60f Richard, Caroline [WorldCat Identities]
WorldCat Identities

Richard, Caroline

Works: 24 works in 34 publications in 2 languages and 142 library holdings
Roles: Editor, Thesis advisor, Other, Opponent
Classifications: HE7581, 620.1
Publication Timeline
Most widely held works by Caroline Richard
Prévention et lutte contre la corrosion : Une approche scientifique et technique( Book )

1 edition published in 2004 in French and held by 73 WorldCat member libraries worldwide

Conception, fabrication et durabilité : actes des [21èmes] Journées internationales francophones de tribologie (JIFT 2009) [5-6 mai 2009, Université de technologie de Compiègne] by Journées internationales francophones de tribologie( Book )

1 edition published in 2012 in French and held by 37 WorldCat member libraries worldwide

Les surfaces et interfaces constituent une véritable butée technologique car elles sont bien souvent le point de départ d'avaries majeures des pièces mécaniques. Maîtriser le frottement et sa conséquence, l'usure, est donc particulièrement crucial compte tenu du contexte économique actuel qui exige des cadences de fabrication de plus en plus courtes sur des matériaux de plus en plus haut de gamme afin de conserver toujours les plus grandes compétitivités, qualités et fiabilités des produits manufacturés. De nouvelles contraintes apparaissent également comme la recyclabilité des matériaux et leur durabilité. Ceci entraîne dans les procédés de fabrication la mise au point d'outillages de plus en plus performants voire la mise au point de nouveaux procédés plus sophistiqués astreints à de nouvelles normes (de type environnemental par exemple). Ce livre regroupe une quarantaine de contributions présentées lors des 21. Journées Internationales Francophones de Tribologie (JIFT) qui se sont tenues les 5 et 6 mai 2009 à l'Université de Technologie de Compiègne (UTC). Les JIFT, tradition mécanicienne depuis 1989, permettent de faire un point annuel sur les derniers développements en tribologie et sont ouvertes aussi bien à la communauté universitaire qu'au monde industriel. L'édition 2009 avait pour axes la conception mécanique, les procédés de fabrication et la durabilité. Les textes publiés sont regroupés sous 5 thèmes principaux : Mécanique du contact ; Microgéométrie des surfaces ; Procédés de fabrication incluant des problématiques liées à la lubrification; Durabilité, effet d'environnement ; Matériaux polymères. Ces contributions montrent en particulier l'extrême multidisciplinarité de la tribologie alliant aussi bien l'approche expérimentale que la modélisation numérique. [Source : 4e de couv.]
Corrosion-abrasion and bacteria induced corrosion of stainless steel AISI 304L (EN 10088 : X2 Cr Ni 18-09) in contact with sugar cane juice by Seeva Durmoo( Book )

2 editions published in 2007 in English and held by 2 WorldCat member libraries worldwide

The main objective of this research study is to assess the behaviour of stainless steel AISI 304L in contact with sugar cane juice. Stainless steel grade 304L is largely used in the sugar cane industry but the acidic nature of sugar cane juice pose a serious challenge in maintaining the life span of vital components. Sugar cane juice is acid having a pH value of around 5.5 at extraction. This acidic property is accounted for by the presence of a variety of acids namely : aconitic, citric, malic, oxalic, glycolic, mesaonic, tartic, suceinic, fumaric and syringic in sugar cane juice. In addition to these acids there are approximately 50 different kind of microorganism present in the green cane and act as a contributor to a rather quick drop in pH (pH~3.1) of the cane juice once extracted. The more so, several minerals like water, salt, sulphate and abrasive particulates and silica are also present throughout the process line and are other contributor in the surface degradation wear mechanism. Faced with all these adverse elements, it is therefore fundamental to investigate thoroughly in the wear corrosion mechanism and bio corrosion on stainless steel grade 304L. To evaluate the mass loss ; corrosion, corrosion erosion and corrosion abrasion experimentations were carried with the help of both potentiostat and acoustic emission in a sterilised juice and none sterilised juice. Analysis of experimental data in terms of weight loss due to corrosion and corrosion abrasion plotted against the acoustic emission RMS data have shown clearly effect of synergy and produces the worst adverse effect on the surface at 90 degree impact
Comportement tribologique de la fonte grise lamellaire 250 contre les polytétrafluoroéthylènes : Rôle des particules d'usure by Christelle Kowandy( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

