Tesi sul tema "Phase de déformation"
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Nguyen, Van Vuong. "Etude structurale de la chaine de truong son (viet-nam central) : evolution tectonique d'une zone de cisaillement polyphasee". Paris 6, 1997. http://www.theses.fr/1997PA066487.
Gérard, Yves. "Etude experimentale des interactions entre deformation et transformation de phase : exemple de la transition calcite-aragonite". Rennes 1, 1987. http://www.theses.fr/1987REN10146.
Sylvain, Wilgens. "Étude de la plasticité du monocristal de phase MAX par déformation aux petites échelles". Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2307/document.
The thesis's goal is to study the deformation, at microscopic scale, of the MAX phase Ti2AlN synthesized by powder metallurgy. This work is divided into three parts: in the first part, the interest has been put on the hysteretic behavior of the MAX phases via cyclic mechanical solicitations, during spherical indentation tests and ex-situ compression of micro-pillars, on differently orientated grains beforehand determined by EBSD. In the second part, we were interested into the micro-pillar's deformation via insitu cyclic compression tests coupled with Laue micro-diffraction. The goal was to analyse the evolution diffraction lines during the pillar's deformation in order to highlight the elementary deformation mechanisms and to observe the finale structures via the post-mortem SEM imaging of the pillars. Finally, a last part was devoted to study the deformation mechanisms in temperature at microscopic scale via nano-indentation tests up to 800°C. The characterization of the slip lines on the surface has been revealed by AFM and that of t he microstructural configurations (dislocations) under the indent has been done by TEM. All data collected by these various tests at the small scales have refined our understanding of the deformation mechanisms of crystal MAX phase, particularly with respect to the models usually proposed in the literature
Fossati, Paul. "Contribution à l'étude des propriétés mécaniques du combustible nucléaire : Modélisation atomistique de la déformation du dioxyde d'uranium". Phd thesis, Ecole Centrale Paris, 2012. http://tel.archives-ouvertes.fr/tel-00780059.
Danard, Yolaine. "Développement d'alliages de titane transformables par déformation : étude des relations microstructure/propriétés mécaniques". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEC035.
The work concerns the development of new titanium alloys possessing unique properties of plastic deformation (distortion) (a ductility near 3 times superior to the classic alloys) and work hardening. An initial work (CIFRE PhD of Cédrik Brozek, 2013-2016) allowed to transpose approaches used initially on model alloys (Ti-Mo in particular), in materials potentially industrialisables with the aim of applications in the field of the aeronautics. It is on these new industrialisables nuances, based on the system Ti-Cr-Sn that we wish today to base the collaboration with our industrial partner. These alloys possess the capacity to be transformed under constraint, by maclage mechanics and transformation of induced phase, they possess a new combination of properties (a very important ductility accompanied with a work hardening not yet reached in the alloys of titanium) but they are also characterized by a very high microstructural complexity on which we don't possess that much informations for the moment. The project concerns the study of the relations microstructures / mechanical properties in this new family of titanium alloys (alloys "TRIP/TWIP")
Guitton, Antoine. "Mécanismes de déformation des phases MAX : une approche expérimentale multi-échelle". Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2280/document.
It is commonly believed that plastic deformation mechanisms of MAX phases consistin basal dislocation glide, thus forming pile-ups and walls. The latter can form local disorientationareas, known as kink bands. Nevertheless, the elementary mechanisms and the exact role ofmicrostructural defects are not fully understood yet. This thesis report presents a multi-scale experimentalstudy of deformation mechanisms of the Ti2AlN MAX phase. At the macroscopic scale,two kinds of experiments were performed. In-situ compression tests at room temperature coupledwith neutron diffraction brought new insight into the deformation behavior of the different grainfamilies in the polycrystalline Ti2AlN. Compression tests from the room temperature to 900 °Cunder confining pressure were also performed. At the mesoscopic scale, deformed surface microstructureswere observed by SEM and AFM. These observations associated with nanoindentationtests showed that grain shape and orientation relative to the stress direction control formationof intra- and inter- granular strains and plasticity localization. Finally, at the microscopic scale,a detailed dislocation study of samples deformed under confining pressure revealed the presenceof dislocation configurations never observed before in MAX phases, such as dislocation reactions,dislocation dipoles and out-of-basal plane dislocations. In the light of these new results, mechanicalproperties of MAX phases are discussed
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.
Liebaut, Christophe. "Rhéologie de la déformation plastique d'un acier Fe-C durant sa transformation de phase "austenite-->ferrite + perlite"". Vandoeuvre-les-Nancy, INPL, 1988. http://www.theses.fr/1988NAN10451.
Nasedkina, Yana. "Etude des transformations de phase dans des alliages Al-Cu et Al-Mg-Si nanostructurés par déformation intense". Rouen, 2015. http://www.theses.fr/2015ROUES023.
Al alloys are widely used for structural application in aerospace, automotive and constructive engineering due to their low density and high strength and for functional application in electrical engineering due to a relatively high electrical conductivity. Precipitation hardening and grain size strengthening are among the main strengthening mechanisms of heat-treatable Al alloys. The precipitation hardening is achieved by artificial aging (AA) and the grain size strengthening could be achieved by several methods, including severe plastic deformation (SPD). The combination of these strengthening effects allows significant improvement of strength of Al alloys. In order to combine these effects, i. E. To design an ultrafine grain structure with nanoscaled precipitates, it is possible to use three different routes: SPD followed by AA; AA followed by SPD or SPD at temperatures of AA. However in practice it turns out to be sometime complex, because of phase transformations induced by SPD in Al alloys. The mechanisms of such phase transformations are still poorly understood. Therefore, the control of microstructure and as a consequence the control of properties becomes very difficult. Therefore, in this work, the first step was to determine the microstructure changes occurring in Al alloys under SPD and to understand the underlying mechanisms of microstructure evolution. In a second step we have also quantified the relationship between structure and mechanical and electrical properties. To reach these goals, model Al-Cu and industrial Al-Mg-Si alloys were studied using Transmission Electron Microscopy (TEM), Atom Probe Tomography (APT), microhardness measurements and electrical conductivity measurements. Alloys were subjected to SPD by high pressure torsion (HPT) under different processing conditions to reveal the influence on microstructure and properties. It is shown that HPT at ambient temperature leads to the decomposition of solid solutions for both Al alloys and dynamic precipitation at grain boundaries only for Al-Cu alloy. The solute drag by grain boundaries motion was identified as the main mechanism supporting the decomposition of solid solutions. The precipitation in the Al-Cu alloy occurs due to an increase of Cu concentration at GBs and a high Cu GB diffusivity. Besides, the optimum thermomechanical treatment, combining HPT and post-deformation heat treatment was also determined in order to optimize the combination of high strength and electrical conductivity
Boucard, Élodie. "Étude de l’influence de l’état métallurgique de l’austénite sur la microstructure de transformation de phase dans les aciers bas carbone". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0245/document.
