Dissertations / Theses on the topic 'Biocomposites – Propriétés mécaniques – Rupture'
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Khalifa, Anissa. "Etude des propriétés mécaniques et de rupture d'un biocomposite à base de particules de coquillages de mer élaboré par fabrication additive." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDENGSYS/2023/2023ULILN050.pdf.
Filaments of PLA biocomposites loaded with seashell particles (Oyster and Mussel) were produced by extrusion with four mass fraction rates of particles (5%, 10%, 15%, 20%) with particle sizes less than 160 microns. These filaments were used for additive manufacturing (AM) in Fused Deposition Modeling (FDM) of test specimens. Thermal and mechanical characterization tests were conducted to understand the behavior of the filaments before their use in printing. X-ray tomographic observations highlight the distribution of seashell particles in the PLA matrix. Microscope observations of fracture surfaces are presented. Finally, thermogravimetric analyses are performed and analyzed.A printing strategy was developed to study the effect of printing parameters such as infill angle, layer thickness, printing temperature, and printing speed on the mechanical properties of the biocomposites. The objective was to identify the optimal parameters for obtaining the best mechanical properties on printed dumbbell-shaped specimens (ASTM D638 standard). The results obtained reveal significant dispersion, especially in terms of elongation at break. A fracture study on SENT (Single Edge Notched Tension) specimens printed with two different infill angles (+45/-45°, 0°/90°) was conducted to determine the toughness of the biocomposites by coupling monotonic tensile tests with Digital Image Correlation (DIC) method. This approach provided a better understanding of the mechanical behaviors of the biocomposites and characterized their fracture resistance
Le, Duc Anne. "Comportement et rupture de fibres cellulosiques lors de leur compoundage avec une matrice polymère." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2013. http://pastel.archives-ouvertes.fr/pastel-00982245.
Randrembason, Vero. "Biocomposites amidon-cellulose : Elaboration, caractérisation et modélisation du comportement viscoélastique." Montpellier 2, 2005. http://www.theses.fr/2005MON20009.
Martin, Nicolas André Michel. "Contribution à l'étude de paramètres influençant les propriétés mécaniques de fibres élémentaires de lin : Corrélation avec les propriétés de matériaux composites." Thesis, Lorient, 2014. http://www.theses.fr/2014LORIS355/document.
This research study has been carried out during a CIFRE joint project between the Van Robaeys Frères Company, UBS and IFREMER. The work aims to improve understanding of the properties of both flax fibres and composite materials reinforced with flax.First, the influence of the degree of retting of flax fibers on the tensile properties of single fibers and short fiber/polypropylene composites has been shown.Then, the properties of scutched flax and flax tow were compared. We have shown that it is possible to reach similar tensile properties for unidirectional composite materials manufactured from the two products.Moreover, the influence of three different flax nonwoven reinforcements on the mechanical properties of thermoplastic matrix composites was studied. These materials were found to show anisotropy of tensile properties.Finally, the mechanical properties of the flax fibres processed by the Van Robaeys Frères Company were examined. A straightforward relationship was found between the tensile properties of the fibres and the tensile properties of unidirectional composite materials. The relationship is more complex for short fibre injected composites
Ben, Ayad Mohamed. "Étude expérimentale des propriétés mécaniques (rupture) et électrique de systèmes de percolation." Nice, 1988. http://www.theses.fr/1988NICE4226.
Réquilé, Samuel. "De la plante aux biocomposites : caractérisation des interfaces multiples et étude des paramètres pertinents Exploring the link between flexural behaviour of hemp and flax stems and fiber stiffness Peeling experiments for hemp retting characterization targeting biocomposites Deeper insight into the moisture-induced hygroscopic and mechanical properties of hemp-reinforced biocomposites. Interfacial properties of hemp fiber/epoxy: effect of moisture sorption and induced hygroscopic stresses Propriétés hygroscopiques et mécaniques d'un biocomposite renforcé par des fibres de chanvre." Thesis, Lorient, 2019. http://www.theses.fr/2019LORIS529.
Industry environmental concerns and strategies to become part of a more sustainable economic system, leads to a growing interest in research on biocomposite. The strong polar and hydrophilic nature of plant fibers leads, when used as a reinforcement, to a complexity of biocomposite manufacturing and limits in terms of load transfer at the fiber/matrix interface. These major locks (fiber polarity and moisture sensitivity) for biocomposites development are the guidelines of this thesis work taking its inspiration in the design of hemp stem tissue interfaces. The multi-scale evolution of gradient microstructure and internal mechanics is crucial for the integrity and functioning of the stem through smooth transitions regions. These potential weak interfaces are investigated by applying a retting process that affect the stem internal microstructure and tissue cohesion. From the stems of agricultural crops to the hierarchical elementary fibers, studying the mechanical behavior of natural systems may serve as inspiration for a biomimetic transfer of the fundamental principles to fiber-reinforced composites. Aimed at increasing the understanding of the effect of moisture present during composite use, hygro-mechanical coupling highlights an optimum in hemp fibre-based unidirectional composites performances from a beneficial effect of moisture sorption. Deeper analysis at the micro-scale attributed a significant contribution of this hygroscopic behavior to fiber/matrix interface performances through the creation of residual stresses and capillary adhesion mechanisms. Generally described in the literature as a drawback, this research demonstrates that water sensitivity of plant fibers and moisture sorption in biocomposite could promote load transfer and be beneficial for their performance
Osmani, Hocine. "Rupture des composites céramique-céramique à fibres." Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0059.
