In-situ Hybridisierung von Faser-Metall Laminaten
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Date
2022
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Abstract
Die Reduktion der bewegten Massen stellt eine wesentliche Maßnahme zur Reduzierung
des Energieverbrauchs im Verkehrswesen dar. Möglichkeiten der Massenreduktion
werden durch Substitution von Werkstoffen oder durch Werkstoffverbunde ermöglicht.
Hierbei finden sich Faser-Metall Laminate aber bisher nur in der Flugzeugindustrie mit
vergleichsweise kleinen Stückzahlen wieder.
Diese Arbeit hat die Entwicklung eines neuen und innovativen Prozesses zur Herstellung
von Faser-Metall Laminaten zum Thema. Mittels der hier beschriebenen In-situ
Hybridisierung wird die Formgebung durch Tiefziehen mit der Infiltrierung des Fasergewebes
durch die Matrix kombiniert. So können Bauteile ohne Werkzeugwechsel in
einem Produktionsschritt hergestellt werden. Für die Entwicklung der In-situ Hybridisierung
ist eine genaue Kenntnis des Deformationsverhaltens des Gewebes wie auch die
Interaktion zwischen Gewebe und Deckblechen notwendig. Der Einfluss der Fasern auf
das Deformationsverhalten der metallischen Bleche wird mittels experimenteller und
numerischer Verfahren untersucht. Bei hohem transversalem Druck führt die Reibung
zwischen Fasern und Metall zu einer Absenkung der Umformbarkeit der Metallbleche.
Die Bedingungen für auftretende Relativverschiebungen zwischen den einzelnen
Schichten wurden untersucht und bestimmt. Hierbei stellt sich heraus, dass die Relativverschiebungen
aufgrund der Werkzeuggeometrien eher gering sind. Dem gegenüber
sind Reibungskräfte aufgrund direkten Kontaktes zwischen Fasern und Blech zu vermeiden.
Ein Demonstratorwerkzeug wurde entwickelt und aufgebaut, um die Eignung der Insitu
Hybridisierung zur Herstellung dreidimensionaler Bauteile aufzuzeigen. Verschiedene
Prozessparameter wurden in Versuchsreihen untersucht, um die Bedingungen eines
stabilen Herstellungsprozesses zu definieren. Die In-situ Hybridisierung stellt eine
Möglichkeit dar, um Leichtbauprodukte für einen breiteren Anwendungsbereich herzustellen.
In terms of reduction of the weight of the body-in-white of cars, different strategies have been applied. One strategy is the substitution of metals by using lighter materials like fibre reinforced plastics. By designing automobile components out of different materials, advantages of those materials can be combined. The use of metal-fibre laminates is nowadays only used in aircraft industry due to the low formability of the structures and the high number of production steps which lead to high costs. This thesis deals with the implementation of a new and innovative process for the manufacturing of fibre metal laminates in shorter production times with lower production costs. The new process, called In-situ-hybridization, combines the deep drawing with the process of polymer injection in one production step. For developing the In-situ-hybridization process, a deeper understanding of the fibre deformation behaviour and the interaction between fibre and metal layers is necessary. The influence of fibres on the forming behaviour of metal sheets is investigated by experimental and numerical methods. Due to high pressures on the layers of fibres and metal sheets, the friction between fibres and metal blanks decreases the formability of the connected sheet metal. As the different layers may slide independently from each other during deep drawing and matrix injection, the displacement between the layers should be minimized to avoid friction effects. The displacement caused by tool geometry or by frictional coefficients is characterized by using analytical and numerical methods. It can be concluded that the friction conditions between tool and metal sheets have much more influence on the offset between the upper and lower sheets than geometrical conditions. Forming experiments demonstrate the ability of the In-situ-hybridization process for manufacturing three-dimensional fibre-metal laminates. Process parameters have been studied and defined for reaching stable process conditions. So, the In-situ-hybridization may allow for a wider range of applications in lightweight products.
In terms of reduction of the weight of the body-in-white of cars, different strategies have been applied. One strategy is the substitution of metals by using lighter materials like fibre reinforced plastics. By designing automobile components out of different materials, advantages of those materials can be combined. The use of metal-fibre laminates is nowadays only used in aircraft industry due to the low formability of the structures and the high number of production steps which lead to high costs. This thesis deals with the implementation of a new and innovative process for the manufacturing of fibre metal laminates in shorter production times with lower production costs. The new process, called In-situ-hybridization, combines the deep drawing with the process of polymer injection in one production step. For developing the In-situ-hybridization process, a deeper understanding of the fibre deformation behaviour and the interaction between fibre and metal layers is necessary. The influence of fibres on the forming behaviour of metal sheets is investigated by experimental and numerical methods. Due to high pressures on the layers of fibres and metal sheets, the friction between fibres and metal blanks decreases the formability of the connected sheet metal. As the different layers may slide independently from each other during deep drawing and matrix injection, the displacement between the layers should be minimized to avoid friction effects. The displacement caused by tool geometry or by frictional coefficients is characterized by using analytical and numerical methods. It can be concluded that the friction conditions between tool and metal sheets have much more influence on the offset between the upper and lower sheets than geometrical conditions. Forming experiments demonstrate the ability of the In-situ-hybridization process for manufacturing three-dimensional fibre-metal laminates. Process parameters have been studied and defined for reaching stable process conditions. So, the In-situ-hybridization may allow for a wider range of applications in lightweight products.
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Keywords
Faser-Metall-Laminat-Bauteile, Umformtechnik