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Harrup, Gutierrez Anthony Albert. "Evolution des dommages lors du traitement thermomécanique de plaques épaisses d'aluminium aérospatial". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALI019.
Pełny tekst źródłaAdvanced aluminium alloys used in the aerospace industry require high performance properties such as fracture toughness, fatigue resistance, and corrosion resistance. AA2050 is an aluminium alloy widely used for aerospace internal structure components because of its high mechanical properties combined with its low density. During the manufacturing process of aluminium alloys undergo various thermomechanical steps, such as hot rolling. In particular, hot-rolling enables to close the segregation porosity that may form during casting. Exploring new process windows for this process may lead to extreme conditions where pore behaviour is not well known. The main objective of this work is to understand how pores may nucleate and grow under hot tensile deformations representative of these extreme hot rolling conditions.In this work, we studied pore nucleation and growth under different thermo-mechanical conditions in AA2050 to mimic damage during hot rolling of thick plates. The central part of this study involved multi-scale X-ray tomography performed at the European Synchrotron Radiation Facility (ESRF). The methodology consisted in performing in situ synchrotron X-ray nano-tomography during high-temperature micrometric tensile tests and ex situ synchrotron X-ray micro-tomography of Secondary Tensile Tests. SEM and EBSD analysis were also performed on post-mortem micrometric tensile specimens.With X-ray nano-tomography, we observed the nucleation and evolution of pores at three different temperatures (400°C, 440°C, and 480°C). The pores were segmented and measured in terms of volume and morphology, along with the intermetallics and precipitates surrounding them. With this, a classification of the pores depending on their nucleation location is proposed.Using Digital Volume Correlation (DVC) algorithms, we tracked the evolution of hundreds of individual pores, learning about their growth behaviour and measuring local strain within the specimens. By coupling pore evolution and local strain data with Finite Element Method simulations of high-temperature tensile tests, we determined the local stress field and compared our experimental results with five existing void evolution models. Model predictions are discussed.To link material behaviour and porosity evolution on a larger scale, we conducted ex situ Secondary Tensile Tests. Using the DVC software PT4D, we extracted the strain field from the obtained 3D images, corroborating the material's behaviour at different temperatures. This study not only enhances our understanding of AA2050's behaviour under extreme conditions but also provides valuable insights into defect formation in advanced thermo-mechanical processes
Acito, Vito. "In situ X-ray computed tomography for soft contact mechanics". Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2023. http://www.theses.fr/2023ECDL0054.
Pełny tekst źródłaThe real contact area AR between two solids in contact is a fundamental quantity that controls the frictional behavior of a contact interface. Although most experimental techniques aimed at measuring this quantity are based on the optical contrast between in-contact and out-of-contact regions, these methods are limited by the optical transparency required for least one of the two contacting bodies. Furthermore, these techniques only provide access to the contact interface without providing information on other important physical quantities such as the global deformation or the out-of-contact phenomena at the surface. Building on some pioneering work, we propose in-situ X-ray tomography (XRCT) as an alternative method to overcome these limitations and access the full 3D contact morphology with potentially non-transparent contact pairs. In all previous studies, analyzes were performed on complex surfaces without focusing on preliminary examinations of the limitations of XRCT (such as estimating errors in measuring AR). In this context, we proposed the use of a model system composed of a smooth elastomer sphere (PDMS) and a smooth rigid plate (PMMA) to simplify the problem and highlight the advantages and disadvantages of this experimental method. We first focused on measuring in-situ the evolution of AR during a compression and shear test carried out on our model system. The results were compared to those of a 2D opto-mechanical device already mastered. Finally, from the in-operando 3D reconstruction of the indented and sheared contact , we were able to extract the displacement, deformation and stress fields in the contact by digital correlation of volumes (DVC) using as markers particles previously dispersed in PDMS. All these results were compared to theoretical predictions from models in the literature
Ando, Edward. "Experimental investigation of microstructural changes in deforming granular media using x-ray tomography". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENI097/document.
Pełny tekst źródłaThis doctoral thesis presents an experimental investigation into the mechanics of granular media.The novelty that this work brings is that the specimens of sand tested in this work are systematicallyand non-destructively imaged using x-ray tomography. Sample size is considerably reducedfrom standard (specimens measure approximately 22 mm height by 11 mm diameter), allowingentire specimens to be scanned at a sufficiently high resolution to identify all the grains (morethan fifty thousand) in each specimen.A campaign of triaxial compression tests has been run on a series of three different naturalsands with different grain shapes (Hostun sand, Ottawa sand and Caicos ooids – all prepared atrelatively dense initial states), and tested at 100 or 300 kPa cell pressure. In each test around 15x-ray scans are performed. In the 3D images resulting from the reconstruction of the x-ray scansperformed, grains are identified each state using a standard watershed algorithm. Starting fromthese discretised data, techniques are developed in order characterise grain-to-grain contacts,as well as to measure the kinematics of all the identified grains between imaged states. Grainkinematics are measured with two specifically-developed tools: “ID-Track” to track grains yieldingtheir displacements, and a discrete image correlation technique to measure grain rotations.Grain-scale measurements are reported in detail for one test, and are then compared to testsin different conditions, in order to highlight the micro-mechanisms responsible for the observedmacroscopic behaviour. This comparison highlights some important micro-scale mechanisms suchas the increasing rotational frustration of more angular grains when the sample’s deformation isconcentrated in a fully developed shear band; this is used to explain to some extent the highervalue of their residual stress for these materials. Signs of localised deformation are seen to occurwell before the peak in many samples, and complex patterns of rotating grains (which match alocal, grain-based measurement of strain) are noticed around the peak of each sample’s response
Ren, Wenyuan. "In-situ X-ray computed tomography characterisation and mesoscale image based fracture modelling of concrete". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/insitu-xray-computed-tomography-characterisation-and-mesoscale-image-based-fracture-modelling-of-concrete(3307ca0b-b492-4bfc-91f7-61c092b21707).html.
