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Mtibaa, Mohamed. "Οptimisatiοn de cοuplage Ρrοcédé/Ρrοpriétés/Fiabilité des Structures en Μatériaux Cοmpοsites Fοnctiοnnels". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH03.
Pełny tekst źródłaThis research focuses on the challenges and interactions between the manufacturing processes (Resin Transfer Molding ‘RTM’ and Compression Resin Transfer Molding ‘CRTM’), the mechanical properties, and the reliability of composite material structures; more specifically the functional composites. A number of numerical models have been developed for simulating the suspension (resin + particles) impregnation through the fibrous medium (fibers) in the RTM and CRTM processes. These models are validated by comparing their results with experimental, semi-analytical, and analytical ones from the literature. A parametric study is carried out to demonstrate the impact of various process parameters on particles’ distribution in the final composite. Moreover, a comparison between the injection and compression modes is done. The results of this part show that the distribution of particles in the final part depends on the initial concentration, the distance travelled, and the initial fibers’ volume fraction. However, it is independent of the parameters values of injection and compression. It is also observed that the CRTM process with imposed pressure injection and imposed force compression represents the most favorable scenario for producing composite parts.For the purpose of controlling the final particles’ distribution in the composite material, manufactured by the RTM process, two key steps have been identified. The first step consists in a sensitivity analysis that examines three parameters: the temporal evolution of the initial injected particles’ concentration, the injection pressure field and the initial fibers’ porosity. The conclusions indicate a minimal impact of the initial porosity and the injection pressure field; while the evolution of the initial concentration of the injected particles has a dominant effect. In a second step, an optimization algorithm is implemented in the numerical model of the RTM process. It is used to determine the optimal configuration of the initial injected particles’ concentration’s evolution; in order to approximate the particles’ distribution in the final composite to the desired profiles. The obtained results from the genetic algorithm provide a very satisfactory control of this distribution. To complete this section, a model, estimating the mechanical properties of the manufactured part, is developed. It is found that there is a positive correlation between the particles’ fraction and certain mechanical properties, namely the elastic modulus E11 and E22, and the shear modulus G12 and G23. Nevertheless, the Poisson’s ratio (Nu12) is inversely proportional to the particles’ fraction. Also, the shear module G12 is the most significantly influenced by this fraction.Following this, the control of the mechanical properties of the composite parts, manufactured by the CRTM process, is targeted, and compared to the results of the RTM process. The conclusions reveal that the RTM process offers a better control of these properties. Whereas, the CRTM process improves considerably the mechanical properties of the parts due to its compression phase, which increases the fibers’ volume fraction and consequently enhances these properties.Finally, a static analysis is conducted based on the developed numerical model that uses the finite element method (Ansys APDL). This model is combined with those of the CRTM process and the mechanical properties calculation. An optimization algorithm is integrated in our global model to adapt the mechanical properties of the composite part according to the configuration (cantilever or simply supported) and the load distribution. Moreover, it minimizes the composite part’s weight and ensures the respect of the predetermined mechanical constraints such as the maximum deformation limit. The obtained results correspond perfectly to these objectives
Simon, Pierre. "Approche multiéchelle du comportement mécanique du bois dans le plan transverse". Lyon, INSA, 2009. http://theses.insa-lyon.fr/publication/2009ISAL0049/these.pdf.
Pełny tekst źródła[The elastic behavior of softwoods presents a huge anisotropy in the transverse plane. It is moreover very heterogeneous at some scales. Transverse mechanical properties also seem to be very different between species or from a piece of wood to another. Here is proposed an experimental and theoretical study of this behavior. To explain, it, at least the cellular scale must be observed. Many shapes of cells exist and an adaptative goemetric model of the cells has been constructed. An analytical calculus then gives the mechanical properties associated to this geometric model. Then the behavior of wood at upper scales is deduced from the morphology of cells in the annual rings. The anisotropy and the heterogeneity of spruce are quantified. Experimental data are compared to the theoretical results. The great variability of cellular shapes locally leads to a very important diversity in their stiffness, from 1 to 10 for some types of loads. Macroscopoic orthotropy come from the microscopic anisotropy but also depends on the regular assembly of cells in annual rings. The behavior of annual rings is less random than cell properties, paradoxically thanks to the great cellular variability. And when the transverse behavior of macroscopic wood pieces is measured, its variability decreases with the number of annual rings in the section, and reach only some ten percents. Nevertheless, the mean transverse elastic behavior of structure pieces is quite variable. It largely depends on the orientation and curvature of the annual rings. And the transverse stiffness can vary from 1 to 5 from one beam to another]
Langlade, Cécile. "Approche physico-chimique et mécanique des propriétés lubrifiantes de poudres graphite + additifs". Ecully, Ecole centrale de Lyon, 1993. http://www.theses.fr/1993ECDL0002.
Pełny tekst źródłaGueguin, Maxime. "Approche par une méthode d’homogénéisation du comportement des ouvrages en sols renforcés par colonnes ou tranchées". Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1062/document.
Pełny tekst źródłaThis work takes place in the context of soil reinforcement techniques, aimed at improving the mechanical performances of poor quality grounds. Among these techniques, the use of soft inclusions taking the form of columns or cross trenches has known important developments. Even if the aspects relative to their construction process are presently well mastered, the design methods of such reinforced soil structures still remain to be greatly improved. The present work advocates the use of the homogenization method for assessing the global behavior of reinforced soil structures, both in the context of linear elasticity (stiffness properties) and in the framework of yield design (strength properties). Taking into account the geometrical periodicity of the various reinforcement configurations, we thus determine the behavior of the reinforced soils first locally and then at the global scale. To assess the strength capacities of reinforced soil structures, the static and kinematic approaches of the yield design theory are performed analytically or numerically depending on the kind of reinforcing material which is used. Adopting innovative numerical formulations dedicated to this theory, we can notably evaluate the macroscopic strength domains of column as well as cross trench reinforced soils which can then be introduced in the yield design of reinforced soil structures. Two illustrative applications of this procedure are performed relating to the bearing capacity problem of a reinforced soil shallow foundation on the one hand, the stability analysis of an embankment on the other hand
Regnet, Jean Baptiste. "Propriétés physiques et comportement mécanique des roches carbonatées microporeuses : Approche intégrée expérimentale et microstructurale". Thesis, Cergy-Pontoise, 2014. http://www.theses.fr/2014CERG0718/document.