The thesis aims to understand the influence of the metallurgical state of austenite at high temperature on the phase transformation mechanisms in two model grades of low carbon steel: 0.06%C-2.4%Mn-0.3%Si (CMn-1) and 0.2%C-2.4%Mn-0.3%Si (CMn-2). A series of heat treatments enabled a thorough crystallographic analysis of the transformation products according to the γ grain size. According to the numerous microstructures obtained, the advantages and limits of the crystallographic reconstruction of austenite from EBSD data are defined according the type of inherited microstructures. Finally, hot compression tests at 800°C (Ar3+100°C) are performed on the grade CMn-1 to follow the evolution of the austenitic microstructures and microtextures based on strain conditions. The characteristics obtained by crystallographic reconstruction are confirmed by an analysis of the 30%Fe-70%Ni hot-rolled model alloy. We identified high misorientations in the vicinity of grain boundaries and two characteristics deformation substructures: grains homogeneously deformed by planar slip mechanism and grains with deformation microbands. These structures depend on the components of texture developed in the austenite. It was found that the bainitic laths are promoted as the deformation increases to the detriment of the martensite formed by quenching, resulting in a decrease of the hardness. Moreover a granular structure also grows along prior [gamma] grains boundaries and spreads across the grain during isothermal bainite transformation at 525°C. Lamellar microstructures are aligned along the most active slip plans {111} [gamma] in homogeneously deformed grains, while the nucleation of small bainitic areas with different orientations is promoted in the microbands
Hua, Ke. "Displacive characteristics of β to α phase transformation and its impact on hot deformation behavior in Ti-7333 metastable β titanium alloy". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0213.
A thorough investigation has been conducted on the Ti-7333 alloy in terms of the β to α phase transformation. It was revealed that the structure transformation is realized by a contraction in the <1"1" ̅"2" ̅>β, an elongation in the <"1" ̅1"1" ̅>β and <110>β, and a shear on the {1"1" ̅"2" ̅}β<"1" ̅1"1" ̅>β slip system. Each α precipitate is composed of two kinds of nano-sized α domains. One is situated on the broad face of the major α precipitate (named interface α), and the other goes through the major α (termed penetrating α). The nucleation of such α is induced by the large shear strain generated by the formation of the major α. The penetrating α does not obey the BOR with the β matrix. The nucleation of such α is induced by the largest normal strain generated by the formation of the main α plate. The selection of the α variants during hot deformation at 700°C happens with dependence on the local crystal perfection of the β grains. In the slightly deformed β grains, 2 BOR variants are formed ‘cross-shaped’ clusters. The selected variants make maximum contribution to the macroscopic deformation and receive the maximum resolved shear stress from the external load resolved on their {1"1" ̅"2" ̅}β<"1" ̅1"1" ̅>β systems for transformation. In the heavily deformed β grains occupied mainly by dislocation slip, 2 to 4 BOR variants are selected in smaller numbers. The selection criterion is still obeyed but with restriction from the local deformation. The deformation behavior during 700°C compression presents three characteristic stress-strain stages: a linear stage (Stage I), a discontinuous yielding (Stage II) and a steady-state (Stage III). At the end of Stage I, more than 90% of the β boundaries are occupied by grain boundaries α (αGB). The discontinuous yielding of Stage II originated from the fragmentation of the αGB and the intensive formation of mobile dislocations near the β grain boundary areas. The steady-state of Stage III arises from two orientation dependent deformation modes of the β grains. For those in favorable activation orientation for their {110}β<1"1" ̅1>β systems with respect to the external compressive load, the deformation is realized by the dislocation slip and by the formation of slip bands; whereas for those with their {1"1" ̅"2" ̅}β<"1" ̅1"1" ̅>β systems - the system for β to α transformation - in favorable orientations, the deformation is achieved by intensive formation of intragranular α precipitates
Bourges, Anthony. "Faisabilité d'un radar à ondes de surfaces sur bouées : problématique de la déformation du réseau d'antennes et réalisation d'une bouée". Rennes, INSA, 2008. http://www.theses.fr/2008ISAR0021.
HFSWR are over-the-horizon radars working in the HF band 3-30 MHz. The propagation of the surface wave with the Earth curvature allows the detection or the observation of phenomena belong 200 km. The target detection and the wave propagation on the sea require a large receiving array near the sea, making it difficult to deploy. The solution investigated is to put the array on buoys on the sea. However, its deformation due to the sea surface movements generates disturbances in the radiation pattern. In order to reduce these disturbances, the main goal of the thesis is to find fast method to compensate for them. Finally, a floating antenna has been built and measured, to quantify the disturbances generated by sea surface movements in the received signal
Verhaeghe, Bénédicte. "Étude microstructurale des modes de déformation et de rupture d'un acier austénoferritique vieilli thermiquement". Grenoble INPG, 1995. http://www.theses.fr/1995INPG0191.
Tattevin, Hélène. "Déformation et transformation de phase induites par ondes de choc dans les silicates. Caractérisation par la microscopie électronique en transmission". Phd thesis, Université Rennes 1, 1987. http://tel.archives-ouvertes.fr/tel-00675863.
Gerard, Y. "Etude expérimentale des interactions entre déformation et transformation de phase.Exemple de la transition calcite - aragonite". Phd thesis, Université Rennes 1, 1987. http://tel.archives-ouvertes.fr/tel-00648807.
Vigouroux, Mathieu Pierre. "Mesure de déformation et cristallinité à l'échelle nanométrique par diffraction électronique en mode précession". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY012/document.