The compressors used for the blowing of the plastic bottles generally consist of a cylinder, a piston and segments which must ensure at the same time the sealing between the parts and the lubrication. The segments must be in materials known as "self-lubricating" such as polytetrafluoroethylene. However, during the contact, wear partic1es can be generated. Their morphology is an indicator of the wear process. Mechanical tests of friction were carried out with an alternate tribometer in a plane contact configuration. The materials tested were polytetrafluoroethylenes, pure or reinforced against lamellate grey cast iron. After the characterization of materials, the morphological partic1e attributes are determined by image analysis technique. Wear mechanisms are proposed and correlations between the characteristics of the wear particles, the wear rates and the tribosystem are obtained thanks to the data mining
Analyse de la réponse tribologique d'un contact cylindre/plan soumis à des sollicitations de fretting sous chargement complexe : influence d'une solution Lithium-Bore by Estelle Marc( )

2 editions published in 2018 in French and held by 2 WorldCat member libraries worldwide

This PhD thesis presents an analysis of the fretting wear of a cylinder/plane contact subject to complex loading conditions, namely a normal sinusoidal force solicitation and a tangential sinusoidal displacement, both possibly subject to fluctuations in amplitude, frequency and phase shift between signals. The purpose of this work is to study the wear of 304L cluster guides by nitrided 316L rods due to flow-induced vibrations of primary fluid in nuclear reactors.Firstly, the experimental study conducted in a dry and ambient temperature - a non-representative but very simple environment - shows significant wear of both counter-bodies, which reveals the fragile properties of the nitrided tube in this environment. A very strong dependence of the fretting scar morphology with the sliding amplitude is noted. Only the wear kinetics of the nitrided tube is influenced by the evolution of the normal load. Also, an analytical description of friction energy is developed, taking into account all loading parameters.In a second hand, in aqueous lithium-boron solution, a slightly more representative choice of medium but still remaining in the ambient, only the 304L steel plane wears out, the 316L nitrided steel cylinder is not subject to detectable wear. A coupling with corrosive phenomena is proposed. In simple fretting, contact confinement locally increases the pH value. Moreover, the analysis of the influence of the fretting frequency suggests that only the passive layer is worn between each slip. Under complex loading, the fluctuation of the normal load allows a better accessibility of the solution in the rubbed interface, increasing locally the tribocorrosive effects. A multiplicative wear law taking into account the various effects of normal force fluctuation is introduced and its stability is checked.Finally a finite element calculation model is used to simulate wear profiles in simple fretting and also in the presence of variable normal force. Only cases where the plan wears out (lithium-boron environment) have been simulated. In simple fretting, test simulation results are satisfactory. On the other hand, the non-superposition of the experimental and numerical profiles when the normal force fluctuates, confirms the presence of physical phenomena in the interface which are not yet represented in the numerical tool
Influence des réactions enzymatiques sur le comportement électrochimique de l'acier inoxydable EN X2CrNiMo17-11-2 (AISI 316L) en biocorrosion : rôle des processus interfaciaux sur la modification du film passif by Jessem Landoulsi( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

The outstanding corrosion behavior of stainless steels (SS) results from the presence of thin oxide layer (some nanometers). ln non sterile aqueous media, stainless steels may exhibit a non stable behavior resulting from interactions between microbial species and passive film. ln fact, microorganisms can be deeply involved in the corrosion processes usually reported as Microbial Influenced Corrosion (MIC). They can induce the initiation or the acceleration of this phenomenon and they do so when organized in biofilms. From the electrochemical point of view, stainless steels showed an increase of the free corrosion potential (Ecorr) attributed to the biofilm settlement. The Eco" ennoblement was broadly reported in seawaters and seems to be confirmed in fresh water according to recent findings. A considerable progress in the comprehension of MIC processes was related to the role of extracellular species, essentially enzymes. Many enzymatic reactions occurring in biofilms consist on using oxygen as electron acceptor to generate hydrogen peroxide and related species. The aim of this work is to understand the mechanisms involved in the electrochemical behavior of stainless steel according to an enzymatic approach in medium simulating fresh water. To this end, glucose oxidase was chosen to globalize aerobic activities of biofilms. Electrochemical measurements in situ and surface analysis allow the comprehension of the role and the nature of interfacial processes. Surface characterization was performed with the help of a new quantitative utilization of XPS analysis and AFM. Results show a significant evolution in term of (I) morphology (surface organization), (II) chemical composition (passive layer, adsorbed organic species) and (III) chemical reaction (oxidation, dissolution, effect of enzyme). Finally, a new enzymatic system is proposed to mimic specific physicochemical conditions at the SS / biofilm interface, in particular enzymatic generation of oxidant species in diffusion limiting conditions
Etude du comportement d'aciers inoxydables austénitiques dans les eaux naturelles : corrosion sous contrainte et biocorrosion dans l'eau de l'Oise by Djamel Aouali( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

