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The primary contributor to greenhouse gases emissions in the European Union is the road transport sector, accounting for over 70% of total emissions. In response to this environmental concern, the EU is working on implementing strict regulations aimed at reducing emissions by 45% by the year 2030, compelling manufacturers of heavy-duty vehicles to produce emission free alternatives. While vehicle electrification is a promising solution,it introduces a new challenge: the need for lighter vehicles becomes more increasing with the incorporation of powerful yet heavy battery systems. This work aims to study the possibility of substituting the steel bus frames with composite material frames with the dual objectives of reducing the overall weight of the bus and minimising its environmental footprint throughout the life cycle of the part. The most suitable composite materials, manufacturing processes and joining methods for the studied frames were investigated based on literature review and a list of requirements. Composite finite element analysis was performed to study the behaviour of the composite assembly when it is inserted into the steel bus model to simulate the real-life environment.  The analysis performed showed that composite frames can facilitate a mass reduction of over half of the steel frames weight. An unfailing structural behaviour of the laminate can be achieved using adhesive bonding as the joining method between the two distinct materials. At the same time, two significant needs were highlighted: the importance of laminate optimisation (in terms of different material properties, number of layers and orientations) both to reduce costs and to maximise the structural strength through effective and efficient material distribution and the importance of partitioning the composite structure in a cost beneficial way (when it comes to scrap levels and moulds complexity). / Den huvudsakliga bidragande faktorn för utsläpp av växthusgaser inom den Europeiska Unionen är vägtransportsektorn som står för över 70% av alla utsläpp. Som gensvar på detta bekymmer för klimatet jobbar EU på att implementera stränga regler som syftar till att minska utsläppen med 45% till år 2030, vilket tvingar tillverkare av tunga fordon att producera utsläppsfria alternativ. Fastän fordonselektrifieringen är en lovande lösning, introducerar den en ny utmaning: behovet av lättare fordon ökar i takt med införandet av kraftfulla men tunga batterisystem.  Syftet med detta arbete är att studera möjligheten att ersätta bussars stålramar med kompositmaterialramar med det dubbla målet att minska bussarnas totala vikt samt minimera deras klimatvtryck under ramarnas livscykel. Tillverkningsprocessen och sammanfogningsmetoderna för de studerade ramarna undersöktes baserat på litteraturgenomgång och en kravlista för att ta fram de mest lämpliga kompositmaterialen. Kompositfinit elementanalys genomfördes för att studera beteendet hos ihopsättningen av kompositen när det sattes in i stålbussmodellen för att simulera den verkliga miljön. Den genomförda analysen visade att kompositramar kan leda till en massreduktion på över hälften av stålramarnas vikt. Ett osvikligt strukturellt beteende hos laminatet kan uppnås genom att använda adhesiv bindning som sammanfogningsmetod mellan de två distinkta materialen. Samtidigt lyftes två betydande behov: vikten av att optimera laminatet (vad gäller olika materialegenskaper, antal lager och orienteringar) både för att minskakostnader och för att maximera den strukturella styrkan genom effektiv materialfördelning och vikten av att dela upp kompositens struktur på ett kostnadseffektivt sätt (när det kommer till avfallsniv ̊aer och gjutningskomplexitet).

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Depuis la deuxième moitié du XXe siècle et le tournant du millénaire, pourquoi se multiplient des figures de la folie et du féminin dans le paysage littéraire haïtien ? En remarquant les grandes tendances qui font coïncider l’expression de la catastrophe, de la défaite du sens et l’apparition de personnages et de figures féminins majeurs dans des œuvres de tous genres, mon interrogation porte sur la folie, la marge et le féminin dans la littérature haïtienne contemporaine en tant qu’expressions concourantes de la dissemblance. Je me penche ainsi, dans des œuvres marquantes, sur le jeu rhétorique des postures de la dissemblance et la manière dont elles pointent depuis le texte vers un au-delà de l’œuvre, soit ce qui en elle indique l’ «espace ménagé» de sa propre faillite ainsi que le travail de la lecture et de la création. Pour cela, il a fallu, à partir des limites (de l’œuvre, de la norme), construire une réflexion capable d’aménager aussi l’espace de sa propre contestation. Dans le premier chapitre, à partir du récit fondateur « Folie », de Marie Chauvet, je pose le problème de la folie en me penchant sur les configurations inaugurales qui me semblent mettre la scène du littéraire contemporain haïtien. J’en profite pour préciser l’approche rhétorique qui me permettra d’aborder les textes littéraires, tout en réfléchissant sur les enjeux théoriques posés par une lecture de la folie comme absence d’œuvre. En m’appuyant sur Chauvet et sur les travaux de Felman, je définis les modalités d’une lecture impliquée. Dans le second chapitre, je brosse un portrait complexe du contemporain haïtien, tel qu’il est médié et rendu à travers les « anthologies » essentielles de Davertige et de Frankétienne. Ces deux œuvres sont l’occasion de poursuivre une interrogation sur les limites en remarquant les formes et les enjeux mobilisés dans le littéraire par les élaborations de la marge, de la mémoire traumatique et de la folie. Une