Micro-formage de composants à partir de tôles ultra-fines en alliages de cuivre

La miniaturisation de nombreux produits et systèmes entraine le développement permanent de micro -systèmes électro mécaniques (M.E.M.S). En raison de leurs taux de production élevés, les procédés de mise en forme demeurent la solution technologique la plus courante pour la fabrication de ces pièces miniatures. Toutefois, en raison des dimensions et épaisseurs (de l'ordre de 100microns ) en jeu, les procédés de micro-formage se révèlent instables et affectés par une grande variabilité. Nos travaux visent à mettre en place une modélisation numérique efficace et précise de ces procédés dans le but de s'en servir comme outil d'optimisation des outillages et procédés. Les deux approches de modélisation développées sont mises en oeuvre sur le cas industriel de pliage des leads d'un boitier électronique LQFP

Simulation of ultra-thin sheet metal forming using phenomenological and crystal plasticity models

Micro-forming of ultra-thin sheet metals raises numerous challenges. In this investigation, the predictions of state-of-the-art crystal plasticity (CP) and phenomenological models are compared in the framework of industrial bending-dominated forming processes. Sheet copper alloys 0.1mm-thick are considered, with more than 20 grains through the thickness. Consequently, both model approaches are valid on theoretical ground. The phenomenological models’ performance was conditioned by the experimental database used for parameter identification. The CP approach was more robust with respect to parameter identification, while allowing for a less flexible description of kinematic hardening, at the cost of finer mesh and specific grain-meshing strategies. The conditions for accurate springback predictions with CP-based models are investigated, in an attempt to bring these models at the robustness level required for industrial application

Genome-Wide Scan Identifies TNIP1, PSORS1C1, and RHOB as Novel Risk Loci for Systemic Sclerosis

Systemic sclerosis (SSc) is an orphan, complex, inflammatory disease affecting the immune system and connective tissue. SSc stands out as a severely incapacitating and life-threatening inflammatory rheumatic disease, with a largely unknown pathogenesis. We have designed a two-stage genome-wide association study of SSc using case-control samples from France, Italy, Germany, and Northern Europe. The initial genome-wide scan was conducted in a French post quality-control sample of 564 cases and 1,776 controls, using almost 500 K SNPs. Two SNPs from the MHC region, together with the 6 loci outside MHC having at least one SNP with a P<10−5 were selected for follow-up analysis. These markers were genotyped in a post-QC replication sample of 1,682 SSc cases and 3,926 controls. The three top SNPs are in strong linkage disequilibrium and located on 6p21, in the HLA-DQB1 gene: rs9275224, P = 9.18×10−8, OR = 0.69, 95% CI [0.60–0.79]; rs6457617, P = 1.14×10−7 and rs9275245, P = 1.39×10−7. Within the MHC region, the next most associated SNP (rs3130573, P = 1.86×10−5, OR = 1.36 [1.18–1.56]) is located in the PSORS1C1 gene. Outside the MHC region, our GWAS analysis revealed 7 top SNPs (P<10−5) that spanned 6 independent genomic regions. Follow-up of the 17 top SNPs in an independent sample of 1,682 SSc and 3,926 controls showed associations at PSORS1C1 (overall P = 5.70×10−10, OR:1.25), TNIP1 (P = 4.68×10−9, OR:1.31), and RHOB loci (P = 3.17×10−6, OR:1.21). Because of its biological relevance, and previous reports of genetic association at this locus with connective tissue disorders, we investigated TNIP1 expression. A markedly reduced expression of the TNIP1 gene and also its protein product were observed both in lesional skin tissue and in cultured dermal fibroblasts from SSc patients. Furthermore, TNIP1 showed in vitro inhibitory effects on inflammatory cytokine-induced collagen production. The genetic signal of association with TNIP1 variants, together with tissular and cellular investigations, suggests that this pathway has a critical role in regulating autoimmunity and SSc pathogenesis

TGFβ receptor gene variants in systemic sclerosis-related pulmonary arterial hypertension: results from a multicentre EUSTAR study of European Caucasian patients

Introduction: Systemic sclerosis (SSc)-related pulmonary arterial hypertension (PAH) has emerged as a major mortality prognostic factor. Mutations of transforming growth factor beta (TGFβ) receptor genes strongly contribute to idiopathic and familial PAH. Objective: To explore the genetic bases of SSc–PAH, we combined direct sequencing and genotyping of candidate genes encoding TGFβ receptor family members. Materials and methods: TGFβ receptor genes, BMPR2, ALK1, TGFR2 and ENG, were sequenced in 10 SSc–PAH patients, nine SSc and seven controls. In addition, 22 single-nucleotide polymorphisms (SNP) of these four candidate genes were tested for association in a first set of 824 French Caucasian SSc patients (including 54 SSc–PAH) and 939 controls. The replication set consisted of 1516 European SSc (including 219 SSc–PAH) and 3129 controls from the European League Against Rheumatism Scleroderma Trials and Research group network. Results: No mutation was identified by direct sequencing. However, two repertoried SNP, ENG rs35400405 and ALK1 rs2277382, were found in SSc–PAH patients only. The genotyping of 22 SNP including the latter showed that only rs2277382 was associated with SSc–PAH (p=0.0066, OR 2.13, 95% CI 1.24 to 3.65). Nevertheless, this was not replicated with the following result in combined analysis: p=0.123, OR 0.79, 95% CI 0.59 to 1.07. Conclusions: This study demonstrates the lack of association between these TGFβ receptor gene polymorphisms and SSc–PAH using both sequencing and genotyping methods

