) a 0.5 MPa pore pressure and a 1.5 MPa confining pressure for Type B samples. Sample types have similar facies and composition (oolithic microporous grainstone with a 500µm average grain size), and porosity ranges from 17% to 20%. Permeability values are also very similar and range from 10-2 mD to 10-1 mD.(1) Type A samples with a rimmed porosity display a typical behavior of the brittle failure regime with stress-strain curves reaching a peak (138 MPa) beyond which strain softening was recorded, and strain localization on a shear fracture. (2) Type A samples with a uniform porosity display a ductile behavior with no localization of the deformation.(2) Type B samples with isopachous cement show a brittle behavior with stress drop (16 MPa to 18 MPa) and localization on a shear fracture. When isopachous cements are absent, a more ductile type of behavior is observed. Our set of data suggests that those two microstructural parameters have a significant control on the mechanical behavior of carbonate rocks
Khalfaoui, Mohamed. « Approche énergétique et analytique de quelques aspects du problème de Saint-Venant : cas de poutres composites ». Montpellier 2, 1997. http://www.theses.fr/1997MON20104.
Texte intégralEl, Yagoubi Jalal. « Effet de l’endommagement mécanique sur les propriétés thermiques de composites à matrice céramique : approche multiéchelle ». Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14297/document.
Texte intégralIn this work the relationship between the evolution of damage and the loss of thermal propertiesof Ceramic Matrix Composites is investigated by a multiscale approach. Research are conductedboth experimentally and theoretically. The implemented approach is to consider two significantscales (micro and meso) where different damage mechanisms are operating and then assess theeffect on the effective thermal properties by homogenization techniques.Particular attention has been given to the development of a thorough experimental work combiningvarious characterization tools (mechanical, thermal and microstructural). At the two aforementionedscales, an experimental setup was designed to perform thermal measurements onCMC under tensile test. Thermal diffusivity of minicomposites is estimated using Lock-in thermography.Also, tranverse diffusivity mapping as well as global in-plane diffusivity of woven CMCare determined by suitable rear face flash methods. The evolution of damage is then derived fromacoustic emission activity along with postmortem microstructural observations. Experimental resultsare systematically compared to simulations. At microscale, a micromechanical-based modelis used to simulate the loss of thermal conductivity of a minicomposite under tensile test. At mesoscale,a multiscale Finite ElementModel is proposed to compute the effect of damage on thermalproperties of woven CMC
Ernst, Emil. « Le principe de Saint-Venant, théorème et axiome. Une approche énergétique ». Montpellier 2, 1995. http://www.theses.fr/1995MON20094.
Texte intégralRobert, Benjamin. « Etude des propriétés viscoélastiques des tissus mous par Elastrographie IRM : une approche multi-échelle ». Paris 7, 2009. https://pastel.archives-ouvertes.fr/pastel-00556732.
Texte intégralUltrasound and MRI elastography has developped rapidly these past days in order to estimate the viscoelastic properties of soft tissues. This new diagnostic tool is particularly adapted to characterize pathologies such as breast carcinoma because of its higher elasticity than the surrounding tissue. In the first part of the manuscript, viscoelastic media are presented in order to describe their mechanical behaviors while an elastic wave is generated. Several rheological models are introduced and analyzed to find the more adapted description of the mechanical properties of soft tissues estimated out of MR-Elastography acquisitions. The second part presents the different techniques of ultrasound elastography and the basis of the Magnetic Resonance Imaging in order to better understand the objectives of MR-Elastography. Two MR-Elastography sequences are theoretically and experimentally analyzed in order to optimize the quality of mechanical properties estimation. The third part enlightens the difficulties to adapt current MR-Elastography sequences to short T2* tissues such as the carotid or the heart. Thus, a new sequence is introduced: the DENSE-MRE sequence. This new MRI sequence is theoretically and experimentally compared to conventional MR-Elastography sequences. And this new sequence is is used in vivo to estimate elastograms of heart during the heart cycle
Gaied, Issam. « Contribution à l'étude de la contention : approche bidimensionnelle, identification du comportement biaxial en grandes déformations des tricots élastomériques ». Saint-Etienne, EMSE, 2004. http://www.theses.fr/2004EMSE0025.
Texte intégralWith a simplified 2D finite element model using ABAQUS, we initially validated the local Laplace law. We use this model to predict the pressure generated by the Medical Compression Stckings on one considered section of the leg. The leg was represented by a perfectly rigid body and the MCS by beam elements. We have also use a pneumatic device named Sig at to make in-situ experimental measurements. A good agreement between the pressures is verified. These same measurements revealed us the importance of treating the problem in 3D. In this case we have to integrate the orthotropic behaviour of the material and the longitudinal variation of the radius of the leg. The second part of the thesis was hence devoted to the development and the validation of an identification methodology for the biaxial behaviour under large deformations of an elastomeric knitted fabric. This methodology is based on the comparaison of the efforts and the experimental displacement field obtained by a correlation images method, with the results of the simulation of the same bidirectional tensile test using ZéBuLon F. E. Code. The material response was modelled through response a behaviour surface implemented under corrotationel formulation with the meta-language Zebfront. These surfaces allowed us to describe simply the biaxial behaviour of these knitted fabric up to deformations of 110%