Precession electron diffraction (PED) is a recent technique used to minimize acquired diffractionpatterns dynamic effects. The primary intention of this PhD work is to improve PED (PrecessionElectron Diffraction) data analysis and treatment methodologies in order to measure the strain at thenanoscale. The strain measurement is intended to reach a 10-3 strain precision as well as usualmicroscopy techniques like high-resolution imaging. To this end, measurements were made with aJEOL 2010A with a Digistar Nanomegas precession module.The approach developed has been used and tested by measuring the strain in a Si/SiGe multilayeredreference sample with a known Ge Content. Strain measurements reached 1x10-4 sensitivity withexcellent finite element strain simulation agreement. This process has been also applied to measure thestrain in microelectronic InGaAs Quantum Well and an "Ω-gate" experimental transistor devices.The second approach developed has been made to provide a robust means of studying electrontransparent nanomaterial polycrystallinity with precession. Examples of applications of this analysismethod are shown on different devices
Grosseau-Poussard, Jean-Luc. "Structures de films minces de MoSx déposés par techniques de faisceaux d'ions sur l'acier martensitique type Z100CD17 : corrélations entre propriétés tribologiques et microstructures de déformation". Poitiers, 1995. http://www.theses.fr/1995POIT2267.
Lambotte, Sophie. "Vibrations propres basse fréquence et déformation de marée : Impact des hétérogénéités locales et contribution à l'étude de la source des grands séismes". Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/public/theses_doctorat/2007/LAMBOTTE_Sophie_2007.pdf.
An instrument recording of a signal always contains noises in addition to the studied signal. This thesis focus on the study of some noises and some signals at low frequency. Several local effects (such as topography, local geology and cavity effects) have been studied in seismological and gravimetric data at tidal frequencies. These local effects imply a strain-tilt coupling. This study has allowed us to find a minimal set of the various observables (tilts, horizontal and vertical displacements, strains and gravity) necessary to explain seismological data. 4 observables are necessary to reconstruct the observed perturbations. Thus, we obtain a set of 4 coefficients stable in time for each station and each instrument, enabling a systematic reduction of the local effects in data. As frequencies increase, the inertial effect becomes more and more prominent relatively to the local effects. The Sumatra earthquake of December 26, 2004 allows us to observe and to characterize these local effects for the first time in the lowest Earth free oscillations data. Finally, this study has demonstrated that the lowest Earth free oscillations can provide useful information to the source study of very large earthquakes. Singlet phases of the gravest multiplets (such as 0S2, 0S3, 0S4, 1S2, 0S0, or 1S0) can be used to constrain an overall picture of the rupture (the length, the duration and consequently the mean rupture velocity) for large earthquakes with magnitude larger than 8. The phase analysis of the gravest free oscillations has been mainly performed for the Sumatra earthquake of December 26, 2004, which is exceptional by its spatial and temporal extension. For this event, we have found a rupture length of 1250 km, a source duration of 550 s, and a mean rupture velocity of 2. 3 km/s
Combes, Vincent. "Les minéralisations aurifères de Yaou et Couriège (Bouclier Guyanais) : des modalités de l’enrichissement primaire aux processus secondaires". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0265.
Gold deposits located in French Guiana (France, South America) within Rhyacian terranes (2.3-2.05 Ga), are the witnesses of the Trans-Amazonian orogeny. These deposits, in the Guiana Shield, are covered by a dense rainforest where well-developed lateritic profiles leave little outcrop of unaltered bedrock. Considering this specific context, this thesis is interested in defining (i) what are the primary gold mineralisation processes and (ii) what is their preservation and enrichment (or not) during secondary supergene processes and is based on two case studies: the Yaou deposit and the Couriège prospect. At Yaou, intrusive bodies (quartz monzodiorite), mainly hosting gold mineralisation, are aligned along a sinistral shear zone affecting a volcano-sedimentary sequence. A polyphase tectono-magmatic evolution, of 5 deformation phases, is proposed at the scale of the mineralized camp. Associated with this deformation framework are two gold events which control the overall gold budget of the deposit. The intrusion hosting the mineralisation is dated at 2130.6 ± 5.8 Ma (U-Pb on zircon). The modalities of supergene processes are studied at the Couriège prospect, which includes several gold occurrences associated either with pyrite-rich quartz veins within in situ lateritic profiles, or with colluvial and alluvial horizons. Two profiles were studied to assess the role of supergene processes in the modification of primary (hypogene) mineralisation. The Achman Giraud site is characterised by an authigenic alteration profile with gold-bearing quartz veins. The weak vertical and lateral dispersion of gold, the predominantly primary character of the gold grains, and the limited evidence of supergene gold reprecipitation, argue for minor supergene remobilisation without clear evidence for gold enrichment during lateritisation. The Lupe site exposes a gold-bearing detrital horizon truncating a barren lateritic profile. Gold is present as electrum inclusions in partially goethitised detrital pyrite crystals and as free gold grains exhibiting a sub-rounded shape, mechanical transport marks and Ag-depleted rim, suggesting transport and exposure to weathering over significant distance and time
Ghoussoub, Elgharib Joumana. "Modélisation du mécanisme de déformation, transfert en solution, à l'échelle du joint de grain". Marne-la-vallée, ENPC, 2000. http://www.theses.fr/2000ENPC0003.
Le, Roux Mélanie. "Simulation numérique du mouvement et de la déformation des neutrophiles : influence de la rhéologie et du type d'écoulement". Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/8868/1/Leroux.pdf.
Penel-Pierron, Laurence. "Transition de phase induite par déformation dans les polymères à liaisons hydrogène : cas des copolymères éthylène-alcool vinylique et du polyamide 6". Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-155.pdf.
Guiheux, Romain. "Comportement d’aciers à transformation de phase austénite-martensite pour la simulation du grenaillage de précontrainte". Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0055/document.
Shot-peening is commonly used in mechanical industries to increase life duration of mechanical and structural parts: residual compressive stresses are developed at the sub-surface of the material by plastic stretching of the surface. In the case of TRIP-effect steels (TRansformation Induced Plasticity), the metastable austenite can transform into martensite during shot-peening. The final distribution of stress is then more complex than for “standard steels” as it results from the mechanical strain imposed by the process and the martensitic transformation leading to a stress redistribution between austenite, martensite and the other phases. This work aims to characterize experimentally the mechanical state, at phase scale, of different TRIP steels (AISI 301LN, TRIP 780 and 23MnCrMo5) as well as the fraction of each phase after shot-peening and to propose a numerical model by finite elements which could be used in the future by engineering offices. An elastoplastic model with phase transformation was developed in this thesis which permits to predict the evolution of mechanical variables, macroscopically and at the phase scale, as well as the evolution of austenite volume fraction
Qiang, Fengming. "Microstructure and texture evolution of high-temperature α phase in TiAl alloy during thermomechanical processing". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0166.
