Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xiv, 189 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 157-160).

In order to fulfill increasing production rates, new automated production technologies are required for manufacturing carbon fiber reinforced plastic components for the aerospace industry. Currently, large, double curved composite components have to be manufactured manually, which leads to high process times and poor scalability. As a consequence, a team of cooperating robots with passively adjustable end-effectors was developed, that is capable of handling dry carbon textiles and can be used for layups in double curved molds. This thesis deals with the implementation of a robot program, that performs an automated adjustment of each end-effector to the surface geometry of the manufactured part. The functional principle and the accuracy of the process are evaluated. Further, the automatically adjusted end-effectors are utilized to cooperatively layup carbon plies. The results show, that the accuracy of the automated adjusting process is sufficient to drape carbon fabrics during pick-up and automated layup is possible with this approach. In conclusion, the developed process can be integrated into a fully automated process for future experiments, but hardware inaccuracies should be improved, in order to further enhance the accuracy of the system.

Orientadores: Lucia Helena Innocentini Mei, Jose Alexandrino de Sousa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-12T07:01:46Z (GMT). No. of bitstreams: 1 Giraldi_AndreLuisFerrarideMoura_D.pdf: 6788806 bytes, checksum: f1a0282da8520c3138e10549183d79b6 (MD5) Previous issue date: 2008 / Resumo: Uma aplicação importante do poli (tereftalato de etileno) - PET - pós-consumo a ser considerada, e ainda pouco explorada, diz respeito ao seu reaproveitamento em outros setores diferentes, tais como o de compósitos híbridos de fibra de vidro (FV) com matriz polimérica e modificador de impacto, para aplicações diversas na área de engenharia. Deste modo, se fez necessário um estudo sistemático de compósitos de PET, reforçado com fibra de vidro e modificador de impacto para sua utilização numa aplicação de engenharia. E necessário que este apresente uma boa relação entre propriedades de rigidez e resistência ao impacto, e para isto dois sistemas de reforço foram propostos com dois tipos de fibra de vidro com diferentes tratamentos superficiais (FV 952 e 983). Ensaios de reometria de torque indicaram a reatividade entre os componentes PET e modificador de impacto. Os ensaios mecânicos demonstraram que o modulo elástico e a resistência a tração dos compósitos diminuem conforme se aumenta a concentração de E-MA-GMA em substituição ao PET na matriz. Entretanto, o modulo e a resistência ao impacto aumentaram da ordem de 300 % e 900% respectivamente para as concentrações de 30% de fibra de vidro (FV 952) e 20% de E-MA-GMA. O modulo de elasticidade e independente do tipo de tratamento superficial da fibra de vidro. A resistência a tração e a resistência ao impacto Izod dependem da natureza do tratamento de silano usado. / Abstract: An important application of poly(ethylene terephtalate) - PET - to be considered, and still not well explored, is its re-use in other different sectors, such as the obtaintion of PET composites reinforced with fibre glass (FG) and elastomer, for several applications in the engineering area. In this way, it is necessary a systematic study of several PET composites hybrids reinforced with fibre glass and impact elastomer to obtain a good balance between engineering properties such strength, rigidity ans impact resistance, two systems of reinforced were investigated using two types treatment of surface different (FG 952 and 983). Torque rheometry investigations during composite mixing indicated the reactivity between PET and elastomer. Mechanical tensile test on PET / fibre glass / elastomer composites hybrids indicated that the elastic modulus and tensile strength reduce monotonically as higher volume fractions of E-MA-GMA substitute PET in the composite matrix. Composites hybrids with 30 wt% of fibre glass (FG 952) and 20 wt% of elastomer indicates mechanical gains of the order of 300% in modulus e 900 % Izod impact. Tensile modulus is relatively independent of type of silane treatment applied to the glass fibers. Yield strength and Izod impact strength depend on the nature of silane treatment used. / Doutorado / Ciencia e Tecnologia de Materiais / Doutor em Engenharia Química

