Дисертації з теми "Composites – Structure – Propriétés mécaniques"
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Reynaud, Emmanuelle. "Etude des relations Structure : Propriétés mécaniques de thermoplastiques renforcés par des particules inorganiques nanoscopiques." Lyon, INSA, 2000. http://theses.insa-lyon.fr/publication/2000ISAL0070/these.pdf.
The works aims to correlate some morphological parameters and the mechanical properties in composite systems based on polymer matrix reinforced by submicronic inorganic fillers. The thought process lies on the study of three distinct filled polymer systems, their internal structure being all the more complex. The first system consists of a polymethyl methacrylate matrix filled with silica nanoparticles. The second system has polyamide 6 as a matrix and silica as fillers. The last system results from the clay introduction to polyamide 6/ First a morphological investigation enables to get insight into the filler influence on the surrounding polymer matrix. It also enlightens the various filler dispersion states (and its possible orientation within the sample geometry) with respect to the composite nature (in particular the inorganic particle size or its surface treatment) and its elaboration route. Then the study focuses on the role played by various morphological parameters (filler fraction, aspect ratio and dispersion state) on some mechanical properties, both elastic and plastic (through an investigation around the yield point). The latter properties were analysed on the various studied systems and compared. The experimental data were further confronted to some mechanical approaches, in order to better identify the morphological parameters leading to the observed macroscopic behaviours. Eventually, on the composites based on PA6, a possible sequence of the damage mechanisms occurring with increased elongation at room temperature was proposed, thanks to complementary experimental observations (through scattering and volume changes measurements). Given the involved parameters, each system was found to be characterised by a particular sequence of events
Phongphinittana, Ekkarin. "Assemblages composites-polymères après traitement par plasma atmosphérique du composite : caractérisation mécaniques et modélisation." Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0070.
Following the proposals of the European Commission, to achieve the goals of emission reduction of carbon dioxide (CO2) from cars. To achieve this objective, automakers must reduce the weight of the car. Thus the supplier Faurecia, manufacturer of car seats desires to replace metal structures by structure plastic-metal hybrid (PMH). And they desire also to use a composite material to replace metal in order to reduce weight. Moreover in order to improve the adhesion strength at the interface piece hybrid structure,Atmospheric plasma technique was used.In this context, we studied the effects of plasma treatment on term of adhesion in the hybrid structure in order to provide the best condition of treatment. The objective of this study was to characterize the effect of plasma treatment by determination at the parameters in the process such as the scanning speed, the distance between the substrate and the plasma torch and the number of passes of the torch, then to predict the initiation of delamination under quasi-static loading test in specimen of single lap shear by using the criterion of rupture. The other objective was to study the micromechanical model to assess the reliability of them. And they will be applied to predict the mechanical behavior of Short Glass Fiber reinforced thermoplastic. In order to achieve the objectives presented, the several tests such as tensile test, single lap shear test and ARCAN-Mines test have been executed. In parallel, techniques acoustic emission (AE), infrared radiation (IR) and optical microscopy were used in order to follow the failure mechanisms of the specimen studied. Finally, the finite element method was used to simulate the tests and allow to verify the reliability of the failure criterion
Andriamanantena, Vonjinirina. "Analyse du comportement mécanique de composites en fonction des défauts de structure générés par les conditions de fabrication." Lille 1, 1997. http://www.theses.fr/1997LIL10206.
Caramaro, Laurence. "Cristallisation du polysulfure de phénylène en présence de fibres de carbone : application à des composites unidirectionnels PPS-carbone." Lyon 1, 1990. http://www.theses.fr/1990LYO10184.
Amici, Marco. "Hybrid Inorganic / Organic polymers based on methacrylate - polyhedral oligomeric silsesquioxanes (POSS®) : morphology and structure - properties relationships." Lyon, INSA, 2006. http://theses.insa-lyon.fr/publication/2006ISAL0004/these.pdf.
Novel hybrid inorganic/organic systems based on methacrylate and polyhedral oligomeric silsesquioxanes (POSS ®) have been synthesised and characterised. The synthesis has been performed via either thermally or UV free-radical polymerization. Chemical characterisation has been done with NMR, NIR and SEC. The POSS have been found to be polymerizable with the organic monomers once a good dispersion is ensured. Structure and morphology, characterised by means of SEM, TEM, AFM and WAXS, have been shown to be mainly dependent on the dispersion of the POSS in the organic matrix. Depending on the POSS grade and concentration, one could obtain a wide array of structure-morphologies, from micro-aggregates to a very fine dispersion, probably to the molecular level. In turn, these different morphologies have an influence on the properties of the final systems. Thermal, thermomechanical and mechanical properties have been analysed. The POSS have been shown to change the crosslinking density of the thermosetting networks, while, in thermoplastic systems, the properties of the hybrid systems have been largely influenced by the nature of the organic ligands borne by the POSS
Razafinimaro, Tolotrahasina Ida. "Etude des relations structure–propriétés rhéologiques et mécaniques de nanocomposites polyamide12/argile organophile : Effet de la fraction volumique et des conditions de mélangeage." Brest, 2006. http://www.theses.fr/2006BRES2034.
This work aims at studying the relationships structure – rheological and mechanical properties of polyamide12/organically modified clay nanocomposites. The effect of solid content and mixing conditions on melt state rheological and solid state mechanical properties was studied using numerous experimental investigation techniques. Linear and non-linear viscoelasticity allowed to characterize the melt state behavior of the nanostructured materials, wide angle X ray diffraction coupled with transmission electronic microscopy were used to characterize the structure; tensile tests were performed to characterize the mechanical behavior up to the total break. The results have clearly shown that both melt and solid state mechanical properties of nanocomposites depend strongly on the solid content and on the processing parameters. We have clearly shown the existence of a threshold solid volume fraction, at about 1%, separating two clay concentration regimes : - a dilute regime, where isolated clay entities govern the mechanical response of the nanocomposites. The rheological and mechanical properties depend on the nature, the number and the shape of these primary entities, which can be tuned by the processing parameters : mixing time and speed. - a concentrated regime, where the mechanical response is governed by a structure composed of “domains”. The rheological and mechanical properties depend on the size of these domains, which can be tuned by the processing parameters : mixing time and speed. However, the mechanical properties at break are disappointing, probably due to the presence of aggregates which induce stress concentration effects
KHERBOUCHE, ALI. "Contribution au predimensionnement des structures composites sandwiches." Le Mans, 1994. http://www.theses.fr/1994LEMA1012.