Increasing demands on modern turbines require (α2+γ) lamellar-structured TiAl alloys with fine colony size and properly aligned lamellae. According to the α → α2+γ phase transformation, the lamellar structure depends directly on the high-temperature α phase. Thus, the lamellar structure optimization could be realized by the modification of high-temperature α phase through thermomechanical processing. In this work, a thorough investigation was conducted on the high-temperature α phase in two TiAl alloys in terms of the deformation behavior, dynamic recrystallization (DRX), grain growth and texture evolution.Under uniaxial compression, the DRX of the α phase is a continuous fragmentation process (CDRX) in three characteristic stages: ⅰ) serrations of grain boundary and formation of symmetrical-tilt boundaries with <0001> disorientation axis near boundary bulging regions; ⅱ) formation of subgrains by evolving symmetrical-tilt boundaries into asymmetrical-tilt boundaries with <10-1x> disorientation axis by absorbing basal dislocations, or tilt-twist boundaries with <11-2y> disorientation axis by rotational movements of the bulged parts; ⅲ) detachment of subgrains from the parent grain with gradually increased misorientation, and mixture with the ones fragmented from other grains by grain boundary sliding. These three processes happened repeatedly from grain boundary regions toward grain interiors until the whole initial microstructure was replaced by the DRXed one. The plastic deformation of the α phase is closely related to the crystallographic orientations of the initial α grains that play an important role in the deformation mechanism and the CDRX progress (softening). For the soft α grains, CDRX was completed quickly at a relatively small macroscopic strain by intragranular dislocation slip. The hard α grains demonstrated two ways: ⅰ) grains with <0001>//LD, in which dislocation accumulation was only assisted by the local strain accommodation with the neighboring α grains from boundary regions; ⅱ) grains with <11-20>//LD, in which dislocation accumulation was achieved by kinking through basal slip and dislocation slip in the boundary regions from incompatible local strain. These grains required large strain to accumulate sufficient dislocations for CDRX. The strain-resolved contribution of the deformation (hardening) and CDRX (softening) result in the specific flow stress states. The texture evolution is mainly induced by dislocation slip. The orientations of the DRXed grains were largely inherited from those of the parents. With the deformation, the tilted basal fiber typed orientations developed in both the retained coarse α and the formed DRXed α grains. The hot compression produces refined α grains but not expected texture to align (α2+γ) lamellae. The microstructure and texture of the α phase during hot extrusion in the (α+β) phase region exhibit different features. The extruded microstructure was very heterogenous, comprising a large population of unRXed α grains and fine primary RXed α grains with <10-10>//ED and a small population of grown α grains with <11-20>//ED. The two texture components are beneficial for lamella alignment. Besides, the thermally-induced α → β phase transformation interweaving with the abnormal α grain growth happened during the transition from extrusion to water-quenching, producing two types of β particles: i) intergranular β particles with the Burger OR with their neighboring α grain; ii) intragranular β particles without the OR with the hosts from the intergranular β ones after being swallowed by the abnormally grown α grains
Baghdouche, Fateh. "Étude des transformations de phase et de l'évolution de texture cristallographique en fonction du taux de déformation et du traitement thermique dans l'alliage equiatomique TiNi". Metz, 1998. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1998/Baghdouche.Fateh.SMZ9843.pdf.
Ln this study the influence of the deformation rate and of the heat treatment on R, martensitic and austenitic transformations and their volume fractions is investigated, and the crystallographic texture evolution is determined across the wire diameter in equi-atornic TiNi shape memory alloy wires by X ray diffraction. The determination needs intensity corrections due to X ray absorption and irradiated volume variations occuring during the movement of the sample. A texture index Ti is defined to describe the texture evolution across the diameter. This index gives the texture shapeness of the wire respect to an isotropie one
Laude, Emmanuelle. "Étude expérimentale et calcul des cinétiques de transformation de phase d'alliages de titane -métastables en fonction des traitements thermomécaniques". Vandoeuvre-les-Nancy, INPL, 1997. http://docnum.univ-lorraine.fr/public/INPL_T_1997_LAUDE_E.pdf.
Coquinot, Yvan. "Physicochimie et origine de la phase fluide impliquée dans les processus d'interactions fluide-roche au cours du métamorphisme rétrograde et de la déformation : exemple des diabases métamorphisées du massif de Rocroi". Lille 1, 2005. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2005/50376-2005-77.pdf.
Liu, Meishuai. "Study on microstructural and crystallogarphic characteristics of phase transformation induced by ECP in annealed Cu-40%Zn alloy". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0210.
A thorough investigation has been conducted on the microstructural and crystallographic features of Electric Current Pulse (ECP) treated Cu-40%Zn alloys. The phase transformation orientation relationship (OR) and its correlation with crystal defects have been studied and the formation mechanisms of ECP induced crystal defects in the parent phase and the sub-structures in the β precipitates were also analyzed. The α to β heating phase transformation can be induced by ECP treatment with the formation of fine β precipitates that can be remained to the room temperature. With the increase of the electric current density, the amount of precipitates is increased and the formation sites increase from α grain boundaries to grain interiors. The β precipitates follow different ORs depending on the formation site. The grain boundary β phase obeys the Kurdjumov-Sachs (K-S) OR; whereas the intragranular β respects the Nishiyama-Wasserman (N-W) OR. In the former sites, the {111}α /<11̅0>α dislocations are observed, whereas in the latter, the {111}α/<112̅>α stacking faults are found. Transformation strain analyses revealed that under the K-S OR the maximum lattice deformation required is a shear on the {111}α /<11̅0>α slip system, whereas under the N-W OR the maximum deformation is a shear on the {111}α /<112̅>α system. Thus the existing {111}α /<11̅0>α dislocations along the α grain boundaries provide pre-strain required by the transformation via the K-S path, whereas the {111}α /<112̅>α stacking faultsboarded by {111}α /<112̅>α partial dislocations offer pre-strain facilitating the transformation via the N-W path. Different types of crystal defects are formed in the α matrix by the ECP treatments depending on the current density. At low density, large amount of {111}α /<112̅>α stacking faults and then nano twins are produced in the α matrix. At high density, dislocation nets are formed near the β precipitates that are composed of edge typed {111}α /< 11̅0 >α perfect dislocations and the Frank typed dislocations. The volume misfit between the α and the β phase analyzed with transformation deformation reveals that the transformation from α to β requires an expansion along [11̅0]α direction and a contraction along [111]α direction. The former results in the appearance of the {111}α /<11̅0>α edge typed dislocation arrays in front of the {31̅1}α broad faces and the latter induces the formation of the Frank typed dislocations in front of the {121}α broad faces. Thus, dislocation nets formed along the edges of the broad faces of the β precipitates where the two kinds of dislocations meet. Furthermore, the β precipitates contain two kinds of nano-sized and diffuse atomic clusters with the structure obeying the Burgers OR and with the ω structure obeying the Blackburn OR with the β matrix. They were each formed through a two-stepped atomic displacement. For the structure, the first step is the atomic shuffle of each second {110}β plane in the <11̅0>βdirection and the second is a structure change mainly by a shear on the {11̅2}β /<1̅11>β. For the ω structure, the first is an atomic shuffle on each second and third {112̅}β plane in the ±[111]β directions and then normal strains in three mutually perpendicular directions (<111>β, <112̅>β and <11̅0>β). The concomitant appearance of the two structures lies in the fact that the volume increase accompanying the formation can be canceled by the volume decrease accompanying the ω distortion, which minimizing the transformation strain energy. The results of this work provide fundamental information on the Cu-40%Zn alloys for interpreting the impact of the crystal defects on the solid phase transformation ORs, on the formation of various types of crystal defects induced by the ultra-rapid phase transformation and on the formation mechanisms of sub structures in the product phase
Laghmach, Rabia. "Modélisation de la cristallisation des élastomères sous sollicitation mécanique par champ de phase". Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0061/document.