Sukiman, Muhamad Shafiq. "Etude des propriétés mécanique et thermique des biocomposites basée sur l'homogénéisation numérique." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10218/document.
This thesis work concerns the determination of mechanical and thermal properties of HDPE-wood particles and PET-hemp fibers biocomposites using experimental, numerical and analytical approaches. The search for the effective properties of these biocomposites involves different parameters such as the fiber morphology and orientation on the one hand, and the porosity and the interphase on the other. A study based on the numerical homogenization technique has been carried out in order to verify the influence of short and long fibers on the apparent properties of the different materials. Numerical calculations have also allowed the estimation of the elastic properties as well as the thermal conductivity of the biocomposites in relation to the fiber and particle volume fraction. The ultimate objective of this work consists in the modelling of the thermoforming procedure on the biocomposites. A study on the thermoformability of the HDPE-wood particles biocomposite into a formwork in relation to the wood particle content has been carried out by using experimental data of the mechanical and thermal behavior for the numerical simulation of the thermoforming procedure
Labache, Gaëlle. "Amélioration par modification chimique de l’interface de biocomposites poly(acide lactique) – fibre courtes de lin." Caen, 2012. http://www.theses.fr/2012CAEN2004.
This project is focused on the identification of chemical modifications to improve the interface quality of biocomposites elaborated from biopolymers and natural cellulosic fibers. The poly(lactic acid) matrix chosen for the project is presented in the first part with a special attention concerning the physical aging. The evolution of thermal (DSC) and mechanical properties (tensile testing) of PLA samples depending on the storage temperature highlight strengthening and weakening of PLA with storage time. This study demonstrates the necessity to clearfully expose the experimental procedures to measure these values. The influence of various surface treatments on the morphology and on the spectroscopic properties of flax fibers has been evaluated. Mercerisation and bleaching lead to the removal of waxes, pectins and hemicelluloses and reveal the cellulosic wall of the fibres. Coupled with acetylation, different satisfiying grafting ratio are obtained. However, the interfacial adhesion is not improved by the modified fibers in the pure PLA matrix through extrusion and injection molding. A second route by matrix chemical modification via reactive extrusion has thus been developped. Cardanol grafting onto PLA chains with the help of peroxides did not lead to the improvement of the interface quality. On the other hand, the addition of diisocyanates to the PLA-fibers systems significantly increases the adhesion between the matrix and the fibers. The obtained composites are more resistant than the pure PLA matrix. The reaction mechanism involves the creation of covalent bondings between the PLA and the flax fibers via the bifunctionnal diisocyanate
JEUNEHOMME, Sylvie. "Relations propriétés mécaniques - microstructure des aciers de structure perlitique." Paris, ENMP, 1991. http://www.theses.fr/1991ENMP0320.
Corbin, Anne-Clémence. "Développement et analyse multi-échelle de renforts en chanvre pour applications biocomposites." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1I021.
This PhD thesis is a part of the European SSUCHY project (H2020-BBI) which aims to develop 100% bio-based composite materials, in terms of reinforcements and matrices. The objective of this thesis is the development and the multi-scale characterization of textile reinforcement made of flax fibers and hemp fibers. These reinforcements have to meet the requirements of the industrial applications of SSUCHY project. First of all, the work focuses on the development of yarns and rovings with sufficient properties for the manufacturing of the reinforcements by weaving technology. For these yarns and rovings, textile and mechanical properties are studied. At the scale of the fibers, properties are obtained by the “Impregnated Fiber Bundle Test” (IFBT) method. Reinforcements are produced by weaving technology with different types of yarns. The influence of production parameters is analyzed on textiles properties, on bending properties in dry state, on uniaxial tensile properties, on plan shear properties and on shape forming capability. These characterization steps allow to build technical data sheets and to choose the reinforcement whose production parameters enables to meet the requirements of the final composite part in the best possible way. Finally, composite plates are manufactured with some of the reinforcements developed, and characterized with tensile tests. Properties of these biocomposites materials are compared with those of biocomposites reinforce by natural fibers from literature or already available on the market
Zarrad, Turki Inès. "Valorisation des sédiments marins dans une matrice agrosourcée : caractérisation expérimentale des biocomposites et modélisation du comportement mécanique." Thesis, Amiens, 2016. http://www.theses.fr/2016AMIE0038/document.