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, October 2017 / This research looks into the manufacturing process of complex geometries using continuous fibre reinforced thermoplastics (CFRTP). The purpose of this work was to develop methods that will enable the production of defect free complex components. This was achieved by investigating the key process parameters in the CFRTP manufacturing process, and optimizing them in order to improve the quality of components. The investi- gations were performed with the aid of software making use of the finite element method, and this was found to be instrumental in predicting the formability of geometries. The re- search showed that the formability of complex geometry is largely determined by the ability of the laminate to be draped into the required geometry. The forming mechanisms that take place during the draping process can be linked to the formation of defects where draping is unsuccessful. The study also showed that the quality of the drape can be influenced by blank and tool design factors. It was also shown that the blank can be manipulated using a restraint mechanism to improve the formability of geometries. The effect of processing parameters such as forming speed, forming pressure and tool temperature were also investigated. The research resulted in the formulation of guidelines to follow when manufacturing CFRTP components. The developments that were made were successfully implemented to improve the formability of a complex component that had previously been difficult to form without defects. / MT2018

Innerhalb dieser Arbeit wird ein Fertigungsverfahren entwickelt und erprobt, das den additiven Aufbau von großvolumigen faserverstärkten Kunststoffbauteilen in Skelettbauweise erlaubt. Dafür wird ein modifizierter Extruder zusammen mit einer speziellen Kinematik genutzt. Der Fokus liegt auf der Analyse des Einflusses der Steuergrößen auf geometrische und mechanische Eigenschaften, sowie Haftung im Bauteil. Hinsichtlich der geometrischen Eigenschaften wird ein Prozessmodell entwickelt, das die Abhängigkeit der Strangbreite und -höhe von den Steuergrößen darstellt. Durch experimentelle Untersuchungen werden die Prozessgrenzen und an diesen auftretende Effekte ermittelt. Das Verfahren weist hier große Freiräume auf. So können z.B. mit einer 1 mm Düse Strangbreiten von 1,2 bis 3,2mm erzielt werden. Die mechanischen Eigenschaften in Strangrichtung erreichen im 3D-Druck annähernd die Steifigkeit und Festigkeit der Spritzgießreferenz. Prozessbedingt ist eine Porosität im Material nicht ganz vermeidbar, allerdings sind die Fasern stark ausgerichtet und die Faserlänge im Granulat bleibt im Prozess weitestgehend erhalten. Mittels direktem 3D-Drucken auf endlosfaserverstärktes Tape kann mit Vorheizen des Tapes ein guter Haftverbund generiert werden. Ergänzend wurden zwei Komponenten entwickelt, die für eine Industrialisierung des Prozesses entscheidend sind: Zum einen wurde ein neues Düsenkonzept vorgestellt, das eine schnelle Anpassung des Massestroms während des 3D-Druckens ermöglicht. Zum anderen wurde eine Temperierdüse vorgestellt, mit der mittels Konvektion der abgelegte Strang gekühlt bzw. erhitzt werden kann.:1 Einleitung 2 Zielstellung 3 Literaturübersicht 4 Konzeption eines neuartigen 3D-Druck-Verfahrens 5 Analyse der kinematischen Eigenschaften 6 Betrachtung der Haftungsmechanismen 7 Untersuchung der mechanischen Eigenschaften 8 Weiterentwicklung von Anlagenkomponenten 9 Zusammenfassung und Ausblick / In this thesis, a manufacturing process is presented which enables the additive manufacturing of largevolume fibre-reinforced plastic components in skeleton construction by using an extruder together with special kinematics. The focus is on the analysis of the influence of the control variables on geometric and mechanical properties, as well as adhesion in the component. With regard to the geometric properties, a process model is being developed that shows the dependence of the strand width and height on the control variables. Experimental investigations are used to determine the process limits and the effects occurring at these limits. The procedure knows here large free spaces, so e.g. with a 1 mm nozzle strand widths of 1,2 bis 3,2mm can be obtained. The mechanical properties in the strand direction in 3D printing approximate the stiffness and strength of the injection molding reference. Due to the process, porosity in the material cannot be completely avoided, however, the fibers are strongly oriented and the fiber length in the granulate is largely retained in the process. Direct 3D printing on continuous fiber-reinforced tape can be used to generate a good adhesive bond by preheating the tape. In addition, two components were developed that are decisive for industrializing the process: On the one hand, a new nozzle concept was introduced that enables rapid adjustment of the mass flow during 3D printing. On the other hand, a nozzle was presented with which the deposited strand can be cooled or heated by convection.:1 Einleitung 2 Zielstellung 3 Literaturübersicht 4 Konzeption eines neuartigen 3D-Druck-Verfahrens 5 Analyse der kinematischen Eigenschaften 6 Betrachtung der Haftungsmechanismen 7 Untersuchung der mechanischen Eigenschaften 8 Weiterentwicklung von Anlagenkomponenten 9 Zusammenfassung und Ausblick