Natural rubber NR and more generally elastomer presents unique physical properties that are very important for many engineering applications. Strain induced crystallization of elastomer presents a major interest because it improves considerably the mechanical properties. In fact, the presence of crystallites within the amorphous phase in a polymer network induces a strengthening of this material, giving NR a self-reinforcement character. In this thesis, we develop a mesoscopic model to describe the crystallization of elastomers under strain. In this context, we present a kinetic model using a new physical approach: a phase field model. This model combines the crystallization thermodynamics with the local stress field. The thermodynamic description of the phase transition is based on a Gibbs free energy functional F which contains all energy contributions of the system: the bulk contributions (enthalpy and entropy) and surface tension. To understand the experimental observation of nanometer size crystalites, an explicit account of the topological constraints induced by both entanglements and/or crosslinks is necessary. We investigated two limiting mechanisms, a kinetic limitation of the growth, and an energetic limitation. Based on both the kinetic and the energetic approaches, we have systematically studied the influence of topological constraints on the growth process. We have shown that the growth process is affected by the accumulation of elastic stress at the interface. The kinetic model predicts the existence of instabilities during the growth. These instabilities induce a heterogeneous dynamical growth which leads to the formation of dendrite like structures. On the contrary, the energetic approach predicts an exponential increase of the surface tension during the growth that limits the size of the crystallites very efficiently. In the last part we investigated elastomer crystallization under cyclic deformation. To this end, we coupled the previous energetic model with the nucleation process. Finally the simulation data are compared with experimental measurements
Lahaie, Franz. "Pertinence du formalisme des transitions de phase pour aborder la mécanique des objets géologiques". Phd thesis, Grenoble 1, 2000. http://tel.archives-ouvertes.fr/tel-00745548.
Wen, Youhai. "Approche micromécanique et simulation numérique par éléments finis de la transformation martensitique sous contrainte". Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL029N.
Chen, Yu. "Analyse InSAR des déformations de volcans actifs : le Piton de la Fournaise (Réunion) et Llaima (Chili)". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30019.
We address in this dissertation the use of Interferometric Synthetic Aperture Radar (InSAR) to measure and characterize the ground surface deformation at two volcanoes - Piton de la Fournaise (La Réunion Island, France) and Llaima (Chile). For Piton de la Fournaise, we analyzed the spatial pattern and temporal evolution of the ground displacement between the historical March-April 2007 eruption and October 2014, based on continuous measurements recorded by GNSS stations and X band COSMO-SkyMed and TerraSAR-X/TanDEM-X time series analysis. For the processing of radar data, we adopted a classical InSAR time series approach that exploits the information redundancy in the interferograms and we implemented an original method for correcting artifacts based on the principal component decomposition. The spatial and temporal complexity of the obtained deformation field indicates that an important part of the volcanic edifice is affected by deformations of various origins that overlap spatially and temporally. We observe also subsidence processes that are not accompanied by horizontal displacements in recent lava fields. We show that there exists a linear relationship between the subsidence and the thickness of lava and that the amplitude of subsidence decreases with time. These relationships allow us to construct an empirical law to estimate the contribution of post-lava emplacement process in the deformation field. We also observe that the Central Cone subsides persistently during the study period. We interpret this subsidence as the expression of a relaxation of the stresses caused by the Dolomieu collapse during the March-April 2007 eruption. Finally, we show that a widespread time-dependent moving sector on the Eastern Flank is affected by downslope motion during the 2007-2014 period. The uncertainties on both the structure and rheology parameters of the edifice leads us to explore different hypotheses to explain the origin of this flank motion which could be controlled by the frictional properties of the rocks along one or more fault planes, or be the expression of a dependent ductile deformation of the viscosity of the medium. Llaima is a large Andean stratospheric volcano whose deformation processes are poorly understood not only because of the complexity of its functioning mode but also because of the absence of observation networks on the ground. In this context, the potential of radar data for monitoring the ground deformations of these volcanoes is a main scientific interest. However, the complex environment conditions (steep slopes, snow- or ice-capped summit, dense vegetation cover, and strong tropospheric artifacts) and limited amount of available radar data make it challenging to accurately measure ground displacement with InSAR
Liu, Shibo. "Numerical and experimental study on residual stresses in laser beam welding of dual phase DP600 steel plates". Thesis, Rennes, INSA, 2017. http://www.theses.fr/2017ISAR0003/document.