Pełny tekst źródłaThis integrated study provides significant insight into parameters controlling (1) the acoustic and reservoir properties of microporous limestone and (2) the mechanical behavior of such rocks. This work improves the knowledge of the relationships among rock physic and rock mechanic on one hand, and the microstructural content on the other hand.(1) Petrophysical properties measured from laboratory and logging tools (porosity, permeability, electrical conductivity and acoustic properties) have been coupled with thin section and SEM observations on the EST205 borehole from the Oxfordian limestone aquifer of the Eastern part of the Paris Basin. A major achievement is the establishment of the link between micrite microtexture types (particle morphology and nature of inter-crystal contacts) and the physical response. Fluid-flow properties are enhanced by the progressive augmentation of intercrystalline microporosity and associated pore throat diameter, as the coalescence of micrite particle decreases between relatively coarser tight morphologies and microporous morphologies. The slow increase of P-wave velocity can be seen as a reflection of crystal size and growing contact cementation leading to a more cohesive and stiffer micrite microtexture. By applying poroelasticity theory on our samples, we show that velocity dispersion can be a very useful tool for data discrimination in carbonates. Finally, a possible origin of high porous levels in neritic limestones is a mineralogical dissolution of carbonates through freshwater-related diagenesis during subaerial exposure time.(2) Regarding rock mechanic, conventional triaxial experiments were performed on samples from the Oolithe Blanche formation (Middle Jurassic Limestone, Paris basin) to investigate the effect of different microstructural parameter on the mechanical behavior of microporous carbonate rocks. Type A samples display two different microporosity distributions within the grains (uniform versus rimmed microporosity) and type B samples are based on the presence/absence of an isopachous cement around the ooids. This work is of primary importance since the Oolithe Blanche formation, a deep saline aquifer, is a possible target for CO2 sequestration and geothermal production in the center of the Paris Basin. Experiments were performed under saturated state with respectively two sets of experimental conditions: (1) a 5 MPa pore pressure and a 28 MPa confining pressure with a temperature of 55°C for Type A carbonates to mimic in-situ conditions in the Center of the Paris Basin; and (2) a 0.5 MPa pore pressure and a 1.5 MPa confining pressure for Type B samples. Sample types have similar facies and composition (oolithic microporous grainstone with a 500µm average grain size), and porosity ranges from 17% to 20%. Permeability values are also very similar and range from 10-2 mD to 10-1 mD.(1) Type A samples with a rimmed porosity display a typical behavior of the brittle failure regime with stress-strain curves reaching a peak (138 MPa) beyond which strain softening was recorded, and strain localization on a shear fracture. (2) Type A samples with a uniform porosity display a ductile behavior with no localization of the deformation.(2) Type B samples with isopachous cement show a brittle behavior with stress drop (16 MPa to 18 MPa) and localization on a shear fracture. When isopachous cements are absent, a more ductile type of behavior is observed. Our set of data suggests that those two microstructural parameters have a significant control on the mechanical behavior of carbonate rocks
Khalfaoui, Mohamed. "Approche énergétique et analytique de quelques aspects du problème de Saint-Venant : cas de poutres composites". Montpellier 2, 1997. http://www.theses.fr/1997MON20104.
Pełny tekst źródłaEl, Yagoubi Jalal. "Effet de l’endommagement mécanique sur les propriétés thermiques de composites à matrice céramique : approche multiéchelle". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14297/document.
Pełny tekst źródłaIn this work the relationship between the evolution of damage and the loss of thermal propertiesof Ceramic Matrix Composites is investigated by a multiscale approach. Research are conductedboth experimentally and theoretically. The implemented approach is to consider two significantscales (micro and meso) where different damage mechanisms are operating and then assess theeffect on the effective thermal properties by homogenization techniques.Particular attention has been given to the development of a thorough experimental work combiningvarious characterization tools (mechanical, thermal and microstructural). At the two aforementionedscales, an experimental setup was designed to perform thermal measurements onCMC under tensile test. Thermal diffusivity of minicomposites is estimated using Lock-in thermography.Also, tranverse diffusivity mapping as well as global in-plane diffusivity of woven CMCare determined by suitable rear face flash methods. The evolution of damage is then derived fromacoustic emission activity along with postmortem microstructural observations. Experimental resultsare systematically compared to simulations. At microscale, a micromechanical-based modelis used to simulate the loss of thermal conductivity of a minicomposite under tensile test. At mesoscale,a multiscale Finite ElementModel is proposed to compute the effect of damage on thermalproperties of woven CMC
Ernst, Emil. "Le principe de Saint-Venant, théorème et axiome. Une approche énergétique". Montpellier 2, 1995. http://www.theses.fr/1995MON20094.
Pełny tekst źródłaRobert, Benjamin. "Etude des propriétés viscoélastiques des tissus mous par Elastrographie IRM : une approche multi-échelle". Paris 7, 2009. https://pastel.archives-ouvertes.fr/pastel-00556732.
Pełny tekst źródłaUltrasound and MRI elastography has developped rapidly these past days in order to estimate the viscoelastic properties of soft tissues. This new diagnostic tool is particularly adapted to characterize pathologies such as breast carcinoma because of its higher elasticity than the surrounding tissue. In the first part of the manuscript, viscoelastic media are presented in order to describe their mechanical behaviors while an elastic wave is generated. Several rheological models are introduced and analyzed to find the more adapted description of the mechanical properties of soft tissues estimated out of MR-Elastography acquisitions. The second part presents the different techniques of ultrasound elastography and the basis of the Magnetic Resonance Imaging in order to better understand the objectives of MR-Elastography. Two MR-Elastography sequences are theoretically and experimentally analyzed in order to optimize the quality of mechanical properties estimation. The third part enlightens the difficulties to adapt current MR-Elastography sequences to short T2* tissues such as the carotid or the heart. Thus, a new sequence is introduced: the DENSE-MRE sequence. This new MRI sequence is theoretically and experimentally compared to conventional MR-Elastography sequences. And this new sequence is is used in vivo to estimate elastograms of heart during the heart cycle
Gaied, Issam. "Contribution à l'étude de la contention : approche bidimensionnelle, identification du comportement biaxial en grandes déformations des tricots élastomériques". Saint-Etienne, EMSE, 2004. http://www.theses.fr/2004EMSE0025.
