Browsing by Author "Mindermann, Pascal"

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Open Access
Adaptive winding pin and hooking capacity model for coreless filament winding
(2023) Mindermann, Pascal; Gresser, Götz T
Coreless filament winding is a manufacturing process used for fiber-reinforced composites, resulting in high-performance lightweight lattice structures. Load transmission elements, which are assembled from commercially available standardized parts, often restrict the component design. A novel adaptive winding pin was developed, which is made by additive manufacturing and can therefore be adjusted to specific load conditions resulting from its position within the component. This allows to decouple the fiber arrangement from the winding pin orientation, which allows a fully volumetric framework design of components. A predictive model for the pin capacity was derived and experimentality validated. The hooking conditions, pin capacity, and occupancy were considered in the creation of a digital design tool.
Open Access
Data processing, analysis, and evaluation methods for co-design of coreless filament-wound building systems
(2023) Gil Pérez, Marta; Mindermann, Pascal; Zechmeister, Christoph; Forster, David; Guo, Yanan; Hügle, Sebastian; Kannenberg, Fabian; Balangé, Laura; Schwieger, Volker; Middendorf, Peter; Bischoff, Manfred; Menges, Achim; Gresser, Götz T.; Knippers, Jan
Open Access
Design of fiber-composite/metal-hybrid structures made by multi-stage coreless filament winding
(2022) Mindermann, Pascal; Müllner, Ralf; Dieringer, Erik; Ocker, Christof; Klink, René; Merkel, Markus; Gresser, Götz T.
The methods presented in this study assist in fabricating load-bearing structures with high mass-specific mechanical performance at various scales. Possible applications include primary and secondary structures in engineering, architecture, automotive, or aerospace industries.Additive manufacturing processes, such as coreless filament winding with fiber composites or laser powder bed fusion with metals, can produce lightweight structures while exhibiting process-specific characteristics. Those features must be accounted for to successfully combine multiple processes and materials. This hybrid approach can merge the different benefits to realize mass savings in load-bearing structures with high mass-specific stiffnesses, strict geometrical tolerances, and machinability. In this study, a digital tool for coreless filament winding was developed to support all project phases by natively capturing the process-specific characteristics. As a demonstration, an aluminum base plate was stiffened by a coreless wound fiber-composite structure, which was attached by additively manufactured metallic winding pins. The geometrical deviations and surface roughness of the pins were investigated to describe the interface. The concept of multi-stage winding was introduced to reduce fiber–fiber interaction. The demonstration example exhibited an increase in mass-specific component stiffness by a factor of 2.5 with only 1/5 of the mass of a state-of-the-art reference. The hybrid design approach holds great potential to increase performance if process-specific features, interfaces, material interaction, and processes interdependencies are aligned during the digitized design phase.
Open Access
Development of an impregnation end-effector with fiber tension monitoring for robotic coreless filament winding
(2021) Mindermann, Pascal; Bodea, Serban; Menges, Achim; Gresser, Götz T.
The manufacturing process of robotic coreless filament winding has great potential for efficient material usage and automation for long-span lightweight construction applications. Design methods and quality control rely on an adequate digital representation of the fabrication parameters. The most influencing parameters are related to the resin impregnation of the fibers and the applied fiber tension during winding. The end-effector developed in this study allows efficient resin impregnation, which is controlled online by monitoring the induced fiber tension. The textile equipment was fully integrated into an upscaled nine-axis robotic winding setup. The cyber-physical fabrication method was verified with an application-oriented large-scale proof-of-concept demonstrator. From the subsequent analysis of the obtained datasets, a characteristic pattern in the winding process parameters was identified.
Open Access
Fortschritte im kernlosen Wickeln für eine digitale Prozesscharakterisierung
(2022) Mindermann, Pascal; Gresser, Götz T. (Prof. Dr.-Ing.)
