Orientador: Michelli Leali Costa / Resumo: Dentre os setores de aplicações comerciais de materiais compósitos avançados, destaca-se o setor aeroespacial com larga aplicação desses materiais. Entre as técnicas de união aplicadas aos compósitos termoplásticos está a soldagem com grandes vantagens em relação aos outros processos de uniões tais como, redução de custo, agilidade de processamento, redução de elementos acumuladores de tensão, preparações mais simplórias das superfícies a serem soldadas. Mesmo com essas vantagens e, embora o processo já seja utilizado nos setores industriais, a soldagem de compósitos tem como desafio a melhoria de sua resistência, a aplicação do processo para reparos ou processamentos em campo, além da necessidade de avaliação dos efeitos das condições climáticas em juntas soldadas, as quais podem estar submetidas quando em operação em uma aeronave, por exemplo. Mediante a isso, esse trabalho visa produzir e estudar juntas soldadas por resistência elétrica e por tocha acetilênica em compósito PEI/fibra de vidro. Os compósitos obtidos foram submetidos ao condicionamento higrotérmico seguido de ensaios mecânicos de LSS (Lap Shear Strength) e ENF (End-Notched Flexure). O mecanismo de fratura das juntas soldadas foi avaliado por microscopia. A partir das análises e dos resultados obtidos, foi observado que os valores de resistência ao cisalhamento em modo II dos compósitos soldados por resistência elétrica (3270,9 J/m²) são similares aos descritos na literatura para os compósitos PEI/fibra de vid... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Among the commercial application sectors of advanced composite materials, the aerospace sector with wide application of these materials stands out. Among the joining techniques applied to thermoplastic composites is welding with great advantages over other joining processes such as cost reduction, processing agility, reduction of stress accumulators, little or no preparation required of the surface to be processed. Even with these advantages, and although the process is already used in the industrial sectors, composite welding has the challenge of improving its resistance, the application of the process for field repairs or processing, and the need to evaluate the effects of weather conditions. welded joints, which may be subjected when operating in an aircraft, for example. Therefore, this work aims to produce and study joints welded by electric resistance and acetylene torch in PEI / fiberglass composite. The composites obtained were subjected to hygrothermal conditioning followed by mechanical tests of LSS (Lap Shear Strength) and ENF (End-Notched Flexure). The fracture mechanism of the welded joints was evaluated by microscopy. From the analyzes and results obtained, it was observed that the shear strength values in mode II of the composites welded by electric resistance (3270.9 J / m²) are similar to those described in the literature for PEI / fiberglass composites. However, for the composites welded by the oxyacetylene process, a reduction of approximately 20% in the va... (Complete abstract click electronic access below) / Mestre

Leichtbau zählt als eines der Zukunftstechnologien des 21. Jahrhunderts, um sowohl die Mobilitätsfragen von morgen zu beantworten als auch die klima- und energiepolitischen Ziele zu erreichen. Ein wesentlicher Fokus wird dabei auf Multi-Material-Systeme gelegt. Insbesondere die Kombination von faserverstärkten Kunststoffen und metallischen Legierungen zu sog. hybriden Laminaten zeigt ein hohes Substitutions- und Leichtbaupotential gegenüber klassischen monolithischen Konstruktionswerkstoffen. Vorrangig werden derartige hybride Schichtverbunde mit einer duroplastischen Matrix hergestellt, wodurch allerdings Restriktionen, bspw. gegenüber Produktivität, Recycling- und Lagerfähigkeit, resultieren. Eine besondere Alternative dazu bieten hybride Laminate auf Thermoplastbasis. Im Rahmen dieser Arbeit wurden die am Bundesexzellenzcluster MERGE entwickelten neuartigen thermoplastbasierten Schichtverbunde Carbon Fibre-Reinforced Polyamid/Aluminium Laminate (CAPAAL®) und Carbon Fibre-Reinforced Thermoplastic Polyurethane/Aluminium Laminate (CATPUAL) erforscht und im optimierten variothermen Pressprozess hergestellt. Um die Werkstoffverbunde über die Grundlagenforschung hinaus, etwa in der industriellen Nutzung, zu etablieren, wurden umfangreiche Charakterisierungen und Fertigungsstudien durchgeführt. Zum einen erfolgten mikrostrukturell-analytische Untersuchungen u. a. zu der Imprägniergüte, der Oberflächenbehandlung der Aluminiumlegierung und des Versagensverhaltens. Zum anderen fanden mechanisch-technologische Charakterisierungen bezüglich quasi-statischer