Elastic-strain distribution in metallic film-polymer substrate composites

Synchrotron x-ray radiation was used for in situ strain measurements during uniaxial tests on polymer substrates coated by a metallic gold film 400 nm thick deposited without interlayer or surface treatment. X-ray diffraction allowed capturing both components elastic strains and determining how these were partitioned between the metallic film and the polymeric substrate. For strains below 0.8%, deformation is continuous through the metal-polymer interface while above, the onset of plasticity in the metallic film induces a shift between film and substrate elastic strains

Controlled biaxial deformation of nanostructured W/Cu thin films studied by X-ray diffraction

The deformation behaviour of 150. nm thick W/Cu nanocomposite deposited on polyimide substrates has been analysed under equi-biaxial tensile testing coupled to X-ray diffraction technique. The experiments were carried out using a biaxial device that has been developed for the DiffAbs beamline of SOLEIL synchrotron source. Finite element analysis has been performed to study the strain distribution into the cruciform shape substrate and define the homogeneous deformed volume. X-ray measured elastic strains in tungsten sub-layers could be carried out for both principal directions. The strain field was determined to be almost equi-biaxial as expected and compared to finite element calculations

Elastic anisotropy of polycrystalline Au films: Modeling and respective contributions of X-ray diffraction, nanoindentation and Brillouin light scattering

Elastic properties of non-textured and {1 1 1}-fiber-textured gold thin films were investigated experimentally by several complementary techniques, namely in situ tensile testing under X-ray diffraction (XRD), nanoindentation and Brillouin light scattering (BLS). Specimens were probed along different directions to reveal the strong effects of elastic anisotropy at the (local) grain and (global) film scales. XRD allows the investigation of both local and global anisotropies, while BLS and nanoindentation are limited to global analyses. A micromechanical model, based on the self-consistent scheme, and accounting for the actual microstructure of the films, is applied to interpret experimental data. Although different types of elastic constants can be determined with the used experimental techniques (static/dynamic, local/global), a good agreement is obtained, showing that comparison of these techniques is feasible when carried out carefully. In particular, the use of a micromechanical model to estimate the effects of the local elastic anisotropy at the film scale is unavoidable. The presented results show that XRD, BLS and nanoindentation should capture anisotropic texture effects on elastic constants measurements for materials with a Zener anisotropy index larger than 2. Conversely, the actual texture of a given specimen should be taken into account for a proper analysis of elastic constants measurements using those three experimental techniques

Avec le plan, contre le modèle. Urbanisme et changement urbain à Riga en URSS (1945-1990)

Composition du jury : Isabelle Backouche, directrice d’études à l’ÉHESS, Centre de recherches historiques ;Alain Blum, président du jury, directeur d’études à l’ÉHESS, CERCEC, directeur de recherches à l’INED ; Viviane Claude, rapporteur, professeure à l’Institut d'Urbanisme de Lyon, Université Lyon II ;Jean-Louis Cohen, professeur à Institute of Fine Arts, New York University ;Jörg Hackmann, rapporteur, professeur à l’Université de Szczecin, Institut d’histoire et des relations international..

Avec le plan, contre le modèle. Urbanisme et changement urbain à Riga en URSS (1945-1990)

Composition du jury : Isabelle Backouche, directrice d’études à l’ÉHESS, Centre de recherches historiques ;Alain Blum, président du jury, directeur d’études à l’ÉHESS, CERCEC, directeur de recherches à l’INED ; Viviane Claude, rapporteur, professeure à l’Institut d'Urbanisme de Lyon, Université Lyon II ;Jean-Louis Cohen, professeur à Institute of Fine Arts, New York University ;Jörg Hackmann, rapporteur, professeur à l’Université de Szczecin, Institut d’histoire et des relations international..

D’une guerre à l’autre : imaginaires allemands de la Première Guerre mondiale sur le front balte

International audienceThe first visual sources relating to the Baltic Region kept at La contemporaine date from the First World War, whose battles continued until 1920 in the region. They are mainly the Product of German views on the Region. As such, they reflect very well several German Narratives that were still much vivid when the German-Soviet Pact was signed in 1939.Les premières sources visuelles relatives à la région balte conservées à La contemporaine datent de la Première Guerre mondiale dont les combats se sont prolongés jusqu’en 1920 dans la région. Elles sont essentiellement le produit de points de vue allemands sur la région. À ce titre, elles reflètent très bien différents imaginaires allemands qui seront encore très vivaces lors de la signature du pacte germano-soviétique en 1939

La question de Vilnius 1939-1989 : entretien avec Catherine Gousseff

International audienceIn 1989, historian Catherine Gousseff went to Vilnius as part of the collective investigation “Grey Memory in the East” initiated by the BDIC. In this interview, she discusses the conditions under which she carried out this research out and the questions that animated her at the time about the memories of the city’s cultural communities.En 1989, l’historienne Catherine Gousseff s’est rendue à Vilnius dans le cadre de l’enquête collective « Mémoire grise à l’Est » initiée par la BDIC. Dans cet entretien, elle revient sur les conditions de réalisation de cette recherche et les questionnements qui l’animaient alors sur les mémoires des communautés culturelles de la ville

Documenter l’histoire des pays de la Baltique (Estonie, Lettonie, Lituanie) à La contemporaine

International audienceL’article introductif analyse les collections sur les pays baltiques / républiques socialistes soviétiques baltes / États baltes de la contemporaine. La région balte est difficilement identifiable dans les collections, du fait de son destin heurté au Vingtième siècle ou du peu d’intérêt qu’on lui porte. Seuls deux grands ensembles documentaires sont abondamment alimentés : l’un concerne les minorités germanophones de la région, l’autre la « question balte » pendant la guerre froide. Cette situation s’explique par des logiques d’acquisition et des enjeux internationaux bien spécifiques.The opening article analyses the collections dedicated to the Baltic states / the Baltic Soviet republics in the library. The Baltic region is not well represented in the collections, probably because of its complicated geopolitical destiny in the XXth century, and because of the lack of interest of many international actors. Only two documentary sets are well founded. The first one deals with the German-speaking minorities, the second – with the “Baltic question” during the Cold War. This can be explained both by inner logics of the library policy of acquisition, and by international stakes that they illustrated

Hybrid piezochromic coatings for impact detection on composite substrates for aeronautic

International audienceStructural Health Monitoring (SHM) is a major issue in the aeronautic field, especially for impact detection on composite materials which can be time consuming. Impact-sensitive coatings are an interesting way to save costs and time associated with these monitoring operations. This paper describes the successful preparation of a reversible piezochromic coating for impacts detection on composite substrates. It results from the incorporation of piezochromic pigments into a hybrid organic-inorganic matrix. It has been optimized by studying and quantifying their piezochromic behavior by UV-visible spectroscopy. It revealed that the piezochromic properties of the sensitive coating and the pigments alone are quite different and ruled by the hardness of the film. The obtained sensitivity and threshold pressure are determined to be 28% GPa−1 and 0.2 GPa respectively