In recent decades, many research activities at the international level have focused on biomaterials with one hand equivalent characteristics and sometimes even higher than that of fossil products and secondly renewability of resources is an asset environmental. In addition, the problem of marine and river sediments is a global problem. Dredged sediment management is thus a general concern because of the quantities produced and their potential nuisance. In this work, an experimental study is conducted on the development of marine sediments to percentages ranging from 0% to 20% as a mineral filler in an agro-sourced matrix and appreciate their influence on the physical-mechanical, thermal and Sustainability elaborate composite HESM (hemoglobin / Marine sediments). The results show that the compressive modulus, flexural, tensile and compressive strength were improved when the addition of marine sediments by against the tensile strength and the flexural strength were decreased compared the reference material. The microstructural study to justify the effect of the addition of sediments in the matrix on the mechanical properties. As for the thermal characterization of biocomposites, the results show the improvement in the thermal stability of the composite relative to the pure polymer. Regarding sustainability, the addition of marine sediments has not almost influenced the durability properties and the charged material or not should not be exposed to the elements without protection. The finite element modeling of the mechanical behavior in compression has yielded satisfactory results to develop this new biocomposite as a floor covering
Bouhrara, Driss. "Comportement mécanique en rigidité et à rupture d'un matériau composite fibres-ciment." Lyon 1, 1993. http://www.theses.fr/1993LYO10261.
Feuerstein, Matthieu. "Influence de la microstructure sur les propriétés mécaniques de tôles d'aluminium AA5182." Saint-Etienne, EMSE, 2006. http://www.theses.fr/2006EMSE0023.
In this PhD, two grades of AA5182 aluminium rolled sheets were analyzed: the REF or reference grade and the SHF or super high formability. Due to its least Fe- and Mn-content, SHF grade has a slighter particles fraction than REF grade. Interdistances between particles are smaller along TD than along RD. REF grade is less ductile than SHF grade, and sheets are more ductile along TD than along RD. The first step of the damage model was dedicated to the loading analysis corresponding to the necked area of a tensile sample. The second step of the damage model consisted in a cellular model whose geometry represents a periodic array of particles. The boundary conditions applied to the unit cell correspond to the loading determined in the first step. The predicted values of local ductility confirmed the experimental results
Chambolle, Damien. "Étude sur la rupture de composites à matrice métallique et à renforts discontinus : aluminium, carbure de silicium." Châtenay-Malabry, Ecole centrale de Paris, 1990. http://www.theses.fr/1990ECAP0133.
Caumes, Philippe. "Rupture d'un matériau anisotrope en conditions polymodales (le bois)." Bordeaux 1, 1987. http://www.theses.fr/1987BOR10559.
Guyon, Gilles. "Prévisions de la rupture différée du Pin maritime." Bordeaux 1, 1987. http://www.theses.fr/1987BOR10556.
Daouadji, Ali. "Modélisation de l'influence de la rupture des grains sur le comportement des matériaux granulaires." Châtenay-Malabry, Ecole centrale de Paris, 1999. http://www.theses.fr/1999ECAP0630.
Zarrad, Turki Inès. "Valorisation des sédiments marins dans une matrice agrosourcée : caractérisation expérimentale des biocomposites et modélisation du comportement mécanique." Electronic Thesis or Diss., Amiens, 2016. http://www.theses.fr/2016AMIE0038.
In recent decades, many research activities at the international level have focused on biomaterials with one hand equivalent characteristics and sometimes even higher than that of fossil products and secondly renewability of resources is an asset environmental. In addition, the problem of marine and river sediments is a global problem. Dredged sediment management is thus a general concern because of the quantities produced and their potential nuisance. In this work, an experimental study is conducted on the development of marine sediments to percentages ranging from 0% to 20% as a mineral filler in an agro-sourced matrix and appreciate their influence on the physical-mechanical, thermal and Sustainability elaborate composite HESM (hemoglobin / Marine sediments). The results show that the compressive modulus, flexural, tensile and compressive strength were improved when the addition of marine sediments by against the tensile strength and the flexural strength were decreased compared the reference material. The microstructural study to justify the effect of the addition of sediments in the matrix on the mechanical properties. As for the thermal characterization of biocomposites, the results show the improvement in the thermal stability of the composite relative to the pure polymer. Regarding sustainability, the addition of marine sediments has not almost influenced the durability properties and the charged material or not should not be exposed to the elements without protection. The finite element modeling of the mechanical behavior in compression has yielded satisfactory results to develop this new biocomposite as a floor covering
Bigaud, David. "Description géométrique pour la caractérisation mécanique multi-échelles de matériaux composites à renforts textiles 2D et 3D." Lyon 1, 1997. http://www.theses.fr/1997LYO10223.
Duprey, Ambroise. "Biomécanique des anévrysmes de l'aorte thoracique ascendante : vers une prédiction personnalisée du risque de rupture." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES021/document.
Aneurysms of the ascending aorta are a life-threatening desease by the risk of rupture or dissection. Currently, the only criterion for deciding an intervention is the maximum diameter of the aneurysm mesured from CT-scan. Biomechanical research aims to characterize the elastic properties of the aorta and to provide a patient-specific approach too assessing the risk of complications. The aim of this thesiswas twofold. In the first part, it was tocharacterize the rupture properties of freshly excised acsending aortic tissue from an inflation bench-test developed in our laboratory. The results were derived to determine a rupture risk index based on the extensibility of the aorta. In the second part, we identified the mechanical properties of aortic aneurysms using preoperative dynamic CT-scan. This identification was based on the simultaneous minimization of two cost functions, which defined the difference between the predictionsof a numerical model and the volumes of the aneurysms measured from the CT-scan in the middle of the cardiac cycle and the sytole. The results were correlated with those of the inflation tests, showing promising application of the dynamic scan for the patient-specific identification of the mechanical properties of the aorta. This work opens a little more the way for the patient-specific assessment of the risk of complications of an aneurysm of the ascending aorta and for a more refined selection of patients for surgery
Guinot, Dominique. "Recherche des paramètres physico-chimiques qui déterminent les propriétés mécaniques des céramiques de ferrite doux." Dijon, 1990. http://www.theses.fr/1990DIJOS023.