Arbaoui, Jamal Eddine. "Etude comparative et caractérisations mécaniques des structures sandwichs multicouches." Thesis, Metz, 2009. http://www.theses.fr/2009METZ048S/document.
The development of modern technologies requires that one use materials presenting high mechanical properties specific to their employment,but whose densities are low. The composite materials are materials which fulfil the preceding requirements. Because of their interest, the composite materials were initially used in aerospace, automotive, and construction industries. In composites, a class of particular interest ragarding the possibilities of design and development concern the sandwich structures resulting from a general assembly of a skin material with high stiffness and core materials of low density. The final properties of the materials are directly derived to the industry, many developments and studies in recent years have been aimed at optimizing the ratio mechanical performance over density. This thesis was undertaken with the same objective, but by having a strategy of optimization being focused more particulary on core materials. Our process is to reconsider in its entirety core materials and to propose a new concept of core complex which rests on the material stacking of different nature according to a quite precise sequence. The experimental results are correlated with those obtained by a theoretical approach based on a finite element method
Khalil, Mostafa. "Logiciel d'optimisation des structures composites sous chargements multiples et contraintes combinées." Toulouse, INSA, 1994. http://www.theses.fr/1994ISAT0048.
Haddou, Geoffrey. "Structure et propriétés physiques de composites à matrice biosourcée/fibres naturelles continues pour applications aéronautiques." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30272/document.
The aim of this work is to propose fully bio-based composites for a potential application in the cabin interior, and compliant with the REACh regulations. The use of vegetable fibers as reinforcement into polymeric matrices is an encouraging way to decrease the environmental impact, end the weight as well. A new bio-based polyamide matrix, synthetized by Arkema - Polyamide meta-xylylene diamine 10 - was used in this work. A preliminary study on Polyamide 11/bamboo powder showed the introduction of the fillers did not modified the physical structure of the matrix. Moreover, the optimization of the mechanical properties occurs with no coupling agent. The continuous bamboo fibers/PA mXD 10 composites, which were also processed without coupling agent, present shear moduli superior than the one of the synthetic reference glass fibers/phenolic, with a gain of weight about 50%
Tran, Van Luan. "Etude du comportement hygro-thermo-mécanique d'un matériau composite sandwich avec âme balsa utilisé en applications navales." Nantes, 2013. http://www.theses.fr/2013NANT2001.
Sandwich composite structures have been widely adopted in the naval field because they exhibit both lightness and good mechanical strength. However, their resistance to moisture in the marine environment is difficult to predict, and their fire resistance is one of the main limitations to their use in a greater number of cases. In this work, we focus on the behavior of a composite sandwich composed with glass-polyester skins and balsa core. Balsa, which is the main constituent, can absorb a large amount of water which may affect its mechanical properties. Moreover, the presence of moisture can influence the fire resistance of the material. Thus, in order to highlight the material durability and the physical phenomena encountered, several experiments were performed in miscellaneous conditions of humidity, temperature and mechanical loadings. In addition to classical results obtained on the balsa, testing of fire resistance combined with bending tests on sandwich composite materials were achieved to estimate the residual strength as a function of the combustion time. Finally, from experimental results related to the water uptake of balsa and of sandwich composite, modelling was computed to better understand and predict the mechanical state of the studied sandwich structure
Ramachandran, Laavanya. "Comportement électrique large bande des composites polymère - fils submicroniques d'or : corrélation avec la structure et les propriétés mécaniques." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30072/document.
The aim of this work is to study the properties of a polymer-metal composite, with regards to physical, thermal, mechanical and broad band electrical analyses. High aspect ratio gold nanowires (Au NW) were prepared using a template electrodeposition method (aspect ratio of 190 determined by image analysis). The gold nanowires were dispersed in a PVDF polymer matrix to form low-filled conducting composites. The electrical conductivity of the composites exhibit electrical percolation behaviour with a critical volume fraction of 1.33%. SEM images show a slightly oriented but homogenous dispersion of AU NWs within the PVDF matrix. Mechanical analysis confirms that the homogenous dispersion Au NWs reinforces the PVDF matrix and highlights the influence of Au NWs on the physical structure of the PVDF matrix. This is confirmed by an increase in G' values and more specifically the ac relaxation process (associated with the crystallite-amorphous phase interface). Analysis of static and dynamic conductivity for low (10-2 to 106 Hz) and high frequency (106 to 109 Hz) regions reveals a thermally-activated charge transport process: tunneling being the predominant mechanism at low temperatures, the Efros and Shklovskii (ES) and Correlated Barrier Hopping (CBH) models being responsible for static and dynamic conductivity, respectively. The models were found to be coherent with the structure and mechanical properties of the composites, leading to a better understanding of charge transport mechanisms in low-filled polymer-metal composites
Benhouna, Mohammed. "Etude du comportement mécanique des structures en béton renforcé de barres en composites (JITEC)." Lille 1, 1997. http://www.theses.fr/1997LIL10014.
Armengaud, Gérard. "Calcul explicite (analytique et numérique) des champs de contraintes dans des structures élancées homogènes et composites à l'aide de méthodes énergétiques." Toulouse 3, 1996. http://www.theses.fr/1996TOU30004.