Dans la nature, les matériaux sont toujours en contacts avec le milieu environnant. Le but de cette thèse est de voir l'incidence que peuvent avoir les eaux naturelles sur le comportement électrochimique, acoustique et mécanique d'aciers inoxydables austénitiques. Le milieu utilisé pour cette étude est l'eau de l'Oise. Dans un premier temps, un portique a été mis au point pour faire une immersion d'éprouvettes dans l'Oise tout en assurant un suivi électrochimique du potentiel libre de corrosion. La durée de l'immersion est longue, permettant ainsi la formation d'un biofilm. Les observations microscopiques ont permis de voir que les microorganismes présents dans le biofilm sont principalement des diatomées. Les résultats obtenus confirment l'augmentation du potentiel libre de corrosion et l'apparition d'un nouvel oxydant : le peroxyde d'hydrogène H2O2. Dans un second temps, nous avons mis au point et utilisé une technique permettant de simuler une corrosion sous contrainte par le biais d'une machine de traction lente, avec un suivi simultané de l'émission acoustique et du potentiel libre de corrosion. Les résultats montrent une absence d'une sensibilité à la corrosion sous contrainte des aciers inoxydables austénitiques liée au biofilm dans les conditions de nos essais. Toutefois on a pu constater des évolutions inverses du potentiel liées à la présence ou non d'un biofilm, attribuées au comportement de ce biofilm durant la déformation
Étude des performances mécaniques surfaciques d'alliages métalliques par traitement duplex nanostructuration-nitruration ionique pour applications biomédicales [prothèses orthopédiques] by Sami Jelliti( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

In terms of biomaterials protection against corrosion and wear, several approaches are possible: modify the chemical environment and operating conditions, change the material or also modify its properties. The first two options require a complete revision of a conceptual set and can therefore lead to new difficulties and additional costs. The third approach, which consists on modifying the biomaterial's surface properties, is the simplest to implement as it aims to adapt the biomaterial to the different constraints of its environment and therefore requires a smaller investment. In order to improve the mechanical surface properties (hardness, roughness...), chemical proprieties (corrosion resistance) and tribological proprieties (wear resistance) of biomaterials, it was decided to set up a nanostructuring treatment SMAT (Surface Mechanical Attrition Treatment). Microscopic observations revealed the presence of a nanostructured layer on the surface of the titanium alloy Ti6Al4V and 316L stainless steel. The electrochemical experimental results showed an improvement in the corrosion resistance of used biomaterials in particular for the titanium alloy. Thus, electrochemical properties have been demonstrated through corrosion tests (monitoring free potential, polarization curves, impedance diagrams ...) associated with microscopic observations (SEM) and XPS analyses. Through this technique, we could appreciate the quality and extent of the layer on the surface which is a fundamental parameter for determining the corrosion behavior of biomaterials. In the second part, a duplex SMAT-nitriding treatment was applied on Ti6Al4V. More significant improvement of corrosion properties was observed on the SMATed and nitridtreated titanium alloy. In the last section, we addressed the surface mechanical properties (hardness, roughness) of biomaterials after SMAT. The roughness profiles have increased and hardness values showed a maximum near the outermost treated surface. Fretting tests were performed on different samples. SMAT treatment slightly reduces the coefficient of friction and decreases the mass loss
Tribométrie à haute température : conception et réalisation d'un banc d'essai à chaud : Application à l'étude d'un acier revêtu (Usibor 1500P) pour emboutissage à chaud by Marouane Marzouki( Book )