Martinez, Lilian. "Etude des précurseurs du comportement catastrophique des céramiques : applications au claquage diélectrique et à la rupture mécanique des alumines de tubes RF de puissance." Lyon 1, 1999. http://www.theses.fr/1999LYO10045.
Apolinario, Testoni Guilherme. "Analyse en service de la durabilité à long terme des biocomposites en environnement marin." Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0046/document.
This work aims to address a complete analysis of the use of flax fibres to substitute glass fibres in composite materials designed for nautical applications. This substitution requires a better understanding of the composites life cycle: from materials selection and processing to its hydric ageing, especially under real conditions (exposition to water, temperature and mechanical loadings).A preliminary study is devoted to the selection of materials (flax fibre fabrics and polyester resin) and to the comparison between two methods for manufacturing composites (vacuum infusion and compression moulding) through their mechanical and the morphological properties.The ageing behaviour of flax fibre reinforced composites (FFRC) and glass fibre reinforced composites (GFRC) is then studied. A set of original methods have been implemented to monitor the evolving morphology (water uptake, swelling) and mechanical properties (statics and dynamics). First of all, hydrothermal ageing of glass and flax fibre composites is characterized until water saturation. This step is followed by the study of a drying phase in order to verify the reversibility of physical and mechanical properties. In parallel, a particular issue of this work was devoted to reducing the hydrophilicity of flax fibres into composites.The hydrothermo-mechanical coupling behaviour of biocomposites is then studied by imposing a creep solicitation to biocomposites immersed in water. The application of this methodology highlighted the significant influence of the coupled solicitations. Contrary to all expectations, superimposing a load during a hydrothermal ageing slows the loss of the elastic properties in comparison with the sum of the uncoupled ageing effects.Finally, a finite element model was stablished in order to predict the hydric diffusion within the composite material. The 2D model integrates the real morphology of composites, and particularly the organisation of the flax fibres in the matrix at different scales. This modelling represents the first step in predicting the evolving behaviour of biocomposites exposed to ageing conditions
Yaacoub, Agha Hassan. "Tolérance aux défauts initiaux : application à une fonte G.S. en fatigue." Paris 6, 1996. http://www.theses.fr/1996PA066828.
Robert-Arnouil, Jean-Paul. "Etude du comportement thermomécanique à la rupture d'une céramique technique sous sollicitations rapides." Bordeaux 1, 1986. http://www.theses.fr/1986BOR10652.
Solas, Denis. "Anisotropie des propriétés mécaniques et endommagement des alliages Al-Zn-Mg-Cu." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0226.
François-Brazier, Joël. "Caractérisation de la tolérance à l'endommagement et de la durabilité des composites ciment-verre par des essais de flexion avec des cycles de chargement-déchargement." Lyon 1, 1991. http://www.theses.fr/1991LYO10093.
Haied, Abdelhamid. "Étude expérimentale de la rupture en mode localisé dans un gré." Lille 1, 1995. http://www.theses.fr/1995LIL10178.
Villechaise, Bernard. "Mécanique des contacts : élasticité et rupture : document de synthèse." Lyon 1, 1985. http://www.theses.fr/1985LYO19043.
Wahyudi, Herman. "Étude des propriétés mécaniques des matériaux argileux en relation avec leur organisation à différentes échelles." Châtenay-Malabry, Ecole centrale de Paris, 1991. http://www.theses.fr/1991ECAP0205.
Atig, Dyhia. "Propriétés physiques et mécaniques de l’hydrate de méthane à l’échelle du pore." Thesis, Pau, 2019. http://www.theses.fr/2019PAUU3021.
Gas hydrates are ice-like crystals stable at high pressure and low temperature. They are ubiquitous on earth, notably at the edges of continental shelves, where they contribute to the mechanical stability of marine sediments, by hydrate cohesion and hydrate adhesion to mineral particles. However, the mechanical behavior of gas hydrates at pore scale has been hardly or not at all studied. The purpose of this thesis is to study the stability conditions and the tensile mechanical properties of methane hydrate at pore scale in a representative pore habit of gas hydrate in a sedimentary medium.Here, using optical microscopy, first the formation, growth and dissociation conditions of methane hydrate are investigated across a water/CH4 interface in glass micro-capillaries used both as a pore model and as an optical cell resisting high pressure and low temperature. Then by developing a contactless and an in situ method, "thermally induced depressing", tensile mechanical properties of polycrystalline methane hydrate shell are determined. At low enough temperature, the hydrate nucleates as a polycrystalline "crust" over the water/CH4 interface. From this crust, the hydrate continues growing on both sides of the interface: in the water as "needle like crystals", in the gas as "hair like crystals", and finally between the gas and the substrate as a polycrystalline film, the "halo". The halo advances slowly on the substrate, riding over a water film, and comes to rest and adheres to the substrate. From then on, the "shell" (crust and halo) isolates the water from the gas. Tensile tests are carried out by generating a depression in the water compartment by increasing temperature at constant methane pressure.Tensile elastic properties of the shell (elastic modulus and the tensile strength) are determined as a function of the grain size, controlled here by two parameters, supercooling compared to the equilibrium temperature and the annealing time. We find elastoplastic behavior, with mixed ductile and brittle characteristics. Our data on tensile strength contribute to fit the gap of five orders of magnitude of grain size, and three orders of magnitude of tensile strength (between molecular simulations at nanometre scale and current experiment at millimetre to centimetre scale). The effect of grain size on the tensile strength of methane hydrate could be a factor contributing to the destabilization of continental slopes
Nazarenko, Emmanuel. "Comportement à rupture d'un composite à fibres céramiques et matrice vitrocéramique sous sollicitations statiques et dynamiques." Châtenay-Malabry, Ecole centrale de Paris, 1992. http://www.theses.fr/1992ECAP0269.