Dobircau, Larisa. "Relations structures-propriétés dans les composites 100 % naturels, bio-sourcés, renforcés par des fibres végétales." Rouen, 2011. http://www.theses.fr/2011ROUES016.
Over the last decades the consumption of synthetic polymers and their products increased rapidly and the problems concerning the plastic wastages are now one of the most important limiting factors for its extensive usages. The research efforts are being harnessed in the development of fully biodegradable "green" materials. Among these new materials , plastics resulting from bio-resources in general, and starch in particular, seem to be able to replace polymers resulting from petro chemistry. Thus, the primary goal of this work was to study the effect of the composition of a wheat flour based matrix on the physical properties. By the mean of an extrusion process, we carried out films with different compositions and compared the structures, morphologies, the thermal and mechanical properties obtained. Then, we focused on the valorisation of natural fibres (cotton, flax and bamboo) by their incorporation in our matrix. These fibres were not chosen by hazard, indeed, cotton is resulting from the recycling of fabric cutting, the short flax fibres are a by-product of the production of long fibres and finally the bamboo because this plant can present very fast growths. We could show initially that the matrix composition initially established in a patent can be simplified and improved by the suppresion of certain components like silica, stearate of magnesium and partly the sorbitol. Then, "low-tech" 100 % natural composites (short life time) were carried out by varying the nature of the reinforcement used. In the future, these performances will make it possible to target quite specific markets
Laurent, François. "Optimisation des caractéristiques mécaniques des structures en composite." Compiègne, 1989. http://www.theses.fr/1989COMPD173.
Sahnoune, Farid. "Relations structure - propriétés mécaniques dans des systèmes PEHD/PS et PEHD/CaCO3 modifiés par des agents élastomères : application au recyclage des matières plastiques." Montpellier 2, 1998. http://www.theses.fr/1998MON20092.
Bayoumi, Mohamed. "Structure et comportement mécanique de composites à matrice Al-Si contenant des particules de carbure de silicium." Grenoble INPG, 1987. http://www.theses.fr/1987INPG0126.
Kim, Moo Sun. "Optimisation des structures composites en intégrant les paramètres de fabrication." Saint-Etienne, EMSE, 2007. http://www.theses.fr/2007EMSE0029.
In this study, optimization of mechanical properties of a composite material product manufactured by compression molding process was performed by considering the changes of fiber states. Fiber states, which changes by the compression molding process, are fiber volume fraction and fiber orientation. These fiber states lose their initial properties and show non-homogeneous and anisotropic properties due to the pressure and velocity field generated during compression process. To predict the fiber states changes during the compression molding process, fiber separation phenomenon and orientation were numerically considered by coupling them with flow analysis computed by CVFEM. Based on the fiber states information, the mechanical properties of chopped fiber composite were computed. Then they were applied to the plate type structure analysis. In the gross, numerical analysis of process and structure were coupled. In addition, the optimization of structural design and process condition was performed. Structural thickness and precharge location and dimension were considered as the design variables. At first, the Complex method was implemented for thickness optimization. The optimization results of two cases, where the compression process was considered in one case and homogeneous and isotropic material were considered in the other, are compared. To resolve the precharge location and dimension optimization problem, genetic algorithm was implemented. The constraints of design vectors and the characteristic of optimization problem divide search space into feasible search space and unfeasible search space. To handle the constraints of optimization problem, the penalty function method and modified repair algorithm were applied. By applying them to the test function, optimization procedures for these two methods were compared. The suggested techniques were applied to symmetric rectangular plate, car-hood type structure and arbitrary and asymmetric shape structure and the optimization results were compared
Lascoup, Bertrand. "Analyse et modélisation du comportement mécanique de structures composites sandwichs multi-D." Compiègne, 2005. http://www.theses.fr/2005COMP1585.
The objective of this work is to apprehend the damaging modes of an original sandwich structure strengthened by stitches and to propose a predictive tool for the choice of the geometrical and material parameters. This objective requires both an experimental and a theoretical approach. The experimental part enables to determine the behavior of this type of structure under static and dynamic stresses. A R TM device was created in order to control the implementation parameters and to highlight the influence of the microstructure of the reinforcements. The analysis of the damage mechanisms highlights the influence of the geometrical parameters of stitches on the behavior of the structure. The problems resulting from the inter-laminar efforts are attenuated: the brittleness of the core/skin interface and delamination into the skins is reduced. The modelling part allows to represent the material behavior by using simple and adapted theories and seeks to predict the rigidity and the maximum stress in the three directions. A data-processing tool named SANDTEX brings a predictive tool to the industrial world
Beaudoin, Olivier. "Contribution à l'étude des relations microstructure - propriétés mécaniques d'une matrice polybutylène térephtalate (PBT) renforcée de billes ou de fibres de verre." Montpellier 2, 1998. http://www.theses.fr/1998MON20058.
Dubaa, Marie. "Etude d’un système innovant de renforcement des élastomères par la synthèse in situ de polyuréthanes." Thesis, Lille, 2018. http://www.theses.fr/2018LIL1R039.
Elastomers are macromolecules which, under the effect of vulcanization, present remarkable properties of hyper-elasticity, making their use essential in many industrial sectors and consumer goods. However, in order to obtain sufficient mechanical properties for such applications, fillers, such as carbon black and silica, need to be incorporated in rubber formulations. Even if they are commonly used in the industry, these fillers present some major limitations, especially their high density (> 1,8), leading to heavy materials when incorporated at high rate. The aim of these works is to study a new type of reinforcement, based on polyurethanes synthesized in situ during elastomers processing, in order to decrease their weight. Elastomer/polyurethane blends thus formed were characterized to determine their rheological, mechanical, thermal, thermomechanical properties in addition of their densities. This work has proven our concept as PUs reinforced materials present lower densities compared to a conventional reinforcement while having correct mechanical properties
Grillard, Fabienne. "Structure et propriétés de fibres composites polymère-nanotubes de carbone obtenues par voie fondu." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14577/document.