Laser welding process is widely used in assembly work of automobi le industry. DP600 dual phase steeis a high strength steel to reduce automobile weight. Residual stresses are produced during laser weldingDP600. Continuum mechanics is used for analyzing res idual stresses by finite element simulation.Based on experimental tensile tests, the DP600 steel constitutive model are identified. The hardening termaccording to Ludwik law, Voce law and a proposed synthesis model are studied. The temperature sensitivityof Johnson-Cook, Khan, Chen and a proposed temperature sensitivity model are investigated. The strain ratesensitivity model proposed by A. Gavrus and planar anisotropy defined by Hi ll theory are also used.Cellul ar Automaton (CA) 20 method are programed for the simulation of solidification microstructureevolution during laser welding process. The temperature field of CA are imported from finite element analysimodel. The analysis function of nucleation, solid fraction, interface concentration, surface tension an isotropy,diffusion, interface growth ve locity and conservation equations are presented in detail. By comparing thesimulation and experimental results, good accordances are found.Modelling by a finite element method of laser welding process are presented. Geometry of specimen, heatsource, boundary conditions, DP600 dual phase steel material properties such as conductivity, density, specifiheat, expansion, elasticity and plasticity are introduced. Models analyzing hardening term, strain ratesensitivity, temperature sensitivity, plastic an isotropy and elastic an isotropy are simulated.The numerical results of laser welding DP600 steel process are presented. The influence of hardening term,strain rate sensitivity, temperature sensitivity and anisotropy on residual stresses are analyzed. Comparisonwith experimental data show good numerical accuracy.Keywords: Laser Welding, DP600, Residual Stress, Cellular Automaton, Hardening, Temperature sensitivity,Strain Rate Sensitivity, Anisotropy, Mixture dual phase law
Frechinet, Stéphane. "Transformations et comportements du Zircaloy-4 en conditions anisothermes". Paris, ENMP, 2001. http://www.theses.fr/2001ENMP1044.
Toussaint, Renaud. "Fracturation des roches en compression : le processus de localisation en tant que phénomène critique". Phd thesis, Université Rennes 1, 2001. http://tel.archives-ouvertes.fr/tel-00012208.
fortes pressions de confinement présente des traits communs avec une transition de phase thermodynamique: la déformation se localise rapidement à l'échelle des grains dès la sortie du régime élastique réversible, tout en restant d'abord homogène aux grandes échelles. Alors que les microfractures individuelles croissent encore de façon stable, apparaissent autour de la contrainte pic des structures de grande échelle (bandes de cisaillement) qui brisent spontanément les symétries translationnelle et rotationnelle du problème.
Analysant des données déformation/contrainte obtenues sur diverses
roches et conditions de charge, on montre que celles-ci présentent
un haut degré d'universalité, à savoir que la pente de charge est une loi de puissance de l'écart à la contrainte pic, avec un exposant identique dans les différentes experiences à la résolution expérimentale près. Cette loi est vérifiée pratiquement de la sortie du régime élastique, à la contrainte pic.
Le fait que cet exposant semble indépendant de la roche, conjoint aux brisures de symétries et à l'émergence d'une structuration macroscopique, est typique d'un point critique. En conséquence, on développe à partir d'un simple postulat de maximisation d'entropie un formalisme de physique statistique adapté à ce problème. On obtient ainsi une distribution de probabilité sur les configurations de microfractures, en fonction de l'énergie nécessaire à leur formation. partir d'un modèle pour ces énergies basé sur des interactions élastiques, on obtient un système présentant deux transitions de phase: la première correspond à l'initiation de l'activité des microfractures, la seconde à la localisation macroscopique.
Ce modèle prédit à l'approche de la seconde transition le comportement quadratique observé dans les données, alors que le module d'Young effectif du matériau reste fini.
Zouari, Meriem. "Modélisation de la recristallisation de l'Inconel 718 pendant sa mise en forme à chaud". Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0072.
Inconel 718 is nickel-based Superalloy widely used in the aeronautic industry to manufacture aircraft parts subjected to extreme in-service conditions of high stresses at elevated temperatures. Controlling the microstructure after hot forming is a key element to control the mechanical properties of the final products and meet the tight specifications imposed by the aeronautic industry.In this work, the microstructure evolution of Inconel 718 was investigated via isothermal and iso-strain rate torsion tests followed by water quenching (to investigate dynamic evolution) or by annealing at deformation temperature then water quenching (to investigate post-dynamic evolution). These tests were conducted in both δ-Supersolvus and δ-Subsolvus temperature domains and for strain rates of 0.01 to 0.1 s-1.Scanning electron microscopy (SEM) and Electron Back Scattered Diffraction (EBSD) were used to characterize the microstructure and follow the evolution of the recrystallized fraction, the recrystallized grain size and the δ-phase precipitation after deformation and during pre-deformation and post-deformation annealing. Based on these experimental observations, the main metallurgical mechanisms have been identified and modelled: hardening, nucleation of new grains, grain boundaries migration and the δ-phase- recrystallization interaction.A two-site mean field approach having a low computational cost was chosen to model the microstructural evolution at different thermomechanical conditions. This model describes the main mechanisms taking place during hot forming of Inconel 718 in both δ-Supersolvus and δ-Subsolvus domains and predicts the recrystallization kinetics in both dynamic and post-dynamic regimes , the δ-phase precipitation and dissolution kinetics and the grain size evolution. The model predicts also the strain-stress curves at high temperatures in the absence of δ-phase particles
Le, Thai Hung. "Rhéologie et microstructures des matériaux composites à matrice polymère thermodurcissable chargée minéralement et renforcée par des fibres de verre". Phd thesis, Grenoble 1, 2008. http://www.theses.fr/2008GRE10006.
Ln this work, the rheology and the microstructures of thermoset polymer composites reinforced with glass fibres, such as Bulk Moulding Compounds (BMC) and Sheet Moulding Compounds (SMC), are analysed. Firstly, the rheology of BMC is studied by using dedicated simple and plane strain compression rheometers. Experimental results emphasize the influences of the strain rate, the type of mineraI fillers, the volume fraction of fibres as weIl as the temperature on the BMC rheology. ID and 3D non-linear viscoelastic rheological models are proposed to reproduce the behaviour of BMC. Secondly, the microstructures of compression moulded SMC plates are analysed by using X-ray phase contrast microtomography. The influences of processing conditions on residual porosity, matrix migration, breakage, bending, compression and orientation of glass-fibre bundles are underlined, allowing a discussion on the relevance of assumptions used to establish rheological models proposed in the literature
Abbal, Rémi. "Utilisation de signaux hypercomplexes en estimation du mouvement et recalage multimodal". Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2329/.