Structure des massifs granitiques de la Méséta marocaine, marqueurs géodynamiques : Aouli-Bou-Mia (Haute Moulouya), Zaër (Massif Central) et Sebt de Brikiine (Rehamna)

Structure of the Moroccan Meseta granitic intrusions, geodynami-cal markers : Aouli-Bou-Mia (Haute Moulouya), Zaër (Massif Central) and Sebt de Brikiine (Rehamna). The Moroccan Meseta is in continuity in Africa with the European Hercynian belt. We think the structural study of granitoids constitues one way to reconstruct the geodynamic evolution of this Hercynian domain. This is because, the structures of partially melted and solid rocks, concerning the granites and the country-rocks, behave as markers of the emplacement of granite bodies in the crust. The magmatic structures in the granitoids have been studied using the anisotropy of magnetic susceptibility (AMS) technique. With respect to the classical structural analysis, the main advantages are a great reliability in the orientation measurement of foliation, and especially of lineation, and the easy quantification of total, planar and linear anisotropics using the magnitudes of the AMS ellipsoid. Three granite massifs are presented in detail. The composite Aouli-Bou-Mia massif in the Eastern Meseta is considered as the earliest of the Mesetian orogen. Structural analysis of the country rocks, along with the concordant regulary oriented magmatic structures, allow to propose a syn-to late-tectonic emplacement of the granite during a low-angle shearing of the country-rocks. However, the com-pressional or extensional context of this event cannot be specified. The granodioritic massif of Zaër (Central Massif), like the Oulmès body studied elsewhere, seems to be associated with the NNE-SSW sinistral transcurrent faults that transect the Western Meseta. In agreement with the radiochronological data, a detailed analysis shows that the monzogranitic body that occupies the south-center of the Zaër massif was emplaced during a late, brittle event, into the already cooled granodiorite. At the western Mesetian boundary, emplacement of the alkaline granitic massif of Sebt has been accomplished along the Western Meseta Shear Zone, during its very last dextral transcurent movements. Compatibility of the extensive Devono-Dinantian events, typical of the Western Meseta, with the low-angle shearing tectonics of the eastern domain at the same period favors the hypothesis of a generalized extensive event during the onset of the Mesetian orogen. Later, during Westphalian times, the account of the large transcurrent faults in the same regional stress system leads us to consider that the Sehoul Block is responsible for the north-south punching of the Meseta previously softened by the extensional event. This tectonic event prevailing in North-West Meseta possibly took place during, and lasted after, the E-W compression event typical of the post-Visean phase, and which was responsible for the NE-SW regional structures of the whole Meseta.La Meseta marocaine constitue sur le continent africain la continuité de la chaine hercynienne d'Europe moyenne. On pense que l'étude des structures internes de granitoïdes constitue l'une des façons de retracer l'évolution géodynamique de ce segment hercynien. En effet, les structures de déformation à l'état partiellement fondu dans les plutons, et à l'état solide, dans les plutons et leur encaissant, sont l'empreinte de la mise en place dans la croûte de ces plutons. Les structures dans les granites sont étudiées par la technique de l'anisotropie de la susceptibilité magnétique. Par rapport à l'analyse structurale classique les avantages essentiels sont : - une grande fiabilité des mesures d'orientation des foliations et surtout des linéations ; - la quantification des anisotropics totale, planaire et linéaire. Trois massifs granitiques sont présentés en détail. Le massif composite d'Aouli-Bou-Mia, en Meseta orientale, est considéré comme le plus précoce de l'orogène mésétien. L'analyse de la déformation de son encaissant, ainsi que ses structures magmatiques orientées de façon très régulière conduisent à proposer une mise en place syn-à tardi-tectonique dans un encaissant soumis à un cisaillement d'angle faible, mais le contexte compressif ou distensif ne peut être précisé. Le massif granodioritique de Zaër (Massif Central) semble, comme celui d'Oulmès étudié par ailleurs, associé aux décrochements sénes-tres NNE-SSW qui parcourent la Meseta occidentale. L'analyse structurale détaillée montre, en accord avec les données radiochronologiques, que le corps monzogranitique occupant le centre-sud du massif du Zaër s'est mis en place tardivement au cours d'un épisode fragile au sein de la granodiorite préalablement refroidie. En bordure occidentale de la Meseta, la mise en place du massif granitique à affinité alcaline de Sebt de Brikiine s'est effectuée le long de la zone de cisaillement de la Meseta Occidentale, lors de ses ultimes jeux décrochant dextres. La compatibilité des phénomènes distensifs dévono-dinantiens de la Meseta Occidentale avec le cisaillement d'angle faible reconnu dans le domaine oriental serait en faveur de l'hypothèse d'une extension généralisée en début d 'orogène (~ 330 MA). Par la suite, au West-phalien, si l'on veut rendre compte des grands décrochements crus-taux nord-mésétiens dans un même système de contrainte, on est conduit à envisager un poinçonnement nord-sud de la Meseta par le Bloc des Sehoul. Ce domaine exotique, à structures clairement sécantes sur celles de la Meseta, joue le rôle de coin de socle entre le Bloc Côtier et la partie est de la Meseta occidentale. Cet événement tectonique dominant dans la partie Nord-Ouest de la Meseta est probablement intervenu pendant et après la phase de serrage E-W post viséenne qui confère à toute la Meseta ses structures régionales NE-SW.Diot Hervé, Bouchez Jean-Luc. Structure des massifs granitiques de la Méséta marocaine, marqueurs géodynamiques : Aouli-Bou-Mia (Haute Moulouya), Zaër (Massif Central) et Sebt de Brikiine (Rehamna). In: Géologie Méditerranéenne. Tome 18, numéro 1-2, 1991. Le paleozoïque du Maroc. II – Carbonifère – Permien (Paléontologie – Biostratigraphie – Aspects structuraux) pp. 81-97