Pełny tekst źródłaLalechos, Antonios V. "Evaluation of X-ray CT tomography as a means for investigating in-situ electrical contact interfaces". Thesis, University of Southampton, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536365.
Pełny tekst źródłaQsymah, Ansam. "In-situ X-ray computed tomography tests and numerical modelling of ultra high performance fibre reinforced concrete". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/insitu-xray-computed-tomography-tests-and-numerical-modelling-of-ultra-high-performance-fibre-reinforced-concrete(7c27ef36-afc8-4ea7-8c72-7d92eba924f9).html.
Pełny tekst źródłaWheatland, Jonathan Antony Thomas. "Characterising the multi-scale properties of flocculated sediment by X-ray and focused ion beam nano-tomography". Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25984.
Pełny tekst źródłaCostin, Marius. "Multiresolution Image Reconstruction in X-ray Micro- and Nano- Computed Tomography : Application in Materials Non-Destructive Testing". Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0034/these.pdf.
Pełny tekst źródłaIn a large international cooperation, the Saphir project aims at producing in a safe, integrated and controlled way, multifunctional nanostructured products. Within this framework, our contribution is the development of a method for three dimensional inspection and characterization of samples and parts produced by the partners. As a starting point, the X-ray computed tomography (CT) was chosen as the most appropriate non-destructive technique. But because the samples are very complex, with features over more orders of magnitude, the available commercial devices could not solve all the requirements and an adapted method for the image reconstruction needed to be developed. This thesis puts a theoretical and an experimental basis for an original method that we abbreviated ASDIR (Approximate Single Detail Image Reconstruction), capable of producing multiresolution images. In a zoom in CT setup, two sets of projections are acquired and combined. The reconstruction is based on the standard filtered backprojection (FBP) algorithm, but we extended it by implementing an acceleration technique that uses a wavelet processing of the data. Two preliminary variants are also presented, which turned out to produce unsatisfactory results, but they were the basis for the final version. We validated our approach on both simulated and experimental data. We generated numerical data with phantoms that we designed specially to assess different features of the method and of the samples. The experimental data was acquired with two different devices, a micro-tomograph and a nano-tomograph, with samples of different sizes. The images that we produced were subject to a basic analysis and we are confident that more information can be extracted from a detailed study
Cai, Biao. "In situ synchrotron tomographic quantification of semi-solid properties of aluminum-copper alloys". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/in-situ-synchrotron-tomographic-quantification-of-semisolid-properties-of-aluminumcopper-alloys(60c222d0-7e70-4a1e-9ed4-75b8f559d5de).html.
Pełny tekst źródłaWeber, Loriane. "Iterative tomographic X-Ray phase reconstruction". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI085/document.
Pełny tekst źródłaPhase contrast imaging has been of growing interest in the biomedical field, since it provides an enhanced contrast compared to attenuation-based imaging. Actually, the phase shift of the incoming X-ray beam induced by an object can be up to three orders of magnitude higher than its attenuation, particularly for soft tissues in the imaging energy range. Phase contrast can be, among others existing techniques, achieved by letting a coherent X-ray beam freely propagate after the sample. In this case, the obtained and recorded signals can be modeled as Fresnel diffraction patterns. The challenge of quantitative phase imaging is to retrieve, from these diffraction patterns, both the attenuation and the phase information of the imaged object, quantities that are non-linearly entangled in the recorded signal. In this work we consider developments and applications of X-ray phase micro and nano-CT. First, we investigated the reconstruction of seeded bone scaffolds using sed multiple distance phase acquisitions. Phase retrieval is here performed using the mixed approach, based on a linearization of the contrast model, and followed by filtered-back projection. We implemented an automatic version of the phase reconstruction process, to allow for the reconstruction of large sets of samples. The method was applied to bone scaffold data in order to study the influence of different bone cells cultures on bone formation. Then, human bone samples were imaged using phase nano-CT, and the potential of phase nano-imaging to analyze the morphology of the lacuno-canalicular network is shown. We applied existing tools to further characterize the mineralization and the collagen orientation of these samples. Phase retrieval, however, is an ill-posed inverse problem. A general reconstruction method does not exist. Existing methods are either sensitive to low frequency noise, or put stringent requirements on the imaged object. Therefore, we considered the joint inverse problem of combining both phase retrieval and tomographic reconstruction. We proposed an innovative algorithm for this problem, which combines phase retrieval and tomographic reconstruction into a single iterative regularized loop, where a linear phase contrast model is coupled with an algebraic tomographic reconstruction algorithm. This algorithm is applied to numerical simulated data
Lauraux, Florian. "Etudes nano-mécaniques in situ de nanostructures métalliques utilisant le rayonnement synchrotron". Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0441.