This thesis reports the study of the properties and structure of carbon nanotube / polymercomposite fibers obtained by melt spinning. By contrast to most fibers produced by thistechnology, the fibers produced in this thesis are electrically conductive. The conductivityproperties are studied as a function of various parameters including temperature andmechanical stress. It is shown that fiber drawing induced by the process leads to a relativetranslation of the nanotubes relative to each other and to a loss of electrical contacts. Ananalytical model accounts for this phenomenon and reproduces the experimental results.Polymer-nanotube fibers exhibit also particularly original thermomechanical properties suchas shape memory effects that are controllable by the programming process. Surprisingly, thefibers have a temperature memory reflected by a peak of the generated stress at thetemperature at which the materials has been programmed. These effects have beendemonstrated for various types of deformations including elongation and torsion. Althoughthese effects are governed by the properties of the polymer, it is shown that the introductionof nanotubes provides significant improvements of the thermomechanical properties
Crouzeix, Laurent. "Identification de champs de propriétés mécaniques de structures composites à partir de mesures de champs de déplacement." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/455/.
This work deals with the use of full field kinematical measurements to identify fields of anisotropic mechanical properties within composite structures. Multi instrumented tests performed on filament winding pipes illustrate the limits of a homogeneous material modelling. A finite difference approach adapted from the Equilibrium Gap Method is proposed. Tensile tests on HexMC(r), assumed to be isotropic heterogeneous, are treated. Identified maps of Young moduli contrasts enable, with the loading, to characterize the material initial heterogeneity, and its damage. A biaxial test on 2,5D C/C composite, assumed to be initially homogeneous orthotropic and damageable, is then treated. Shear moduli contrasts at various loadings, associated with a modelling of the anisotropic damage, lead to damage law identification and damage maps
Tamoud, Abderrahman. "Mécanique multi-échelle et multiaxiale des composites souples multicouches : application à l'annulus fibrosus humain." Thesis, Université de Lille (2018-2021), 2021. https://pepite-depot.univ-lille.fr/ToutIDP/EDENGSYS/2021/2021LILUN034.pdf.
The damage in annulus fibrosus soft tissues is a complex multiscale phenomenon due to a complex structural arrangement of collagen network at different scales of hierarchical organization. A fully three-dimensional constitutive representation that considers the regional variation of the structural complexity to estimate annulus multiaxial mechanics till failure has not yet been developed. In the present PhD dissertation, a model, formulated within the framework of nonlinear continuum mechanics, is developed to predict deformation-induced damage and failure of annulus under multiaxial loading histories considering as time-dependent physical process both chemical-induced volumetric effects and damage accumulation.In a first part, a microstructure-based model is proposed to connect structural features, intrinsic mechanics and electro-chemical properties of annulus soft tissues. The multi-layered lamellar/inter-lamellar annulus model is constructed by considering the effective interactions between adjacent layers and the chemical-induced volumetric strain. The model/experiments comparison demonstrates that the evaluation of the overall time-dependent response involves considering stress, volumetric change and auxetic feature simultaneously in relation to structural features.In a second part, the model is enriched by considering the hierarchical structure of the soft tissue from the nano-sized collagen fibrils to the micro-sized oriented collagen fibers. The stochastic process of progressive damage events operating at different scales of the solid phase is introduced for the extracellular matrix and the network of nano-sized fibrils/micro-sized fibers. The directional effects on annulus mechanics and failure are highlighted in relation to external loading mode, structure features, damage events and hydration.In a third part, the model is further developed by considering the regional variation of the complex structural organization of collagen network at different scales to predict the regional anisotropic multiaxial damage of the intervertebral disc. After model identification using single lamellae extracted from different disc regions, the model predictability is verified for various multiaxial elementary loading modes representative of the spine movement. The stretching along the circumferential and radial directions till failure serves to check the predictive capacities of the annulus model for the different regions. Model results under simple shear, biaxial stretching and plane-strain compression are further presented and discussed.In a fourth part, a full human disc model is constructed using the regional annulus model to examine the heterogeneous mechanics in the disc core. Damage fields in the disc are analyzed under axial compression, axial twist and combined loadings to assess the areas where the risk of failure is the highest
Bugnicourt, Elodie. "Development of sub-micro structured composites based on an epoxy matrix and pyrogenic silica : mechanical behavior related to the interactions and morphology at multi-scale." Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0113/these.pdf.
Les réseaux époxys présentent des propriétés insuffisantes pour certaines applications, en particulier à cause de leur fragilité. L'objectif de ce travail était de développer des composites à matrice époxy-amine et charges de silice pyrogénée afin d'améliorer les propriétés mécaniques des époxys pour des utilisations comme revêtements, adhésifs ou matériaux de structure. La silice pyrogénée a été fréquemment employée pour renforcer des élastomères ou dans un but de modification rhéologique, mais peu d'études traitent de l'addition de silice pyrogénée dans des réseaux thermodurcissables. Contrairement aux additifs conventionnels (organiques ou micro-charges), les charges sub-microniques permettent généralement d'augmenter à la fois la rigidité et la ténacité des matériaux polymères, tendance qui a été vérifiée dans ce travail pour la silice pyrogénée. En faisant varier la nature des comonomères époxy-amine et de la modification chimique de la surface de la silice, la nature des interactions développées au sein du système a pu être modulée (liaisons covalentes vs. Interactions physiques) et l'influence de la silice pyrogénée a pu être étudiée à la fois sur des réseaux dans l'état caoutchoutique et vitreux à température ambiante. Un des principaux défis de cette étude était le contrôle de l'état de dispersion de la silice grâce à l'optimisation de chaque étape du procédé. Les morphologies ont été caractérisées à de multiples échelles tout au long de la mise en œuvre par diverses techniques complémentaires. Une attention particulière a été portée aux interactions effectivement développées entre les charges et la matrice. Le comportement mécanique des matériaux a été caractérisé par analyse mécanique dynamique, test de traction et mécanique de la rupture. Les relations entre la structure et le comportement mécanique des composites époxy / silice pyrogénée ont enfin été discutées afin de comprendre les mécanismes de renforcement impliqués. L'effet de la silice a également été investigué sur les propriétés thermiques et la résistance au feu des réseaux époxys
Peurton, Frédéric. "Nanocomposites à matrice thermoplastique et renforts plaquettaires : relations élaboration-structure-propriétés." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10168/document.
