Search

Your search keyword '"Völkl, Harald"' showing total 128 results
Start Over Author "Völkl, Harald"
128 results on '"Völkl, Harald"'

4. A NEW METHOD FOR PASSIVE ANKLE FOOT ORTHOSIS DESIGN – INTEGRATION OF MUSCULOSKELETAL AND FINITE ELEMENT SIMULATION.

Author

Scherb, David, Steck, Patrick, Völkl, Harald, Wartzack, Sandro, and Miehling, Jörg

Subjects
FOOT orthoses, MOVEMENT disorder treatments, MUSCULOSKELETAL system, ORTHOPEDIC apparatus, FINITE element method, PRODUCT design
Abstract

Motor disorders are diseases affecting the muscle function of the human body. A frequently occurring motor disorder affects the lower leg muscles resulting in a pathological gait called foot drop. Patients have a higher risk of stumbling and falling. The most common treatment is the use of a passive ankle-foot-orthosis (AFO). However, the compensation of foot drop is only limited due to the non possible support of all rotational directions of the ankle joint. Therefore, a newly developed concept for a passive AFO is currently in work. To ensure a best possible treatment of the patient, the provided support by the AFO and required support by the patient have to be in accordance. Thus, in this contribution a method is presented that integrates model order reduced finite element analysis for computing the provided support of the AFO and musculoskeletal human models for representing the patients' gait behaviour. With the method, the design of the force generating structures of the AFO can be realized regarding the patients' requirements. The presented method is further evaluated with a specific use case. The main focus lies here in the principal functionality of the method and the provision of valid results. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

5. A NEW DESIGN METHOD FOR GENERATING SURROGATE KINEMATIC TRUSS ORTHOSES TO SUPPORT PATHOLOGICAL GAIT PATTERNS IN HUMAN MODEL SIMULATIONS.

Author

Steck, Patrick, Scherb, David, Mayer, Johannes, Jäger, Michael, Miehling, Jörg, Völkl, Harald, and Wartzack, Sandro

Subjects
GAIT in humans, ORTHOPEDIC apparatus, LIFE expectancy, CENTRAL nervous system diseases, HUMAN kinematics, USER-centered system design
Abstract

With increasing life expectancy, the risk of diseases of the central nervous system, such as cancer, strokes, etc., also increases. Strokes often result in injury to the sciatic nerve, which is responsible for controlling the calf muscles (plantar and dorsal flexors). A so-called ankle joint orthosis (AFO) helps to support the pathological gait and to avoid foot drop during gait. Passive orthoses are of particular importance for research, as they do not require additional incoming energy from outside to the orthotic system. However, current passive orthoses are often not personalized. On the one hand, because they usually have only a temporary muscle-building function and, on the other hand, because the individual design process is computationally time consuming and thus expensive. This paper presents a possibility to pre-dimension and pre-design passive orthoses fast and cost-efficiently by reducing the complexity of the model based on volume-optimized truss elements. Therefor a traditional high calculation intensive design procedure is compared with the complexity reduced model to show its effectiviness and the similarity of the results. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

8. A simulation-based approach to Design for Additive Manufacturing of Fused Layer Modelling lightweight structures

Author

Völkl, Harald

Subjects
Ingenieurwissenschaften, Maschinenbau, 620 Ingenieurwissenschaften und zugeordnete Tätigkeiten, Rapid Prototyping, ddc:620, Fused Deposition Modeling, 600 Technik, Technologie, ddc:600, Produktionstechnik
Abstract

