Search results for "Mécanique"
showing 10 items of 83 documents
Study of acoustic properties and impact behavior of porous materials homogeneous type metal foams and inhomogeneous
2015
This work is concerned with the theoretical and experimental study of the acoustical properties of macroscopically homogenous and inhomogeneous porous media as well as their mechanical response to impacts. The model of Johnson - Champoux - Allard appeared adapted for the acoustical modeling. This model, associated with a recently developed approach involving the concept of parallel transfer matrices has lead to a new approach of macroscopically inhomogeneous porous materials based on “mixtures of materials”. Furthermore, a parametric study of the absorption coefficient as a function of porosity and frequency has been proposed. The maximums of absorption as well as the envelop of the absorpt…
Influence of aluminates phases hydration in presence of calcium sulfate on silicates phases hydration : consequences on cements optimum sulfate
2012
The mechanical properties of hydrated cements need to be optimized according to the nature of cement products. Among the factors of optimization, the addition of calcium sulphate intended to regulate the reactivity of tricalcium aluminate (C3A), in quantity and quality in cement is an essential parameter.The advancement of knowledge on the mechanisms of hydration of each cement phase allows a study devoted entirely to the concept of optimum of sulphate. We studied simple system that we complicated and we studied the evolution of hydration, porosity and mechanical properties of cement at different age. The first system studied was the mixture C3S/gypsum, the objective was to determine whethe…
Elaboration et caractérisation mécanique et physico-chimique des revêtements déposés sur des substrats en laiton par les techniques de projection the…
2019
Brass alloys are used in many applications, especially in the sanitary industrial application. In this field, the brass is coated with an electroplated chromium layer. However, the electroplating technique is achieved by means of solutions in which the chromium is in the six oxidation state. At this degree of oxidation, chromium is toxic and has the reputation of being carcinogenic. In this context, the main objective of this work is to develop functional coatings on brass substrates using new techniques namely thermal and pneumatic spraying techniques. The mechanical and physical-chemical properties are studied in order to evaluate the performances of these coatings and the potency of thei…
Manufacturing and characterization of Al matrix composites with nano reinforcements via cold spraying
2019
This study aims at developing new routes for manufacturing Al matrix composites (AMCs) strengthened with nano reinforcements by solid-state cold spraying (CS) process. Three different AMCs including CNTs/Al, TiB2/AlSi10Mg and TiB2/7075Al were successfully fabricated by CS of the composite powders prepared using different approaches. The microstructure evolution of as-sprayed composite samples was investigated by means of different characterization methods like X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM) and electron backscatter diffraction (SEM/EBSD). The adhesion strength, tribological behaviour, corrosion properties as well as the mechanical performa…
Comportement en fatigue thermomécanique à haute température d’un système barrière thermique texturé par laser
2020
In service life of Thermal Barrier Coating (TBC) systems for blade applications can be limited by the top-coat (TC) spallation under thermo-mechanical fatigue (TMF) loadings. To improve its TMF life, laser texturing at the bond-coat/top coat interface in the CMSX-4 Plus / γ-γ’ BC/ EB-PVD TC system has been investigated.Thanks to the study of the laser-matter interaction, it seems that the different Ni-based single crystal superalloys have similar laser ablation behaviors and they present almost no sub-surface damage after ablation. Nevertheless, the formation of melted matter near created cavities, possibly recrystallized, is often observed.Different patterns (holes, lines, grids) have been…
Simulation numérique de la propagation d'une onde de choc issue d'une explosion en champ libre et son interaction avec un modèle biomécanique humain
2017
International audience; Les chargements liés à l’explosion sont fréquents dans le domaine militaire avec des conséquences plus ou moins sévères sur les structures en interaction avec cette sollicitation. Dans le contexte de protection du combattant, la compréhension de ce phénomène physique est important dans l’élaboration de systèmes de protection et pour prévenir les traumatismes liés aux chargements du "blast primaire". Dans ce contexte, ce papier décrit l’étude numérique d’une onde de souffle et son interaction avec un modèle biomécanique du corps humain, en utilisant les notions de similitudes
Influence de l'atmosphère gazeuse sur la cinétique de formation du titanate de baryum par réaction solide-solide
1986
International audience; Les études consacrées à la synthèse, par réaction solide-solide, du titanate de baryum (BaTiO3) ont montré l'importance des propriétés physicochimiques des solides initiaux (BaCO3 et TiO2) sur les propriétés du titanate obtenu. Lors de l'élaboration de céramiques diélectriques, il est en effet nécessaire d'éviter la formation de phases intermédiaires (Ba2TiO4, BaTi4O9, ...) qui nuisent à leurs propriétés diélectriques. La présence de ces phases peut être liée à une maîtrise imparfaite des nombreux paramètres influant sur la cinétique de la réaction. Le rôle de deux de ces paramètres : les traitements mécaniques et la nature de l'atmosphère gazeuse, fait l'objet de ce…
以认知的方法探讨法语和中文的时空心智结构
2022
In Mandarin, the word for the world is shìjiè (mandarin 世界), the morpheme shì (mandarin 世) indicates time, while the morpheme jiè (mandarin界) indicates space. Derived from the classic book of Buddhism, this dissyllabic word shìjiè (mandarin 世界) refers to both the notion of time and that of space. It remains true that understandings and representations of the world are inevitably based on those of space and those of time.Moreover, according to Gustave Guillaume, the distinction between noun and verb is fundamentally explained by that of the universe-space and the universe-time (see 1973a: 97). Indeed, the name, used to designate a being, either visible or invisible, is closely linked to the …
Quand la psychomécanique du langage rencontre le taoïsme : épistémologie élémentaire de la linguistique cinétique (I)
2022
While noting a homogeneity between the two schools of thought, namely the psychomechanics of language and Taoism, Bernard Pottier wrote an insightful article: Guillaume et le Tao: l'avant et l'après, le yang et le yin (1980). Although the two schools belong to two different disciplines and were born in two countries very far away, he was right to eliminate more or less their demarcations and to outline a continuity between the two. After all, according to Taoism, Yin-Yang conceives of both opposition and complementarity; the Yin-Yang coupling is in perpetual motion, each is both upstream and downstream of the other. This powerful dynamism is closely linked to the vector kinetics of the lang…
Systématique de la langue française au prisme du Tao
2022
Dans un contexte de la mondialisation, les échanges entre différentes communautés socio-culturelles sont de plus en plus faciles ; le principe de la pluralité des cultures valorisé largement par la Chine permet les rencontres heureuses de diverses civilisations. Dans ce contexte, nous étudierons à nouveau l’architecture de la langue française au niveau mental dans la perspective du Tao, dans le but d’expliquer son fonctionnement interne tout en profitant des principes Yin-Yang. De plus, la philosophie chinoise préconise souvent l’harmonie ; à dire vrai, existe une harmonie au sein de l’architecture de la langue française au niveau mental : l’avant et l’après, le support et l’apport, le mouv…