Vacuum bags in conjunction with autoclaves are currently employed to generate the consolidation pressures and temperatures required to manufacture aerospace level composites. As the scale of continuous fiber composite structures increases autoclaving becomes prohibitively expensive or impossible. The objective of this work is to develop flexible magnetic clamping structures to increase the consolidation pressure in conventional vacuum bagging of composite laminates, thereby obviating the need for an autoclave. A ferromagnetic rubber, which consists of rubber filled with iron, is being developed as a conformable and reusable vacuum bag that provides increased consolidation through attractive forces produced by electromagnets. Experiments and finite element modeling indicate that consolidation pressure in the range of 100 kPa can be generated by such a device with realistic power requirements. The effects of the magnetic clamping device process parameters on the consolidation pressure magnitude are modeled and characterized. In addition, a method for the efficient design of the magnetic clamping device is developed.

This thesis presents a technique used to stochastically estimate the location of hidden discontinuities in carbon fiber composite materials. Composites pose a challenge to signal processing because speckle noise, as a result of reflections from impregnated laminas, masks useful information and impedes detection of hidden discontinuities. Although digital signal processing techniques have been exploited to lessen speckle noise and help to localize discontinuities, uncertainty in ultrasonic wave propagation and broadband frequency based inspections of composites still make it a difficult task. The technique proposed in this thesis estimates the location of hidden discontinuities stochastically in one- and two-dimensions based on statistical data of A-Scans and C-Scans. Multiple experiments have been performed on carbon fiber reinforced plastics including artificial delaminations and porosity at different depths in the thickness of material. A probabilistic approach, which precisely localizes discontinuities in high and low amplitude signals, has been used to present this method. Compared to conventional techniques the proposed technique offers a more reliable package, with the ability to detect discontinuities in signals with lower intensities by utilizing the repetitive amplitudes in multiple sensor observations obtained from one-dimensional A-Scans or two-dimensional C-Scan data sets. The thesis presents the methodology encompassing the proposed technique and the implementation of a system to process real ultrasonic signals and images for effective discontinuity detection and localization.

L’utilisation des fibres végétales dans les polymères composites suscite de nombreuses investigations. Avant de mélanger les fibres végétales dans le polymère, un traitement chimique peut être effectué permettant de réduire l’hydrophilicité des fibres et d’améliorer l'adhérence à l’interface fibre/matrice. Dans cette thèse, l'eau et l'alcali sont utilisés d'abord pour traiter les fibres de chanvre, puis trois agents silane : 3-(triméthoxysilyl)propyl méthacrylate (MPS), N-[3- (triméthoxysilyl)propyl] aniline (PAPS) et (3-Aminopropyl)-triéthoxysilane (APS), sont utilisés pour modifier plus ou moins la surface des fibres de chanvre. Ces fibres traitées ou modifiées sont ensuite mélangées avec le polypropylène (PP) pour la fabrication des composites. Les effets de ces différents traitements sur la structure, les composants et l’hydrophilicité des fibres, et les propriétés mécaniques de ces composites sont mis en évidence. Nous avons étudié ensuite l’effet de vieillissement sur leurs comportements mécaniques, notamment l'humidité, la température et le rayonnement ultraviolet. Les résultats ont montré que le traitement de fibres par l'eau et l’alcali a des effets considérables sur la structure de fibres, les propriétés mécaniques et la durabilité des composites renforcés. La modification par l'agent de silane a une influence moins importante sur la structure des fibres, pourtant son groupe fonctionnel a une influence significative sur les propriétés mécaniques et la résistance au vieillissement des composites renforcés / Using agro fiber as reinforcement of polymer com-posites attracts numerous investigations due to the good mechanical properties and environmental benefits. Prior to blend agro fiber with polymer, chemical treatment can be employed to treat agro fiber for the purpose of reducing the hydrophilicity of fiber and improving the interfacial adhesion fi-ber/polymer matrix. In this thesis, water and alkali are utilized to treat hemp fiber firstly and then three silane agent as 3-(Trimethoxysilyl)propyl methacry-late (MPS), N-[3-(Trimethoxysilyl)propyl]aniline (PAPS) and (3-Aminopropyl)-triethoxysilane (APS) are employed to modify the hemp fiber surface. These treated or modified fibers are blended respectively with polypropylene (PP) to fabricate the hemp fiber/PP composites. The effects of these different treatments on the structure, components and hydro-philicity of fiber, and the mechanical properties of the reinforced PP composites are studied. Moreover, the accelerated ageing experiments including humidity, temperature and ultraviolet of the reinforced PP composites are conducted. The results showed that the fiber treatment of water and alkali has a considerable effect on fiber structure, mechanical properties and durability of the reinforced compo-sites. The silane agent modification of fiber has less influence on the fiber structure but its functional group has great influence on the mechanical proper-ties and ageing resistance of the reinforced compo-sites.