2 editions published in 2005 in French and held by 2 WorldCat member libraries worldwide

Hot stamping is a process in progress used in the automobile sector, particularly for an aluminised and quenchable steel sheet working: Usibor 1500P. In this process, working tools are subjected to thermal, mechanical and metallurgical stress. These constraints are fully coupled and are acting in synergy. Therefore, it is difficult to control friction and wear in this process. The understanding of the tribological phenomena occurring in the tool/sheet interface becomes very important in order to control the dissipated energy and the tools durability which directly affects the surface quality of the final product. This study concerns these problems with a scientific and technological approach. In this work, the first chapter relates to a bibliographical study describing the process of metallic material stamping and in particular hot stamping with simultaneous hardening of a coated steel Usibor 1500P. The process, mechanical, tribological and experimental simulation aspects of stamping are approached. The second chapter treats to the experimental methodology which is required in terms of design and achievement in order to satisfy the industrial specifications. The high temperature pin on disc in open contact tribometer, designed and built up, is described. The material tools (represented by pins) and material product (Usibor 1500P) are presented. The analysis and observation means are briefly exposed. The third chapter concerns the essential validation of the tribometer by the analysis of its response in terms of the surface temperature evaluation and the spiral trajectory analytical modelling. The fourth and final chapter gives all the experimental results and their discussion such: § The Usibor 1500P surface analysis for a better understanding of its tribological behaviour. § The coefficient of friction for the different couples of materials. § The characterization and analysis of the various types of pin and disc wear. After that, a discussion on the coefficient of friction is done. Then, a numerical model of pin on disc in open trajectory system is proposed. The objective is to predict a friction law formulation according to the experimental conditions. Lastly, pin and disc wear mechanisms are proposed and the importance of the tribosystem is shown. Some practical recommendations are finally proposed from this work
Étude du comportement mécanique et tribologique des aciers austénitiques au manganèse : application aux cœurs de voies ferroviaires by Ridha Harzallah( Book )

2 editions published in 2010 in French and held by 2 WorldCat member libraries worldwide

Cette étude s'inscrit dans le domaine de la conception et du dimensionnement de structures industrielles. Elle consiste à proposer une méthodologie permettant de simuler l'endommagement ductile de structures métalliques, suivi de l'amorçage et de la propagation de fissures. La démarche s'organise en trois temps. La première étape consiste à pouvoir décrire correctement l'évolution de l'endommagement jusqu'à l'amorçage de la fissure, par un modèle continu. Or, l'utilisation de modèles de comportement ductiles endommageables classiques avec la méthode des éléments finis conduit à de nombreux problèmes, tels que la dépendance pathologique à la finesse et à l'orientation du maillage ou le verrouillage volumique. Une nouvelle formulation mixte non locale à quatre champs est proposée dans le cadre des petites perturbations afin de surmonter ces problèmes. L'étape suivante vise à améliorer la qualité du calcul. Pour cela, une procédure d'adaptivité de maillage reposant sur un indicateur d'erreur est mise en place afin de permettre d'atteindre le niveau de qualité désiré par l'utilisateur, tout en minimisant les coûts de calculs. Associée au lissage des champs aux anciens points de Gauss avant projection directe aux nouveaux points de Gauss et à l'ajout de viscosité dans le modèle, elle permet de reprendre les calculs sur le nouveau maillage plus adapté après quelques divisions du pas de temps. Enfin, une fois toute la phase d'endommagement décrite avec précision, la dernière partie est consacrée au développement d'une stratégie d'amorçage et de propagation de fissure utilisant l'adaptation de maillage. Pour cela, le chemin de fissure est représenté par un maillage auxiliaire dont le front est le plus régulier possible. Pour déterminer l'orientation de cette discrétisation, un critère reposant sur le gradient de l'endommagement lissé est formulé. Cette stratégie est mise en oeuvre sur un cas test académique en dimensions deux et trois. Par la suite, il serait intéressant de pouvoir appliquer cette méthodologie avec des modèles plus réalistes faisant intervenir le taux de triaxialité, et ce en grandes déformations
Influence du couplage frottement-oxydation sur l'usure d'un acier à outil de travail à chaud : développement d'un tribomètre spécifique au cyclage de matriçage by Mohamed Kchaou( Book )