Chafra, Moez. "Comportement mécanique des matériaux composites fibres et tisses (modélisation tridimensionnelle, endommagement et rupture)." Paris, CNAM, 1994. http://www.theses.fr/1994CNAM0192.
Borchani, Karama. "Développement d'un composite à base d'un polymère biodégradable et de fibres extraites de la plante d'Alfa." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES010/document.
This study is a contribution to the search for new composite material from vegetable natural resources. It aims at the exploitation of natural fibers extracted from the Alfa plant with a bioplastic of the Mater-Bi® type in order to develop biocomposites. Three kinds of short fibers extracted from Alfa plant were prepared; untreated, 1% and 5% alkali treated. The various techniques used for fibers characterization showed an increase in the roughness, cellulose level, crystallinity index and thermal stability after the alkali treatment. The composite materials were prepared by twin screw extrusion flowed by an injection operation by varying the fiber contents of 0 to 25%. Thermal analysis showed significant increase of the crystallization rate with the incorporation of Alfa fibers and enhancement of thermal stability by alkali treatment. Modulus and tensile strength of biocomposites also improved whereas toughness and elongation at break decreased upon increasing the fibers fraction. Scanning electron microscopy (SEM) on fractured surfaces indicated good adhesion between the matrix and the treated or untreated Alfa fibers. The study of crystallization kinetics of biocomposites showed strong nucleating effect of treated or untreated Alfa fibers
R'Mili, Mohamed. "Application de la mécanique de la rupture au composite carbone-carbone bidirectionnel." Lyon, INSA, 1987. http://www.theses.fr/1987ISALA028.
Hamdani, Djelloul. "Comportement mécanique d'assemblages de tôles d'acier galvanisé sollicités en mode d'ouverture à différentes vitesses : influence des traitements de surface et des épaisseurs de joint de colle." Compiègne, 1988. http://www.theses.fr/1988COMPD143.
In this study we have been tenting to bind a surface property (roughness and surface energy) of galvanised steel which it prepared of four different treatments (cleaning attack acid and basic, parcodine) with a mechanical behaviour of adhesively bonded assemblies. The bind show which conjugate roughness and superficial energy action of substrate can be optimised the propagation energy. The effect of solicitation rate (0. 5, 5, 50 and 500 mm/mn) and adhesive bond thickness (720, 360, 180 et 120 um) have been observed. For propagation energy term, the solicitation rate and adhesive bond thickness seems to that have a same effect on adhesively bonded structure toughness. For the characterization of the beginning of the microscopic damage and of the crack propagation, we have, in parallel with the test, recorded the acoustic emission from the specimen
Voicu, Raluca. "Évolution microstructurale à haute température et propriétés mécaniques d'aciers austénitiques Fe-Cr-Ni." Toulouse, INPT, 2008. http://www.theses.fr/2008INPT132G.
The HP40-Nb modified austenitic stainless-steels are used for reformer tubes fabrication in the refining, petrochemical and fertilizer industries, and especially by Air Liquide for cracking reaction of hydrogen. These tubes are the main components of hydrogen production plants. The tubes are designed for exploitation duration of around 11 years. Nevertheless, the operation of the facilities under more severe conditions leads to a greatly decreases the lifetime of these components. These tubes are prone to various degradation mechanisms. The combination of factors such as local overheating, a complex stress field (induced by the heat, the internal gas pressure and weight of the tubes), a corrosive environment inside and an oxidant atmosphere outside of the tubes can lead to premature rupture, braking of these parts. The objective of this study is to understand the coupling between the microstructural aging and mechanical behaviour in creep regime in order to establish a new criterion for end of life of reformer tubes. Microstructural examinations of aged structures have allowed to highlight the effect of several important factors, like the chemical composition and the environment, and to establish a TTT diagram for these steel grades. The systematic study of the creep mechanical behaviour has enabled to identify several factors that influence the lifetime of these alloys, like aging and a change of creep mechanism when passaging from high to low stress levels. Metallographic observations and quantification of the damage confirmed the creep tests results. A criterion for the end of life has been established by integrating these data. Finally, we proposed two thermal loading protocols to optimize the time to rupture of these tubes
Tanguy, Morgane. "Contribution à l’étude de matériaux composites à matrice polypropylène et renforcés par des fibres végétales : de la fibre à la pièce automobile." Thesis, Lorient, 2016. http://www.theses.fr/2016LORIS425.