Pełny tekst źródłaWith a simplified 2D finite element model using ABAQUS, we initially validated the local Laplace law. We use this model to predict the pressure generated by the Medical Compression Stckings on one considered section of the leg. The leg was represented by a perfectly rigid body and the MCS by beam elements. We have also use a pneumatic device named Sig at to make in-situ experimental measurements. A good agreement between the pressures is verified. These same measurements revealed us the importance of treating the problem in 3D. In this case we have to integrate the orthotropic behaviour of the material and the longitudinal variation of the radius of the leg. The second part of the thesis was hence devoted to the development and the validation of an identification methodology for the biaxial behaviour under large deformations of an elastomeric knitted fabric. This methodology is based on the comparaison of the efforts and the experimental displacement field obtained by a correlation images method, with the results of the simulation of the same bidirectional tensile test using ZéBuLon F. E. Code. The material response was modelled through response a behaviour surface implemented under corrotationel formulation with the meta-language Zebfront. These surfaces allowed us to describe simply the biaxial behaviour of these knitted fabric up to deformations of 110%
Ziane, Elbekkaye. "Approche mécanique et physicochimique du comportement des assemblages collés : application aux tôles d'acier galvanisées". Compiègne, 1986. http://www.theses.fr/1986COMPE057.
Pełny tekst źródłaQuittau, François. "Vers un comportement de synthèse de particules cohésives par une approche de nanomécanique". Toulouse, INSA, 1996. http://www.theses.fr/1996ISAT0035.
Pełny tekst źródłaThuault, Anthony. "Approche multi-échelle de la structure et du comportement mécanique d'une fibre de lin". Caen, 2011. http://www.theses.fr/2011CAEN2055.
Pełny tekst źródłaThis 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
Micol, Alexandre. "Approche probabiliste dans la conception des modules de puissance". Toulouse 3, 2007. http://www.theses.fr/2007TOU30307.
Pełny tekst źródłaThe major failure mode of power IGBT modules is thermo-mechanical fatigue. Thermal heating leads to mechanical stress due to the difference in the coefficients of thermal expansion of the materials involved. How long they last, which is linked to dissipated inelastic energy, strongly depends on the nonlinear behaviour of materials. The interest of this work lies in the application of traditional reliability methods to the field of power electronics. We first introduce the different stochastic methods, taking into account the random behaviour of the model's data. Modelisation, used to define the limit state surface, is made of the different failure modes of power module. We present here an original strategy of finite element modelisation. Since failure is assessed by material behaviour, we identify the Sn/Ag3. 5 solder nonlinear law with relaxation and work-hardening test. An adaptive surface response method with parallel computing is implemented and applied on several reliability studies : electrical, thermal and mechanical
Soulié, Fabien. "Cohésion par capillarité et comportement mécanique de milieux granulaires". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2005. http://tel.archives-ouvertes.fr/tel-00010079.
Pełny tekst źródłaBecquart, Frédéric. "Première approche du comportement mécanique d'un milieu granulaire issu d'un mâchefer d'incinération d'ordures ménagères : valorisation en technique routière". Lille 1, 2007. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2007/50376-2007-13.pdf.
Pełny tekst źródłaAnoukou, Kokou. "Modélisation multi-échelle du comportement mécanique de nanocomposites polymères à renforts d’argile de type montmorillonite : approche micromécanique et simulation de dynamique moléculaire". Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10139/document.
Pełny tekst źródłaPolymer nanocomposites reinforced with clay minerals have attracted a great consideration during the last two decades. That can be explained, firstly, by the availability and the reduced production cost of the reinforcing phase, and secondly, by the remarkable improvements in physical and mechanical properties. These improvements are observed even at very low amounts of reinforcements compared to their microcomposite counterparts. The development of these new materials creates a keen interest both in academic and industrial research. However, the mechanisms responsible of these property improvements are still poorly understood and remain a major concern of researchers. This work contributes to the understanding and to the development of predictive tools of the mechanical behavior of polymer nanocomposites reinforced with montmorillonite clay using two modeling approaches: the micromechanics of heterogeneous materials and the molecular dynamics simulation. An analytical micromechanical model based on the self-consistent approach is developed. The proposed model is validated by our experimental data and those from the literature. A new molecular dynamics simulation protocol is proposed for the modeling of these nanomaterials at the nanometric scale. This approach has allowed us, inter alia, to get insight into the molecular interactions between the different components and to determine the effective elastic properties of the nanocomposite
Saiyouri, Nadia. "Approche microstructurale et modélisation des transferts d'eau et du gonflement dans les argiles non saturées". Châtenay-Malabry, Ecole centrale de Paris, 1996. http://www.theses.fr/1996ECAP0446.
Pełny tekst źródłaNguyen, Thi Thuy Linh. "Approche micromécanique du comportement d'une suspension de bulles dans un fluide à seuil". Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1092/document.