Pełny tekst źródłaThe nano-mecanic behavior of Au sub-micronic islands has been studied by in situ nano-indentation using the atomic force microscope SFINX coupled with the Laue X ray microdiffraction and the Bragg coherent diffraction imaging (BCDI°techniques. These coupled studies have been led on synchrotron beamlines, ID01 and BM32 at the ESRF (France Grenoble). New methods have been developped during this PHD work : a mesure of the in situ applied force by measuring the deflexion of the AFM Si cantilever by Laue microdiffraction with a resolution of 90 nm. A brand new multi-wavelength BCDI approach allowing real in situ nano-mecanical tests coupled with X ray diffraction. The mecanical tests coupled with Laue microdiffraction led to the determination of defaults density in a Au nanocristal function of the applied force, which demonstrated a mecanical annealing by the drop of the GNDs. The mw-BCDI has also be coupled with nanoindentation tests on a Au nano-cristal, which allowed us to visualize in 3D the evolution and the nucleation of dislocations. It also showed the disapearing of the dislocations after a full unloading, leaving the nano-cristal with no defaults. These in situ coupled experiments will shed some new light about the nucleation of the first defaults in metalic FCC nanostructures
AGASHE, NIKHIL R. "IN-SITU SMALL ANGLE X-RAY SCATTERING STUDIES OF CONTINUOUS NANO-PARTICLE SYNTHESIS IN PREMIXED AND DIFFUSION FLAMES". University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092055991.
Pełny tekst źródłaJonsson, Åsa, i Grim Skarsgård. "Synchrotron tomography of pressboard during in-situ compression loading : Construction of compression rig, image acquisition procedure and methods for image processing". Thesis, Uppsala universitet, Tillämpad mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-257276.
Pełny tekst źródłaSencu, Razvan. "Multiscale stochastic fracture mechanics of composites informed by in-situ X-ray CT tests". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/multiscale-stochastic-fracture-mechanics-of-composites-informed-by-insitu-xray-ct-tests(85a0be40-9e7a-4df3-a366-69ac6ce02e35).html.
Pełny tekst źródłaLi, Zhen [Verfasser], Andreas [Gutachter] Magerl i Jürgen [Gutachter] Ristein. "In-Situ X-ray Study of Nano SiO_x with Germanium Doping in Czochralski Silicon / Zhen Li ; Gutachter: Andreas Magerl, Jürgen Ristein". Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1144619238/34.
Pełny tekst źródłaKalasová, Dominika. "Rentgenová počítačová nano tomografie polymerních strukturovaných bio materiálu". Doctoral thesis, Vysoké učení technické v Brně. CEITEC VUT, 2019. http://www.nusl.cz/ntk/nusl-409089.
Pełny tekst źródłaYu, Boliang. "3D analysis of bone ultra structure from phase nano-CT imaging". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI016/document.
Pełny tekst źródłaOsteoporosis is a bone fragility disease resulting in abnormalities in bone mass and density. In order to prevent osteoporotic fractures, it is important to have a better understanding of the processes involved in fracture at various scales. As the most abundant bone cells, osteocytes may act as orchestrators of bone remodeling which regulate the activities of both osteoclasts and osteoblasts. The osteocyte system is deeply embedded inside the bone matrix and also called lacuno-canalicular network (LCN). Although several imaging techniques have recently been proposed, the 3D observation and analysis of the LCN at high spatial resolution is still challenging. The aim of this work was to investigate and analyze the LCN in human cortical bone in three dimensions with an isotropic spatial resolution using magnified X-ray phase nano-CT. We performed image acquisition at different voxel sizes of 120 nm, 100 nm, 50 nm and 30 nm in the beamlines ID16A and ID16B of the European Synchrotron Radiation Facility (ESRF - European Synchrotron Radiation Facility - Grenoble). Our first study concerned phase retrieval, which is the first step of data processing and consists in solving a non-linear inverse problem. We proposed an extension of Paganin’s method suited to multi-distance acquisitions, which has been used to retrieve phase maps in our experiments. The method was compared theoretically and experimentally to the contrast transfer function (CTF) approach for homogeneous object. The analysis of the 3D reconstructed images requires first to segment the LCN, including both the segmentation of lacunae and of canaliculi. We developed a workflow based on median filter, hysteresis thresholding and morphology filters to segment lacunae. Concerning the segmentation of canaliculi, we made use of the vesselness enhancement to improve the visibility of line structures, the variational region growing to extract canaliculi and connected components analysis to remove residual noise. For the quantitative assessment of the LCN, we calculated morphological descriptors based on an automatic and efficient 3D analysis method developed in our group. For the lacunae, we calculated some parameters like the number of lacunae, the bone volume, the total volume of all lacunae, the lacunar volume density, the average lacunae volume, the average lacunae surface, the average length, width and depth of lacunae. For the canaliculi, we first computed the total volume of all the canaliculi and canalicular volume density. Moreover, we counted the number of canaliculi at different distances from the surface of each lacuna by an automatic method, which could be used to evaluate the ramification of canaliculi. We reported the statistical results obtained on the different groups and at different spatial resolutions, providing unique information about the organization of the LCN in human bone in three dimensions
Liu, Yuanyuan. "Inkjet printed drops and three-dimensional ceramic structures". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/inkjet-printed-drops-and-threedimensional-ceramic-structures(36785d3d-cca6-4903-8e5b-043fd2198e0f).html.
