Now showing 1 - 10 of 25
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Feasibility study of joining of carbon fibre-reinforced polymer composites and aluminium alloys by electron beam welding for use in lightweight construction

2023-05-12 , Yalcinyüz, Behiye Aybike , Brunner-Schwer, Christian , Biegler, Max , Rethmeier, Michael

In recent years, new solutions to reduce the weight of components used in the automotive, railway, and aircraft industries have been researched. Carbon Fibre Composites (CFC) have been used to replace metals in products requiring lightweight construction, such as aircraft or high-performance vehicles due to their exceptional mechanical strength. However, the use of CFCs is limited by the reason of their poor thermal conductivity, particularly on components requiring effective dissipation of power losses. To respond to the requirements, the idea of the material combination of metals and polymer-based composites is proposed. In this study, electron beam welding is used for the joining of aluminium alloys and polymer-based composites. Within the experiments, the relevant process parameters such as beam current, welding speed, and heat input have been optimized to achieve the welding of the aluminium alloys. Then, the joining of aluminium alloys and carbon fibre-reinforced polymer composites has been investigated through the optimized welding process parameters for aluminium alloys. Conclusions are drawn regarding the carbon-fibre reinforced polymer composites (PA6-CF) and aluminium alloys (AlMg3) being joinable through electron beams.

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Mechanical properties of laser welded joints of wrought and heat-treated PBF-LB/M Inconel 718 parts depending on build direction

2023 , Simón Muzás, Juan , Brunner-Schwer, Christian , Hilgenberg, Kai , Rethmeier, Michael

Laser-based Powder Bed Fusion of Metal (PBF-LB/M) is a broadly used metal additive manufacturing (AM) method for fabricating complex metallic parts, whose sizes are however limited by the build envelope of PBF-LB/M machines. Laser welding arises as a valid joining method for effectively integrating these AM parts into larger assemblies. PBF-LB/M components must usually be stress-relieved before they can be separated from the build plate. An additional heat treatment can be beneficial for obtaining homogeneous mechanical properties across the seam or for the formation of desired precipitations in nickel-based-alloys. Therefore, the tensile performance of laser welded hybrid (AM/wrought) and AM-AM tensile samples of Inconel 718 is examined after undergoing three different heat treatments and considering three relevant build directions. It can be shown that the build orientation is an influencing factor on weld properties even after two applied heat treatments.

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Analysis and recycling of bronze grinding waste to produce maritime components using directed energy deposition

2021 , Müller, Vinzenz , Marko, Angelina , Kruse, Tobias , Biegler, Max , Rethmeier, Michael

Additive manufacturing promises a high potential for the maritime sector. Directed Energy Deposition (DED) in particular offers the opportunity to produce large-volume maritime components like propeller hubs or blades without the need of a costly casting process. The post processing of such components usually generates a large amount of aluminum bronze grinding waste. The aim of the presented project is to develop a sustainable circular AM process chain for maritime components by recycling aluminum bronze grinding waste to be used as raw material to manufacture ship propellers with a laser-powder DED process. In the present paper, grinding waste is investigated using a dynamic image analysis system and compared to commercial DED powder. To be able to compare the material quality and to verify DED process parameters, semi-academic sample geometries are manufactured.

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Identification of Human Dynamics in User-Led Physical Human Robot Environment Interaction

2018 , Haninger, Kevin , Surdilovic, Dragoljub

Human dynamic models are useful in design of physical human-robot and human-robot-environment interaction: informing choice of robot impedance, motivating relaxations to passivity-based safety constraints, and allowing online inference to user intent. Designing for performance objectives such as stable well-damped contact transitions also requires nominal models, but the use of human models in controller design is limited. Established approaches to identify human dynamics apply position or force perturbation and measure the corresponding response, mostly to validate neuromuscular hypotheses on motor control, which raises questions about their transferability to human-led collaboration. Here, human dynamics are identified in a task which closely resembles the final application, where the human leads the robot into contact with a (virtual) wall. This paper investigates the impact of human dynamics on coupled system behavior, and establishes a general framework for identification in human-led scenarios, making consideration of unmeasured human input. Experiments with different stiffness environments allow inference to human dynamics, and characterize the range of human dynamics which can be modulated by the user.

