Now showing 1 - 10 of 1830
  • Publication
    Untersuchung zum Elektronenstrahlschweißen additiv gefertigter Ni-Basis-Bauteile
    ( 2022-10-26)
    Raute, Maximilian Julius
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    Die vorliegende Untersuchung befasst sich mit dem Einfluss des Additive Manufacturing auf die Schweißeignung von Bauteilen aus Inconel 718. Hierfür wurden Proben mittels DED und L-PBF hergestellt und ihr Verhalten in Blindschweißversuchen anhand eines Vergleichs mit konventionellen Gussblechen untersucht. Im zweiten Schritt wurden die verschiedenen additiv hergestellten Proben mit dem Gussmaterial im I-Stoß sowie untereinander verschweißt. Als Schweißverfahren wurde für alle Proben das Elektronenstrahlschweißen angewandt. Zur Auswertung wurde anhand von Schliffen das Nahtprofil vermessen und die Proben auf Poren und Risse untersucht. Zusätzlich wurde die Dichte vermessen und eine Prüfung auf Oberflächenrisse durchgeführt. Das AM-Material zeigte dabei Unterschiede in Nahtform und Defektneigung im Vergleich zum Gusswerkstoff. Insbesondere die DED-proben neigten unter bestimmten Parameterkonstellationen verstärkt zu Porenbildung. Risse konnten nicht beobachtet werden. Trotz auftretender Nahtunregelmäßigkeiten wurde in den kombinierten AM-Schweißproben die Bewertungsgruppe C erreicht. Eine Prüfung der bestehenden Regelwerke zur Schweißnahtbewertung anhand der gewonnenen Erkenntnisse zu additiv gefertigten Proben im Elektronenstrahlschweißprozess zeigte keinen Ergänzungsbedarf.
  • Publication
    Untersuchung zur Herstellung von Cu-Strukturen mittels Wire Electron Beam Additive Manufacturing
    ( 2022-09)
    Raute, Maximilian Julius
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    Das Additive Manufacturing gewinnt zunehmend an Bedeutung für die Fertigung metallischer Bauteile im industriellen Umfeld. Hierbei wird zunehmend auch auf drahtförmige Ausgangswerkstoffe gesetzt, da diese Vorteile im Handling bieten, bereits in der Industrie etabliert sind und sich in der Regel durch geringere Beschaffungskosten auszeichnen. In den letzten Jahren entwickelte sich neben den bereits im großen Umfeld untersuchten Wire-DED-Verfahren auch eine Prozessvariante unter Nutzung des Elektronenstrahls zur industriellen Marktreife. Dabei zeigt die als Wire Electron Beam Additive Manufacturing bezeichnete Technologie besondere Vorteile gegenüber anderen, zumeist Laser-oder Lichtbogen-basierten DED-Prozessen. Das Verfahren bietet vor allem Potenzial für die Verarbeitung von hochleitfähigen, reflektierenden oder oxidationsgefährdeten Werkstoffen. Insbesondere für die Herstellung von Bauteilen aus Kupferlegierungen zeigt sich der Elektronenstrahl als besonders geeignet. Um das Verfahren einem breiten Anwenderkreis in der Industrie zugänglich zu machen, fehlen jedoch übergreifende Daten zu Leistungsfähigkeit, Prozessgrenzen und Anwendungsmöglichkeiten. Die vorliegende Untersuchung beschäftigt sich mit dieser Problemstellung am Beispiel zweier Cu-Werkstoffe. Dabei werden ein korrosionsbeständiger Werkstoff aus dem maritimen Bereich sowie eine Bronze mit guten Verschleißeigenschaften aus dem Anlagenbau getestet. Über mehrstufige Testschweißungen wurden die physikalisch möglichen Prozessgrenzen ermittelt und Rückschlüsse über die Eignung der Parameter zum additiven Aufbau gezogen. Hierfür wurden zunächst optimale Bereiche für den Energieeintrag anhand von Volumenenergie sowie mögliche Schweißgeschwindigkeiten untersucht. Anschließend wurde die Skalierbarkeit des Prozesses anhand von Strahlstrom und Drahtvorschub getestet. Als wesentliche Zielgrößen wurden dabei Spurgeometrie, Aufmischung und Härte herangezogen. Die Eignung der ermittelten Parameter wurde im letzten Schritt exemplarisch anhand einer additiven Testgeometrie in Form eines Zylinders nachgewiesen.
