La PESD et ses évolutions

Chapitre traçant un bilan et les perspectives de la PESD en 2005

The EU as a global peace actor? A challenge between EU conflict management and national paths

This paper raises the question of a policy for conflict in the making for the EU: the European Defense and Security Policy. After a brief presentation of our analytical method, we structure the paper in three axes. First, where does CSDP come from and what are its main objectives? Then, what is European specificity in developing specific crisis management tools, and how do these tools work and socialize the diplomatic and politico-military actors involved? Last but not least, how does CSDP interplay between Brussels and the member states? What does CSDP change for them, and what are its obvious and more pregnant limits up to now? CSDP constitutes a way for the Europeans to exit the world order of the Cold War and aims at providing the EU with a median way of crisis and conflict management between the approaches developed by traditional international organizations as NATO, the UNO or the OSCE. CSDP incarnates also the commitment of the three leading countries in defense and security matters in Europe–France, Great Britain and Germany- to overcome the shock of the Balkans crisis where Europe had been characterized by its division and inability to act effectively to solve the conflict. Therefore the member states had built specific organs, tools and procedures in the framework of CSDP. The originality and added value of the EU with its crisis management policy as the heart of CSDP is to propose an integrated approach combining military and civilian instruments. This however raises several fundamental questions. CSDP still lacks cross-pillar coherence, particularly regarding the financing of CSDP operations. This also raises the question of the interplay between Brussels and the member states: deploying troops is still a national sovereign decision and EU states keep on analyzing situations in the light of their national security interest. Yet CSDP combined with the new trends in military socialization since the 80’s constitute a strong incentive to reform both the armies and military education. Thus CSDP seems to be a hopeful way of developing a European crisis management policy putting into light the assets of the EU in this area.Straipsnyje siekiama apžvelgti konfliktų sprendimo strategijos įtaką Europos Sąjungos strategijos ir Europos gynybos ir saugumo politikos formavimuisi (EGSP). Pateikus trumpą analitinio metodo apžvalgą siekiama atsakyti į šiuos klausimus: kokia EGSP kilmė ir kokie jos pagrindiniai tikslai?; kokius europinius ypatumus atspindi siūlomi krizių valdymo metodai?; kaip šie metodai veikia ir kaip jie telkia į konfliktą įtrauktus diplomatinius ir politinius karinius veikėjus? Dar vienas ne mažiau aktualus klausimas – EGSP formavimas Briuselio ir šalių narių santykiuose? Kokius pokyčius ši politika įneša į jų egzistavimą ir kokie šiuo metu akivaizdūs ir spręstini pokyčių ribojimo veiksniai? EGSP – tai europiečių būdas išvengti šaltojo karo pasaulio suskirstymo; ES krizių ir konfliktų valdymo būdas, tarpinis tarp strategijų, kuriomis vadovaujasi tradicinės tarptautinės organizacijos, kaip, pavyzdžiui, NATO, JTO ar ESBO. EGSP taip pat įkūnija trijų didžiųjų Europos Sąjungos šalių – Prancūzijos, Didžiosios Britanijos ir Vokietijos, įsipareigojimus Europos gynybai ir saugumui, siekiant atsigauti po Balkanų krizės, kai Europa liko susiskaidžiusi, negebanti žengti ryžtingų konflikto sprendimo žingsnių. Dėl šios priežasties šalys narės sukūrė specialius EGSP įgyvendinimo organus, įrankius ir procedūras. ES krizių valdymo būdų, kurie sudaro EGSP šerdį, išskirtinumas – originalumas ir pridėtinės vertės suponavimas. Siūloma taikyti integruotą karinių ir civilinių įrankių visumą. Tačiau čia kyla esminių klausimų. EGSP vis dar nesukūrė atskirus politinius ramsčius siejančio mechanizmo, ypač kai kalbama apie EGSP opercijų finansavimą. Vėl kyla klausimas dėl Briuselio ir šalių narių bendradarbiavimo, t. y. karinių dalinių dislokavimas lieka nacionalinio suverenumo prioritetu, ir ES šalys analizuoja [...