2 editions published in 2010 in French and held by 2 WorldCat member libraries worldwide

L'amélioration de la durée de vie des outillages de mise en forme à chaud constitue un enjeu industriel important et encore mal maitrisé. En effet, les sollicitations induites lors de la mise en forme mettent en jeu des couplages impliquant des phénomènes thermiques, mécaniques, tribologiques et physicochimiques. Les modes de dégradation engendrés sont multiples, principalement par déformation plastique, par fatigue thermomécanique, par frottement et par oxydation. Les dégradations par frottement demeurent parmi les plus pénalisantes et les plus difficiles à appréhender et à maîtriser compte tenu de la complexité des couplages mis en jeu.Cette thèse aborde l'usure de l'acier à outil X40CrMoV5-1 dans le cas du matriçage à chaud du laiton. Les mécanismes d'endommagement et d'usure ont été analysés par le biais d'une expertise de matrices usées en production. Elle révèle différents types de dégradations, activés selon la localisation et l'exposition des surfaces aux sollicitations cycliques de matriçage. Elle a permis d'établir un scénario d'usure par abrasion à trois corps entretenu par le cyclage et dans lequel les oxydes du laiton et de l'acier à outil sont déterminants.L'oxydation de l'acier à outil et son comportement tribologique dans un état pré-oxydé ont été étudiés. Un essai original est proposé pour étudier l'influence du cyclage de matriçage sur le couplage frottement oxydation et ses conséquences sur l'usure. Un tribomètre spécifique a été développé et mis au point. Les essais de frottement reposent sur une analogie avec le cycle de matriçage, sans reproduire la mise en forme, et un contact conforme favorable à la formation et au piégeage des oxydes
Adhérence et propriétés mécaniques de dépôts obtenus par projection thermique : application de l'émission acoustique à l'étude des modes d'endommagement by Davy Dalmas( Book )

2 editions published in 2001 in French and held by 2 WorldCat member libraries worldwide

Dans l'industrie, les techniques de revêtement ont toutes pour but d'ano¬blir la surface d'un matériau pour lui conférer des propriétés d'usages mieux adaptées à une application donnée, sous réserve que le dépôt ne s'altère pas en service. Ainsi, dans ce travail, nous avons étudié, pour différents revêtements (un cermet WC-Co, un spinelle et un chrome électrolytique), les mécanismes d'endommagement qui sanctionnent la qualité d'un dépôt. Dans un premier temps, certaines des propriétés mécaniques de nos revêtements ayant une influence sur les modes d'endommagement ont été déterminées : le module d'Young, le moment critique d'apparition de fissure transverse, la répartition des contraintes résiduelles et la ténacité. Dans un second temps, nous avons mis au point et validé une méthode de caractérisation des modes d'endommagement d'un revêtement basée sur l'utilisation conjointe de l'émission acoustique (E.A.) et d'un microscope électronique à balayage. Lors de tests de flexion quatre points, des mesures in situ de IlE.A., exploitées en terme d'amplitude, d'énergie absolue et de position des évènements, ont été corrélées à l'observation microscopique des éprouvettes. Les résultats, confirmés par une méthode statistique utilisant des réseaux neuronaux, ont révélé la présence de deux populations d'évènements représentatives des deux modes de fissuration observés dans le dépôt (fissuration cohésive périodique et délaminage). De plus, il a été montré qu'il est essentiel de prendre en compte la plastification du substrat dans l'analyse de l'E.A. Grâce à un logiciel utilisant les équations intégrales, nous avons pu proposer une modélisation de la fissuration périodique d'un dépôt. Pour compléter notre étude, des tests de rayage et des essais d'indenta¬tion interfaciale instrumentés en émission acoustique ont été réalisés afin de valider et confirmer certains résultats concernant l'adhérence d'un dépôt sur son substrat
Caractérisation des variabilités Matériaux/ Process pour une convergence produit de fonderie par approche prédictive by Imane Outmani( )