Le Quaternaire littoral girondin.

Livret-guide de l'excursion de l'AFEQ (16-18 mai 1996) en MédocNous présentons la situation géographique, l'histoire géologique, les traces d'occupations humaines, l'histoire contemporaine et le vin en Médoc.We present the geographical situation, the geological history, the human settlements, the contemporary history and the wine in Médoc

: Note d'excursion

81p., 20 fig., 3 tab.Livret-guide de l'excursion de l'AFEQ (16-18 mai 1996) en MédocWe present the geographical situation, the geological history, the human settlements, the contemporary history and the wine in Médoc.Nous présentons la situation géographique, l'histoire géologique, les traces d'occupations humaines, l'histoire contemporaine et le vin en Médoc

Numerical investigation of the modelling of elastic behaviour in a wiping-die bending process.

International audienceThe prediction of springback effect in the field of sheet metal forming is of primary interest. This article deals with the interest of accurate modelling of the elasto-plastic behaviour of a metallic material especially in bending operation. A 3D finite element model is used for the prediction of both springback and stress distribution in a wiping-die bending process. Two models have been used to describe the elasto-plastic be-haviour of the material: (i) one phenomenological and (ii) one built on more physical basis. For the first model, Young's modulus of the material and the plastic material characterization were carried out by tensile tests. In the other model, a parameterized bilinear hardening is distributed in each integration point of the finite element of the numerical simulation. The identification of parameters for this model was also carried out by tensile tests. Numerical simulations were carried out with these two models by using ABAQUS Stan-dard finite element code to predict stress distribution and springback during the bending process. Results have been compared and underline the importance of introducing even small, non-linear effect during elastic stage

Etudes quaternaires en Grande Limagne d'Auvergne. I : La «rase» de Maison-Rouge, commune de Saint-Beauzire (Puy-de-Dôme). Avec une note de palynologie de M. F. Diot

Analyses of sedimentary and volcanic processes which affected the Grande Limagne swamp in the Riom sector of the Auvergne have been done. The results enable us to establish a preliminary chronostratigraphic and paleocli-matic schema for the Tardiglacial and Holocene. The successive modifications of the physical environment determined the distribution of human sttlements and the development of particular protohistoric facies.L'analyse des phénomènes sédimentaires et volcaniques ayant affecté le marais de Grande Limagne d'Auvergne dans le secteur de Riom permet de proposer une première esquisse chronostratigraphique et paléoclimatique du Tardi-glaciaire et de l'Holocène. Les modifications successives du milieu physique ont conditionné la répartition des habitats humains et sont responsables du développement de faciès protohistoriques particuliers.Daugas Jean-Pierre, Debénath André, Pelletier Henri, Raynal Jean-Paul, Tixier Luc, Diot Marie-Françoise. Etudes quaternaires en Grande Limagne d'Auvergne. I : La «rase» de Maison-Rouge, commune de Saint-Beauzire (Puy-de-Dôme). Avec une note de palynologie de M. F. Diot. In: Comptes rendus d'activités annuelles. Association régionale pour le développement des recherches de paléontologie et de préhistoire et des Amis du Muséum, tome 16, 1978. pp. 47-58