Das kernlose Wickeln ist ein aufstrebendes additives Fertigungsverfahren zur Herstellung von duroplastischen Faserverbundstrukturen. Ein imprägniertes Faserbündel wird frei zwischen räumlich angeordneten punktförmigen Ankern frei aufgespannt, wodurch die Geometrie der herzustellenden gitterförmigen Bauteile definiert wird. In Verbindung mit der Automatisierung des Prozesses kennzeichnet diese Gestaltungsfreiheit das kernlose Wickeln als relevant unter den verfügbaren Leichtbautechnologien. Allerdings bedarf es noch mehrerer Weiterentwicklungen, um das Potenzial des kernlosen Wickelns für den Maschinenbau und die Architektur nutzbar zu machen. Im Maschinenbau werden effiziente Strukturen zur Erreichung der Klimaneutralität und hoch-leistungsfähige Strukturen für technische Innovationen benötigt. Hingegen besteht im Bauwesen aufgrund des Bevölkerungswachstums ein ansteigender Bedarf nach Gebäudeflächen, während die Produktivität jedoch infolge mangelnder Digitalisierung stagniert. Die technologische Verbreitung des kernlosen Wickelns wird durch die inhärenten Streuungen in Prozess- und Strukturparametern verlangsamt. Abweichungen im Material und Schwankungen in den Prozessparametern führen zu Unsicherheiten im Auslegungsprozess, welche durch eine Erhöhung der Sicherheitsfaktoren und des Ressourcenverbrauchs kompensiert werden. Daher ist die Aufgabe dieser Arbeit die Verbesserung der Charakterisierung des kernlosen Wickelprozesses. Dies wurde durch eine Weiterentwicklung der Methoden zur digitalen Erfassung umgesetzt, wobei das primäre Ziel in der Vergrößerung der Übereinstimmung zwischen dem digitalen Modell und dem physischen Gegenstück bestand. Durch die Implementierung von physikalischen und digitalen Anpassungen wurde das primäre Ziel erreicht. Zugleich wurden im Rahmen dieser Arbeit auch Fortschritte in der Bauteilqualität und der Prozesseffizienz gemacht. Darüber hinaus wurde das Verfahren auf neue Funktionen und Anwendungen erweitert. Das kernlose Wickeln wurde ganzheitlich anhand von vier Forschungsansätzen betrachtet, welche auf das Fertigungssystem, das Materialsystem, die Lasteinleitung und die Datenverarbeitungsinfrastruktur ausgerichtet sind. Der kumulative Entwicklungsfortschritt, welcher anhand der Forschungsansätze aus den eingebundenen wissenschaftlichen Beiträgen gewonnen wurde, zeigt aufgrund der konsistenten digitalen Charakterisierung eine übergreifende Verbesserung in den Prozessbewertungskriterien. Zudem ermöglicht das vermehrte Verständnis über die Eigenheiten des kernlosen Wickelns eine effektivere Handhabung von zukünftigen spezifischen Anforderungen, indem die Entscheidungsfindung während des Auslegungsprozesses in allen Prozessaspekten vereinfacht wird.
Open Access
Investigation of the fabrication suitability, structural performance, and sustainability of natural fibers in coreless filament winding
(2022) Mindermann, Pascal; Gil Pérez, Marta; Knippers, Jan; Gresser, Götz T.
Coreless filament winding is an emerging fabrication technology in the field of building construction with the potential to significantly decrease construction material consumption, while being fully automatable. Therefore, this technology could offer a solution to the increasing worldwide demand for building floor space in the next decades by optimizing and reducing the material usage. Current research focuses mainly on the design and engineering aspects while using carbon and glass fibers with epoxy resin; however, in order to move towards more sustainable structures, other fiber and resin material systems should also be assessed. This study integrates a selection of potential alternative fibers into the coreless filament winding process by adapting the fabrication equipment and process. A bio-based epoxy resin was introduced and compared to a conventional petroleum-based one. Generic coreless wound components were created for evaluating the fabrication suitability of selected alternative fibers. Four-point bending tests were performed for assessing the structural performance in relation to the sustainability of twelve alternative fibers and two resins. In this study, embodied energy and global warming potential from the literature were used as life-cycle assessment indexes to compare the material systems. Among the investigated fibers, flax showed the highest potential while bio-based resins are advisable at low fiber volume ratios.
Open Access
Material monitoring of a composite dome pavilion made by robotic coreless filament winding
(2021) Mindermann, Pascal; Rongen, Bas; Gubetini, Drilon; Knippers, Jan; Gresser, Götz T.
A hemispherical research demonstration pavilion was presented to the public from April to October 2019. It was the first large-scale lightweight dome with a supporting roof structure primarily made of carbon- and glass-fiber-reinforced composites, fabricated by robotic coreless filament winding. We conducted monitoring to ascertain the sturdiness of the fiber composite material of the supporting structure over the course of 130 days. This paper presents the methods and results of on-site monitoring as well as laboratory inspections. The thermal behavior of the pavilion was characterized, the color change of the matrix was quantified, and the inner composition of the coreless wound structures was investigated. This validated the structural design and revealed that the surface temperatures of the carbon fibers do not exceed the guideline values of flat, black façades and that UV absorbers need to be improved for such applications.