Nowadays, medical imaging is necessary to help doctors to understand and interpret the mechanical and functional behavior of the human body. The different existing modalities provide complementary information, which can improve this comprehension. In particular, the tissue deformation provide an indication on the presence of a pathology. This qualitative appreciation is easy to perform for the human eye, but it would be useful to get an automatic and accurate estimation of this deformation. The most natural choice to process images is to use the intensities of the pixels. However, some approaches estimate the motion decomposing the image in several descriptors, such as spatial phase, which is a strucural information of the image. The aim of this thesis is to evaluate the contribution of this kind of descriptors, when they are used for motion estimation on ultrasound (US) sequences and multimodal registration, between a magnetic resonance images (MRI) and US images. For this, we first showed that for ultrasound images, an approach based on the monogenic spatial phase was a good compromise, facing block matching technics or optical flow estimation based on 2D analytic complex signal. Then, we continued this study, considering all the features extracted from the 3D monogenic signal. It allowed us to propose a translation estimator based on another descriptor : the main local orientation. Afterward, we evaluated the contribution of the phase for MR-US registration based on the mutual information. We noted that, in this case, the spatial phase gave more accurate results than the intensity-based approach in the lateral direction, but not in the axial direction. Finally, we present the clinical issues of the pelvic organ prolaps. Thus, we introduced a phase-based block deformable block matching estimator. We applied this estimator on in vivo US sequences. Although this estimator tends to minimize the degree of the pelvic floor disorders, it allows a better tissues monitoring than the intensity-based block deformable estimator all along the sequence
Le, Thai Hung. "Rhéologie et microstructures des matériaux composites à matrice polymère thermodurcissable chargée minéralement et renforcée par des fibres de verre". Phd thesis, Grenoble 1, 2008. http://tel.archives-ouvertes.fr/tel-00369701.
Hérault, Diane. "Du formage virtuel à la tenue en service de pièces métalliques : influence des trajets complexes de déformations". Thesis, Lorient, 2021. http://www.theses.fr/2021LORIS800.
In order to reach an integrated design of car body components, a first step towards an end-to-end chain of simulations is established in this thesis beginning with the sheet metal forming process until the service life prediction of the formed part. The deep drawing of cylindrical cup in one or two stages is considered as a reference able to reproduce complex strain paths occurring during the manufacturing of industrial parts. The selected material is a DP600 dual phase steel with high strength and commonly used for this kind of application in the automotive field. The material behavior is firstly characterized for linear, non-linear and cyclic strain paths in order to calibrate an advanced constitutive law dedicated to sheet metal forming and a fatigue criterion. The deep drawing in one and two stages is experimentally performed and analyzed with measures of the strain field and the residual stresses. A comparison of these different elements with numerical predictions is carried out to highlight the occurrence of strain path changes and their influence. Numerically, the final state and particularly the strain and stress fields obtained after deep-drawing and springback are used as inputs in the fatigue loading simulation. A simplified method, based on the adaptation of uniaxial criteria to multiaxial loads, is then used to estimate the service life of cylindrical cups
Ayt, Ougougdal Mohamed. "Contrôles magmatiques, structuraux et hydrothermaux de la formation des épisyénites de la marche occidentale". Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_AYT_OUGOUGDAL_M.pdf.
Zhang, Jiansheng. "Influence de la contrainte sur la transformation martensitique d'alliages Fe Ni C". Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL092N.
Moumni, Ziad. "Sur la modélisation du changement de phase solide : application aux matériaux à mémoire de forme et à l'endommagement fragile partiel". Phd thesis, Ecole Nationale des Ponts et Chaussées, 1995. http://tel.archives-ouvertes.fr/tel-00529370.
Hulin, Claudie. "Couplage géochimie-géomécanique dans les milieux poreux insaturés : Tension capillaire – Pression de cristallisation". Thesis, Orléans, 2017. http://www.theses.fr/2017ORLE2028/document.
The alteration of porous media in drying conditions is generally attributed to the pressure exerted by growing salts from the poral evaporating solution against the pore wall (crystallization pressure). In drying conditions, the water retained by capillarity in nanometric pores is under absolute negative pressure. Water under capillary tension exerts a mechanical traction against the pore walls but also modifies the chemical equilibria and so rock-fluid interactions. Crystallization pressure and capillary tension, which are physical processes, are both induces by the disequilibrium between poral water and dry air.Salt crystallization experiments in microtubes (Na2SO4, NaCl) show some favorable conditions for crystallization pressure - in terms of supersaturation and geometry – which is transient and brutal. A second series of experiments shows that capillary tension, generated by a nanometric liquid air interface, can be transmitted to a macrovolume of aqueous solution in a particular geometric system built with salts. The tensile state is metastable (superheated), but long enough to modify significantly the chemical budget of the system and to see mechanical effects. The brutal relaxation of the superheating state by vapor nucleation induces a rapid salt supersaturation which is the driving force of the crystallization pressure.The salt growth (during evaporation) and capillarity cooperate in drying conditions to alter porous media.During climate cycles (especially humidity) they control and induce transient and brutal events which mark the end of metastable states (superheating and salt supersaturation)
Cabrol, Elodie. "Étude et compréhension des mécanismes d'endommagement de surface de matrices de forgeage à chaud rechargées". Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2015. http://www.theses.fr/2015EMAC0012.
In the field of hot forging of aeronautical parts, the steel dies are commonly hardfaced, on few millimeters thick, by a cobalt-based alloy (Stellite 21) deposited by arc welding (MIG). As part of this thesis, this "classic" hardfacing is compared to Stellite 21 and Stellite 6 hardfacings deposited by two emerging processes in this area, the PTA and the LASER one. The objective is to assess surface damage mechanisms, especially induced by plastic strain, of these various hardfacings. Tribological tests (laboratory and semi-industrial) were used to create surface damage comparable to those observed in industrial dies. Associated with these tests, multiscale microstructural, structural and mechanical investigations have been performed (tensile, bending, microhardness, OM, SEM, STEM, XRD, EBSD). According to the « material/process » couple, plastic strain mechanisms by perfect dislocation glide and by FCC to HCP phase transformation have been identified. The activation of the latter has been connected to the temperature of the allotropic phase transformation (FCC/HCP) in cobalt. This temperature depends on (i) the alloying elements, varying according to the deposited grade (Cr, C, ...), (ii) the dilution (Fe content evolution) connected to the welding parameters and (iii) the number of deposited layer. Moreover, a significant influence of the phase transformation on the evolution of the friction coefficient has been evidenced. Indeed, if the phase transformation is not observed, the friction coefficient is stable during the test, while a drop of the friction coefficient curve is connected with the FCC to HCP phase transformation. Moreover, the plastic flow of dendrites is observed at the extreme surface, on a few tens of micrometres in thickness, in the direction of sliding. It is associated with a high morphologic and crystallographic texturing of the identified phase (FCC or HCP), with the highest atomic density planes mostly oriented parallel to the sliding surface. The results also show that, under tribological laodings, a significant hardening is observed on the surface (up to 90%) and a correlation has been established between the increase in the microhardness and the plastic deformation ratio
Nicotra-Barbe, Angela-Maria. "Transformations de phases et mécanismes de déformation dans les alliages de titane bêta". Metz, 1996. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1996/Nicotra_Barbe.Angela.M.SMZ9647.pdf.
