Now showing 1 - 10 of 421
  • Publication
    Business Events im Wandel der Zeit. Die Auswirkung disruptiver Veränderungen auf die Rolle von Business Events
    ( 2024-02-26)
    Streicher, Anne-Sophie
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    Laube, Alina
    Die vorliegende Masterarbeit widmet sich den Forschungsfragen "Inwiefern haben die Covid-19-Pandemie und die digitale Transformation die Rolle von Business Events verändert?" und "Wie haben sich die Bedürfnisse der Teilnehmer an Business Events verändert?". Um die Forschungsfragen zu eruieren, werden sechs Forschungsannahmen gebildet, die mit Hilfe qualitativer Experteninterviews eruiert werden. Die Stichprobe umfasst acht Experten, die differente Hintergründe im Kontext von Business Events aufweisen. Die Befunde zeigen, dass gegenwärtig Business Events gefragt sind, die sich durch einen Erlebnischarakter auszeichnen, der mit einem verbesserten Kundenerlebnis einhergeht. Des Weiteren hat sich die Rolle durch die Technologieintegration gewandelt, wodurch neue Möglichkeitsräume geschaffen werden. Zudem kommt dem Networking sowie der ökologischen Nachhaltigkeit, abhängig von verschiedenen Faktoren eine wesentliche Bedeutung zu. Nicht zuletzt werden veränderte Anforderungen in Form einer gezielteren Inhaltsgestaltung an Business Events gestellt. Die gewonnen Erkenntnisse werden genutzt, um entsprechende Handlungsempfehlungen für generische als auch wissenschaftliche Business Events abzuleiten mit dem Ziel Business Events in einer Ära des Wandels besser zu gestalten und zu optimieren.
  • Publication
    Abschlussbericht CaRMA. Carbonfaser Recyclingvliese im Multi-Material-Ansatz
    ( 2024-02-16) ;
    Öttel, Ronny
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    Höhn, Wolfgang
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    Baumgärtel, Alexander
    Das Forschungsprojekt CaRMA befasst sich mit der Entwicklung und Validierung von Multi-Material-Vlieswerkstoffen, sowie der Bewertung deren mechanischen Einsatzpotentials zur Erschließung neuer Anwendungsfelder. Die untersuchten Multi-Material-Vlieswerkstoffe (MMV) bestehen aus jeweils drei Faserkomponenten, wobei neben recycelten Carbonfasern (rCF) eine zusätzliche funktionelle/ strukturelle Faser (z.B. Glasfaser, Naturfaser, Aramidfaser) zum Einsatz kommt, sowie eine weitere thermoplastische Faser (PP bzw. PA6), welche die spätere Composite-Matrix bildet. Die verschiedenen Fasern werden jeweils direkt im Vliesherstellungsprozess auf Filament-Niveau miteinander vermischt. Durch diesen materialintrinsischen Multi-Material-Ansatz können potentiell aussichtsreiche mechanische Eigenschaftsprofile erzielt werden. Außerdem werden zusätzliche prozessseitige Synergieeffekte erwartet. Die Verarbeitung von recycelten Carbonfasern zu Vlieswerkstoffen ist auf dem Stand der heutigen Technik mit einigen Herausforderungen verknüpft, die entlang der hier gewählten Prozessführung teilweise kompensiert werden können. Im vorliegenden Demonstrationsfall soll dadurch das mechanische Leistungsspektrum von recycelten Carbonfasern verbreitert werden, sodass zukünftig neue Anwendungsmöglichkeiten erschlossen werden können. Der Aufbau eines ökonomisch tragfähigen Anwendungsmarktes stellt aktuell eine der zentralen Herausforderungen für das Recycling von Carbonfasern dar, sodass das vorliegende Forschungsprojekt CaRMA in diesem Bereich einen wichtigen Beitrag auf Basis eines innovativen Materialkonzepts liefern kann. Um den gewählten Projektansatz umzusetzen und eine bestmögliche Nutzung der verfügbaren Ressourcen zu ermöglichen bzw. diese auf die aussichtsreichsten Entwicklungsrichtungen zu fokussieren, waren mit Projektbeginn vier Aspekte der Gesamtprozesskette hinsichtlich der Verarbeitbarkeit von Multi-Material-Vliesstoffen weiterzuentwickeln: (1) Vliesherstellung, (2) Konsolidierung/Imprägnierung, (3) Prüftechnik und (4) Bewertung & Demonstration.