This thesis was funded by the automotive supplier Cooper Standard to develop auto parts in polypropylene (PP) reinforced with plant fibers. Its major objective is to identify key parameters for obtaining high performance composites and then develop industrially. A great variety of plant cell walls was tested mechanically, critical step for the composite behavior analysis. The selected fibers were then mixed in PP and the study of compounding highlighted its impact on the properties of future composite and the difficulty of mixing plant fibers into a molten matrix. The compounds PP / vegetal fibers were then processed by extrusion and the work carried out has allowed the development of composite reinforced with wood fibers respecting the specifications of Cooper Standard. A comparison between extrusion molding and injection molding has showed the effect of molding process on mechanical properties and microstructure of composites. Unidirectional composites models reinforced with long fibers helped to understand the mechanisms of strengthening of a polypropylene matrix with jute and flax fibers, and highlighted the importance of constituents’ mechanical properties. Unlike injected composites and reinforced by short jute and flax fibers have them, showed the predominance of microstructure, compared with the performance of the fibers, on the mechanical properties of the parts
Kapinga, Kalala Iris, and Kalala Iris Kapinga. "Caractérisations structurale et mécanique du massif rocheux de la fosse Tiriganiaq du projet Meliadine à l'aide de la modélisation synthétique du massif rocheux." Master's thesis, Université Laval, 2013. http://hdl.handle.net/20.500.11794/24903.
Ce mémoire porte sur l’application de la modélisation du massif rocheux synthétique (SRM) à la caractérisation du massif rocheux fracturé de la fosse Tiriganiaq du projet minier Meliadine. Les conditions structurales in-situ ont été représentées à l’aide de la modélisation des systèmes de fractures (FSM). Les résultats ont permis de définir un volume élémentaire représentatif (REV) du massif rocheux égal à 7,5 m x 15 m x 7,5 m. L’approche a également permis de quantifier l’impact de la variation des propriétés géométriques du FSM sur le comportement mécanique du massif. Les analyses paramétriques des propriétés géométriques du SRM font ressortir que le comportement du massif rocheux est particulièrement sensible à une variation de l’intensité des fractures (P32), de l’aire des fractures et du pendage de la foliation. De plus, la résistance en compression uniaxiale est fortement anisotrope.
Volozinskis, Xavier. "Étude de la résistance à la fissuration d'un matériau hétérogène anisotrope appliquée à l'optimisation du processus de fabrication du papier." Bordeaux 1, 1988. http://www.theses.fr/1988BOR10618.
Cherait, Yacine. "Contribution à l'étude et l'optimisation des bétons renforcés de fibres de fonte amorphe." Lyon 1, 1992. http://www.theses.fr/1992LYO10045.
Cordonnier, Tiphaine. "Tenue mécanique d'interfaces modèles dans les alliages Fe-40%at. Al (ordonnés B2)." Saint-Etienne, EMSE, 2006. http://www.theses.fr/2006EMSE0010.
Use of FeAl alloys is still severely limited by their room temperature intergranular brittleness, assumed to be due to a low intrinsic cohesion of the interfaces. Until now, doping with boron was the only way to reinforce these weak boundaries. The fracture behaviour of some special boundaries, with <100> symmetric tilt boundary, pure or doped with boron, was characterized. Results indicate that boron would suppress intergranular fracture by improving slip transfert across the grain boundaries. Then, and on the contrary to the common knowledge, boundaries of B-free bicrystals exhibit a cohesion high enough to avoid intergranular fracture. <100> tilt boundaries are thus special boundaries regarding fissuration resistance, with grain boundary plane playing a major role. The existence of such highly cohesive interfaces opens a new way to efficiently modify macroscopic behaviour of B-free FeAl through a "grain boundary engineering" approach
Toulemonde, Paul-Aymé. "Etude de la relation microstructure/propriétés mécaniques jusqu’à rupture des propergols composites : Caractérisation expérimentale et modélisation micromécanique par éléments finis." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0038/document.
This work aims at understanding the relationship between solid propellants particles volume fraction, particles size distribution, binder mechanical properties and binder/particles bonding with the mechanical behavior up to failure of these materials. Finite elements analyses on 2D microstructures are performed in order to qualitatively characterize the microstructure evolution throughout uniaxial tensile loading at small strain rate. These simulations account for the binder/particles debonding with a cohesive zone model and implement an original failure criterion. Simulation and experimental results are consistent. Besides, a quantitative comparison between simulations on 3D microstructures and experimental data is drawn in order to validate the above qualitative results. It is performed on a model composite and compares both the mechanical behavior and the volume variations. At last, the propellant failure during a peeling test of the liner/propellant structure is studied experimentally
Varenne, Chloé. "Etude d'un alliage de titane β "transformable par déformation" : lien entre propriétés mécaniques, microstructures de déformation et mécanismes de rupture." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLM030.