Pełny tekst źródłaThis thesis contributes to characterizing the behavior of a suspension of bubbles dispersed in a non-Newtonian fluid (yield stress fluid type).It consists of three parts. The first part is a literature review identifying the theoretical and experimental works for bubbles sheared in a Newtonian material. The second part is dedicated to the experimental study of the simple shear of a bubble suspended in a yield stress fluid. The last part consists in developing an upscaling approach to study the macroscopic behavior of a suspension of bubbles in a yield stress fluid. For experimental work, we developped a first prototype of device for the study of the shearing of a bubble in a yield stress fluid. For that purpose, an air bubble is injected in a big volume of Carbopol sheared far from the bubble by a system in two parallel bands. A fist series of tests allowed to show the efficiency of the device and to obtain some results on the deformability of a sheared bubble in a yield stress fluid. For theoretical work, first we proposed estimates of the behavior of the suspension in the case of diluted scheme, Mori-Tanaka, autocoherent and morphological patterns. These models have allowed us to find that in the elastic regime the macroscopic elastic modulus of the suspension depends on the capillary number Caelast defined as the ratio of the shear modulus of the fluid suspended over the capillary pressure of the bubble. Then using a modified secant homogenization method (Suquet 1997), we estimated the overall nonlinear properties of the suspension. The model predicts that the overall yield stress of the suspension is that of the suspending fluid regardless of the size of bubbles. The validation of these micromechanical models was achieved thanks to the experimental results obtained in the laboratory (Ducloué 2014).Keywords: bubbles suspensions, yield stress fluid, rheology, capillary number, upscaling approach
Nik, nezhad Davood. "Contribution à l'étude du comportement mécanique, du retrait et des propriétés de transport des bétons autoplaçants avec additions minérales, approche numérique et expérimentale". Thesis, Rennes, INSA, 2015. http://www.theses.fr/2015ISAR0035/document.
Pełny tekst źródłaSelf-compacting concretes (SCC), developed several years ago are still considered as “•novel concrete" as their use remains modest although they have a strong development potential. This is mainly due to their higher cos, their sensitivity to segregation and cracking due to their high shrinkage and also due to the lack of information about their durability. SCCs are distinguished from ordinary concrete mainly by their high content of paste. The use of supplementary cementitious materials (SCM), grow increasingly for economic and environmental reasons. This thesis falls within this context and aims to contribute to the development of greener SCCs and to the study of their durability.Two industrial blended cements containing high amounts of SCM, slag cement CEM Ill and CEM V cement containing slag and fly ash as well as two mineral additions still little studied in the literature: metakaolin and calcined dredged sediment are used. Various SCC mixtures derived from a reference SCC based on CEM 1 cement were developed. The results of the mechanical, physical and chemical testing on the different formulations show a greater or lesser effect of SCM on the mechanical behavior at early age and some positive effect over the long term. The results of measurements of the autogenous and drying shrinkage from fresh state (plastic) to well hydrated state show that some SCMs increase the drying shrinkage of SCCs (slag and calcined sediment) while ethers significantly reduce its amplitude (metakaolin).The undeniable effect of SCMs on improving some durability indicators (chloride diffusion and gas permeability) and on increasing the sensitivity to carbonation was quantified. The rather complex influence of the different SCMs is studied in the light of physicochemical and microscopie analyzes. Finally, mesoscopic modeling is developed and applied to SCCs for a parametric investigation. The effect of the shape of aggregates and their concentration on the overall behavior in compression and tensile SCC specimen as well as the effect of the mechanical damage on the evolution of permeability are studied
Oumarou, Mairagouna Mamane. "Approche probabiliste du comportement mécanique des composites thermoplastiques assemblés par soudage laser". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00819162.
Pełny tekst źródłaTouboul, Marion. "Approche multi-échelles morphologique et directe pour une classe de composites particulaires fortement chargés hyperélastiques et viscohyperélastiques". Poitiers, 2007. http://www.theses.fr/2007POIT2300.
Pełny tekst źródłaThis study is devoted to multi-scale modelling of a wide class of highly-filled particulate composites such as solid propellants. Inspired by the previous work of Christoffersen (1983), the approach at stake (MA) is based on a preliminary geometrical and kinematical schematization. The objective of this work can be split into two parts : proving the ability of the MA to deal with viscohyperelasticity (behaviour of solid propellants’ elastomeric matrix) and evaluating its quantitative relevance. The first point is treated by applying the MA to a numerically generated composite with random microstructure and viscohyperelastic matrix. The localisation-homogenisation problem is solved in a direct manner thanks to a particular algorithm operating in real time-space domain. Qualitative results are obtained. Concerning the second point, comparisons between MA estimates and finite element (FE) results (global and local levels) are made in order to evaluate the effects of the kinematical hypotheses relative to the MA. These comparisons are made on periodic microstructures (simple and involved) satisfying the MA geometrical schematisation, for hyperelastic ant viscohyperelastic constituents. Some advantages and weaknesses to be improved are highlighted. Finally, a transversal program aiming at confronting MA estimates to experimental and FE results on a real propellant is elaborated. Each step –experimental tests on the composite and its phases, morphological characterisation via tomography, automatic FE meshing of real microstructure, determination of the RVE (a few hundred of grains) relative to both methods (MA and FE)– is detailed and prospective works are presented
Chu, Tuan-Long. "Étude du comportement mécanique d’un matériau tissé soumis à un impact balistique basée sur une approche multi-échelle". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10122/document.
Pełny tekst źródłaThe thesis focuses on the study of mechanical behavior of a fabric subjected to ballistic impact by using a multi-scale modeling that takes into account fibers and yarns. This micro-meso approach allows highlighting the physical phenomena that may occur during the ballistic impact on fabric. At the yarn level, a parametric study enables investigation into the influences of physical and mechanical yarn properties on the ballistic behavior of a plan-woven-fabric. Also, the effects of the impact localization are investigated to take into account the strike position of the projectile on a 3D fabric. At the fibers level, a detailed analysis of transverse compressive deformation of yarn is developed. These phenomena are considered to predict the ballistic response of a yarn subjected to a transverse impact using modeling at the microscopic scale (the scale of fiber). A modeling of fabric using a multi-scale approach is also performed. In this model, the area affected by the impact is modeled on the microscopic scale, while other areas are modeled on the mesoscopic scale. An analysis of the results is carried out regarding projectile velocity history, the kinetic energies and deformation, and impact forces in the cases of impact with and without perforation. The numerical results are validated by comparison with experimental data
Bourissai, Monsef. "Comportement thermo-chimio-hydro-mécanique d'un ciment pétrolier au très jeune âge en conditions de prise HP/HT : approche expérimentale et analyse par changement d'échelle". Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00582893.