Nanocomposites based on polymerie matrix and clay reinforcements have created a huge effort from academic and industrial researches. This investments are recompensed by the significant amelioration of several properties in comparison to conventional composites. The present work is devoted to a key parameter which is the elaboration conditions, in relation to structural organizations and mechanical properties. The first part deals with the clarification, in case of Nylon 6 nanocomposites, of the relationship existing between thermo-mechanical history and crystalline organization. Those elements are then used in properties optimization of blown films. The second part of the work tackles the elaboration of nanocomposites with a biodegradable polymerie matrix (Polylactide) and an unmodified clay using an original process of water injection, in collaboration with the university of Louvain La Neuve (High Polymer Unit). The obtained films exhibit a dispersion of fine clay aggregates intercalated by PLA (tactoïdes). The presence of this dispersion gives raise to a remarkable mechanical behavior, especially in term of ultimate properties
Billon, Kevin. "Composites périodiques fonctionnels pour l'absorption vibroacoustique large bande." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2018/document.
The understanding of wave propagation in periodic structures is proposed in this work. Periodic structures exhibit very specific properties in terms of wave propagation. First, some numerical tools for dispersion analysis of periodic structures are presented. The classical Floquet-Bloch approach is first presented, as a reference. This technique uses proper boundary conditions on the unit cell, but dealing with damping is not easy for 2D or 3D cases. Secondly, a metamaterial with hierarchical, auxetic (negative Poisson ratio) rectangular perforations is presented using the Floquet-Bloch method as a reference. Some numerical eigenvalue tools are used for the dispersion analysis of this structure. A geometric parametric investigation of these rectangular perforations using a numerical asymptotic homogenisation finite element approach is done. The experimental validation is performed with a network based on polymethyl methacrylate (PMMA) using a 3D scanning vibrometer. Third, the Shift cell operator technique is described. It consists in a reformulation of the PDE problem by shifting in terms of wave number the space derivatives appearing in the mechanical behavior operator inside the cell, while imposing continuity boundary conditions on the borders of the domain. Damping effects can be introduced in the system. This strategy make it possible to solve the problem with an arbitrary frequency dependency of the physical properties of the cell. A focus is proposed on tools for the post-processing of dispersion diagrams in damped configurations like group velocity. Finally, an adaptive metamaterial based on the combination of metallic parts with highly dissipative polymeric interface is designed. In order to validate the design and the adaptive character of the metamaterial, results issued from a full 3D model of a finite structure embedding an interface composed by a distributed set of the unit cells are presented. After this step, a comparison between the results obtained using the tunable structure simulation and the experimental results is presented
Zhang, Xuan. "Contribution à l'étude de l'apport des coutures sur les performances mécaniques des structures composites cousues." Compiègne, 2012. http://www.theses.fr/2012COMP2029.
One of the main problems of composites laminates is their low resistance in the thickness direction. The introduction of the stitch is considered as a promising technology to solve this problem : delamination. The objective of this study is the experimental analysis of the mechanical behavior of stitched composite to evaluate the contribution of the stitch in the thickness direction. This evaluation was carried out on one hand 2D plates reinforced by transverse stitch and on the other hand on "I" stiffened structures. A unique aspect of this thesis is that all the work has been done in full autonomy, ranging from the manufacture to the numerical modeling, namely the realization of the stitch, the impregnation of dry performs by the infusion method, mechanical testing multi-instrumented with microscopic observations and modeling based on a numerical tool developed in our laboratory. The 3D mechanical characterization of unstitched and stitched composites showed that the out of plan properties, and z• were respectively improved by 200% and beyond 50% for Z-. Paradoxically, the out of plane shear properties (elasticity and fracture) showed no significant differences between stitched and unstitched materials. It should be noted that the determination of out of plane shear modules G 13 and G23, already difficult to achieve in traditional 2D laminates, which has been discussed for the stitched materials through three points bending tests, the measure of deformation fields was performed with DIC (Digital Image Correlation). The 3D mechanical characterization campaign also confirmed the fact that the improvement of the out of plan properties is accompanied by a degradation of 2D properties. Overall, we have found a decline in 2D properties of the stitched composites by about 20%, compared with the unstitched composites. These falls in properties are attributed to the damages caused during the manufacturing phase: the passage of the needle separated and damaged the strands of laminate, forming resin rich areas. The stiffened structures, unstitched and stitched, were characterized by 4-point bending, compression and tension. The results showed that in the case of a tension solicitation, stitches bring a stiffening effect, limiting the delamination between the primary structure and the stiffener. The ultimate performances are improved by 20%. In the case of the compression configuration, the contribution of these stitches prevents delamination and thus repelling significantly the ruins the structure. The performance increase more than 50%. The stiffened structures were modeled through a calculation code developed by Hocine KEBIR, who is a member of our laboratory Roberval. The originality of this code lies in managing the mesh of stitches, in the sense that it can automatically manage the coincidence between the nodes of primary structure and stitches. These are modeled either by rod elements, or by bearn elements. The numerical modeling results showed very good agreement with experiment in a macroscopic point of view as well as local
Chomat, Dimitri. "Élaboration et mise en forme de composites micro-fibrillaires par fibrillation in-situ : optimisation de la microstructure et des propriétés mécaniques résultantes." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10127.