In order to tackle the lack of ductility and work-hardening of titanium alloys, a new family is being developed, namely, strain-transformable β titanium alloys. The deformation mechanisms involve transformation induced plasticity (TRIP effect) and twinning induced plasticity (TWIP effect). They have been widely studied over the last ten years. On the otherhand, the understanding of fracture mechanisms of TRIP/TWIP titanium alloys still remains poorly documented although this is a key to improve the development of these alloys. Therefore, this project is an in-depth study of the mechanical behavior of a Ti-8.5Cr-1.5Sn β TWIP alloy, under various loading conditions. The coarse microstructure of the alloy was used to investigate deformation and fracture on a grain-by-grain basis. First, a methodology for the systematic study of this family of alloys has been developed. We selected the most relevant tests for a complete study of the mechanical behavior of a TRIP/TWIP alloy by investigating heat treatment conditions (quenching thickness) and mechanical testing conditions (specimen geometry, loading mode). Then,this methodology was validated on the Ti-8.5Cr-1.5Sn alloy first at room temperature, then at subzero temperatures, in order to get closer to the Ms point. The mechanical behavior was evaluated under a wide range of conditions giving access to tensile strength, impact toughness, and fracture toughness. The respective contributions of crack initiation and crack propagation were determined. A multi-scale correlation (optical, SEM, TEM) highlighted fracture by localized plastic flow, without damage development, strongly correlated with the plastic deformation mechanisms and independent of variations in strain rate and stress triaxiality. At subzero temperatures, the absence of ductile-to-brittle transition was demonstrated on the failure mechanisms, as was thepreservation of the phenomenology observed at room temperature (no triggered TRIP effect). Low energy fracture encountered at lower temperatures still involved a ductile dimple mechanism. It remained governed by localized plastic flow, which is triggered all the earlier the lower the test temperature. This new and comprehensive study has improved the understanding of fracture mechanisms of a TRIP/TWIP alloy and provides a solid database for further studies of this family of alloys
Dang-Hoang, Thong. "Rupture et endommagement d’un assemblage boulonné : approche expérimentale et simulation numérique." Electronic Thesis or Diss., Lille 1, 2009. http://www.theses.fr/2009LIL10066.
This study focuses on the study of fracture and damage of a bolted assembly made up of thin sheets of aluminum alloy 6082 T6, thickness e= 2 millimeters, in single recovery. Several configurations of assemblies (number and arrangement of fasteners) are studied in monotonous solicitations, analyzing the effects of board. The influence of torque and clearance will be considered for the study of the behavior of the link. An experimental approach was implemented to analyze the sequence of damage mechanisms simultaneously using the technique of acoustic emission (AE) and measurement of fields by digital image correlation (DIC). EA Technology has tracked the evolution of acoustic activities by planar localization to better identify the initiation and propagation of cracks. The DIC technique confirms the damage scenarios evaluating, the deformation field at any point near the fastener. The finite element technique was used to predict the overall behavior of these assemblies. The calculations are performed in a 3D computer code using solid elements, shell elements and and are undertaken both in élastoplasticité without and with damage. The prediction of damage has been done using two models : modeling decoupled depending on the model of Latham and Cockroft and coupled modeling based on the model of Gurson modified
Mazian, Brahim. "Approche intégrée du procédé de rouissage des fibres de chanvre : Vers une amélioration de la qualité des intrants pour la fabrication des matériaux biocomposites." Thesis, IMT Mines Alès, 2018. http://www.theses.fr/2018EMAL0006/document.
The natural fibres are increasingly used as reinforcements in polymer composites due to their challenging performances compared to conventional fibres in term of good specific mechanical properties, damping and thermal insulation. In the hemp industry, the retting is an upstream processing applied to the plants in order to facilitate the separation of fibres from the central woody part of the stem. This treatment is currently carried out in an empirical way in the fields that leads to a large variability in the hemp fibres instrinsic characteristics (color, morphology, biochemical composition, microstructure, thermal and mechanical properties) which limit their large use in high-performance composites. Therefore, controlling retting treatment is a crucial step. The aim of this thesis is to develop a global approach to this key step in the production of hemp fibers by combining the study of the biological mechanism of retting, the intrinsic characteristics of fibers and that of emissions volatile organic compounds and odors associated with the retting step. Different items were particularly examined:- The influence of retting duration and harvest period on the intrinsic characteristics of hemp fibers (color, morphology, biochemical composition, microstructure, mechanical and thermal properties).- The evolution of Volatile Organic Compounds (VOCs) and odors of hemp stems during field retting- Temporal dynamics of population densities of bacterial and fungal communities during retting- The impact of field retting (Mediterranean climate) and accelerated retting (controlled conditions in the laboratory) on the microstructural, thermal and mechanical properties of a polypropylene / hemp fibers biocomposite
Busignies, Virginie. "Recherche de lois de mélange sur des propriétés mécaniques de systèmes granulaires compactés." Phd thesis, Université Paris Sud - Paris XI, 2005. http://tel.archives-ouvertes.fr/tel-00012167.
L'objectif de ce travail de recherche est d'évaluer les propriétés de mélanges granulaires compactés. Etant donnée la complexité du problème et la difficulté d'interprétation lorsque l'on s'intéresse à des mélanges d'excipients, les études doivent être réalisées sur des systèmes simples (mélanges binaires faisant intervenir des systèmes monodisperses). Il a donc été nécessaire d'étudier de la façon la plus complète possible les systèmes simples choisis avant de pouvoir passer à l'étude de leurs mélanges binaires.
