Literatura científica selecionada sobre o tema "Polycristaux – Élasticité"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Índice
Consulte a lista de atuais artigos, livros, teses, anais de congressos e outras fontes científicas relevantes para o tema "Polycristaux – Élasticité".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Teses / dissertações sobre o assunto "Polycristaux – Élasticité"
Dang, Van Truong. "Etude numérique statistique des champs locaux de contraintes en surface de polycristaux cubiques et hexagonaux en élasticité". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2016. http://www.theses.fr/2016ESMA0003/document.
Texto completo da fonteThe first stages of fatigue damage in metallic polycrystalline materials are governed by local mechanical field at the grain scale. Fatigue crack initiation is often related to the emergence of persistent slip band at surface.Localization of cyclic plasticity occurs within grains of polycristals in which elastic stress field can be highly heterogeneous due to the granular microstructure and crystalline anisotropic elasticity. The main goal of this study is to evaluate and analyse statistically the stress fields in surface grains of polycristals. In this work, the elasticregime only is considered in order to study the subsequent activation of plastic slip and its variability. The possibleconsequences regarding crack formation are also addressed but in a lesser extent. The methodology is based on fullfield finite element numerical simulation of the elastic response of a set of polycrystalline aggregates in which grains orientation is chosen randomly.The two materials chosen for this study exhibit different characteristics regarding crystal elasticity and slip systems.The first one is an austenitic stainless steels 316L (face centered cubic) and the second one a titanium alloy TA6V(hexagonal close packed). The distribution of resolved shear stress within several sets of surface grains, for different classes of crystal orientation, are analysed in relation to local crystallographic configurations in order to identify those which promote - or prevent from - plastic slip activation. For TA6V, the results suggest in particular that basal slip is activated earlier than prismatic slip. In addition, the simulation strategy has been modified tomodel the presence of some sharp band-like crystallographic textures named “macrozones” whose influence has been qualitatively predicted. Plastic slip activation in TA6V is also studied experimentally. In situ tensile test using SEM has shown the earlier activation of basal slip. Experimental data has been combined with simulated distribution of resolved shear stress in order to estimate the critical resolved shear stress of basal and prismatic slip systems
Li, Chenhui. "Application de techniques d’opto-acoustique et de calculs de premiers principes à la caractérisation des propriétés élastiques de films minces". Electronic Thesis or Diss., Paris 13, 2019. http://www.theses.fr/2019PA131091.
Texto completo da fonteElastic properties are of fundamental importance for a material. With the combination of picosecond laser ultrasonic and Brillouin light scattering techniques, we measured sound velocities in various magnetron-sputtering-deposited thin films including epitaxial binary and ternary transition metal nitrides (TaN, TiN, ZrN, Ti1-xZrxN), polycrystalline high entropy alloys or multicomponent transition metal alloys ((CoCrCuFeNi)1-x(Al,Nb)x), and their nitrogen interstitial alloys (CoCr(Cu,Mn)FeNiNx). The longitudinal and shear sound velocities (VL and VT respectively) are correlated to the effective elastic constants through ⟨C33⟩= ρV2L and ⟨C44⟩= ρV2T. On the other hand, Density functional theory (DFT) based ab-initio calculations were performed to provide single crystal elastic constants w/o considering vacancies. It was found that for the epitaxial binary and ternary nitrides, vacancies play a huge role on elastic properties especially in the case of TaN. While in the case of TiN, ZrN and Ti1-xZrxN, the influence of vacancies is smaller but still noticeable. In the case of polycrystalline multicomponent alloys and interstitial alloys, the sound velocities and effective elastic constants were found to be associated to chemical alloying (Al, Nb and N) effects, phase transitions (FCC, BCC and amorphous), textures and porosity changes. The elastic modulus agrees to nanoindentation modulus EIT. The overall agreement between our elastic property measurements and DFT calculations were reached. Besides, DFT calculations also provided valuable insights into structural properties and phase stability. Additionally, we studied structural and mechanical (including elastic) properties of a bulk CoCrCuFeNi as a reference to thin film properties. With the CoCrCuFeNi films on a flexible Kapton® substrate, we performed tensile tests and studied fracture properties of thin films, as a preliminary work to further link thin film elasticity to plasticity. Keywords: Thin film, epitaxial, polycrystalline, sound velocity, elastic constant, transition metal nitride, multicomponent alloy, interstitial alloy, point defects, microstructure, porosity, texture, Brillouin light scattering, picosecond laser ultrasonic, nanoindentation, mechanical property, flexible substrate, fracture toughness, crack and buckle, ab-initio, DFT
Djaka, Komlan Sénam. "Développement et applications d’une technique de modélisation micromécanique de type "FFT" couplée à la mécanique des champs de dislocations". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0250/document.
Texto completo da fonteFast Fourier transform (FFT)-based methods are developed to solve both the elasto-static equations of the Field Dislocation Mechanics (FDM) theory and the dislocation density transport equation of polarized or geometrically necessary dislocation (GND) densities for FDM and its mesoscopic extension, i.e. the Phenomenological Mesoscopic Field Dislocations Mechanics (PMFDM). First, a numerical spectral approach is developed to solve the elasto-static FDM equations in periodic media for the determination of local mechanical fields arising from the presence of both polarized dislocation densities and elastic heterogeneities for linear elastic materials. The elastic fields are calculated in an accurate fashion and without numerical oscillation, even when the dislocation density is restricted to a single pixel (for two-dimensional problems) or a single voxel (for three-dimensional problems). These results are obtained by applying the differentiation rules for first and second derivatives based on finite difference schemes together with the discrete Fourier transform. The results show that the calculated elastic fields with the present spectral method are accurate for different cases considering individual screw and edge dislocations, the interactions between inhomogeneities of various geometries/elastic properties and different distributions of dislocation densities (dislocation dipoles, polygonal loops in two-phase composite materials). Second, a numerical spectral approach is developed to solve in a fast, stable and accurate fashion, the hyperbolic-type dislocation density transport equation governing the spatial-temporal evolution of dislocations in the FDM theory. Low-pass spectral filters are employed to control both the high frequency oscillations inherent to the Fourier method and the fast-growing numerical instabilities resulting from the hyperbolic nature of the equation. The method is assessed with numerical comparisons with exact solutions and finite element simulations in the case of the simulation of annihilation of dislocation dipoles and the expansion/annihilation of dislocation loops. Finally, a numerical technique for solving the PMFDM equations in a crystal plasticity elasto-viscoplastic FFT formulation is proposed by taking into account both the time evolutions of GND and SSD (statistically stored dislocations) densities as well as the jump condition for plastic distortion at material discontinuity interfaces such as grain or phase boundaries. Then, this numerical technique is applied to the simulation of the plastic deformation of model microstructures like channel-type two-phase composite materials and of polycrystalline metals
Vaxelaire, Nicolas. "Etude des Inhomogénéités de Déformation dans les Films Minces Polycristallins par Diffraction X Cohérente". Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2011. http://tel.archives-ouvertes.fr/tel-00622848.
Texto completo da fonteSab, Karam. "Sur quelques méthodes en mécanique aléatoire". Phd thesis, Ecole Nationale des Ponts et Chaussées, 1989. http://tel.archives-ouvertes.fr/tel-00519684.
Texto completo da fonteSab, Karam. "Sur quelques méthodes en mécanique aléatoire". Phd thesis, Marne-la-vallée, ENPC, 1989. http://www.theses.fr/1989ENPC8912.
Texto completo da fonte