Tesi sul tema "Glissement plastique"
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Le, Lu Tuan. "Etude par essais in situ MEB et AFM sur monocristaux des mécanismes de glissement à température ambiante de la ferrite de pureté commerciale". Paris 13, 2013. https://tel.archives-ouvertes.fr/tel-01725850.
Testo completoKhalil, Walid. "Développement d'outils de dimensionnement d'applications en alliages à mémoire de forme à base Fer : prise en compte du couplage transformation de phase - glissement plastique". Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0021/document.
Testo completoThe Fe-based shape memory alloys (SMAs) present a specific thermomechanical behaviour compared with classical SMAs. In this PhD thesis, experimental thermomechanical tests were performed in order to study such behavior. The applied loading is a tension followed by a significant heating. The loading cycle is repeated at different constant temperatures and maximum stresses. The experimental results show a coupling between two non linear inelastic mechanisms: phase transformation and plasticity. The reverse transformation activated only during heating, the effect of plastic strain on the transformation one, were also analysed. Taking into account all these specificities, a finite element numerical tool adapted to Fe-based SMA structural analysis is proposed. It is based on a developed constitutive model which describes the effect of phase transformation, plastic sliding and their interactions on the thermomechanical behavior. Two scalar internal variables were considered to describe phase transformation and plastic sliding effects. This model was derived from an assumed expression of the Gibbs free energy taking into account, in addition to mechanical and chemical quantities, the non linear interaction quantities related to inter- and intra-granular incompatibilities. The numerical tool derived from the implicit resolution of the non linear partial derivative constitutive equations was implemented in the Abaqus finite element code via the UMAT subroutine. After verification tests for homogeneous and heterogeneous thermo-mechanical loadings, two examples of Fe-based SMA applications were studied. They correspond to Fe-based SMA tightening systems: a fish plates for crane rails and a ring for tubes connection
Lineau, Corinne. "Analyse expérimentale de la déformation plastique d'un polycristal d'acier. Comparaison avec les simulations de modèles polycristallins". Phd thesis, Ecole Nationale des Ponts et Chaussées, 1997. http://tel.archives-ouvertes.fr/tel-00529716.
Testo completoBeaude, Nicolas. "Etude théorique et expérimentale du comportement élasto-plastique et de la localisation de la déformation dans les monocristaux". Paris 13, 1988. http://www.theses.fr/1988PA132005.
Testo completoFnaiech, Mustapha. "Contribution a l'etude "in situ" du glissement et de la montee des dislocations dans un compose semiconducteur (3/5) : insb". Toulouse 3, 1987. http://www.theses.fr/1987TOU30070.
Testo completoTounsi, Bouchaïb. "Etude par microscopie en faisceau faible de la dissociation des dislocations dans Ni(3)Si : relation avec le comportement plastique". Poitiers, 1988. http://www.theses.fr/1988POIT2338.
Testo completoForget, Mathilde. "Laminage asymétrique de l'alliage de magnésium AZ31". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00930193.
Testo completoGazo, Hanna Eddie. "Procédé de formage des composites à fibres longues et matrice thermoplastique : analyse expérimentale et numérique du glissement interpli". Ecole centrale de Nantes, 2011. http://www.theses.fr/2011ECDN0043.
Testo completoThe industrial problem of thermoforming of composites materials with long fibers and thermoplastic matrix is in the desire to control the forming process at high mechanical performance while ensuring a reasonable cost of manufacture. The process is a challenge cause it attemps fo form a material during its processing: heating, transfer to the press, pressing and cooling. Complex part forming reveals the occurence of detects such as "fiber buckling", porosity and migration of the resin. The simulation of the process is not yet as mature, even if software of draping or thermoforming begin to appear. The current codes are not suitable to use in distributed areas, while unfortunately this is the key point of the simulation. Moreover, as we expect, the calculation results depend very strongly on the friction "friction coeffecient", scalar parameter which is strongly varaible. The objective of this work is to obtain a better understanding of the thermoforming through the study of physical processes involved in the ply deformation. In fact, a good knowledge of the behavior and good determination of experimental parameters associated in the modeling lead to a better data for coding and therefoer a better simulation of the process
Ait, Saadi Bachir. "Configuration des dislocations dans l'acier z3 cnd 17-12 apres fatigue : correlation au comportement mecanique". Poitiers, 1988. http://www.theses.fr/1988POIT2259.