Pełny tekst źródłaMajcherczak, Didier. "Étude thermique d'un contact glissant : approche numérique et expérimentale : application au freinage". Lille 1, 2003. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2003/50376-2003-169-170.pdf.
Pełny tekst źródłaDang-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.
Pełny tekst źródłaThis 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
Gras, Jean-Philippe. "Approche micromécanique de la capillarité dans les milieux granulaires : rétention d'eau et comportement mécanique". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2011. http://tel.archives-ouvertes.fr/tel-00821687.
Pełny tekst źródłaDang-Hoang, Thong. "Rupture et endommagement d’un assemblage boulonné : approche expérimentale et simulation numérique". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10066/document.
Pełny tekst źródłaThis 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
Astruc, Laure. "Caractérisation et modélisation du comportement mécanique des tissus conjonctifs de la paroi abdominale humaine par approche histologiquement fondée". Thesis, Ecole centrale de Lille, 2019. http://www.theses.fr/2019ECLI0003/document.
Pełny tekst źródłaAbdominal hernia operations are one of the most common surgeries in the world. However, despite considerable progress, particularly in the development of prosthetic textiles to strengthen the abdominal wall, the recurrence rate remains very high. It therefore appears necessary to develop patient-specific numerical models of the abdominal wall in order to measure and improve the impact of care solutions. The tissues that ensure the cohesion and stability of the abdominal wall are the anterior and posterior rectus sheaths and the linea alba, which are connective tissues. Their particular structure, composed of an intertwining of collagen and elastin fibers, is at the heart of this study. This thesis highlighted the relationship between microscopic architecture and macroscopic behaviour of fibrous tissues. Thanks to experimental campaigns combining mechanical tests and microscopic observations, the structure of tissues has been identified and correlated to mechanical parameters. Three-dimensional image analysis tools have been developed to automatically estimate the anisotropy of a texture. The collected information then led to the development of a hypo-parameterized anisotropic constitutive model. Based on a three-dimensional description of the fibrillary network, the model was written in such a way as to uncorrelate the parameters related to the structure and those related to the nature of the material. By considering similar material parameters for every individual, the model demonstrated its ability to predict mechanical behaviour based on textural information
Travaillot, Thomas. "Caractérisation mécanique des matériaux élastiques à l'échelle locale par microscopie à pointe vibrante : Approche multimodale et mesure de champs". Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2011/document.
Pełny tekst źródłaThis work proposes an improvement of the Scanning Microdeformation Microscope (SMM), a scanningprobe microscope, for the mechanical elastic characterization of materials at local scale. It demonstratesthat using n > 2 SMM resonance frequencies allows to decouple Young’s modulus andPoisson’s ratio values for an isotropic material.The mechanical description of the resonator has been enriched in order to allow for an accuratemodeling over a wide frequency range. Procedures have been developed to identify the modellingparameters and the elastic constants of the materials from n > 2 resonant frequencies. Finally, theseprocedures have been applied to the characterization of various materials at local scale in order tovalidate the method and to present possibilities and limits.To improve robustness and move towards the characterization of anisotropic materials, a polarizedlightimaging interferometer was developed to measure the rotation field of reflecting surfaces in aparticular direction. The sensitivity to the rotation originates from a homemade birefringent prism withuniaxial gradient of refractive index. This system is able to measure a localized rotation field as it isinduced in the vicinity of the tip of the SMM. Its interest is also demonstrated in cases in which scaleeffects make the rotation measurement preferable to the out-of-plane displacement measurement
Ayadi, Zoubeïr. "Contribution à la modélisation du comportement mécanique de polymères à partir d'une approche thermodynamique de la relaxation des milieux continus : application aux expériences de fluage/recouvrance". Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL073N.
Pełny tekst źródłaBouissou, Stéphane. "Approche de l'instabilité sismique par l'analyse du glissement saccadé avec un analogue de roche (PMMA)". Montpellier 2, 1998. http://www.theses.fr/1998MON20079.
Pełny tekst źródłaGong, Xiao Lu. "Développement d'une méthodologie expérimentale associée à une approche analytique pour la compréhension du comportement de plaques composites non-trouées et trouées sous chargement simple et combiné de traction-torsion". Compiègne, 1994. http://www.theses.fr/1994COMPD741.
Pełny tekst źródłaBarbier, David. "Etude du comportement mécanique et des évolutions microstructurales de l'acier austénitique Fe-22Mn-0.6C à effet TWIP sous sollicitations complexes : approche expérimentale et modélisation". Thesis, Metz, 2009. http://www.theses.fr/2009METZ004S/document.
Pełny tekst źródłaThe TWIP steel (Twinning Induced Plasticity) Fe-22Mn-0.6C exhibits outstanding mechanical properties combining a good ductility and a high mechanical resistance thanks to the activation of dislocation glide and mechanical twinning. As the volume fraction of twins increases with the deformation, the mean free path of the dislocations is reduced (dynamical Hall-Petch effect). The goal of this study was to supply a much more precise analysis and understanding of the mechanical behavior of this TWIP steel during different mechanical loadings. We studied the mechanical behavior during different mechanical loadings (tension, simple and reverse shear, strain path changes), and more precisely the strain hardening evolution in relation to the microstructure and texture evolutions analyzed by X-ray diffraction, FEG SEM EBSD and TEM. By combining data obtained by EBSD and X-rays diffraction, we propose an approach that allows us to evaluate the twin volume fraction. The examination of the mechanical and microstructural observations allowed us to show that the different stages of hardening are linked to particular characteristics of the microstructure and texture, the interaction between dislocations and twins leading to an increase of the hardening. The hardening is maintained at a high level by the activation of two twin systems and by the texture evolution. The latter sustains this mode of deformation in the polycrystal. We also observed that the occurrence of the different stages of hardening and of the effect TWIP varies according to the type of solicitation imposed. The analysis of the mechanical behavior during reverse shear tests showed that the steel exhibits a strong Bauschinger effect related to the dynamic Hall-Petch effect. The dislocation piles-up at grain and twin boundaries create local stress fields that influence the mechanical behavior during the reverse deformation. Finally, these experimental results allowed us to check the predictive capacities (mechanical behavior, twin kinetics, texture) of an elasto-viscoplastic micromechanical model incorporating the TWIP effect. The simulations of monotonous deformation are in good agreement with experimental results. To improve prediction of the reverse shear tests and strain path changes, additional developments are suggested
Frąś, Teresa. "Modélisation de la surface d'écoulement des matériaux incluant l'anisotropie initiale et l'effet différentiel des contraintes : approche expérimentale et numérique". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0271/document.