Pełny tekst źródłaStockmar, Marco Kurt Verfasser], Franz [Akademischer Betreuer] Pfeiffer, Pierre [Akademischer Betreuer] Thibault i Reinhard [Akademischer Betreuer] [Kienberger. "Ptychographic phase retrieval for the near-field regime with applications in x-ray nano-tomography / Marco Kurt Stockmar. Betreuer: Franz Pfeiffer. Gutachter: Pierre Thibault ; Reinhard Kienberger ; Franz Pfeiffer". München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1095766244/34.
Pełny tekst źródłaChen, Yang. "Damage mechanisms in SiC/SiC composite tubes : three-dimensional analysis coupling tomography imaging and numerical simulation". Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1056/document.
Pełny tekst źródłaBecause of their outstanding physical and chemical properties at high temperature, in comparison with metals, silicon carbide (SiC) composite materials are studied as possible nuclear fuel cladding materials either for future advanced fission/fusion reactors, or more recently, for the currently existing light water reactors. 2D-braided SiC/SiC composite tubes, manufactured by chemical vapor infiltration (CVI), exhibit an anisotropic, hardly deformable (~1%) mechanical behavior. Understanding the relations between the microstructure, the damage mechanisms and the macroscopic behavior is essential to optimize the structural design of this material for the considered applications. One important manufacturing parameter is the braiding angle, i.e. the angle between the fiber tows and the tube axis. The objective of this work is to provide a comprehensive understanding of the damage-microstructure relations, in particular of the effects of the braiding angle on the damage mechanisms. For this purpose, an investigation combining experimental observations at macro and micro-scale and numerical simulations is developed. The composite tubes are first studied through in situ tensile testing under X-ray computed tomography. Experiments were carried out on the PSICHE beamline at synchrotron SOLEIL using a pink polychromatic beam. The recorded 3D images are processed using the digital volume correlation (DVC) technique, extended by a series of advanced image processing algorithms specifically developed in order to analyze the 3D microstructures, to measure the deformations through the tube thickness, and to detect and quantitatively characterize the network of micro-cracks created by the mechanical loading. In addition, numerical simulations are performed on the real microstructures as observed in the high-resolution images recorded during the in situ tests. Stress fields are calculated at the microstructural scale in the elastic regime using a numerical tool based on the Fast Fourier Transform (FFT). They help to better understand crack initiation and interpret the experimental observations within one-to-one comparisons. Both the experimental and numerical approaches are applied to three tubes with different braiding angles (30°, 45° and 60°). The effect of the braiding angle on the initiation and evolution of damage in the bulk of the composite materials can thus be highlighted
Engelberg, Dirk Lars. "Grain boundary engineering for intergranular stress corrosion resistance in austenitic stainless steel". Thesis, University of Manchester, 2006. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:207805.
Pełny tekst źródłaWilke, Robin Niklas [Verfasser], Tim [Akademischer Betreuer] Salditt i Claus [Akademischer Betreuer] Ropers. "Coherent X-Ray Diffractive Imaging on the Single-Cell-Level of Microbial Samples: : Ptychography, Tomography, Nano-Diffraction and Waveguide-Imaging / Robin Niklas Wilke. Gutachter: Tim Salditt ; Claus Ropers. Betreuer: Tim Salditt". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://d-nb.info/1064148360/34.
Pełny tekst źródłaLemarié, Quentin. "Développement et caractérisation in situ d'électrodes positives pour batteries Lithium/soufre". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI041.