Testo completoManyo, Edem Yawo. "Modélisation avancée du contact pneu-chaussée pour l'étude des dégradations des chaussées en surface". Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0034/document.
Testo completoThe recent appearance of new materials in road structures associated with surface layers thickness decreasing and the increasing of trucks loading and their passage frequency has led to new pathologies of degradation. In addition to the well-known rutting problems, top down cracking is now appearing as well as problems of decohesion at the interfaces. These new pathologies led to considerable expenditure on the entire network (around 15 billion euros per year), particularly in urbanized areas that are more prone to surface damage and do not make it possible to adequately estimate the lifetimes of the roadway, most often overestimated in current design methods. This doctoral work proposes a new approach of the tire-road contact allowing for better apprehend of the main and residual stresses in a bituminous pavement structure. Using a fast numerical tool based on a semi-analytical approach ("Semi-Analytical Methods" (SAM)), the precise geometry of the tire is integrated in order to obtain a real contact pressure distribution as well as surface shear on the pavement surface. Initially, an elastic tractive rolling contact model is implemented for simple theoretical cases and validated by analytical and numerical results from the literature.Then, this model is extended to take into account the elastoplastic behavior of the bodies in contact. This is compared to a numerical result based on the nite element method from the literature. The application for tire-pavement contact results, show a non-uniform distribution of stresses in the structure and mainly in the rst centimeters below the surface with much higher levels than can be predicted by current models that use a uniformly distributed load. The contact pressure is compared to the measurements made by a system called TekScan and the mechanical elds in sublayers are compared to those of Alizé-LCPC in the case of a simple structure. The surface shears are determined in the case of tractive rolling. An application is carried out on the modeling of surface pavement damage. Firstly, analyzes of the behavior of the surface pavement are carried out for a semi-innite semi-grit asphalt concrete layer supposed to be elastic, homogeneous under conditions of acceleration, braking and turning. For studies on top down cracking, principals deformations and directions are determined and analyzed. Then, the elastoplastic contact model is applied on a semi-innite asphalt agragate layer. Deformations and residuals stresses generated in the structure are determined for an analysis on the instability ruts. Once validated, these results will make it possible to more accurately estimate the residual life of pavements but also to understand and avoid surface or near surfacedegradation mechanisms
Cheneau-Späth, Nadine. "Comportement de monocristaux et de polycristaux de métaux hexagonaux en grandes déformations plastiques : compression plane du titane et du magnésium". Grenoble INPG, 1996. http://www.theses.fr/1996INPG4201.
Testo completoQueyreau, Sylvain. "Etude des mécanismes d'écrouissage sous irradiation de la ferrite par simulations de dynamique de dislocations". Paris 6, 2008. http://www.theses.fr/2008PA066228.
Testo completoFournier, Jean-Étienne. "Analyse des écoulements de thermoplastiques par vélocimétrie par imagerie de particules : application aux procédés d'extrusion et d'injection". Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10167/document.
Testo completoQuality or aesthetic defects of the plastic parts manufactured by injection moulding process are partly controlled by the flow conditions during filling stage. Sorne hypotheses, notably that of a slipping at the mould wall, are proposed in literature to explain their origin. But, because a lack of appropriate tools, compatible with the very severe environment of plastic processing, they have not been confirmed yet by experimental works. The present study tries to fill up this lacuna by analysing the validity of an original method of direct visualization of flows in extrusion and injection moulding processes by particle image velocimetry. Results obtained for extrusion experiments are conclusive and confirm the validity of this method. ln the particular case of a polycarbonate, they obviously show a wall slip phenomenon; confirmed by classic rheological measurements. This wall slip can lead the perturbations of the flow, especially near the geometrical discontinuities. The transposition in the injection moulding case, more delicate, clearly shows the practical difficulties related to the process environment. Neverthelesse, a qualitative analysis allows to relate the flow conditions at the mould wall with the appearance of a defect on the surface of the part. The quantitative analysis remains however to be confirmed in future studies
Chieragatti, Rémy. "Influence de l'orientation cristallographique sur le comportement en fatigue oligocyclique du mar-m200 monocristallin". Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0024.