telle approche est aussi l’occasion d’une réflexion de fond sur le contemporain haïtien, abordé d’emblée comme panorama et comme problème façonné et façonnant des sujets d’écriture. Enfin, dans le troisième chapitre, je me penche sur les filiations larvées qui permettent aux configurations précédemment décrites de persister, alors que le féminin, comme dissemblance, négocie sa place du côté de la marge ou de la folie, dans les textes plus récents de Jan Dominique et de Lyonel Trouillot. Les réflexions que je propose sur les destinations, sur l’œuvre impossible ou absente (Foucault) me permettent de distinguer les processus de différenciation spécifiques de la marge et de la folie, mais surtout d’apercevoir, au cœur du texte littéraire, la folie comme l’absence essentielle où se risque et se joue la création. Le dissemblable devient alors cet objet fuyant d’une lecture impliquée dans laquelle, le regard critique s’adossant à une écriture littéraire chargée d’en interrompre systématiquement le flux, constitue en effet ce « moment insolite de la théorie» (Felman), qui, dévoilant son propre jeu rhétorique, maintient la théorie en échec tout en la faisant parler. / Since the second half of the twentieth century and the turn of the millennium, why have representations of madness and the feminine proliferated in the Haitian literary landscape? Whilst reflecting on the broad tendencies that brought together the expression of catastrophe, the unravelling of meaning and the emergence of important feminine characters and figures in works of all genres, I will question madness, margins and the feminine in contemporary Haitian literature as concurring expressions of dissimilarity. Examining Haitian literary works, I want to propose a reading on the rhetoric postures and performances of dissimilarity and the manner in which they point towards an outsideness of literature: the unspeakable “thing” that signals – from within – the (im)possibility of the text, the (im)possibility of reading and creation. To achieve this purpose, I have chosen to construct a reading on limits (of the text, of the norm) that also considers its own contestation. Chapter one is built around the novel « Folie » by Marie Chauvet. It addresses the topic and rhetoric of madness while taking note of important aesthetic configurations that I suggest set the stage for contemporary Haitian literature. I also address methodological problems arising when “reading” madness as “absence d’œuvre” (Foucault). Intersecting Chauvet’s writing with the theoretical contributions of Felman, I specify my approach as a compromised or involved reading. In the second chapter, I paint the portrait of the contemporary Haitian general context using the essential anthologies of Davertige and Frankétienne. These two works allow me to address the notion of “limits” while considering the forms and issues created by the fabrications of margins, traumatic memory and madness. I therefore approach the contemporary Haitian context as a complex panorama and as a problem, both shaped by and shaping literary subjectivities. Finally, in the third chapter, analysing the more recent texts of Jan Dominique and Lyonel Trouillot, I reflect on hidden genealogies that perpetuate previously identified configurations when the feminine, as dissimilarity, negotiate a place on the side of margins or madness. The reflection I propose on destinations, the absent or impossible oeuvre allows me to differentiate the specificities of margins and madness, and most importantly, to glimpse, while reading the literary text, at the essential absence where creation risks itself. Thus, dissimilarity becomes the fleeting object of my compromised reading. A critical reading, which compromises itself with creative writing, in a decisive attempt to subvert theory, forcing it to unveil its own rhetorical play, to reveal its possible failure while making it eloquent.

A soldagem por fricção (Friction Stir Welding - FSW) é um processo eficiente de unir ligas de alumínio de alta resistência evitando defeitos que são usualmente criados quando técnicas convencionais de soldagem são utilizadas. A indústria aeronáutica tem mostrado grande interesse neste método de soldagem, tanto para a união de ligas similares como dissimilares. Entretanto, este processo causa modificações microestruturais dependentes das condições de tratamento térmico ou termomecânico. Contato elétrico entre zonas de microestruturas diferentes, por sua vez, pode resultar em acoplamento galvânico. No presente estudo, a soldagem por FSW foi usada para unir duas ligas de alumínio dissimilares, AA2024-T3 e AA7475-T651 e o efeito desta soldagem na resistência à corrosão das juntas soldadas e na microestrutura das ligas foi avaliada. Na investigação da resistência à corrosão foram utilizados ensaios eletroquímicos, especificamente, medidas de potencial de circuito aberto (OCP) em função do tempo de exposição ao meio corrosivo, ensaios de polarização e de espectroscopia de impedância eletroquímica, global (EIS) ou local (LEIS), em duas soluções, seja 0,1 M Na2SO4 ou 0,1 M Na2SO4 + 1 mM NaCl. Os ensaios eletroquímicos evidenciaram efeito de acoplamento galvânico nas juntas soldadas. A caracterização microestrutural foi realizada por microscopia ótica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão e por calorimetria diferencial. As zonas afetadas pela solda tiveram importantes modificações na microestrutura indicadas pela precipitação e dissolução de precipitados que afetam a resistência à corrosão localizada. A resistência à corrosão intergranular e a resistência à esfoliação das juntas soldadas também foram avaliadas e comparadas com as das ligas AA2024-T3 e AA7475-T651 não soldadas. Os resultados mostraram