Pełny tekst źródłaEven though the Li-ion technology is dominating nowadays battery market, it is suffering from the high cost and toxicity of some of its materials as well as struggling to reach the performance goals set by always more demanding hybrid and electric vehicles. Facing the need for a new battery generation, the lithium/sulfur (Li/S) technology stands as a promising candidate for a medium term industrialization and commercialization. Based on an abundant and low-cost active material, elemental sulfur, it enables practical energy densities two to three times higher than current Li-ion batteries. However, the intermediate electrochemical reactions of this system imply many dissolutions/depositions of the active material, causing important morphological variations at the positive electrode which have a major impact on the capacity and cycling performance of the batteries. Hence a better comprehension of those degradation mechanisms is required in order to develop new and innovating electrode materials enabling an optimization of the performance of the system. Therefore, the first goal of the thesis was to employ innovative in situ characterization techniques in order to develop tools allowing to link the properties of the different electrode materials to the performance of the batteries. To do so, three techniques were used: acoustic emission, X-ray tomography and dilatometry. Then, the conclusions drawn from the observations made from the characterization tools enabled us to focus the conception of the electrodes on using a new binder based on a polyelectrolyte material. In this work, we were in particular able to demonstrate a relationship between the measured acoustic activity during the first charge/discharge cycles of different electrode formulations to their mechanical properties. Then, coupling in situ X-ray tomography and diffraction enabled us to shed light on new phenomena linked to the dissolution and deposition of sulfur during the 1st cycle. Finally, the combination of the study of thickness variation via dilatometry, of the monitoring of the acoustic activity and of tomographic observations was the key to prove the better mechanical properties of the polyelectrolyte binder. Together with its properties of regulation of the sulfur species, our conclusions strengthen the certain interest in the family of materials as a binder of positive electrodes for Li/S batteries
Messager, Alexandre. "Étude de l'amorçage et de la propagation de fissures de fatigue internes courtes en régime gigacyclique dans un alliage d'aluminium de fonderie". Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAE032.
Pełny tekst źródłaCasting allows the mass production of parts with complex geometry at a low cost. However, defectsinherent to the manufacturing process (pores, shrinkages, etc.) are natural stress concentrators and act as amajor cause of fatigue crack initiation. The defect position from the part surface influences its harmfulnessand the fatigue strength of the component. Initiation and propagation mechanisms of internal fatiguecracks are currently less studied than those emanating from surface defects. The purpose of this work is tocharacterize short internal fatigue crack initiation and propagation mechanisms and kinetics in the A357-T6 cast aluminium alloy. An experimental testing device allowing the observation of internal fatigue crackinitiation and propagation by in-situ synchrotron tomography and infrared thermography was developed.The propagation kinetics of internal cracks were quantif ied through tomographic data processing. Stressintensity factor ranges were calculated by f inite element analysis along the crack fronts assuminghomogeneous material. In addition, the microstructure of the specimens was characterized by diffractioncontrast tomography (DCT) which allowed polycrystalline aggregates simulation in order to betterunderstand the interactions between cracks and microstructure. Finally, thanks to f inite elementthermomechanical simulations, the surface temperature increases of the specimens, measured by infraredthermography, were correlated to the 3D evolution of the crack fronts observed by tomography
Pushkareva, Marina. "Study of Void Growth in Commercially Pure Titanium". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35667.
Pełny tekst źródłaHallouard, François. "Formulation de nano-particules iodées comme agents de contraste a longue rémanence vasculaire pour tomodensitométrie". Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10307.
Pełny tekst źródłaThe aim of this thesis is to formulate a blood pool contrast agent for preclinical X-ray imaging application. In collaboration with the galenic laboratory of Strasbourg, this work has allowed to obtain iodinated nano-emulsions produced by spontaneous diffusion of surfactant and nano-particles produced by iodine ”emulsion - solvent diffusion” as blood pool contrast agent. These emulsions and polymer particles present indeed a vascular persistence of several hours, a sufficient contrast to be use in computed tomography (between 170 and 400 HU), the ability to be administered intravenous and stability of several months. Nano-emulsions, including those produced from Lipiodol®, are the most promising as blood pool contrast media by their high radiopacity (475 ± 30 HU) and vascular persistence (T1/2 of 4.1 ± 1.10 h). Iodinated nano-particles of PCL have a lower X-ray attenuation (168 ± 13 HU), but they are known for their control release of the encapsulated substances. Therefore even if inorganic or lipidic contrast agents show a better contrast, they remain attractive for rapid visualization of the co-encapsulated substance distribution in the body. This thesis also introduced several features for understanding the formulation of nano-emulsions obtained by spontaneous diffusion of surfactant and the nano-particles produced by ”emulsion - solvent diffusion.”
Guillou, Raphaëlle. "Étude in-situ des propriétés mécaniques de films minces d'or nanostructurés déposés sur substrats flexibles lors d'essais de traction biaxiale contrôlée sous rayonnement synchrotron". Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2271/document.
Pełny tekst źródłaThe main purpose of this thesis is to study the size and microstructure effects on the mechanical response of gold nanostructured thin films deposited on flexible substrates during biaxial tensile tests. Gold thin films are deposited onto polyimide substrates by sequenced ion sputtering technique in order to control the grain size in the growth direction. We have carried out in situ deformation experiments using the biaxial tensile device installed on the diffractometer of the DiffAbs beamline at synchrotron SOLEIL (Saint-Aubin, France), an intense X-rays source which allows to determine applied strains in polycrystalline thin films thanks to x-ray diffraction measurements. In a first step, we performed tensile biaxial tests for different load ratio using “step by step” procedure on two series of gold thin films showing different thicknesses in order to study the mechanical response analyzing the yield surface that can be extracted with the biaxial device. In a second step, we validated a continuous loading procedure which allows gaining a factor of 10 in the time frame. Validation is made by comparing the mechanical properties of two series of gold thin films investigated using “step by step” loading and “continuous” loading. After validation of the continuous loading procedure, tensile biaxial tests have been performed on different series of gold thin films with different grain size and architecture in order to put in highlight a size effect on the mechanical behavior of nanolayered thin films
Kožiol, Martin. "Návrh vhodného etalonu délky pro nano-CT měřicí přístroj". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417542.