1 edition published in 2017 in French and held by 1 WorldCat member library worldwide

Secondary Al-Si alloys are widely used in automotive industry for engine blocks because they offer a considerable weight reduction whilst maintaining good mechanical properties. The ever-expanding internationalisation of production, with same stages of production processes spread across a number of countries to produce locally, causes however high variability in the casting products. The chemical composition of the same alloys and the working variables of the unchanged high-pressure die casting process (HPDC) may change for the same casting parts from one country to another, they can even sometimes vary from one manufacturing site to another within the same country. Designing for aluminium automotive components does call today for new deterministic design methods that are often achieved from European material and casting process databases, which can affect the properties of these parts in the case of a location outside Europe. Thus, it is important to adapt the design of die casting parts quickly and inexpensively by taking into account the material and process local constraints. In this work, a methodological approach which permits to predict mechanical properties as a function of material and process variability based on an experimental/ statistical study on the effect of the variability of the primary factors of alloying elements contents (Si, Cu and Mg) and HPDC process parameters (casting temperature and injection pressure) on mechanical properties of die cast aluminium alloys has been proposed. The microstructural features and the porosity level were also investigated and assessed. This approach has resulted in statistical design tool that will allow designers to make changes to the design of their casting and to industrialize them outside Europe
Frottement, usure et lubrification de couples de biomatériaux : Cas du PEHD / zircone et cas de l'acier inoxydable austénitique 316L / zircone by Hamoudi Mazouz( Book )

1 edition published in 2003 in French and held by 1 WorldCat member library worldwide

Les potentialités des biomatériaux demeurent très grandes dans les applications tribologiques. Dans tous les cas, il faut bien connaître les matériaux pour définir concrètement leurs domaines d'applications et donc disposer des moyens fiables et significatifs de caractérisation. Ceci est d'autant plus vrai que le comportement tribologique n'est pas une propriété intrinsèque des matériaux, il dépend, en effet, d'un certain nombre de paramètres:les conditions nominales d'essai, le chargement, la fréquence, la température et l'humidité par exemple, les propriétés et les structures des couples des matériaux en ±contact[alpha] ainsi que les caractéristiques propre du dispositif d'essai et du milieu environnant. Les essais de frottement et usure ont été effectués sur un tribomètre alternatif. Une variété de biomatériaux a été testée, dont le comportement tribologique des couples de biomatériaux PEHD/ zircone et acier inoxydable austénitique /zircone en fonction de plusieurs paramètres, notamment du milieu. Plusieurs moyens ont été utilisés pour analyser les surfaces en frottement: la stréographie, le microscope électronique à balayage, le microscope interferrométrique et l'analyse par diffraction X, en outre un test de cytotoxicité a été pratiqué. Cette approche globale a permis de montrer le rôle important du milieu en présence sur le comportement des couples considérés. Une comparaison en termes morphologiques et analytiques, des débris obtenus en conditions réelles et a été également réalisée ceux provoqués par les essais de frottement et usure sur machine dans les différents milieux.L'analyse d'émission acoustique semble prometteuse pour la tribologie, des essais de frottement et usure ont été réalisés en conditions d'instrumentation de cette technique afin de conforter, à partir de l'analyse des signaux, les phénomènes tirés de la caractérisation, montrer un apport significatif sur l'analyse de la genèse des débris et leurs évacuation, et contribuer à la constitution de banque de données
Maîtrise du procédé hybride de projection thermique avec refusion laser in-situ : approches numérique et expérimentale by Jiangwei Liu( )

1 edition published in 2016 in French and held by 1 WorldCat member library worldwide