  • Publication
    Material-adapted and process-reliable multi-wire submerged arc welding of large-diameter pipes
    ( 2022-03-07) ; ; ; ;
    Lichtenthäler, Frank
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    Stark, Michael
    Ensuring the required mechanical-technological properties of welds is a critical issue in the application of multi-wire submerged arc welding processes in the manufacture of largediameter pipes made of high-strength fine-grained steels of grade X70 and higher according to API 5L. Excessive heat input of up to 10 kJ/mm is one of the main causes of the formation of microstructural areas in the heat-affected zone with deteriorated mechanical properties, such as impact toughness and tensile strength. In this work, a variant of a five-wire submerged arc welding process is proposed that reduces the weld volume and the heat input, while retaining the high process stability and production speed of multi-wire submerged arc welding. By adapting the welding wire configuration of a five-wire submerged arc welding process and the energetic parameters of the arcs, the high penetration depth of approx. 24 mm and a 10 % reduction in the weld cross-section could be achieved compared to the usual process configuration. This effect was transformed into a higher welding speed, which led to a reduction in the heat input. A concept for process monitoring is proposed in order to maintain constant manufacturing quality in large-diameter pipe production. In addition to the analysis of electrical process signals such as welding current and welding voltage, acoustic process monitoring using vibro-acoustic sensors provides reliable information on the stability of the welding process.
  • Publication
    Potentials of Design Thinking for knowledge transfer of Model-Based Systems Engineering
    ( 2022)
    Manoury, Marvin Michael
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    Horländer, Toni
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    Zimmermann, Thomas
    Industrial products are becoming increasingly complex due to the use and development of mechatronic systems. This increasing complexity is addressed by virtual representations of the systems in the form of interdisciplinary models. Model-Based Systems Engineering (MBSE) supports product development from the early development phase through validation, verification and integration up to later life cycle phases of the product by means of system modeling.Typical drivers for innovations in the industrial environment are business viability, technology driven feasibility and human driven desirability. While business viability and feasibility are considered in most product development processes and innovation driven projects, the human factor is often neglected in this context. This is addressed by a MBSE Capability and Maturation Matrix (CMM), which consists of capabilities for the acquisition and mastering of the MBSE competencies. The authors have considered Design Thinking as a feasible approach to transfer MBSE knowledge and thus support this acquisition MBSE competencies. This publication shall present the first findings on the application of Design Thinking for the creation of a user-centered MBSE introduction event. This event shall be used in further iterative steps to teach non-experts in the MBSE field the required competencies for their work and thus support the CMM development capability.
  • Publication
    Redundancy Concepts for Real-Time Cloud- and Edge-based Control of Autonomous Mobile Robots
    ( 2022)
    Nouruzi-Pur, Jan
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    Lambrecht, Jens
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    Nguyen, The Duy
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    Deploying navigation algorithms on an edge or cloud server according to the Software-as-a-Service paradigm has many advantages for autonomous mobile robots in indus-trial environments, e.g. cooperative planning and less onboard energy consumption. However, outsourcing corresponding real-time critical control functions requires a high level of reliability, which cannot be guaranteed either by modern wireless networks nor by the outsourced computing infrastructure. This work introduces redundancy concepts, which enable real-time capability within these uncertain infrastructures by providing redundant computation nodes, as well as robot-controlled switching between them. Redundancies can vary regarding their physical location, robot behavior during the switchover process and degree of activeness while quality of service concerning the primary controller is sufficient. In the case that fallback redun-dancies are not continuously active, when a disturbance occurs an initial state estimation of the robot pose has to be provided and an activation time has to be anticipated. To gain some insights on expected behavior, redundant computation nodes are deployed locally on the robot and on an outsourced computation node and consequently evaluated empirically. Quantitative and qualitative results in simulation and a real environment show that redun-dancies help to significantly improve the robot-trajectory within an unreliable network. Moreover, resource-saving redundancies, which are not continuously active, can robustly take over control by using an estimated state.