Pełny tekst źródłaArif, Muhamad Fatikul. "Mécanismes d’endommagement du polyamide-66 renforcé par des fibres de verre courtes, soumis à un chargement monotone et en fatigue : Influence de l’humidité relative et de la microstructure induite par le moulage par injection". Thesis, Paris, ENSAM, 2014. http://www.theses.fr/2014ENAM0008/document.
Pełny tekst źródłaThe current work focuses on extensive experimental approaches to identify quasi-static and fatigue damage behavior of PA66/GF30 considering various effects such as relative humidity and injection process induced microstructure. By using in situ SEM tests, it was observed that relative humidity conditions strongly impact the damage mechanisms in terms of their initiation, level and chronology. The X-ray micro-tomography analysis on fatigue loaded samples demonstrated that the damage continuously increases during fatigue loading, but the evolution occurs more significantly in the second half of the fatigue life. From the results of damage investigation under quasi-static and fatigue loading, it was established that both loading types exhibit the same damage mechanisms, with fiber/matrix interfacial debonding as the principal damage mechanisms. General damage chronologies were proposed as the damage initiates at fiber ends and more generally at locations where fibers are relatively close to each other due to the generation of local stress concentrations. Afterwards, interfacial decohesions further propagate along the fiber/matrix interface. At high relative flexural stress, matrix microcracks can develop and propagate, leading to the damage accumulation and then the final failure. The experimental findings are important to provide a physically based damage mechanisms scenarios that can be integrated into multiscale damage models. These models will contribute towards reliable predictions of damage in reinforced thermoplastics for lightweight automotive applications
Wang, Long. "Etude de l’influence de la microstructure sur les mécanismes d’endommagement dans des alliages Al-Si de fonderie par des analyses in-situ 2D et 3D". Thesis, Ecole centrale de Lille, 2015. http://www.theses.fr/2015ECLI0004/document.
Pełny tekst źródłaAn experimental protocol was developed in this thesis in order to study the influence of casting microstructure on the fatigue behavior in Lost Foam Casting Al-Si alloys in tension and in Low Cycle Fatigue at room temperature. First of all, the microstructures of studied alloys were thoroughly characterized both in 2D and in 3D. The most suitable and representative specimens and Region of Interest (ROIs) where the in-situ monitoring was performed were selected through a preliminary characterization using X-ray tomography, which is also necessary to understand damage mechanisms after failure. In-situ observations performed on surface using Questar long distance microscope and in volume using X-ray tomography allow following cracks initiations and their propagations and thus allow identifying the relation between damage mechanisms and casting microstructure. 2D/3D displacement and strain fields measured using Digital Image Correlation and Digital Volume Correlation allows analyzing the relation between measured fields and damage mechanisms. Postmortem analysis and FEM simulation gave more information for the damage mechanisms. Large pores favor crack initiation as they strongly increase local stress level. Hard inclusions (Si phase, iron intermetallics and copper containing phases) also play an important role in crack initiation and propagation due to strain localizations at these inclusions
Spartacus, Gabriel. "Evolution des nano-oxydes et de la microstructure au cours du procédé de fabrication d'aciers renforcés par dispersion d'oxydes". Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALI085.