Pełny tekst źródłaThis thesis proposes physically consistent description of the elastic limit of the material on the basis of the results associated with FEM simulations experiments. The theoretical approach is based on the assumption that the limit of elasticity of material Burzynski. The hypothesis effort material is derived from the definition of the end energy of variable stroke volume change or distortion. In special cases, the criteria include asymmetry elastic range and in an expanded form, it is applicable to initially anisotropic materials. The thesis has demonstrated the need to provide an integrated view on experiments and numerical simulations to obtain the description of the onset of plasticity. To achieve this goal, a specific methodology was developed - the procedure which combines experimental techniques with numerical simulations supported by a precise description of the behavior of materials. As part of the approach to numerical modeling, numerical analyzes were performed to correct the inaccuracies of the experimental results presented. In addition, Burzy?ski isotropically been implemented in the finite element method via UMAT (user subroutine for ABAQUS). The versatility of description performance is illustrated by the application of materials with amorphous structure and cubic crystals of different systems: structure FCC (face centered cubic) and BCC (body centered cubic). Examples : - type material FCC structure - OFHC Cu, Oxygen Free High Conductivity Copper material BCC structure type - E335 , not alloyed high strength and example of the amorphous steel materials - polycarbonate (PC) and biopolymers ( PLA / PBAT ) . Materials for specific analyzes were performed to obtain microstructural and mechanical properties via wide range of stress tests in various loading conditions. The number of copies of data found in the literature of the pressure sensitive and / or anisotropic materials was initially analyzed. It has been proven that the proposed criteria provide accurate approximation of the state of early plasticity in relation to other terms in common use. The resulting criteria appear to be universal and widely applicable method of obtaining a description of the appearance of the plasticity
Moukadiri, Dounia. "Développement d'une approche numérique par la MED pour la prédiction des propriétés mécaniques des matériaux hétérogènes avec prise en compte de leur variabilité : application aux matériaux composites biosourcés". Electronic Thesis or Diss., Amiens, 2019. http://www.theses.fr/2019AMIE0061.
Pełny tekst źródłaNatural fiber composites are attracting growing interest. However, pieces made from this type of material exhibit a high variability in terms of mechanical properties, which makes them less competitive compared to conventional materials. In this work, a numerical approach, based on Discrete Element Method (DEM) and the probabilistic method Certain Generalized Stress Method (CGSM) is proposed, in order to take into account the different sources of variability. For validation purposes, a unidirectional bio-based composite material based on flax fibers is considered. The first part of this work describes the material's manufacturing, the elastic properties experimental characterization and the quantification of their variability. The DEM is then introduced to simulate the macroscopic behaviour of the material. Since the stress field obtained using DEM modelling is heterogeneous, an approach named Halo is introduced to control this dispersion. The proposed approach is tested and validated in homogeneous and heterogeneous media. Finally, the variability of elastic properties is introduced into the discrete model via a coupling approach with the probabilistic method CGSM
Reda, Hilal. "Modeling and computation of the effective static and dynamic properties of network materials accounting for microstructural effects and large deformations". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0007/document.
Pełny tekst źródłaMicropolar and second gradient effective continua are constructed as two different strategies to account for microstructural effects. The influence of additional degrees of freedom or higher order displacement gradients on the dispersion relations is analyzed in both situations of elastic and viscoelastic behaviors of the material. Generalized effective continua lead to dispersive waves, as observed in experiments. In the second part of the thesis, we analyze the influence of large deformations on the propagation of acoustic waves in repetitive network materials. Both theoretical and numerical methods are developed in order to assess the influence of finite strains developing within the networks on the evolution of their band diagrams. An incremental scheme for the update of frequency and phase velocity of the computed homogenized medium is developed based on a perturbation method for 1D, 2D and 3D structures, considering with a special emphasis auxetic networks. This scheme shows an important effect of the applied finite deformation on the frequency and phase velocity of the propagating waves. A perturbation method for nonlinear periodic structures is developed to extend Bloch’s theorem to cover both geometrical and material nonlinearities. Hyperelastic first and second order gradient constitutive models of different network materials are identified based on dedicated homogenization methods, from which specific wave equations are formulated - Burgers and Boussinesq equations - the dispersion properties of which are analyzed
Roothaer, Xavier. "Approche multi-échelle du comportement mécanique des os porteurs et non-porteurs : vers une personnalisation des modèles numériques EF de l'être humain". Thesis, Valenciennes, Université Polytechnique Hauts-de-France, 2019. http://www.theses.fr/2019UPHF0020.