The aim of this Phd was to design a Ti-bêta alloy that would have a good Y. S/ductility balance. The mechanical properties of these alloys depend on their deformation mechanisms (glide system, twinning, stress induced phase transformation) and the parameters to be controled are the chemical composition and the grain size metastable alloys that deform essentially by twinning show low yield strength and large elongation. On the contrary, stable alloys deform by gliding and are characterised by higher Y. S. And smaller elongation. The ideal alloy should therefore start deformation by glide and later in the deformation, activate twinning. For two specific chemical compositions, Ti-20V and Ti-20V-5Al, we have carried out thermomechanical heat-treatments to obtain different grain sizes. The influence of the microstructure on the deformation mechanisms has been studied. During plastic deformation, the Ti-20V alloy deforms by 332 <113> twinning. In addition, stress induced [omega] s transformation and 110 <111> glide are also involved in the deformation. Twinning is always activated first, except when the grain size lower than 40[mu]m. In this case, its contribution to the deformation is limited. Twinning occurs more easily for sufficiently large grain sizes and high deformations rates. Modeling of the texture evolution during rolling allowed us to verify these observations through the analysis of the main texture componenets. The presence of these components can be associated to 110 <111> glide. For the Ti-20V-5Al loaded in a static deformation mode, only glide was activated. During the first percentage of strain, only one glide system is actived. Using a plasticity model, we have shown that the main texture components were associated with 112 <111> glide. Comparison of the various alloys has allowed to select the optimum alloys as well as its optimum microstructure for improving mechanical properties. The reasons of this choice have been discussed in the light of our experimental results
Staniek, Éric. "Etude des mécanismes de déformation du polypropylène dans un complexe métal-polymère". Lille 1, 1995. http://www.theses.fr/1995LIL10109.
André-Mayer, Anne-Sylvie. "Fluides et fracturations dans les gisements de type porphyre et épithermal". Nancy 1, 2000. http://www.theses.fr/2000NAN10176.
In metallogeny, it is now obvious that fluids are the main vectors of metals and that fluids and deformations are closely associated in the mineralizing processes. This work deals about this two main aspects in the porphyry and epithermal environment. Fluid studies, realised in the epithermal district of Shila (SW Peru), allow to state a mineralizing model at the district scale. The differences observed in the PVT properties of the fluids seem to explain the different types and styles of mineralization. At Apacheta, studies of the vertical evolution of the physico-chemical parameters of the fluids in parallel to the mineralization show that differences, observed between deep levels (Pb-Zn) and shallower levels (AuAg), is directly linked to a fractionation of gases present in fluids during a boiling event. The geochemistry (crush-leach) of the fluids associated to this type of mineralization in various districts (Shila, Pero; Baia Mare and Apuseni Moutains, Romania; Pongkor, Indonesia) are similar whatever their geodynamic context and are comparable with the fluids associated to geothermal systems. Analyses of fracture networks has been realised at macroscopic scale on different (mineralized or not) vein systems. They allow in a first time to establish a new methodology to characterize paleostresses taking into account the influence of the fluid pressure. Applied on the Soultz-sous-Forêts vein system, this method gives realistic paleostress magnitudes linked to the reopening of quartz veins. The mineralized stockwerk of the Rosia Poieni porphyry copper (Apuseni Mts, Romania) has been chosen for a statistical and hydraulic characterization in order to understand how mineralized vein system evolve and grow. A 1D sampling of the stockwerk has been realized on 2000 fractures distributed on five levels of the open pit (910, 940, 1000, 1045 and 1060 ml. Various statistical analyses has been applied and heterogeneities observed in the stockwerk (metric scale) express directly variations in the copper content. Statistical description of the stockwerk properties seems thus to be a very powerful prospective tool. Estimation of hydraulic conductivities developed by veins has been realized and show equally heterogeneities at the quarry scale. The mean permeability developed by all the veins on each profile decrease from the deeper and more mineralized level (910m) to the highest level (1060m). High permeabilities developed on the 910 m profile are linked to the presence of major drains and the clustered organization of veins. The level 1060 m, characterized by numerous and thin veins with a homogeneous spatial repartition, develop a more pervasive permeability
Pionnier, Delphine. "Eude de la transformation de phases [beta - alpha] induite sous contrainte dans l'alliage de titane [beta]-Cez". Metz, 1997. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1997/Pionnier.Delphine.SMZ9748.pdf.
This work is devoted to the study of the [alpha] phase texture formation in [beta]-Cez alloy. The [alpha] phase is inherited by martensitic phase transformation induced by stress from a part of the [beta] matrix. We were particularly interested in variant selection occuring during the phase transformation. To this purpose, different mechanical tests were carried out on [beta]-Cez sheets : uniaxiale tensile tests and rolling, in rolling and transverse direction. The [beta] phase textures before and after deformation and orthorhombic [alpha] phase textures were determined by X-ray diffraction. By comparing experimental [beta] phase textures at different levels of deformation and the corresponding deformation textures simulated by a Taylor model, we showed the important role of the [beta - alpha] transformation in the accommodation of total deformation. The simulations of [alpha] phase textures using a model of phase transformation without variant selection allowed us to conclude that the [beta - alpha] phase transformation occurs with strong variant selection depending on the imposed modes of deformation. A new model including the variant selection was deloped. The best selection assumption that allows us to predict the general trends of transformation textures is such that the selected variants are those for which the strain energy due to the external stress was higher than a given threshold evaluated in this study
Chillan, José. "Déformation d'un signal acoustique dans un milieu aléatoire stratifié : (approximation diffusion et phases stationnaires)". Palaiseau, Ecole polytechnique, 1996. http://www.theses.fr/1996EPXX0015.