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Praktische Anwendung der SysML v2 API am Beispiel von MCAD und Simulation

2023 , Manoury, Marvin Michael , Muggeo, Christian

Modellbasiertes Systems Engineering als transdiziplinärer Ansatz soll Domänen verbinden - dazu wurde schon mehrfach der Ansatz eines integrierten Systemmodells postuliert. Häufig herrscht jedoch eine Vielzahl an Datensilos der unterschiedlichen Domänen vor, die sich über Importe und Exporte sowie proprietäre Tool-Schnittstellen austauschen. Dadurch entstehen teilweise Datenverluste bei der Konvertierung und hohe Kosten für die Konfiguration und Wartung der Schnittstellen. Die SysML v2 eröffnet mit ihrer API die Möglichkeit, bidirektional mit Systemmodellen zu interagieren. Das bedeutet, dass sowohl Informationen aus dem Systemmodell gelesen, als auch in die Modelle geschrieben werden können. Die Veröffentlichung beleuchtet die API an sich sowie die damit verbundenen Möglichkeiten am Beispiel der MCAD-Konstruktion und der Simulation eines Produktes. Grundlage dafür bildet das Beispiel der Entwicklung eines Staubsaugerroboters.

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Inertial Measurement Unit based Human Action Recognition for Soft-Robotic Exoskeleton

2021 , Kuschan, Jan , Burgdorff, Moritz , Filaretov, Hristo , Krüger, Jörg

Absence from work caused by overloading the musculoskeletal system lowers the life quality of the worker and gains unnecessary costs for both the employer and the health system. Exoskeletons can present a solution. Typically, such systems struggle with stiffness and discomfort and primarily a lack of battery lifetime. Soft-robotic exoskeletons offer a possibility to overcome these problems by increasing the system flexibility, not limiting the supported DoF and being actuator and joint together. Since soft-robotic exoskeletons can be designed only using power when supporting the wearer, it is possible to increase the battery lifetime by only acting on those actions for which the wearer needs support. Dealing with controls for soft-robotic exoskeleton one major difficulty is to find a compromise between saving energy and supporting the wearer. Having an action-depending control can reduce the supported actions to cover only relevant ones and increase the lifetime of the battery. The system conditions are to detect the user actions in real-time and distinguish between actions which require support and those which do not. We contribute an analysis and modification of human action recognition(HAR) benchmark algorithms from activities of the daily living, transferred them onto industrial use cases containing short and mid-term action and reduce the models to be compatible using embedded computers for real-time recognition on soft exoskeletons. We identified the most common challenges for inertial measurement units based HAR and compare the best-performing algorithms using a newly recorded data set overhead car assembly for industrial relevance. As a benchmark data set we focused on the "Opportunity" data set. By introducing orientation estimation, we were able to increase the F1 scores by up to 0.04. With an overall F1 score without a Null-class of up to 0.883, we were able to lay the foundation to use HAR for action dependent force support.

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Model-Based Systems Engineering (MBSE) as computer-supported approach for cooperative systems development

2020 , Schmidt, Marvin M. , Stark, Rainer

With rising globalization and a trend towards Cyberphysical systems (CPSs) as well as smart products the demand for cross-company and interdisciplinary collaboration increases. To handle the complexity of these systems and products Model-Based Systems Engineering (MBSE), as an enhanced form of Systems Engineering (SE), has emerged in engineering and is adopted by many companies. While this approach tries to cope with the current complexity trends, it does address the collaborative aspect of product creation only in a small scope. This paper shall address the combination of MBSE and collaboration in engineering to form a computer-supported approach for collaborative systems development.