Elaboration of microfibrillar composites based on immiscible polymer blends was performed by means of in-situ fibrillation. First, a polypropylene / polyamide 6 blend (PP/PA6) was used as a reference in order to develop an extrusion - drawing process. Upon variation of rheological parameters, it appeared that fibrillation requests a viscosity ratio less than 4 and an elastic ratio less than 1. Experiences about influence of processing temperature demonstrated that the injection step must be proceed at a temperature lower than the melting temperature of the dispersed phase in order to preserve the morphology. In a second part, this study dealt with the incorporation of organically modified montmorillonite with the aim of compatibilizing PP/PA6 blends. Several ways of nanoclay addition have been tested. Among them, nanoclay pre-dispersion in the PP matrix lead to the migration of clay platelets from PP to PP/PA6 interface during the in-situ fibrillation process. Hence, fibrils refinement was observed, inducing an improvement of impact resistance. Finally, one last part was dedicated to the development of a poly(lactic acid) / polyamide 11 bio-based micro-fibrillar composite. Whereas a partially fibrillar morphology was formed upon drawing, injection of the composite involved fibrils destruction due to overheating and subsequent relaxation
Ferreira, Manuela. "Etude des fibres et câbles haute performance en poly(p-phénylène -co-3,4' -oxydiphénylène téréphtalamide) (Technora) : relation structure-comportement mécanique et recherche de critères de dépose des câbles." Lille 1, 1996. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1996/50376-1996-212.pdf.
Cochereau, Thibaud. "Structure et Mécanique du pli vocal humain : caractérisation et modélisation multi-échelles." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI018/document.
The human vocal fold owns exceptional vibratory properties. It is capable of withstanding large deformations, for different types of loading, in a repeated and reversible manner. These particular vibro-mechanical properties are closely linked to its microstructure: a multi-layer complex structure composed of highly heterogeneous protein fibre networks. However, it is still difficult today to describe precisely the implication of the microstructural specificities of the fold in its biomechanical behaviour.In order to clarify this link and to move towards a better understanding of the behaviour of the vocal tissue, this study proposes to approach the problem under three complementary approaches, combining microstructural characterization, mechanical characterization and numerical modelling. First, the microstructure of the fold was studied emph{ex vivo} using an original technique based on X-ray tomography. The use of synchrotron tomography in phase retrieval mode has revealed the structure of the tissue at different scales. In particular, high-resolution 3D images of the fibrous structure of the upper and muscular layers of the tissue were acquired. These images gave rise to a quantitative 3D analysis of the fibrous arrangement, allowing the determination of descriptors of orientation and 3D geometry of the fibers.In a second step, the mechanical behaviour of the fabric under different loading conditions was studied. A protocol has been proposed to characterize the same sample in tension, compression and shear. These tests have complemented existing knowledge on fold biomechanics, and constitute important reference data for the construction and validation of digital models.Finally, based on the data acquired experimentally, a micro-mechanical model was developed. This model has the specificity to take into account the 3D arrangement of the tissue through an idealized but relevant representation of its fibrous microstructure. The macroscopic responses predicted for different loading conditionds could be compared to the experiment for validation. At the microscopic scale, the kinematics of the fibres during the loading could be simulated. The micromechanisms that occur during the deformation of the fibrous network could thus be identified, opening new perspectives in the understanding of the multi-scale properties of the tissue
Schmitt, Hélène. "Développement de bio-nanocomposites à structure maîtrisée d’intérêt biomédical." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10192.
This study concerns the development and manufacture of nanocomposite materials having a controlled structure of biomedical interest based on plasticized starch reinforcement by halloysites nanocharges. Initially, effect of storage time and plasticizers on the structural variations of melt processed thermoplastic starch has been comprehensive investigated. The best choice of plasticizer is found to be plasticizer having amino groups, which improves the structural stability of plasticized starch. This stability is not affected by the incorporation of halloysite nanotubes. Addition of nanofillers effectively improves the thermal and mechanical properties of the resulting bio-nanocomposites. The tubular structure of nanocharges chosen in this study allows to temporarily trap an active ingredient in the material. So protected by the starch matrix during the development and digestion phases, the efficiency of the colon and intestinal specific inflamed drug delivery systems has been improved. Finally, the nanofillers in the thermoplastic starch matrix act a cell nucleating agent for the expansion and stabilization of cell morphology by blocking the coalescence of cells. The developed materials are potentially suitable for the manufacture of bone cement or bone substitute combining mechanical strength and controlled porous morphology
Thuault, Anthony. "Approche multi-échelle de la structure et du comportement mécanique d'une fibre de lin." Caen, 2011. http://www.theses.fr/2011CAEN2055.
This PhD thesis deals with the understanding of the flax fibres structure at different scales and the studying of its mechanical behaviour. Indeed, in the context of sustainable development, using plant resources covers several fields of industrial applications including structural eco-composites. At first, seven varieties of flax fibres were compared in terms of morphology (diameter), biochemical composition and mechanical properties. Then, the structural study of the flax fibre dealt with the cell wall layers (number, thickness) and the microfibrils orientation in these layers. The analysis of the stress-strain curves obtained by uniaxial tensile test was used to estimate the elastic, viscoelastic and "plastic" contributions to the global behaviour of the fibre. The orthotropy of its mechanical behaviour has been demonstrated by nanoindentation testing. Finally, these data were used to identify the principal parameters that define the mechanical behaviour of the flax fibre. Thus, simulations of the mechanical behaviour of the fibre have been initiated to propose a phenomenological description
Tadlaoui, Samir. "Influence de l'état de la réticulation de la matrice thermodurcissable (soc) sur les propriétés mécaniques des matériaux composites obtenus : expérimentation et modélisation." Saint-Etienne, 1994. http://www.theses.fr/1994STET4009.
Knapp, Thomas Alarich. "Étude structurale d'un avion de voyage, de formule canard, en matériaux composites." Toulouse, ENSAE, 1990. http://www.theses.fr/1990ESAE0008.