Study and prevention of cracking during weld-repair of heat-resistant cast steels

International audienceHeat-resistant cast steels are highly sensitive to cracking as they are weld-repaired because of their very low ductility. To prevent weld-repair cracking of three different heat-resistant cast steels used for the manufacturing of superplastic forming (SPF) dies, the effect of various welding parameters, such as the choice of the filler material, the number of weld passes and the pre-heating temperature has been investigated. The choice of an appropriate filler metal and the pre-heating to 400 °C of the material prior to welding drastically lower the propensity to cracking, but remain unable to eliminate cracks entirely. To further reduce weld-repair cracking and hopefully prevent it completely, a buttering technique has been developed. Buttering of the base metal surface with nickel alloys before weld-repair has been shown to prevent cracking of the base metal, but results in some hot-cracking of the buttering layer itself. On the other hand, buttering with Ni-Fe alloys, less sensitive to hot-cracking, results in crack-free weld repairs

Oxidation modelling of a Si3N4–TiN ceramic: microstructure and kinetic laws

International audienceThe oxidation of a silicon nitride–titanium nitride ceramic has been studied. Based on microstructural observations, a phenomenological oxidation model is described, and an oxidation kinetic model has been proposed. For temperatures <1000 °C, only the TiN phase is oxidised. The oxidation process is then controlled by oxygen diffusion through TiO2, described by a parabolic oxidation kinetic law. The process is more complex above 1000 °C, because of the simultaneous oxidation of both Si3N4 and TiN phases. Three oxidation modes, controlled by distinct diffusion mechanisms, take place successively. In a first step, Si3N4 and TiN phases are independently oxidised, respectively into SiO2 and TiO2 phases. Si3N4 oxidation is controlled by oxygen diffusion through SiO2, while TiN oxidation is controlled by titanium diffusion through TiO2. In a second step, the TiN oxidation is controlled by oxygen diffusion through TiO2 and through SiO2 formed by Si3N4 oxidation. In the third step, oxidation of the TiN and Si3N4 phases is controlled by oxygen diffusion through the silica layer. Kinetic laws have been proposed for each of these three oxidation modes

Experimental and numerical investigation of the weld repair of superplastic forming dies

Issu de : AMPT 2003 - International conference on advances in materials and processing technologies, Dublin, IRELAND, July 8-11, 2003International audienceSuperplastic forming process (SPF) is an advanced process conducted at high temperature using moderate strain rates, typically used for shaping TAW sheets for aerospace applications. Thermomechanical stresses on the forming dies due to successive forming cycles may result in the earl), degradation and even fracture of SPF tools through fatigue crack propagation. To reduce cost and extend service life. dies are generally weld-repaired and subsequently re-used in the typical severe conditions of SPF. The implementation of robust, easy processing welding techniques resulting in high quality repair able to sustain cumulative thermomechanical stresses is of utmost concern to SPF parts manufacturers. The paper focuses on the development of an automated TIG technique to weld repair high nickel, high chromium heat resistant alloys based on a complementary approach including thermal instrumentation, numerical simulation using Sysweld(TM) and metallurgical investigation: this former being performed on either as-received, repaired and repaired plus damaged materials

Effect of process parameters on the quality of aluminium alloy Al5Si deposits in wire and arc additive manufacturing using a cold metal transfer process

International audienceA 3D print device using a cold metal transfer arc welding station to melt a metallic filler wire is developed to build aluminium part by optimising the process parameters. First tests achieved using standard pre-recorded process parameters allow to study the effect of the travel speed and the average welding power on the geometrical characteristics of mono-layer deposits and on walls built by layers superposition. Finally, a parametric study of the effect of each process parameter controlling the shape of the arc current or voltage and the filler wire feeding is carried out in order to try to improve the geometrical regularity of the deposits, and to better understand the effect of each parameter on the melting of the filler wire, its transfer on the support plate, and the geometry of the formed bead

Hot tearing test for TIG welding of aluminum alloys: application of a stress parallel to the fusion line