Pełny tekst źródłaOxide Dispersion Strengthened (ODS) steels with a Fe-Cr matrix are of great interest in the development of generation IV fission nuclear power plants as a fuel cladding material. These materials, elaborated by powder metallurgy, include a high density of Y-Ti-O oxide precipitates of a few nm, providing the main contribution to the ODS steels strength. During the fabrication process, powders of Fe-Cr steel, Y2O3 and TiH2 are milled together to obtain a super-saturated solution of Y, Ti and O, otherwise insoluble in Fe. The obtained powder is subsequently processed by Hot Extrusion or Hot Isostatic Pressing around 1100℃. This induces the precipitation of Y-Ti-O and leads to a fully dense steel with finely dispersed nano-oxides in high density, extremely stable even at very high temperature. Moreover, the complex microstructure induced by the milling stage, including high density of dislocations and very small grain size, also evolve during the heating, in an intricate ways with the evolution of the nano-oxides that act as strong pinning points for both grain boundaries and dislocations. This features leads to abnormal grain growth (significant growth of some grains, while others remain stable) and therefore a bimodal grain size after consolidation.The aim of this thesis is to characterize both kinetics and chemical evolution of the nano-oxides during the fabrication process of these steels, as well as the grain microstructure evolution, which are still misunderstood. Such experimental characterization would be invaluable to further control the fabrication process and improve available model of the ODS precipitation kinetics. For this purpose, cold pressed specimens from as-milled powder were prepared (in order to achieve dense specimens without precipitation) and observed by means of various in-situ or ex-situ techniques. In particular, in-situ Small Angle X-ray Scattering measurements were performed during the heating until 1100℃ to measure the precipitation kinetics of several ODS grades. The chemistry and structure of nano-oxides were assessed thanks to anomalous SAXS at Y (performed in-situ) and Ti (ex-situ) edges, ex-situ small angle neutron scattering and atom probe tomography. Then, the grain microstructure was monitored by in-situ X-ray diffraction.These characterizations allow to describe the whole kinetics of purely ferritic ODS, ferritic / martensitic ODS and ODS strengthened with variation of the strengthening powders. In particular, this study highlights a non-homogeneous as-milled stage with clusters containing Y, O and Ti in lesser extent. These clusters evolve in chemistry and structure until reaching a stable structure and stoichiometry, revealed to be Y2Ti2O7 pyrochlore and Y2TiO5 orthorhombic depending on the ODS steel grade. Moreover, a kinetic modification induced by the in temperature phase transformation of the matrix in the ferritic / martensitic ODS (increasing the growth and coarsening rate) was observed. Correlation between nano-oxide and the grain microstructure evolutions were performed and help in the comprehension of the abnormal grain growth temperature and final grain morphology, from one ODS grade to another. Finally, comparisons of the precipitation simulations with experimental data allow to get more insights on the nano-oxides properties
Vanpeene, Victor. "Étude par tomographie RX d'anodes à base de silicium pour batteries Li-ion". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI023/document.
Pełny tekst źródłaBecause of its theoretical specific capacity ten times higher than that of graphite currently used as active anode material for Li-ion batteries, silicon can play an important role in increasing the energy density of these systems. However, the alloying reaction set up during its lithiation results in a high volume expansion of silicon (~300% compared with only ~10% for graphite) leading to the structural degradation of the electrode, which is significantly affecting its cycling behavior. Understanding in detail these phenomena of degradation and developing strategies to limit their impact on the functioning of the electrode are of undeniable interest for the scientific community of the field. The objective of this thesis work was first to develop a characterization technique adapted to the observation of these degradation phenomena and to draw the necessary information to optimize the formulation of silicon-based anodes. In this context, we have used X-ray tomography which has the advantage of being a non-destructive analytical technique allowing in situ and 3D monitoring of the morphological variations occurring within the electrode during its operation. This technique has been adapted to the case study of silicon by adjusting the analyzed electrode volumes, the spatial resolution and the temporal resolution to the phenomena to be observed. Appropriate image processing procedures were applied to extract from these tomographic analyzes as much qualitative and quantitative information as possible on their morphological variation. In addition, this technique could be coupled to X-ray diffraction to complete the understanding of these phenomena. We have shown that the use of a carbon paper structuring 3D current collector makes it possible to attenuate the morphological deformations of an Si anode and to increase their reversibility in comparison with a conventional copper current collector of plane geometry. We have also shown that the use of graphene nanoplatelets as a conductive additive to replace carbon black can form a conductive network more able to withstand the large volume variations of silicon. Finally, the X-ray tomography allowed studying dynamically and quantitatively the cracking and delamination of an Si electrode deposited on a copper collector. We have thus demonstrated the significant impact of a process of "maturation" of the electrode to minimize these deleterious phenomena of cracking-delamination of the electrode
Sorel, Julien. "Tomographie électronique analytique : Automatisation du traitement de données et application aux nano-dispositifs 3D en micro-électronique". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI078.
Pełny tekst źródłaThe aim of this thesis is to automate the process of hyperspectral analysis for analytical electron tomography applied to nanodevices. The work presented here is focused on datasets obtained by energy-dispersive X-ray spectroscopy in a scanning transmission electron microscope (STEM-EDX). STEM-EDX tomography has benefited greatly from recent developments in electron sources such as the ‘X’-FEG (Field Emission Gun), and multiple X-ray detector systems such as the Super-X, incorporating four SSD (Silicon Drift Detectors) detectors. The technique remains however very time-consuming, and low X-ray count rates are necessary to minimize the total acquisition time and avoid beam damage during the experiment. In addition, tomographic stacks of STEM-EDX datacubes, acquired at different tilt angles, are too large to be analyzed by commercial software packages in an optimal way. In order to automate this process, we developed a code based on Hyperspy, a Python library for multidimensional data analysis. Multivariate statistical analysis techniques were employed to optimize and automate the denoising, the energy calibration and the separation of overlapping X-ray lines, with the aim to achieve quantitative, chemically sensitive volumes. Moreover, a compressed sensing based algorithm was employed to achieve high fidelity reconstructions with undersampled tomographic datasets. The code developed during this thesis was used for the 3D chemical analysis of four microelectronic nanostructures: FinFET, HEMT and GAA transistors, and a GeTe thin film for memory device applications. The samples were prepared in a needle shape using a focused ion beam, and the data acquisitions were performed using a Titan Themis microscope equipped with a super-X EDX detector system. It is shown that the code yields 3D morphological and chemical information with high accuracy and fidelity. Ways to improve the current methodology are discussed, with future efforts aiming at developing a package dedicated to analytical electron tomography
Devillard, Julie. "Lien entre microstructure et résistance à la compression du gypse moussé". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI043.