Pełny tekst źródłaThe human skeleton aims at participating to the locomotor system, protecting and serving as brackets for the internal organs. To ensure the mechanical stiffness of the entire body, the cortical bone can be found in every part of the skeleton. A dynamic process occurs throughout the life and is named bone remodelling. This process adapts the cortical bone architecture and the shape of bones according to their functions. Due to its complexity, bone remodelling can defect in the elderly and weakens bones. This thesis studies the bearing and non-bearing long human bones by focusing on the humerus and femur. A survey of the state of the art, detailed in the first chapter, reveals several lacks. First, the femur is widely investigated compared to the other bones and this unbalance creates a lack of data for the other bones. Therefore, inputs for numerical human models come from deprecated and contradictory studies where the extra-individual differences impact the trends. Second, architectural studies are mainly limited to in-plane assessment whereas the vascular network is complex and needs more robust analyses. Thus, the second chapter describes an innovative method to 3D assess the cortical vascular network from tomographic data. This Python script automatically detects canals, connectivity and Bone Multicellular Units (BMUs), cradle of the bone remodelling activity. Then, 77 samples from left and right femurs and humeri of ten human cadavers are scanned and analysed using this method. As this method provides numerous novel features of the cortical architecture, tensile and indentation tests are also carried out in order to understand and exhibit the impact of the architecture on the mechanical behaviour. Hence, all the scanned samples are tested and available for statistical analysis. So as to identify global trends, humerus and femur are compared using different statistical tests. Likewise, the bias impact is also investigated. Finally, a correlation study followed by a regression study is described so as to provide polynomial functions in order to be used to predict the mechanical behaviour from an architectural study
Shen, Yang. "Comportement et endommagement des alliages d’aluminium 6061-T6 : approche micromécanique". Thesis, Paris, ENMP, 2012. http://www.theses.fr/2012ENMP0089/document.
Pełny tekst źródłaThe AA6061-T6 aluminum alloy was chosen as the material for the core vessel of the future Jules Horowitz testing reactor (JHR). The objective of this thesis is to understand and model the tensile and fracture behavior of the material, as well as the origin of damage anisotropy. A micromechanical approach was used to link the microstructure and mechanical behavior. The microstructure of the alloy was characterized on the surface via Scanning Electron Microscopy and in the 3D volume via synchrotron X-ray tomography and laminography. The damage mechanism was identified by in-situ SEM tensile testing, ex-situ X-ray tomography and in-situ laminography on different levels of triaxiality. The observations have shown that damage nucleated at lower strains on Mg2Si coarse precipitates than on iron rich intermetallics. The identified scenario and the in-situ measurements were then used to develop a coupled GTN damage model incorporating nucleation, growth and coalescence of cavities formed by coarse precipitates. The relationship between the damage and the microstructure anisotropies was explained and simulated
Champagne, Jonathan. "Modélisation physique du comportement mécanique linéaire et non-linéaire des élastomères renforcés". Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLM043.
Pełny tekst źródłaThe addition of fillers into a polymer matrix, such as nano-silica into silicone rubbers, brings an outstanding enhancement in the mechanical properties (stiffness, hysteresis, ultimate strength,...). In return, many dependencies or nonlinearities appear in the mechanical behaviour which do not exist in the pure rubber. The relation between the microstructure and the macroscopic mechanical properties is not yet clearly understood.Thus, we start with the development of a stochastic model describing the linear mechanical response of filled rubbers. This model is based on the glassy bridges theory. The typical microstructure of the system is composed by a bridges lengths and orientations distribution, i.e. confined polymer chains between aggregates. The local mechanical response of a single bridge can be glassy or rubbery depending on the confinement degree, the temperature and the strain amplitude. The macroscopic mechanical properties of the distribution are calculated by the mean of a self-consistent homogenization. For all our materials, the bridges distribution has been identified based on the linear mechanical reinforcement measurements.The stochastic model also provides the physical origin of the pressure-temperature superposition highlighted on the stiffness. The temperature makes the glassy bridges disappear (softening) while the pressure creates new ones (hardening). The glassy bridges theory allows us to suggest a new pressure-temperature superposition law for filled elastomers.Then, we show that the theory is also capable, to a first approximation, to describe the nonlinear mechanical properties (Payne effect) of our samples. Finally, we implement the constitutive equations of a macroscopique behaviour into a finite element software. Although the thermodynamical framework is standard, the material parameters are given by responses surfaces which are identified based on the stochastic model
Bilotta, Giovambattista. "Influence de l'hydrogène gazeux sur la vitesse de propagation d'une fissure de fatigue dans les métaux : approche expérimentale et modélisation". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2016. http://www.theses.fr/2016ESMA0002/document.
Pełny tekst źródłaThe main purpose of this work is to understand the mechanisms that govern hydrogen assisted cracking in metals, based on the experimental analysis of crack propagation data under gaseous hydrogen and the interaction between hydrogen and lattice defects on the one hand, and on the development of a cohesive zone model influenced by hydrogen on the other hand.Fatigue crack propagation tests were performed under high pressure of gaseous hydrogen on the Armco iron. The results show a strong influence of the pressure, the frequency and the ΔK value, on the modification of the failure modes and on the fatigue crack growth rates. In order to identify the physical parameters that govern the changing of the failure modes, a study on the interaction between hydrogen and the crystallographic defects developed during a cyclic loading was performed. We observe an increase in the total absorption of hydrogen with the cumulated plastic deformation, which can be attributed to the increase in the hydrogen trapping by the dislocations generated during the cyclic deformation. These data have to be introduced into a numerical model to reproduce the modification of the hydrogen diffusion at the crack tip, and its effect on plasticity.Moreover, measurements of the out-of-plane plastic deformation at the crack tip in presence of hydrogen have conducted to an improvement of the cohesive zone model by introducing an effect of hydrogen on the plastic behavior of the volume elements. In addition, the study of Krom diffusion law components has shown the importance of the hydrostatic stress gradient on the diffusion and accumulation of hydrogen at the crack tip. The model predicts a strong dependence of the crack propagation with respect to the hydrogen diffusion at the crack tip, and it is able to simulate the propagation under static load, thus validating the cyclic cracking and static cracking superposition, and explaining the transient regime in fatigue crack growth rates experimentally observed
Gautier, Ewann. "Plasticité cyclique multiaxiale en zone confinée : approche théorique et expérimentale". Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2023. http://www.theses.fr/2023ENTA0002.