The hybrid spraying process consisting in plasma spraying and laser remelting is an alternative method to minimize or even eliminate the potential defects within the as-sprayed coatings.During the treatment of plasma spraying or laser remelting, the substrate/coating system undergoing heating, melting, solidification and fast cooling processes is submitted to high temperature gradients, high stress levels and even risks of crack formation. It is therefore important to control the temperature variation and stress level within the substrate/coating system. In this study, thermal and mechanical models established with ANSYS were developed to provide a fundamental understanding of thermal and mechanical behaviors of deposited coatings during plasma spraying and laser remelting processes.3D simulation models were first developed to predict the temperature field, the final deformation of the specimen, and the residual stresses within ceramic (alumina) and metallic (NiCrBSi) coatings. The final residual stresses result from the balance between quenching stresses (tensile) and thermal stresses (compressive or tensile). Due to the low value of the yield stress, the thermal stresses (compressive for that case) dominate the final stress level in the case of the ceramic coating (alumina). On the contrary, the final residual stresses within the NiCrBSi coating are tensile. It is also predicted that an increase of the cooling efficiency induces a lower stress level for the alumina coating, while improving the cooling efficiency slightly increases the residual stresses for the case of the metallic coating (NiCrBSi).Thermal analysis to predict laser post-remelting of a NiCrBSi coating was then carried out to investigate the effects of the laser parameters on the temperature field as well as on the remelted pool shape. An absorption coefficient of 0.5 was estimated by comparison of the remelted pool depths obtained by experimental and numerical methods. In addition, the morphologies of theremelted coating were characterized by experimental methods. According to the mechanical analysis for laser post-remelting of NiCrBSi coatings, the predicted residual stresses were tensile within the remelted coating, whereas those within the non- emelted zone were reversed from tensile before remelting to compressive after laser post-remelting. According to the numerical analysis of in situ laser remelting by a multi-layer model, transient stresses in the former deposited layers were decreased progressively due to the heat accumulation during the following deposition process. For the residual stresses after final cooling, the stress component along the displacement direction presents a higher level in comparison with the transverse andthrough thickness components. Solutions allowing decreasing the stress level within the remelted coating were studied by changing the cooling efficiency and the initial temperature of the substrate. It was noted that the generated residual stress (tensile) was more sensitive to the initial temperature of the substrate, than to the efficiency of the cooling system. In particular, increasing the initial temperature of the substrate could significantly decrease the stress magnitude within the remelted coating, and even reverse the residual stresses within the nonremelted part of the coating to compressive values
Caractérisation et modélisation du comportement hyper-viscoelastique d'un élastomère chargé pour la simulation de pièces lamifiées élastomère-métal et étude en fatigue by Alexis Delattre( )

1 edition published in 2014 in French and held by 1 WorldCat member library worldwide

In association with Airbus Helicopters, the aim of the project is to develop a model to pre-size elastomer-metal laminated devices whose role is critical in terms of design and safety for helicopters rotor architectures. To do so, the first part of this thesis consisted in characterizing the elasto-dissipatice behavior of the studied material (a carbon black filled butadiene rubber) thanks to static and dynamic tests, with several kind of loading (uni-axial and bi-axial) and over a wide range of frequences, amplitudes and temperatures. From these observations, a phenomenological hyper-viscoelastic model is proposed. Based on a generalized Maxwell model, it is able to describe the phenomena over the loading range of concern. A particular focus is made to take in account the Payne effect thanks to an original approach. The model parameters are identified with a fast and robust method. The model is then implemented in a commercial finite element code and in a tool based on a model reduction method. Last, a study of the behaviour in fatigue is performed with an original characterization campaign from which a continuous damage law is proposed
Fretting et fretting-fatigue à haute température d'alliages de titane revêtus by Benjamin Van Peteghem( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

Fretting damage is a major cause of defect. It is mandatory to study fretting in order to improve material performances, especially for titanium alloys used in aeronautics. Fretting induces wear, cracking or both damages in bodies in contact. The usual topics of fretting studies deal with one of these damages. In the one presented here, wear and cracking are studied simultaneously. This point of view allows a global approach of the blade-disk contact behavior in case of fretting in a turbojet high pressure compressor. Due to industrial constraints, the temperature of this study is 450°C and the contact geometry is coated plane on plane. This study is performed on an original experimental setup made for it. This setup enables fretting-fatigue tests at constant fretting force even if fatigue force varies. The first's results regard tribological behavior. A significant effect of pressure is shown: the more the pressure, the smaller the coating friction coefficient. The given hypothesis is an expulsion of solid lubricant contained in surface treatment. Wear results show a sacrificial behavior of the coating. The surface treatment is worn preferentially than counter-body. From an industrial point of view, this characteristic is a good way to protect the uncoated counter-body (disk) instead of coated part (blade). In parallel, another study shows effect of frequency and load variation during cycle in a more fundamental case. Wear scar profile and wear rate is modified by these two parameters. Plain fretting tests and fretting-fatigue tests are performed to study fretting cracking process. Fretting induced cracking on counter-body is modified by coating on the punch. Maximal crack length is twice as short in coating condition as in uncoated condition. In fretting-fatigue, the coating is more efficient in high cycle fatigue. As a conclusion, a polar diagram is used in order to present global results and performances of the coating
Contribution à la compréhension des liens entre microstructure et propriétés tribologiques d'aciers inoxydables haute dureté après traitements de surface by Edson thiago Silva santos( )