Versuche unter Zug- und Biegebelastung sowie Ermüdungsversuche unter Biegebelastung im Niedrig-Frequenzbereich statt. Die quasi-statischen Untersuchungen der Subkomponenten (Aluminiumlegierung, Verbundwerkstoff) und der hybriden Laminate wurden sowohl unter Raumtemperatur als auch unter definierten Temperaturbelastungen und Konditionierungszuständen durchgeführt, um deren Sensitivität zu analysieren sowie zu bewerten. Ebenfalls erfolgten analytische Berechnungen zur Auslegung der hybriden Schichtverbunde basierend auf der klassischen Laminattheorie und der Mischungsregel unter Einbeziehung des Metallvolumengehalts. Darüber hinaus wurden die thermisch induzierten Eigenspannungen analytisch ermittelt und in die Berechnungen der quasi-statischen Kennwerte inkludiert. Anhand der Untersuchungen konnte nachgewiesen werden, dass CAPAAL® und CATPUAL als „maßgeschneiderte“ Halbzeuge oder Strukturbauteile mit einem hohen Leichtbaupotential für großseriennahe Anwendungen prädestiniert sind. Diese weisen in Abhängigkeit der medialen Belastungen eine höhere Performance und ein weniger katastrophales Versagensverhalten als die entsprechenden Faser-Kunststoff-Verbunde auf. Zudem wurde konstatiert, dass eine hervorragende Ermüdungsfestigkeit unter Biegebelastung vorliegt. Die theoretischen Vorhersagen weisen vor allem über den Ansatz der Mischungsregel eine gute Korrelation zu den experimentell ermittelten Kennwerten auf.:1 Einleitung 2 Stand der Wissenschaft und Technik 3 Materialien und experimentelle Untersuchungen 4 Versuchsergebnisse und Diskussion 5 Bewertung der erzielten Ergebnisse 6 Ausgewählte Leichtbaulösungen 7 Zusammenfassung und Ausblick / Lightweight construction is considered one of the future technologies of the 21st century, both to answer tomorrow's mobility questions and to achieve climate and energy policy goals. A major focus is placed on multi-material systems. In particular, the combination of fibre-reinforced plastics and metal alloys to form so-called hybrid laminates shows a high substitution and lightweight construction potential compared to classic monolithic construction materials. Such hybrid laminates are primarily produced with a thermoset matrix, which results in restrictions, e. g. with regard to productivity, recyclability and storability. Hybrid laminates based on thermoplastics offer a special alternative. In the context of this work, the novel thermoplastic-based laminates Carbon Fibre-Reinforced Polyamid/Aluminium Laminate (CAPAAL®) and Carbon Fibre-Reinforced Thermoplastic Polyurethane/Aluminium Laminate (CATPUAL) were researched and produced in an optimised vario-heat pressing process. In order to establish the material composites beyond basic research, for example in industrial use, extensive characterization and manufacturing studies were carried out. On the one hand, microstructural-analytical characterisations were conducted, for example, on the impregnation quality, the surface treatment of the aluminium alloy and the failure behaviour. On the other hand, mechanical-technological investigations were carried out with regard to quasi-static tests under tensile and bending load as well as fatigue tests under bending load in the low-frequency range. The quasi-static tests of the subcomponents (aluminium alloy, composite material) and hybrid laminates were carried out both at room temperature and under defined temperature loads and conditioning conditions in order to analyse and evaluate their sensitivity. Analytical calculations for the design of the hybrid laminates based on the classical laminate theory and the rule of mixtures including the metal volume content were also considered. Furthermore, the thermally induced residual stresses were determined analytically and included in the calculations of the quasi-static characteristic values. Based on the investigations, it was possible to prove that CAPAAL® and CATPUAL are predestined as 'tailor-made' semi-finished products or structural components with a high lightweight construction potential for applications close to large-scale production. Depending on the medial loads, these exhibit higher performance and less catastrophic failure behaviour than the corresponding fibre-plastic composites. In addition, it was stated that there is an excellent fatigue strength under bending load. The theoretical predictions show a good correlation to the experimentally determined characteristic values, especially via the rule of mixtures approach.:1 Einleitung 2 Stand der Wissenschaft und Technik 3 Materialien und experimentelle Untersuchungen 4 Versuchsergebnisse und Diskussion 5 Bewertung der erzielten Ergebnisse 6 Ausgewählte Leichtbaulösungen 7 Zusammenfassung und Ausblick