Testo completoDouin, Joël. "Structure fine des dislocations et plasticité dans Ni(3)Ai". Poitiers, 1987. http://www.theses.fr/1987POIT2313.
Testo completoHo, Hsin Shen. "Fundamental mechanism of surface damage associated with the localization of the plastic deformation in fatigue". Compiègne, 2011. http://www.theses.fr/2011COMP1967.
Testo completoThe main objective of this thesis is to investigate the influence of local behaviour related to metallurgical parameters (grains and precipitated sizes) on damage mechanism. In this work, the effects of metallurgical states (grain size, precipitate size and size distributions associated with), under one constant plastic deformation amplitude on irreversibility of plastic deformation are investigated. For this purpose, it is necessary to obtain a range of well controlled precipitate size with a same grain size and inversely. The fatigue tests are conducted until crack initiation phase. The analysis and observations are made subsequently with multiple experimental techniques (atomic force microscope (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD)). This partial results of my thesis have shown that the correlation that exists between the mechanical behavior and the behavior of the irreversible plastic deformation (microreliefs or extrusions) studied by AFM, SEM and TEM is very promising. Moreover they are found to have a significant dependence on metallurgical states (grain size and precipitate their distributions). When the parameters of the irreversible plastic deformation (extrusion height criticism and critical rate of irreversible strain accumulated in a band) meet certain conditions, the nucleation of cracks is favored
Plessier, François. "Simulation par éléments finis du comportement mécanique de polycristaux chargés en hydrogène". Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14202/document.
Testo completoThe modification of plasticity observed in hydrogen-charged metalic polycristals has been studied using numerical modeling (Finite Element Method). This effect has been quantified by a previous study using Atomic Force Microscopy (AFM), by measuring the slip steps forming at the surface of (hydrogen-)charged or uncharged 316L polycristals. However the heterogeneity of the strain field in a polycristal makes it difficult to compare precisely the results from different grains and aggregates.After analyzing the impact of the geometrical modelling on the numerical results, this present study porposes a method using numerical simulations (Crystal Plasticity model) to access the local plastic strain field at grain scale, and improve the analysis of the AFM results. The projections of the slip step "real" dimensions into AFM measures (heights and spacings) are taken into consideration in order to convert AFM data into data that are directly linked to plastic activity: the average number of dislocations and slip step spacing. This quantities make it possible to compare the experimental plastic behaviours of the differents agregates in order to quantify the impact of the hydrogen absorption.The capacity of the crystal plasticity model to simulate plasticity modification at intragranulare scale is then studied by implementing material heterogeneities within a grain model, and the resulting modification of the slip developpement within the grain is then analyzed
Tabourot, Laurent. "Loi de comportement élastoviscoplastique du monocristal en grandes transformations". Phd thesis, Grenoble INPG, 1992. http://tel.archives-ouvertes.fr/tel-00177810.
Testo completoLe comportement est décrit par des relations simples mais dans lesquelles les principaux mécanismes physiques sont inclus : interactions entre les dislocations de différents systèmes, génération-annihilation des dislocations, seuil d'écoulement des dislocations et viscosité du matériau.
Une identification de ce modèle est faite pour le cuivre en utilisant des résultats caractéristiques extraits de la littérature.
Pour intégrer ces relations, un programme informatique utilisant la méthode des éléments finis en trois dimensions a été spécialement conçu pour la simulation des agrégats de monocristaux. Les résultats de simulations d'essais de traction dans différentes conditions (géométrie de l'éprouvette, orientation cristalline...) sont en bon accord qualitatif avc les résultats expérimentaux (rotation du réseau, nombre et qualité des systèmes actifs, glissements accumulés) prouvant que le modèle proposé est adapté à la description du comportement plastique des monocristaux.
A l'aide du programme, l'influence des paramètres physiques du modèle sur le comportement du monocristal est également analysée.