Les excipients étudiés (A TAB®, Fast Flo®, Vivapur 12®) sont représentatifs des excipients utilisés dans le domaine pharmaceutique. Les données de la littérature ont également mis en évidence des comportements en compression très différenciés.
Le premier objectif de ce travail a donc été de caractériser de la manière la plus exhaustive possible le comportement sous pression des trois excipients ainsi que les propriétés mécaniques de ces systèmes compactés.
Les résultats obtenus sur la compressibilité des trois excipients (énergies mises en jeu au cours de la compression, consommation de la porosité, modélisation de Heckel et seuil moyen d'écoulement plastique) ont confirmé des aptitudes à la compression très différentes.
En complément, la technique de microtomographie X a été utilisée pour caractériser la fraction solide des comprimés de Vivapur 12®. Cette technique est une technique émergente dans l'étude des comprimés pharmaceutiques. Il a donc été nécessaire au préalable de la valider dans le domaine d'application dans lequel nous voulions la mettre en oeuvre (vérification de la loi de Beer-Lambert). Après une étape de calibration, une hétérogénéité au niveau de la répartition de la masse volumique a été mise en évidence au sein des comprimés, avec une différence importante entre la surface (surdensifiée) et le centre du comprimé. A la vue de ces observations, il apparaît donc que la différence entre les propriétés du volume (résistance à la rupture, module de Young, ...) et les propriétés de surface (dureté en indentation, ...) doit être faite.
Concernant les propriétés mécaniques des systèmes simples compactés (résistance à la rupture, module de Young, ténacité, dureté Brinell), des différences ont été observées entre les trois excipients pour une même propriété. De plus, pour un même excipient, des variations marquées entre les propriétés mécaniques caractéristiques du volume du compact et les propriétés mécaniques caractéristiques de la surface ont été mises en évidence.
Le modèle de la percolation qui est de plus en plus rencontré dans le domaine de la compression de composés pharmaceutiques a été appliqué aux trois systèmes étudiés. Les résultats de nos essais de modélisation semble montrer que ce modèle présente des limites. L'exposant critique ne semble pas universel pour une propriété donnée et les seuils de densité critique obtenus restent difficile à interpréter.
La deuxième partie de ce travail est consacrée à l'étude des mélanges binaires formés à partir des trois excipients étudiés dans la première partie.
Le suivi de l'évolution de la porosité des mélanges (à une contrainte de compression donnée) en fonction de la composition massique du mélange a permis de mettre en évidence une relation linéaire Porosité/Composition. Cette relation permet de déterminer la porosité d'un mélange compacté sous une pression donnée à partir des données recueillies au cours de l'étude des systèmes simples. Par contre, le seuil moyen d'écoulement plastique des mélanges n'évolue pas linéairement avec la composition massique du mélange. Mais en raison de la relation précédemment obtenue, une méthode de calcul indirect du seuil moyen d'écoulement plastique est possible. Cette méthode prédictive permet une bonne approximation des propriétés de densification et de déformation d'un mélange binaire quelle que soit sa composition.
Pour toutes les propriétés mécaniques étudiées, les lois de proportionnalités simples classiquement utilisées en mécanique ne sont pas applicables. Dans la majorité des cas, une déviation négative est même observée par rapport à ces lois simples.
Dans le cas particulier des propriétés mécaniques qui caractérisent la surface des compacts, il est apparu qu'elles étaient régies par le composé le plus plastique du mélange dès que sa proportion massique est égale à environ 30 à 20 %.
Pour s'inscrire dans une optique d'aide à la formulation, un modèle a été proposé pour décrire l'évolution du module de Young et de la résistance à la rupture en fonction de la composition du mélange. Après ajustement, une approche basée sur des interactions triangulaires et sur la probabilité de présence de ces interactions semble la plus adaptée.
Pour compléter l'étude des systèmes binaires, des essais de microtomographie X ont également été menés sur des mélanges Vivapur 12®/A TAB® compactés. Les représentations obtenues ont permis de mettre en évidence le Vivapur 12® au niveau des surfaces des compacts qui ont été en contact avec les pièces mécaniques. Ces observations confirment les résultats obtenus en microindentation sur ce mélange. Les seuils de percolation des deux excipients ont également été mis en évidence.
Gauchet, Séverine. "Etude de l'influence du type de noir de carbone sur la tenue en fatigue de caoutchouc HNBR." Tours, 2007. http://www.theses.fr/2007TOUR4049.
The fatigue resistance optimization of the alternator pulley needs to understand damage mechanisms influence on the rubber fatigue behaviour used in mecanical power transmission. Although the toughness of rubber was log time studed, the fatigue of HNBR filled with carbon black is not described in literature. The aim of this work is to understand the influence of filler on theses complex mechanisms through the modifications induiced by filler on the microstructure and dynamical properties. Two damage mechanisms at starting initiate several microcracks which are propagated in rosette forme. Size and number of petals depend on the type of carbon black. This characteristics represent the cracking speed and they describe a mechanisme of crack rotation. The influence of filler on the damage is highlighted by solid NMR H. This original technique proves to be a power technique for studying degradation of rubber having a complex formulation. These results open new propects in order to understand damage mechanisms
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