  • Publication
    Investigation on surface characteristics of wall structures out of stainless steel 316L manufactured by laser powder bed fusion
    ( 2024-02-13)
    Vu, Minh Hoang
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    Meiniger, Steffen
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    Ringel, Björn
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    Hoche, Holger
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    Oechsner, Matthias
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    Weigold, Matthias
    ;
    Pressure equipment poses a high risk of harming people and the environment in case of failure. They are, therefore, highly regulated by the Pressure Equipment Directive. To enable laser powder bed fusion of metals (PBF-LB/M) for the manufacturing of such components, component appearance and quality need to be characterized and qualified for each specific system. In this study, the surface roughness of wall structures out of austenitic stainless steel (316L) is investigated. Wall structure specimens were produced by four manufacturing systems on different PBF-LB/M machines and with different powder materials. Surface roughness of specimens are compared in the upskin and downskin areas in relation to different slope angles and wall thicknesses. Although different process setups, parameters and powder feedstocks have been used, similarities in the dependency of the surface roughness related to the slope angle and wall thickness can be observed. This work furthermore presents a mechanism-based analytical approach to predict system-specific surface roughness. Particularly, the analytical approach on the influence of slope angle on the surface roughness of the downskin areas has not been covered in publications about PBF-LB/M before. The results of this work enable the prediction of system-specific surface roughness, which is especially important for parts with downskin areas and hidden surfaces without the possibility of additional surface treatment.
  • Publication
    Hybrid Joining of Cast Aluminum and Sheet Steel Through Compound Sand Casting and Induction Heating To Enable Thin-Walled Lightweight Structures
    ( 2024)
    Locke, Christopher
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    Guggemos, Martin
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    Maier, Lorenz
    ;
    Hartmann, Christoph
    ;
    ;
    Combining different joining processes to form a hybrid process offers new manufacturing possibilities. Adding induction heating to compound sand casting with additively manufactured lost sand moulds to preheat a metallic solid insert increases the degree of the metallic bond between sheet metal and casting metal. In this study, the manufacturability of thin-walled sheet steel/cast aluminum structures with reduced cast wall thickness in sand casting is characterized for the first time. Enabling lower wall thicknesses of sheet metal/cast metal structures in sand casting shifts the current limits and offers more significant lightweight construction potential. Shear tensile, compression shear, and pullout tests characterize the mechanical properties of the joints. Light microscopic imaging of metallographic samples quantifies the compound zone intermetallic (IMC) thickness. The shear tensile test specimens fail at wall thicknesses below 10 mm in the cast material, so metallurgical bond strength characterization does not occur. Therefore, the compression shear test is used to evaluate the metallurgical bond. Sound metallic bonding with smaller cast wall thicknesses of 8, 6 and 4 mm is achieved. Pullout specimens with 3 mm cast wall thickness further investigate the force-transmitting mechanisms of metallic bond, force-fit and form-locking. It is shown that metallic bonding is the predominant mechanism for force transmission when the compound sand casting process is enhanced by induction heating.
  • Publication
    Bringing light into the dark - Overview of environmental impacts of carbon fiber production and potential levers for reduction
    Carbon fibers (CFs) are a crucial material for lightweight structures with advanced mechanical performance. However, there is still a paucity of detailed understanding regarding the environmental impacts of production. Previously, mostly singled-out scenarios for CF production have been assessed, often based on scarce transparent inventory data. To expand the current knowledge and create a robust database for future evaluation, a life cycle assessment (LCA) was carried out. To this end, a detailed industry-approved LCI is published, which also proved plausible against the literature. Subsequently, based on a global scenario representing the market averages for precursor and CF production, the most relevant contributors to climate change (EF3.1 climate change, total) and the depletion of fossil energy carriers (EF3.1 resource use, fossil) were identified. The energy consumption in CF manufacturing was found to be responsible for 59% of the climate change and 48% of the fossil resource use. To enable a differentiated discussion of manufacturing locations and process energy consumption, 24 distinct scenarios were assessed. The findings demonstrate the significant dependence of the results on the scenarios’ boundary conditions: climate change ranges from 13.0 to 34.1 kg CO2 eq./kg CF and resource use from 262.3 to 497.9 MJ/kg CF. Through the investigated scenarios, the relevant reduction potentials were identified. The presented results help close an existing data gap for high-quality, regionalized, and technology-specific LCA results for the production of CF.
  • Publication
    Deep learning-based inline monitoring approach of mold coating thickness for Al-Si alloy permanent mold casting
    ( 2024) ;
    Rui, Xingyu
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    Liu, Zhang
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    Sun, Haoran
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    In the permanent mold casting process, the distribution of mold coating thickness is a significant variable with respect to the coating's thermal resistance, as it strongly influences the mechanical properties of cast parts and the thermal erosion of expensive molds. However, efficient online coating thickness measurement is challenging due to the high working temperatures of the molds. To address this, we propose an indirect monitoring concept based on the analysis of the as-cast surface corresponding to the coated area. Our previous research proves linear correlations between the as-cast surface roughness parameter known as arithmetical mean height (Sa) and the coating thickness for various coating materials. Based on these correlations, we can derive the coating thickness from the analysis of the corresponding as-cast surface. In this work, we introduce a method to quickly evaluate the as-cast surface roughness by analyzing optical images with a deep-learning model. We tested six different models due to their high accuracies on ImageNet: Vision Transformer (ViT), Multi-Axis Vision Transformer (MaxViT), EfficientNetV2-S/M, MobileNetV3, Densely Connected Convolutional Networks (DenseNet), and Wide Residual Networks (Wide ResNet). The results show that the Wide ResNet50-2 model achieves the lowest mean absolute error (MAE) value of 1.060 µm and the highest R-squared (R 2) value of 0.918, and EfficientNetV2-M reaches the highest prediction accuracy of 98.39% on the test set. The absolute error of the surface roughness prediction remains well within an acceptable tolerance of ca. 2 µm for the top three models. The findings presented in this paper hold significant importance for the development of an affordable and efficient online method to evaluate mold coating thickness. In future work, we plan to enrich the sample dataset to further enhance the stability of prediction accuracy.