1 edition published in 2015 in French and held by 1 WorldCat member library worldwide

Des industriels du domaine aéronautique se sont regroupés autour du projet MEKINOX (Mécanique Inoxydable) visant à développer l'utilisation de différentes nuances d'aciers inoxydables en raison de leur haute résistance mécanique et de leur résistance à la corrosion. Cependant ces aciers sont réputés sensibles au frottement. Dans ce contexte, ce travail de thèse est dédié dans un premier temps à l'étude de l'effet des différents traitements thermiques et de surface sur la microstructure des aciers inoxydables visant à améliorer leur aptitude au frottement. Nous avons mis en évidence différents mécanismes de durcissement : par précipitation, par changement de phase et par solution solide. Dans un deuxième temps, nous avons mis en place une démarche expérimentale permettant de comparer la réponse des différents couples de matériaux sous contact roulant et glissant extrêmes. Ces essais nous ont permis de caractériser l'évolution du coefficient de traction et de classer les différents états métallurgiques selon leur résistance à l'usure. Dans un troisième temps, nous avons caractérisé les différents types d'endommagements se produisant en surface et en sous-couche. Enfin, l'utilisation de l'EBSD nous a permis caractériser la déformation plastique en sous couche et de tenter de corréler la valeur de la densité de HAGB (Angles à forte désorientation) avec la résistance à l'usure des différents états métallurgiques des aciers étudiés
Gant Haptique by Guillaume Olivieri( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

This project has consisted to create a haptic glove and its software. The haptic glove's purpose is to measure the pressure in the hand and display it in on a screen computer
Caractérisation multi-échelle du comportement morpho-mécanique de la fibre capillaire suite à une sollicitation thermomécanique by Juliette Jamart( )

1 edition published in 2015 in French and held by 1 WorldCat member library worldwide

When use on a daily basis, heat appliances can be harmful to human hair. This study deals with the effect of a thermomechanical solicitation, generally applied by the friction of the hot plates of a hair straightener, on the properties of human hair. This work is built on an experimental approach and on the development of rheological models. It aims at understanding the effects on the different levels of the hair's multiscale structure, from the cuticle to the cortex. A strong correlation between the changes of the cortical architecture and of the mechanical properties of hair has been emphasized. A thermomechanical treatment leads to the disorganization or the stretching and reorientation of the molecular and supra-molecular well-organized structure, depending on the temperature and on the shear force applied. From a mechanical point of view, these microstructural modifications create changes in the free volume and in the moving hability of the keratin molecules in the cortex, thus modifying the visco-elasto-plastic properties of the fiber. The link between the micro- and macroscopic changes allows to build rheological models that describe the global hair's mechanical behavior and for which the evolution of the rheological parameters follows the evolution of the architectural factors of the cortex. A thermomechanical treatment has also an effect on the perceptible part of hair, the cuticle. A multiresolution analysis allowed to link the different components of the surface to sensory qualities, such as the brightness, softness and fluidity of hair. For temprature higher than 170°C, the friction of the hot plates flattens the small roughnesses of the surface, improving its brightness and softness. However, it can also lead to the melting of the overlapping scales among each other and hair loses its natural fluidity, due to the loss of the multilayer aspect of the cuticle. To remedy this harmfull effect, a steam flow can be delivered just before the contact of the hot plates against the hair fiber. Water acts like a plasticizer and small roughnesses can be flatten for lower temperatures, allowing to preserve the shape of the scales and the multilayer structure of the cuticle
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