Welding processes are extensively used to assemble components in many manufacturing industries, such as aeronautics, construction, energy and automotive. To increase their productivity, constructors try to reduce manufacturing time. This involves for welding operations an increase of welding speed. However, various defects such as hot tearing might limit this increase. Hot tearing appears at the solidification end of an alloy, and is commonly observed in welding. During welding, components are subjected to high thermal gradients around the melting zone due to localized heat input. The solidification zone, where microstructure forms, is located at the rear of the melting zone and is bordered by two isothermal surfaces corresponding to liquidus and solidus temperatures. In welding, due to high thermal gradients, solidification by epitaxial growth of columnar dendrites is generally observed from the border of the melting zone. However, equiaxed dendritic grains can also form in the center area of the melting zone

De l'Eurocorps à une armée européenne ?<br />Pour une sociologie historique de la politique européenne de sécurité et de défense (1991-2007)

Réalisée en 4 ans, rédigée en 2007-2008.This dissertation deals with the construction, practices and legitimating uses of the European Security and Defence Policy since the 1990's. First we study the genesis of the European defence policy taking into account short-term factors opening a policy window (the end of the Cold War, the Balkan conflicts, NATO's reform) as well as structural factors, in this case the socializing framework of the French-German military cooperation. We demonstrate the political entrepreneurship of Mitterrand and Kohl seizing this policy window. They were later taken over by the diplomatic services of the EU states. Secondly we analyze the construction of the European defence policy as a specific social figuration within the EU framework. This new social figuration, relying on proper organs and on intergovernmentalism, interplays with the national defence figurations structured in time, modifying the interdependence games between the capitals and Brussels, and between the main actors groups (in this case officers, diplomats and defence civil servants). Moreover this ESDP figuration is deeply affected and modelled by the weight of the socialization of theses actors on a threefold level: national, professional and institutional. These several socialization weigh on the way theses actors daily practice and conceive the European defence policy .Indeed this new social space is invested on different ways by each categories of actors (military and diplomatic/civilian). Last but not least, the national security cultures are still very pregnant and go on framing ESDP in different ways according to the security representations of each state. This raises legitimating questions for this policy. Eventually European Security and Defence Policy does not aim at building a Euro-army, but fulfils latent functions as a political and symbolic substitute for European security action in the world. These latent functions appear to be at least as important as, if not more than, its manifest functions of reactivity to crisis. Thus ESDP aims at helping construct politically an international role for the EU in security matters.Cette thèse porte sur la construction, la pratique et les usages de la Politique Européenne de Sécurité et de Défense depuis les années 1990. Elle étudie en premier lieu la genèse de la politique européenne de défense en prenant en compte tant les facteurs conjoncturels comme fenêtre d'opportunité politique (la fin de la guerre froide, conflits balkaniques, réforme de l'OTAN) que structurels, en l'occurrence le cadre de socialisation de la coopération militaire franco-allemande. La thèse démontre le rôle d'entrepreneurs politiques joués par Mitterrand et Kohl, relayés ensuite par les services diplomatiques européens. Dans un second temps, la thèse analyse la construction de la politique européenne de défense comme une configuration sociale spécifique au sein de la construction européenne. Cette configuration nouvelle, dotée d'organes propres et régie par l'intergouvernementalisme, interfère avec les configurations nationales de politique étrangère et de défense structurées sur le temps long, en modifiant les jeux d'interdépendance entre les capitales et Bruxelles, et entre les différents groupes d'acteurs concernés (en l'occurrence avant tout les militaires, et les diplomates et acteurs civils de la Défense). De plus, la configuration PESD est largement affectée par le poids de la socialisation tant nationale que professionnelle et organisationnelle des acteurs, qui influence leurs pratiques et leurs représentations de cette politique. Ce nouvel espace social fait l'objet d'un investissement différencié par les principaux acteurs qui la font fonctionner. Enfin, le poids des représentations nationales de sécurité joue à un niveau macro comme un obstacle pour la PESD, ce qui soulève dès lors des enjeux de légitimation pour elle. Finalement, la PESD ne vise pas à construire une armée européenne, mais remplit des fonctions latentes de substitut politique et symbolique au moins aussi importantes, si ce n'est plus, que ses fonctions manifestes de réactivité aux crises. La PESD contribue ainsi à construire politiquement le rôle d'acteur international de l'UE en matière de sécurité