Eléments continus de coques appliqués en interaction fluide structure

Actuellement, la modélisation des vibrations des structures telles que les modélisations des plaques et des coques est menée par des méthodes traditionnelles, notamment par les méthodes des éléments finis et des éléments de frontière. Ces deux méthodes sont efficaces pour modéliser la plupart des structures. Cependant, des limitations se révèlent lorsque l on élargit le domaine fréquentiel d etude, la finesse du maillage requis pouvant s avérer rédhibitoire pour des assemblages complexes. Pour remédier a cet inconvénient, la méthode des éléments continus est une alternative intéressante pour l etude de la réponse harmonique des structures sur une large gamme de fréquences. Dans cette thèse, nous avons établi un élément continu de coque axisymétrique à laquelle un chargement réparti sous différentes formes est introduit. La procédure de mise en œuvre de cet élément est présentée. La réponse harmonique de l élément cylindre est comparée a celle obtenue avec un modèle éléments finis pour montrer les performances du modèle proposé. La même procédure est ensuite abordée pour le phénomène de couplage fluide structure, auquel, la méthode est bien adaptée.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceTunisiaFRT

Analytical and numerical analysis of an internally and/or externally pressurized thick-walled sphere made of radially nonuniform material

International audienceIn this work, a thick-walled spherical vessel made of nonhomogeneous materials subjected to internal and/or external pressure was analyzed within the context of three-dimensional elasticity theory. A closed-form analytical solution was obtained for computing the displacement and stress fields. It has been assumed that the elastic stiffness is varying through thickness of the functionally graded material according to a nonlinear general expression, while Poisson’s ratio is considered as constant. In order to check the relevance of the analytical solution, a finite element model of the pressurized vessel were constructed, taking into account variations in Young's modulus. Very good agreement has been found between the numerical results and the predictions of the analytical solution, which confirms the accuracy of our model. Thus, the inhomogeneity in material properties can be exploited to optimize the distribution of displacement and stress fields

Formulation of the dynamic stiffness of a cross-ply laminated circular cylindrical shell subjected to distributed loads

International audienc

Study of the Effects of Marble Powder Amount on the Self-Compacting Concretes Properties by Microstructure Analysis on Cement-Marble Powder Pastes

The marble powder (MP), obtained from waste sludge marble processing, has a high specific surface area; this could mean that it can be used as filler added to self-compacting concrete (SCC). The aim of this experimental work is to study the effects of the cement-MP paste volume on the rheology in the fresh state and the hardened properties (compressive strength) of SCC by a microstructure analysis on paste samples with different amounts of MP. For all pastes, the morphological forms and the chemical composition of the main mineral components were analyzed by the scanning electron microscope (SEM) and X-ray diffraction (XRD). The hydration, microstructure, and mineralogical changes has been studied. Experimental results show that the cement-MP paste volume has significant effects on the self-compacting and the self-leveling properties in the fresh state of SCC. In addition, the paste volume has a significant contribution on the compressive strength of SCC. Results indicate also that the difference in chemical composition between MP and cement have not any contribution on the paste volume effects

Analytical and numerical analysis of an internally and/or externally pressurized thick-walled sphere made of radially nonuniform material

International audienceIn this work, a thick-walled spherical vessel made of nonhomogeneous materials subjected to internal and/or external pressure was analyzed within the context of three-dimensional elasticity theory. A closed-form analytical solution was obtained for computing the displacement and stress fields. It has been assumed that the elastic stiffness is varying through thickness of the functionally graded material according to a nonlinear general expression, while Poisson’s ratio is considered as constant. In order to check the relevance of the analytical solution, a finite element model of the pressurized vessel were constructed, taking into account variations in Young's modulus. Very good agreement has been found between the numerical results and the predictions of the analytical solution, which confirms the accuracy of our model. Thus, the inhomogeneity in material properties can be exploited to optimize the distribution of displacement and stress fields

Development of new baked bricks based on clay and sawdust

Current research in the field of building materials is oriented towards the recovery of waste to ensure the lightening of certain building elements and energy saving. The objective of this study is to produce a new bricks by adding sawdust to clay mixtures. The first part of this experimental work consists on detremining the proper manufacturing process and cooking diagram for these new bricks. In the second part, the effect of the maximum cooking temperature, the firing phase time's of the bricks and the sawdust prportion on the physical and mechanical properties of the new bricks have been studied. The studied properties are the absorption ratio, the unit weight and the compressive strength. The results showed that the addition of an increasing amount of sawdust tends to modify the physical and mechanical properties of the cooked samples. The presence of sawdust reduces the number of connections between the clay grains and produces a lighter, more absorbent and less resistant material. Finally, the results showed that the manufacture of bricks based on sawdust is possible

Experimental and Theoretical Study of a New Technique for Mixing Self-Compacting Concrete with Marble Sludge Grout

Currently, marble waste is valued by incorporating powders, obtained by drying and grinding sludge resulting from marble blocks cutting operation, or the aggregates, obtained by crushing the solid waste, on self-compacting concrete. These two procedures require a lot of energy. This experimental and theoretical work focuses on the direct incorporation of marble sludge in self-compacting concrete. The first part needs the study of the rheological behavior of the marble sludge grout (MSG) as a function of the added water amount. For this, different grouts were prepared and tested by varying the water/sludge ratio. In the second part, four self-compacting concretes (SCCs) were mixed with MSG having different water/sludge ratios in order to validate a new technique of gassing self-compacting concrete with MSG. The test results show that the marble grains of grout is totally dispersed when the water/sludge ratio was equal to 1.2. The results also show that the gassing with MSG allows us to obtain SCC having both self-compacting property and self-leveling property compared to SCC made by adding marble filler to the cementitious matrix

Development of new baked bricks based on clay and sawdust

Current research in the field of building materials is oriented towards the recovery of waste to ensure the lightening of certain building elements and energy saving. The objective of this study is to produce a new bricks by adding sawdust to clay mixtures. The first part of this experimental work consists on detremining the proper manufacturing process and cooking diagram for these new bricks. In the second part, the effect of the maximum cooking temperature, the firing phase time's of the bricks and the sawdust prportion on the physical and mechanical properties of the new bricks have been studied. The studied properties are the absorption ratio, the unit weight and the compressive strength. The results showed that the addition of an increasing amount of sawdust tends to modify the physical and mechanical properties of the cooked samples. The presence of sawdust reduces the number of connections between the clay grains and produces a lighter, more absorbent and less resistant material. Finally, the results showed that the manufacture of bricks based on sawdust is possible

Effects of Incorporation of Marble Powder Obtained by Recycling Waste Sludge and Limestone Powder on Rheology, Compressive Strength, and Durability of Self-Compacting Concrete

Marble has been commonly used as a building material since ancient times. The disposal of waste materials from the marble industry, consisting of sludge that is composed of powder mixed with water, is one of the current worldwide environmental problems. This experimental study aims to valorize marble powder, which is achieved by grinding the sludge as filler added to the cementitious matrix of self-compacting concrete (SCC). The main purpose of this work is to evaluate the marble filler effects on the rheology in the fresh state and on the hardened properties of SCCs compared to those of limestone filler. To this end, two SCCs, SCCM and SCCL, manufactured using marble powder and limestone filler, respectively, were prepared and tested. The fresh properties of the two SCCs’ mixtures were determined by slump flow, L-box, V-funnel, sieve stability, bulk density, and air content. Tests on hardened SCCs included compressive strength, homogeneity, and quality in terms of ultrasonic pulse velocity and durability against carbonation and water penetration. In addition, scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to analyze the specimens