Pełny tekst źródłaThis study focuses on the microstructural and mechanical characterization of foamed gypsum, the core material of lightweight gypsum boards, with a high (75%) multi-scale porosity. The objective of this work is to determine the influence of the microstructure of foamed gypsum on the hardness measured in spherical indentation and to analyze the damage mechanisms for different microstructures. Spherical indentation tests were conducted on samples showing variations in microstructural features of foamed gypsum. The results of these tests show that density has a first-order influence on hardness and that the dispersion of hardness measurements in spherical indentation can be related to heterogeneity in macroporosity. In situ indentation tests were also carried out, with X-ray tomography and digital volume correlation (DVC) analysis, in order to accurately study the damage mechanisms. Two different modes of damage were determined according to the densities considered (variable macropore fraction). The results of these tests were used to feed an analytical model, based on an energy criterion that links the indentation force to the damaged area under the indenter. This provides the prediction of the indentation force-displacement curve specific to a microstructure with a scan of the initial microstructure as the only input data. Numerical modelling was also carried out using the finite element method with consideration of the actual microstructure, at two scales. The densified areas were properly predicted by different behaviour models based on plasticity criteria
Ornek, Cem. "Performance characterisation of duplex stainless steel in nuclear waste storage environment". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/performance-characterisation-of-duplex-stainless-steel-in-nuclear-waste-storage-environment(4db73e9b-c87c-40a6-9778-0b823b1c499f).html.
Pełny tekst źródła"Corrosion and Corrosion-Fatigue Behavior of 7075 Aluminum Alloys Studied By In Situ X-Ray Tomography". Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.46294.
Pełny tekst źródłaDissertation/Thesis
Doctoral Dissertation Materials Science and Engineering 2017
"Deformation Behavior of adidas BOOST(TM) Foams Using In Situ X-ray Tomography and Correlative Microscopy". Doctoral diss., 2020. http://hdl.handle.net/2286/R.I.62793.
Pełny tekst źródłaDissertation/Thesis
Doctoral Dissertation Materials Science and Engineering 2020
(8780756), Imad A. Hanhan. "Investigating damage in discontinuous fiber composites through coupled in-situ X-ray tomography experiments and simulations". Thesis, 2020.
Znajdź pełny tekst źródłaComposite materials have become widely used in engineering applications, in order to reduce the overall weight of structures while retaining their required strength. Due to their light weight, relatively high stiffness properties, and formability into complex shapes, discontinuous fiber composites are advantageous for producing small and medium size components. However, qualifying their mechanical properties can be expensive, and therefore there is a need to improve predictive capabilities to help reduce the overall cost of large scale testing. To address this challenge, a composite material consisting of discontinuous glass fibers in a polypropylene matrix is studied at the microstructural level through coupled experiments and simulations, in order to uncover the mechanisms that cause microvoids to initiate and progress, as well as certain fiber breakage events to occur, during macroscopic tension. Specifically, this work coupled in-situ X-ray micro computed tomography (μ-CT) experiments with a finite element simulation of the exact microstructure to enable a 3D study that tracked damage initiation and propagation, and computed the local stresses and strains in the microstructure. In order to have a comprehensive 3D understanding of the evolution of the microstructure, high fidelity characterization procedures were developed and applied to the μ-CT images in order to understand the exact morphology of the microstructure. To aid in this process, ModLayer - an interactive image processing tool - was created as a MATLAB executable, and the 3D microstructural feature detection techniques were compared to traditional destructive optical microscopy techniques. For damage initiation, this work showed how high hydrostatic stresses in the matrix can be used as a metric to explain and predict the exact locations of microvoid nucleation within the composite’s microstructure. From a damage propagation standpoint, matrix cracking - a mechanism that has been notably difficult to predict because of its apparent stochastic nature - was studied during damage propagation. The analysis revealed the role of shear stress in fiber mediated flat matrix cracking, and the role of hydrostatic stress in fiber-avoidance conoidal matrix cracking. Overall, a sub-fiber simulation and an in-situ experimental analysis provided the microstructural physical phenomena that govern certain damage initiation and progression mechanisms, further enabling the strength and failure predictions of short fiber thermoplastic composites.
"Characterization of Thermo-Mechanical Damage in Tin and Sintered Nano-Silver Solders". Doctoral diss., 2018. http://hdl.handle.net/2286/R.I.49323.
Pełny tekst źródłaDissertation/Thesis
Doctoral Dissertation Materials Science and Engineering 2018
Wilke, Robin Niklas. "Coherent X-Ray Diffractive Imaging on the Single-Cell-Level of Microbial Samples:". Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0023-996A-0.
Pełny tekst źródła"Structure-Property Relationships in Aluminum-Copper alloys using Transmission X-Ray Microscopy (TXM) and Micromechanical Testing". Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.46186.
Pełny tekst źródłaDissertation/Thesis
Doctoral Dissertation Materials Science and Engineering 2017