Paradis, François. "Analyse du comportement structural d'un composite mince en béton. : nalyse du comportement structural du canoë de béton." Thesis, Université Laval, 2004. http://www.theses.ulaval.ca/2004/21701/21701.pdf.
This thesis presents bares the analyses of Laval University’s Apogee 2002 concrete canoe. The predominant objective is to investigate and understand the canoe’s reaction under various loading patterns. A second objective is to elaborate design criteria for these types of structures. These criteria and comprehension of the structural behavior will be used for the upcoming canoes. These objectives are achieved coalescing experimentation and modeling. The present work begins with the elaboration of the concrete design used for Apogee’s construction. The characterization of the physical and mechanical properties of the composites used in the structure follows. Additionally, the sub-structures of the canoe and the entire canoe’s structural reaction analyses are predicted fulfilled using a finite element software. Finally, in-situ tests are performed on the canoe and the results compared to that obtained with the numerical model. The experimentation comprised both static and dynamic tests. Dynamic testing is used to determine the strain amplification due to paddling and turning. The design criteria are determined and presented according to the results obtained from the finite element software followed by experimentation.
Inscrit au Tableau d'honneur de la Faculté des études supérieures
Magno, Massimo. "Modèle mécanique du comportement de structures souples aux échelles mésoscopique et macroscopique : application aux matériaux fibreux." Mulhouse, 1999. http://www.theses.fr/1999MULH0554.
Speisser, Evelyne. "Étude sur les propriétés physico-mécaniques des tiges d'armature composites à base de fibres pour les structures en béton." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1995. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq21831.pdf.
Speisser, Evelyne. "Étude sur les propriétés physico-mécaniques des tiges d'armature composites à base de fibres pour les structures en béton." Mémoire, Université de Sherbrooke, 1994. http://savoirs.usherbrooke.ca/handle/11143/1002.
Tarsha, Kurdi Kheir Eddine. "Contraintes résiduelles de cuisson dans les stratifiés composites à finalité aéronautique : intégration du procédé de mise en oeuvre et étude de leur influence sur les caractéristiques mécaniques." Toulouse 3, 2003. http://www.theses.fr/2003TOU30061.
Martin, Clélia. "Films multicouches à base de nanocristaux de cellulose : relation entre structure et propriétés mécaniques et/ou optiques." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAS021/document.
CNCs are biobased nanorods that are attracting increasing attention from both the academic and industrial communities due to their numerous properties such as renewability, high specific surface area, excellent mechanical properties, light weight, or non-toxicity. CNCs are thus considered as highly promising blocks for the production of high performance biobased composites. In the last ten years, negatively charged CNCs have been associated with natural or synthetic polycations or neutral biopolymers within multilayered films built by the layer-by-layer assembly technique. In the present study, we have investigated three new research axes in the CNC-based multilayers field. In a first part, polymer chains have been replaced by positively charged inorganic Gibbsite nanoplatelets (GN) to form innovative hybrid nanoparticules-based thin films. We have shown that the architecture of (CNC/GN) films can be tuned over a wide range by adjusting the physico-chemical parameters such as the aspect ratio of the CNC, the ionic strength, or the drying protocol. The detailed internal structure of the multilayered films has been elucidated by the complementary use of AFM and neutron reflectivity (NR) and was attributed to a combination of different interaction forces. In a second part, the resistance to humidity of purely biobased films was investigated by comparing films where CNCs are associated either with neutral xyloglucan chains or with oxidized ones. AFM and NR reveal that the kinetics of water intake and hydration strongly depends on the possibility to form inter- and intra-layer hemiacetal bonds forming a covalent network. The third axis concerns the production of uniformly oriented macroscopic surfaces of CNCs to build anisotropic multilayered nanocomposites. Enhanced alignment was achieved by the use of laminar shear flow.The fine tuning of the structural features of all the multilayered systems studied gives rise to specific macroscopic physical properties. The mechanical properties of films of various architectures (Young’s modulus) have thus been measured using the strain induced elastic buckling instability for mechanical measurements (SIEBIMM) technique and tentatively related to the film’s structure. The tunable properties of such multilayered systems pave the way to the design of thin films and coatings for separation membranes or supports for flexible electronics
Amara, Dehman. "Assemblage structural collé alumine-acier 304L : propriétés superficielles des substrats et adhérence." Toulouse, INPT, 1993. http://www.theses.fr/1993INPT005G.
Lainé, Cyril. "Contribution à la modélisation du comportement mécanique de structures sandwichs 3D par homogénéisation périodique." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10013.
3D composite sandwichs have superior mechanical characteristics compared to usual composite sandwichs, in particular in the through-thickness direction. The structures studied in this work are 3D reinforced sandwichs using the Napco® technology which is based on transverse needling. In a first step, a complete experimental study is realized (creation of the through-thickness reinforcements, composite manufacturing by infusion process, experimental tests, measurement of geometric and material parameters) lead to better understanding of the sandwich architecture and their mechanical behaviour. In a second step, an interest is carried on the determination of the effective mechanical properties of this structures, using different homogenization techniques (periodic), analytical and numerical, in order to assess an equivalent plate model. An interest is devoted to the out-of-plane behaviour such as buckling of the reinforcements during compressive loading in the thickness direction and the importance to take into account the effects of transverse shear. Analytical models have been developed in 2D and a PythonPM program (using Abaqus software) have been created, allowing a fully parameterized modelling and mechanical analysis. The results are finally validated, using numerical computations on 3D heterogeneous structures or by experimental results, for several sandwichs considering different density of reinforcements
Pouderoux, Patrick. "Codéposition électrolytique par courant pulsé d'alliages nickel-phosphore et fer-chrome-nickel." Toulouse 3, 1991. http://www.theses.fr/1991TOU30245.
Bounasser, Meriem. "Étude du comportement mécanique des renforts tressés pour les matériaux composites." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI004.