Depuis quelques années les matériaux composites à base de fibres naturelles sont de plus en plus utilisés pour les nouvelles performances qu’ils proposent. C’est surtout au niveau des fibres naturelles que de nouvelles propriétés sont proposées. Dans ce travail, nous nous sommes essentiellement intéressés aux fibres naturelles de chanvre. Ces fibres sont déjà fortement utilisées dans l’automobile et la construction. En Europe, ces fibres sont produites principalement en France et plus particulièrement dans l’Aube. Pour développer des agro-composites hautes performances, c’est sous la forme de fibres longues et de tissus que nous avons choisi d’orienter ce travail de thèse. Nous avons choisi la thermocompression pour élaborer des plaques avec des tissus de chanvre et une matrice en polypropylène (PP). Ce travail permet de voir l’influence des conditions d’élaboration sur le comportement mécaniques de ces agro-composites. Cette thèse permet aussi de voir l’effet du vieillissement aux UV et à l’Humidité sur les performances de ces matériaux. Enfin une analyse des contraintes résiduelles par la méthode du trou incrémental permet de voir leurs effets sur ces agro-matériaux / In recent years composite materials based on natural fibers are more and more used for their new performances. Natural fibers propose attractive environmental, mechanical and thermal properties.In this work, we are firstly interested in hemp fibers. These fibers are already used in the automotive and construction industry. In Europe, these fibers are produced mainly in France and especially in Aube. To develop agro-composites with high performances, we have focused this thesis on hemp woven. We chose to elaborate the plates with hemp woven and a polypropylene matrix (PP) by compression molding. This work allows us to see the influence of elaboration conditions on the mechanical behavior of these agro-composites. This thesis also allows us to see the effect of aging conditions UV and humidity on the performance of these materials. Finally an analysis of residual stresses determined by the hole drilling method is proposed to see their effects on the agro-materials

Im Luftfahrtbereich haben sich kohlenstofffaserverstärkte Kunststoffe (CFK) wegen ihrer hohen spezifischen Festigkeiten und Steifigkeiten längst als Konstruktionswerkstoffe etabliert. In der Großserienfertigung von Automobilkarosserien kommt diese Materialgruppe jedoch nur zögerlich zum Einsatz. Offensichtlich sprechen noch viele Argumente für den Einsatz von metallischen Werkstoffen: Denn auch Leichtmetalle und pressgehärtete Stähle ermöglichen immer höhere Leichtbaugrade, ohne dabei signifikante Kostensteigerungen zu generieren. Zudem sind Fertigungs- und Montageabläufe für Metallkarosserien etabliert und weitgehend frei von Entwicklungsrisiken. Vor diesem Hintergrund erscheint es schwer, mit neuen Leichtbaumaterialien und den zugehörigen Bauweisen einen Durchbruch erzielen zu können. Dabei zeigt das Produktsegment der Supersportwagen schon deutlich, dass zusätzliche Leichtbaupotentiale durch beanspruchungsgerecht gestaltete und optimierte CFK-Strukturen für den Automobilbau eröffnet werden. Bislang lassen sich derartig optimierte CFK-Strukturen jedoch kaum wettbewerbsfähig in Großserie realisieren. An dieser Stelle ergeben sich Chancen und zugleich neue Herausforderungen für die Produktentwickler: Zum einen sind Faserverbundbauweisen zu erarbeiten, mit denen die Leichtbaupotentiale von CFK weitgehend ausgereizt werden. Zum anderen ist die automatisierte Fertigung bei hohen Taktraten zu ermöglichen. Die Lösung beider Teilaufgaben setzt den Einsatz geeigneter materialspezifischer Konstruktionsmethoden voraus.