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A life cycle assessment of joining processes in the automotive industry, illustrated by the example of an EV battery case

2023 , Brunner-Schwer, Christian , Lemke, Josefine , Biegler, Max , Schmolke, Tobias , Spohr, Sebastian , Meschut, Gerson , Eckstein, Lutz , Rethmeier, Michael

Current ecological, economic and social changes are leading to a change in development, design and production of future vehicles. In this context, it is the stated goal of many manufacturers to advance the development of an environmentally friendly vehicle and climate-neutral production throughout the entire supply chain. This study presents a comparative life cycle assessment of the joining processes laser beam welding, laser brazing and resistance spot welding. For this purpose, an approach tailored to welding processes is presented and applied to the example of a battery case for electric vehicles. For the welding process under consideration, the main influences on the resulting environmental impact categories are evaluated and compared. The requirements for ecologically efficient welding processes are discussed and outlined. The results show that particularly the materials involved, such as the consumption of the filler material, have the greatest environmental impact and thus offer the greatest potential for savings.

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Production environment of tomorrow (ProMo)

2021 , Kuschan, Jan , Müller, Vinzenz , Monchinger, Stephan , Heimann, Oliver , Niebuhr, Carsten , Kabha, Oday

Small defects in the grain or major damage to a moulded part or tool can bring production to a standstill. SMEs in particular have neither the personnel nor the equipment to repair such damage on their own, so they send it to specialised contractors. The repair process is carried out manually, depending on the accuracy requirements, and is usually completed by a finishing process. This work requires qualified personnel and, at the same time, requires a lot of time in case of larger damages. In this paper we present a way to map the Maintenance, Repair and Operations (MRO) process chain in a partially automated manner. The symbiosis of individual technologies results in a significantly increased efficiency of the MRO process chain, which continues to focus on people and their process knowledge. While Directed Energy Deposition (DED) for the MRO of moulded parts is used widely, usually a high manual effort in measuring the component geometries and teaching of the machine tool paths is necessary. However, there are clear advantages compared to the manufacture of new parts or manual laser welding repair. At the same time, the resource and energy requirements can often be significantly reduced compared to new part production. ProMo focuses on automating the time-consuming machine programming by reducing the number of necessary work steps in CAD/CAM-based program creation. Based on a subsequent robot-guided scan, a digital actual 3D model is generated. Due to intelligent path planning algorithms, no manual programming of the robot is necessary and at the same time it is possible to detect components of different sizes, shapes and covers in this system with a minimum of effort. In addition, the operator passes on elementary information, such as the approach path of the milling head, to the subsequent processes by means of finger gestures and can thus significantly reduce tedious CAM programming steps. Now, the scanned component is transferred to a 3D-CAD model and a target/actual comparison is created for the damaged areas. Those are milled out in a defined manner and then restored using DED.

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Automated tool-path generation for rapid manufacturing and numerical simulation of additive manufacturing LMD geometries

2019 , Biegler, Max , Wang, Jiahan , Graf, Benjamin , Rethmeier, Michael

In additive manufacturing (AM) Laser Metal Deposition (LMD), parts are built by welding layers of powder feedstock onto a substrate. Applications for steel powders include forging tools and structural components for various industries. For large parts, the choice of tool-paths influences the build-rate, the part performance and the distortions in a highly geometry-dependent manner. With weld-path lengths in the range of hundreds of meters, a reliable, automated tool path generation is essential for the usability of LMD processes. In this contribution, automated tool-path generation approaches are shown and their results are discussed for arbitrary geometries. The investigated path strategies are the classical approaches: ""Zig-zag-"" and ""contour-parallel-strategies"". After generation, the tool-paths are automatically formatted into g-code for experimental build-up and ASCII for a numerical simulation model. Finally, the tool paths are discussed in regards to volume-fill, microstructure and porosity for the experimental samples. This work presents a part of the IGF project 18737N ""Welding distortion simulation"" (FOSTA P1140)