The use of textile composites is increasing in several areas, such as aerospace industries, transportation, civil engineering and others, due to their high strength-weight ratio. Braided structures are one of the textile reinforcements used in different industrial applications for the cost effectiveness of their manufacturing technique, its versatility and the wide range of shapes it can offer. The special structures with the special functionalities needed in each composite application make the braiding a delicate process that needs to be studied in order to fulfill the demands of each specific sector. This PhD project aims to achieve a proper understanding of the process, the structures, the various parameters and the behavior of the final products. The study is conducted using the Herzog 2D braiding machine of Ifth, which, combined with a 6 axes robot, can prototype 3D structures by over-braiding complex shaped mandrels. Multiple carbon fiber braided samples are produced by varying the process parameters (Braid angle, Braid's diameter ...) and characterized in order to assess the influence of these parameters on the braid's geometry and its mechanical properties. To reach a better understanding of the materials' behavior and to avoid the time-consuming trial and error manufacturing and testing way, a modeling procedure is necessary to support the experimental work and optimize the design phase of the braids. Different models have been developed by researchers to predict the properties of braids at different scales of the structure (microscopic - mesoscopic - macroscopic). This work will be focused on the finite element analysis at the meso-scale, i.e. the braid unit cell scale, which considers the orientation of the yarns and the braid's architecture. This analysis is conducted using a hypo-elastic constitutive law which is implemented in user subroutine Vumat in Abaqus/Explicit. In this work, the geometric model is obtained using micro-computed tomography, which is a nondestructive scanning technique that allows detailed and precise analysis of the geometry of a textile reinforcement
Ouchiar, Saadia. "Étude des relations structure – propriétés physiques de composites verts biopolymère/argile : effet de la nature et de la teneur en renfort." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10023.
Although in constant development, the use of biobased polymers for industrial applications is still limited mainly because of their intrinsically limited physical properties. Adding clay is one solution to outclass these limitations. The main goal of this thesis, with an applied nature, was to elaborate and characterize new composite materials based on biopolymers and clays for applications in the packaging field. More especially, the influence of the clay nature was assessed. One of the distinctive features of this PhD work is the use of a high clay contents (≥ 30 wt%). Moreover, a particular attention was paid to study the role of the interface between the polymer matrix and the mineral filler on the structure as well as on the thermomechanical and barrier properties of the elaborated biocomposite.A screening of different biopolymer/clay compound elaborated at the laboratory scale was firstly studied in terms of structure, morphology and physical properties. Then the most promising formulations were selected and elaborated at a larger scale using industrially processes. The results obtained on Polylactide (PLA)/clay compounds showed that rather than the content of clay or its dispersion degree, it is the nature of the clay, i.e. its chemistry and its crystallography, that mainly govern the thermomechanical properties. Furthermore it was highlighted that applying a biaxial stretching on this kind of materials offsets the PLA brittleness and increases its barrier properties. Finally, regarding the alginate based composites, plasticization leads to a heterogeneous material and adding clay involves an increase of the material rigidity without any decrease of stretchability
Perrot, Grégory. "Modélisation du comportement des composites à matrice céramique auto-cicatrisante sous charge et atmosphère oxydante." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0442/document.
Self-Healing Ceramics Matrix Composites (HT-CMC) are developed since several years for theirapplication in aeronautic applications and are interesting for their good resistance to criticalenvironments. As part of a study program of the HT-CMC behavior and their damagemechanisms, the objective of this thesis is to build a multi-physics numerical model todetermine the lifetime of a sample such a material subjected to a mechanical stress in anoxidizing environment. The study focuses on the establishment of a coupling between twocomputer codes: a code of mechanical damage and a physical-chemical code that wasdeveloped during this thesis. In an unprecedented way, we place ourselves in the 2D geometryof a crack plane, starting from a detailed picture of the arrangement of the components (fiber,interphase, multi-layer matrix). The different parts of the code have been independentlyvalidated and the results of the complete calculation are presented and discussed
Kamdem, Signe Christian. "Caractérisation et modélisation du comportement mécanique des structures tissées aux températures cryogéniques." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I063/document.
The exploitation and use of Liquefied Natural Gas (LNG) is growing worldwide, resulting in a booming market with many LNG terminal installation projects. These liquefied natural gas installations, which operate at very low temperatures (~ -160 ° C) to facilitate its transport, however require continuous maintenance without cutting the supply valves upstream or downstream. This study is a part of a global project funded by the government named CRYOBTURE which aims to design and develop a new solution of inflatable shutter to facilitate the maintenance of LNG (Liquefied Natural Gas) pipeline facilities. This solution would be obtained from a sealing balloon formed of several layers coated textile composite materials capable of obstructing the flow of LNG. Th question is therefore to find the ideal composition and combination of these woven structures which must have optimum mechanical properties and in adequacy with the operating conditions, in particular in terms of breaking strength and deformability. At first, the mechanical behavior in tension of certain synthetic textile fibers was investigated under cryogenic temperatures. The analysis of the obtained results made possible to discriminate some of them with regard to their mechanical properties and thus to make choices that were exploited for the elaboration of the woven structures. From there, we have been able to characterize the tensile mechanical behavior at cryogenic temperatures of some coated woven structures obtained from the previous fibers. The analysis of the various results allows us to consider several architectures for designing the shutter and thus to propose choices on the woven structures for each of the composite layers of the LNG shutter. These structures generally exhibit nonlinear orthotropic behavior. Modeling such behavior requires the use of specific models such as Fung's. We were able to numerically simulate the mechanical and thermal behavior (decoupled) of the shutter in an LNG environment.The results of this project have shown a number of limitations but open up prospects in terms of transfer to other application sectors requiring flexible supports subjected to cryogenic temperatures
Barrère, Tricca Cécile. "Relation entre les propriétés de la résine et le phénomène de perlage de tubes composites verre - époxy." Paris 6, 1998. http://www.theses.fr/1998PA066019.