  • Publication
    Monitoring the evolution of dimensional accuracy and product properties in property-controlled forming processes
    ( 2024)
    Stebner, Sophie Charlotte
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    Martschin, Juri
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    Arian, Bahman
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    Dietrich, Stefan
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    Feistle, Martin
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    Hütter, Sebastian
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    Lafarge, Rémi
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    Laue, Robert
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    Li, Xinyang
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    Schulte, Christopher
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    Spies, Daniel
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    Thein, Ferdinand
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    Wendler, Frank
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    Wrobel, Malte
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    Rozo Vasquez, Julian
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    Dölz, Michael
    ;
    Münstermann, Sebastian
    As recent trends in manufacturing engineering disciplines show a clear development in the sustainable as well as economically efficient design of forming processes, monitoring techniques have been gaining in relevance. In terms of monitoring of product properties, most processes are currently open-loop controlled, entailing that the microstructure evolution, which determines the final product properties, is not considered. However, a closed-loop control that can adjust and manipulate the process actuators according to the required product properties of the component will lead to a considerable increase in efficiency of the processes regarding resources and will decrease postproduction of the component. For most forming processes, one set of component dimensions will result in a certain set of product properties. However, to successfully establish closed-loop property controls for the processes, a systematic understanding of the reciprocity of the dimensions after forming and final product properties must be established. This work investigates the evolution of dimensional accuracy as well as product properties for a series of forming processes that utilize different degrees of freedom for process control.
  • Publication
    Laser powder bed fusion recoater selection guide - Comparison of resulting powder bed properties and part quality
    Spreading devices used to create powder layers in the laser powder bed fusion of metals (PBF-LB/M) were found to have a significant impact on the additive manufacturing process. However, previous research primarily focused on theoretical investigations, including recoater concepts that are not available on the market, while no comprehensive comparison of commercially available spreading devices currently exists. The aim of this study is therefore to examine the powder bed properties and part qualities that can be achieved with the three most common types of recoater: carbon fiber brushes, polymer lips, and high speed steel (HSS) blades. Identical build jobs were produced using each of the spreading devices. Their capabilities were assessed by nine evaluation criteria, including dimensional, metallurgical, and mechanical properties and criticality of particles abraded from the spreading devices. Based on these quantitative findings, a spreading device selection guide was compiled for the benefit of PBF-LB/M practitioners. All recoaters yielded processes with high stability and part properties that were on a par with or even outperformed the nominal values from the literature. However, the HSS blade was found to provide higher accuracy and stability in steady-state processes. In turn, the brush and lip are better suited for parameter development and design studies. Additionally, the lip was found to have economic benefits over the brush, while the brush was deemed an effective all-rounder.
  • Patent
    Verfahren und Vorrichtung zum Formen einer aushärtbaren Formmasse
    ( 2023-11-22) ; ; ; ;
    Hartmann, Christoph
    ;
    Lechner, Philipp
    ;
    Steinlehner, Florian
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    Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
    ;
    TU München
    Die Erfindung betriff eine Vorrichtung (10) und ein Verfahren zum Formen einer aushärtbaren Formmasse (202), mit:- Aufnehmen einer aushärtbaren Formmasse (202), die sich in einem flüssigen Zustand befindet, in einer Kavität (14), die von einem ersten Formteil (100) und wenigstens einem zweiten Formteil (101) eines Formwerkzeugs (12) begrenzt wird;- Erzeugen wenigstens einer ersten Relativbewegung zwischen dem ersten und dem zweiten Formteil (100, 101), so dass sich die Kavität (14) verkleinert;- Aushärtenlassen der Formmasse (202).
  • Publication
    Extracting robotic task plan from natural language instruction using BERT and syntactic dependency parser
    Natural language encodes rich sequential and contextual information. A task plan for robots can be extracted from natural language instruction through semantic understanding. This information includes sequential actions, target objects and descriptions of working environment. Current systems focus on single-domain understanding such as household or industrial assembly settings, and many rule-based approach have been developed in this context. Thanks to the development of deep learning, data-driven contextual language understanding shows promising results. In this work, an information extraction system is proposed for domain-independent understanding of robotic task plans. The developed approach is based on a pre-trained BERT-model and a syntactic dependency parser. To evaluate the performance, experiments are conducted on three different datasets.