  • Publication
    Design and Validation of an Adaptive Force Control Algorithm with Parameter Estimation Unit for Electromechanical Feed Axis
    ( 2022)
    Sewohl, André
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    Norberger, Manuel
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    Sigg, Stefan
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    Schlegel, Holger
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    Dix, Martin
    Production technology is characterized by the use of electromechanical feed axes, for which the concept of cascade control has become established. The concept is based on linear control engineering. It is not suitable for the control of process forces, which is associated with nonlinearities. Here, adaptive control algorithms from the field of higher control engineering represent a promising approach for improvements of manufacturing strategies and processes in terms of stability, quality, and efficiency. This can also ensure in reducing the number of parts rejected due to bad quality and thus aiding as a significant economic benefit. In this paper, the development of an adaptive control concept that automatically reacts to different and changing environmental conditions during the process is presented. The digital, parameter-adaptive controller consists of a recursive online parameter estimation unit, the controller design procedure, which is based on the setting rule for the symmet ric optimum, and the control algorithm. The functionality of the adaptive control concept is demonstrated in simulation and validated by means of experiments on a test setup. It is real-time capable and implemented directly on the machine control together with all calculation algorithms.
  • Publication
    OptTopo: Automated set-point optimization for coupled systems using topology information
    ( 2022)
    Thiele, Gregor
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    Johanni, Theresa
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    Sommer, David
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    Eigel, Martin
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    Krüger, Jörg
    The manufacturing sector has witnessed a rapid rise in the importance of energy-efficient operation. For finding optimal set-points for industrial facilities, optimization problems of increasing complexity occur. Key challenges are the leak of derivative information and the curse of dimensionality. For systematic reduction of the search-space by decomposition of the model, a methodology for the inclusion of topology knowledge in the optimization procedure is developed. An implementation of OptTopo (Optimization based on Topology), embedded in a testbed, demonstrates its advantages compared to popular out-of-the-box-optimization. OptTopo could be integrated in energy management software offering advanced set-point control for complex facilities.
  • Publication
    PowerGrasp: Development Aspects for Arm Support Systems
    ( 2022)
    Goppold, J.-P.
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    Kuschan, J.
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    Schmidt, H.
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    Krüger, J.
    Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).
  • Publication
    Application of Uncertainty-Aware Sensor Fusion in Physical Sensor Networks
    (IEEE, 2022)
    Gruber, Maximilian
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    Pilar von Pilchau, Wenzel
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    Koutrakis, Nikolaos-Stefanos
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    Schönborn, Nicolas
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    Eichstädt, Sascha
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    Hähner, Jörg
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    Modern industrial processes often collect redundant information from multiple sensors. It is of interest to leverage this information to form a more accurate or robust estimate of an observed quantity utilizing a sensor fusion operation. To be able to comply with quality requirements on the fused value, preservation of traceability is required. Moreover, the sensor fusion needs to be implemented within suitable digital architectures for Industrial Internet of Things (IIoT) environments. In a continuation of previous work, this is achieved by the usage of digital twins that represent the entities of two IIoT testbeds and the adoption of a method for uncertainty-aware homogeneous sensor fusion, which is presented in full detail. Metrological traceability of the fused value is established by propagating the measurement uncertainty of the input sensor according to metrological standards. The method is implemented as a modular service connected to an existing IIoT architecture. The flexibility of the method is shown by application to two different scenarios with only minimal adaption efforts. The fused sensor values are (as indicated by earlier work) robust to outliers and perform well in practical scenarios within the chosen IIoT architecture.