Pełny tekst źródłaThe structural components exhibit zones of stress concentrations leading to heterogeneous stress states, that can lead to local plasticity and low cycle fatigue failure. In this work, two parts are proposed to study the local cyclic elasto-plastic behavior at the critical point. First, an analytical method is proposed to predict the local response only at the critical point of the structure. In the second step, experimental measurements are obtained through in-situ X-ray diffraction measurements to question the predictions of the simplified finite element method. The study of the behavior at the critical point of the structure is carried out using a method based on the use of an Adjustable Location Operator (ALO). Until now, two strategies have been used to identify this operator on a structure. Based on these methods, two lines of improvement are proposed to improve the numerical predictions. These two in the presence of a new interesting compromise between the identification cost and the quality of the predictions with respect to the numerical reference. In order to compare these numerical results with experimental results, a protocol for in-situ stress monitoring by X-ray diffraction was set up. Subsequently, tests were carried out to observe cyclic behavior, with a progressive and continuous relaxation of the average stress until the initiation of a crack
Ricard, Jonathan. "Approche locale de la rupture dans un thermoplastique semi-cristallin : le PolyOxyMéthylène : Application : modélisation thermomécanique d'un procédé de vissage-taraudage". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2013. http://pastel.archives-ouvertes.fr/pastel-00945520.
Pełny tekst źródłaTran, Quoc Anh. "Modélisation numérique du comportement des milieux granulaires à partir de signaux pénétrométriques : approche micromécanique par la méthode des éléments discrets". Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22561/document.
Pełny tekst źródłaIn the field of in situ mechanical characterization of soils, penetration tests are commonly used. Penetration tests measure the properties of soils in the domain of large deformations. The tip resistances, deduced from pile driving theory, can be measured either in dynamic conditions (q d ) either in static conditions (q c ). Recently, the measurement technique in dynamic conditions has been improved and it is now possible to record the whole response of the soil during one impact in terms of tip force and penetration distance. The exploitation of this new curve provides information not only on dynamic tip resistance but also on additional mechanical parameters involved during the driving of the tip. The objective of this work is to develop a numerical model in 2D able to reproduce the penetrometric record obtained experimentally by static or dynamic penetration tests. This model is based on the discrete element method with a simple linear contact model. After the validation of the model, a parametric study was performed essentially on the loading type (static or dynamic), the penetration rate, the particle size of the granular material and the arrangement (density variation). Besides the influence of these parameters on the penetrometer signals and the tip resistance, a particular attention was focused on micromechanical analysis: energy dissipation in the medium, force chain evolution, contact orientation. This analysis requires the development of specific numerical tools to better understand the penetration mechanism and try to explain the macroscopic mechanical response obtained. The penetration rate influences significantly only in the dense flow regime on the static and dynamic penetration tests. There is no significant microscopic difference between static and dynamic penetration tests with similar penetration rates. Regarding the influence of the characteristics of the material, the numerical results obtained conform to the real results when the particle friction or the compactness of the medium varies. Concerning the particle size, the dynamic signal variation and the dynamic tip force increases when the average particle diameter increases
Laplanche, Karine. "Etude du comportement au feu des assemblages de structures bois : approche expérimentale et modélisation". Phd thesis, Clermont-Ferrand 2, 2006. https://theses.hal.science/docs/00/69/39/99/PDF/2006CLF21665.pdf.
Pełny tekst źródłaLaplanche, Karine. "Etude du comportement au feu des assemblages de structures bois : approche expérimentale et modélisation". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2006. http://tel.archives-ouvertes.fr/tel-00693999.
Pełny tekst źródłaChrétien, Marie. "Compréhension des mécanismes de retrait-gonflement des sols argileux : approche sur site expérimental et analyse de sinistres sur constructions individuelles". Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14033/document.
Pełny tekst źródłaHomes built on sensitive clayey soils, considered as medium risk, are showing cracks evidencing differential movements occurring in their foundations after drought periods of 2003 and 2005. To address this problem in a first part of the thesis, the swell-shrinkage behaviour has been investigated specifically to the Plio-quaternary clayey formation of Brach, both at the scale of a district and a small land. The results reveal the variability of the clay behaviour when sandy lenses occurred inside the formation. The present work aims to assess geotechnical and compressibility parameters to analyse the variability of the swelling-shrinkage parameters inside a same clayey formation. The aim of a second part of this study is to identify the seasonal soil moisture variations occurring between wet period and dry summer down to 3 meter depth, using a new method integrating geophysical and geotechnical data obtained in situ and in laboratory. This research is based on the setting of an experimental site on Pessac town (Gironde) in order to monitor clayey behavior, to establish correlations between geotechnical properties, water content variations and electrical resistivity on soils over time and every month. The purpose is to survey and evaluate kinetics of soil water content evolution, temperature and vertical displacements down to 3 m depth. This work presents the first results which compare geotechnical, volumetric and electrical resistivity data by combining the field and laboratory measurements
Renault, Norbert. "Etude du couplage thermomécanique du PEHD par essais mécaniques et inversion d'images infrarouges". Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL100N/document.
Pełny tekst źródłaThis research aims at looking further into current knowledge of the mechanical behavior of semi-crystalline polymers at multiple scales. It relies on the simultaneous acquisition of coupled information relating to me-chanical, thermal and microstructural behaviors. For this purpose, we have studied the response of High Density Polyethylene (HDPE) under tensile tests with controlled strain rates, using three optical techniques : (i) Vidéotraction®, a videoextensemeter to access the true stress and strain. (ii) Infrared thermography to access the thermal sources evolution. (iii) Backscattering of Incoherent Light (ISLT technique) to access information on damage mechanisms. The core of the research concerns the reconstruction of the 2D thermal sources starting from temperature fields maps measured during the test. This ill-posed problem has been solved with two different methods : A constrained optimization based on the adjoint formulation and a minimization based on a reduced spectral model. The regularization tools used in the problem are detailed for each method. The ISLT technique allows to monitor damaging processes due to crazing : the creation of isotropic micro-cavities followed by the development of a strong anisotropy during the hardening phase. We show that these information at microstructural level confirm the evolutions of the heat source thermal. All these experimental information are finally considered within a thermodynamical framework used for deri-ving constitutive laws. A sensitivity analysis applied to the parameters of our law led to a reduced model that is more appropriate for their proper estimation
Blais, Philippe. "Approche stochastique de l'endommagement en fatigue d'engrenages en composite renforcé avec des fibres de bouleaux". Thèse, 2019. http://depot-e.uqtr.ca/id/eprint/9667/1/eprint9667.pdf.
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