aumento da suscetibilidade das juntas soldadas a estas formas de corrosão em comparação com as ligas não soldadas sendo observado ataque mais severo na liga AA7475-T651. A identificação das áreas anódicas e catódicas resultantes do acoplamento galvânico nas juntas soldadas foi realizada por teste que consistiu na deposição de camada de gel (ágar-ágar) com indicador universal na superfície das ligas soldadas. A liga AA2024-T3 atuou como cátodo, enquanto a AA7475-T651, como ânodo no par galvânico. Além disso, evolução de hidrogênio foi observada na região de interface entre a zona termomecanicamente afetada e a termicamente afetada da liga AA7475-T651 mostrando que reações catódicas também ocorreram localmente nesta última liga. Resultados de LEIS obtidos nas diferentes zonas das duas ligas soldadas por FSW mostraram acoplamento galvânico na interface entre elas para tempos curtos de ensaio e deslocamento da região mais ativa com o tempo de ensaio para a liga AA7475-T651, mais precisamente para a interface entre a zona termomecanicamente afetada e a térmicamente afetada desta liga. / Friction Stir Welding (FSW) is an efficient process of joining high strength aluminum alloys avoiding defects that are usually created when conventional welding techniques are used. The aircraft industry has shown great interest in this welding method, both for welding of similar or dissimilar alloys. However, this process causes microstructural changes that are dependent on the thermal or thermomechanical conditions applied. Electrical contact between zones of different microstructures, in turn, can result in galvanic coupling. In the present study, FSW was used to join two dissimilar aluminum alloys, AA2024-T3 and AA7475-T651 and the effect of this process on the corrosion resistance of the welded joints and on the microstructure of the alloys was evaluated. For corrosion resistance evaluation, electrochemical tests were used, specifically, open circuit potential measurements (OCP) as a function of time of exposure time to the corrosive environment, polarization tests, and electrochemical impedance spectroscopy, global (EIS) or local (LEIS), in two solutions, either 0.1 M Na2SO4 or 0.1M Na2SO4 + 1 mM NaCl. The electrochemical tests showed galvanic coupling effects in the welded joints. Microstructural characterization was carried out by optical microscopy, scanning electron microscopy, transmission electron microscopy and differencial scanning calorimetry. The welded affected zones showed significant microstructural changes indicated by precipitation and dissolution of precipitates that affect the localized corrosion resistance. Intergranular and exfoliation corrosion resistance of the welded joints were also evaluated and compared to those of unwelded AA2024-T3 and AA7475-T651 alloys. The results showed increased susceptibility of welded joints to these forms of corrosion in comparison with the unwelded alloys with more severe attack associated to the AA7475-T651 alloy. Identification of anodic and cathodic areas due to galvanic coupling in the welded joints was evaluated by a test consisting in depositing a gel layer (ágar-ágar) with universal indicator on the surface of the welded alloys. The AA2024-T3 alloy worked as cathode, while the AA7475-T651 as anode in the galvanic coupling. Furthermore, hydrogen evolution was observed at the interface region between the thermomechanically affected zone and the heat affected alloy AA7475-T651 showing that cathodic reactions also occurred on this last alloy. LEIS results obtained in different zones of the two FSW welded alloys showed galvanic coupling at the interface between them for short test times and displacement of the most active region to the AA7475-T651 alloy, at longer periods of test, specifically to the interface between the thermomechanically affected and the heat affected zones of this last alloy.

Industrial products of high-strength Al-alloys are currently manufactured by thermo-mechanical processes, which are only applicable in the integrated plants requiring high investment cost. Moreover, reduction of the average grain size not less than 10 &mu / m and re-adjustment of process parameters for each alloy type is evaluated as disadvantage. Therefore, recently there have been many research studies for development of alternative manufacturing techniques for aluminum alloys. Research activities have shown that it is possible to improve the strength of Al-alloys remarkably by severe plastic deformation which results in ultra-fine grain size. This study aims to design and manufacture the laboratory scale set-ups for severe plastic deformation of aluminum alloys, and to characterize the severely deformed samples. The stages of the study are summarized below: First, for optimization of die design and investigation of parameters affecting the deformation finite element modeling simulations were performed. The effects of process parameters (die geometry, friction coefficient) and material properties (strain hardening, strain-rate sensitivity) were investigated. Next, Equal Channel Angular Pressing (ECAP) system that can severely deform the rod shaped samples were designed and manufactured. The variations in the microstructure and mechanical properties of 2024 Al-alloy rods deformed by ECAP were investigated. Finally, based on the experience gained, a Dissimilar Channel Angular Pressing (DCAP) system for severe plastic deformation of flat products was designed and manufactured / then, 6061 Al-alloy strips were deformed. By performing hardness and tension tests on the strips that were deformed by various passes, the capability of the DCAP set-up for production of ultra-fine grain sized high-strength aluminum flat samples were investigated.