Additive Fertigungsverfahren erlauben große Designfreiheiten, die durch Design for Additive Manufacturing (DfAM) ausgeschöpft werden können. An AM-Leichtbauteile werden besonders hohe Steifigkeits- und Festigkeitsanforderungen gestellt. Hierfür eignen sich besonders Faser-Kunststoff-Verbunde. Mit dem Fused Layer Modelling-(FLM-)Verfahren lässt sich die ausgeprägte Anisotropie der Faser-Kunststoff-Verbunde im Vergleich zu anderen AM-Verfahren sehr zielgerichtet einsetzen. In dieser Dissertation wird daher ein strukturierter DfAM-Ansatz zur Auslegung kurzfaserverstärkter FLM-Leichtbauteile vorgestellt. Dieser berücksichtigt die orthotropen Materialeigenschaften zunächst durch eine Baurichtungsoptimierung, die den Kraftfluss im Bauteil möglichst planar in der Druckplattformebene führt. Anschließend folgt eine Topologieoptimierung mit orthotropem Materialmodell, die sowohl Außengestalt als auch Infill simultan optimiert. Eine Extrusionspfadgenerierung überführt Ergebnisse dann in druckbare Bauteile. Eine strukturmechanische FLM-Simulation erlaubt den Vergleich verschiedener FLM-Bauteile mit verschiedenen Infill-Mustern. Zur Demonstration wird ein Tragwerksknoten unter zwei Lastfällen mit dem neuen Ansatz optimiert. Die entstehende Geometrie; dieselbe Geometrie, jedoch mit anderen Infill-Mustern; und eine konventionell ausgelegte Variante werden mittels FLM-Simulation verglichen. Die Ergebnisse zeigen einen deutlichen Steifigkeitsgewinn des neuen Ansatzes gegenüber konventionellen Alternativen, der Produktentwickelnde zudem strukturiert durch den DfAM-Prozess mit seinen herausfordernden Designfreiheiten führt., Additive Manufacturing (AM) offers great design freedom to be exploited by Design for Additive Manufacturing (DfAM). However, AM components for structural lightweight applications are subject to particularly high stiffness and strength requirements, which necessitate special material, process, and design engineering measures. Fibre-reinforced plastics (FRP) are especially suitable due to their high stiffness and strength. Moreover, the Fused Layer Modelling (FLM) process allows to exploit the pronounced anisotropy of FRP effectively. This thesis therefore presents a DfAM approach for short-fiber-reinforced lightweight structures. It considers the orthotropic properties of FLM components by build-up direction optimisation to keep the force flow as parallel to the printing platform as possible – and thus, to bypass low stiffness and strength between layers. This step is followed by a topology optimisation with orthotropic material model, which simultaneously optimises both the outer shape and in-plane projected inner material orientations. Subsequent extrusion path generation transforms the optimisation results into printable components. Finally, a simulation approach is presented to compare different FLM components with various infill patterns. For demonstration, a truss node is optimised under two load cases. The resulting geometry; the same geometry but with different infill patterns; and a conventionally designed variant are compared using the simulation approach. Results show a considerable stiffness gain of the new approach offering structured guidance for product developers., FAU Studien aus dem Maschinenbau; 393

Published
2022
Full Text
View/download PDF

11. Generating Digital Twins for Path-Planning of Autonomous Robots and Drones Using Constrained Homotopic Shrinking for 2D and 3D Environment Modeling.

Author

Denk, Martin, Bickel, Sebastian, Steck, Patrick, Götz, Stefan, Völkl, Harald, and Wartzack, Sandro

Subjects
DIGITAL twins, ROBOTIC path planning, POTENTIAL field method (Robotics), AUTONOMOUS robots, DETERMINISTIC algorithms, INDUSTRIAL safety
Abstract

A digital twin describes the virtual representation of a real process. This twin is constantly updated with real data and can thus control and adapt the real model. Designing suitable digital twins for path planning of autonomous robots or drones is often challenging due to the large number of different dynamic environments and multi-task and agent systems. However, common path algorithms are often limited to two tasks and to finding shortest paths. In real applications, not only a short path but also the width of the passage with a path as centered as possible are crucial, since robotic systems are not ideal and require recalibration frequently. In this work, so-called homotopic shrinking is used to generate the digital twin, which can be used to extract all possible path proposals including their passage widths for 2D and 3D environments and multiple tasks and robots. The erosion of the environment is controlled by constraints such that the task stations, the robot or drone positions, and the topology of the environment are considered. Such a deterministic path algorithm can flexibly respond to changing environmental conditions and consider multiple tasks simultaneously for path generation. A distinctive feature of these paths is the central orientation to the non-passable areas, which can have significant benefits for worker and patient safety. The method is tested on 2D and 3D maps with different tasks, obstacles, and multiple robots. For example, the robust generation of the digital twin for a maze and also the dynamic adaptation in case of sudden changes in the environment is covered. This variety of use cases and the comparison with alternative methods result in significant advantages, such as high robustness, consideration of multiple targets, and high safety distances to obstacles and areas that cannot be traversed. Finally, it was shown that the environment for the digital twin can be reduced to reasonable paths by constrained shrinking, both for real 2D maps and for complex virtual 2D and 3D maps. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

23. Impaired renal Na+ retention in the sgk1-knockout mouse

Author

Wulff, Peer, Vallon, Volker, Huang, Dan Yang, Völkl, Harald, Yu, Fang, Richter, Kerstin, Jansen, Martina, Schlünz, Michaela, Klingel, Karin, Loffing, Johannes, Kauselmann, Gunther, Bösl, Michael R., Lang, Florian, and Kuhl, Dietmar

Published
2002

34. Inhibition of the heterotetrameric K+channel KCNQ1/KCNE1 by the AMP-activated protein kinase

Author

Alesutan, Ioana, primary, Föller, Michael, additional, Sopjani, Mentor, additional, Dërmaku-Sopjani, Miribane, additional, Zelenak, Christine, additional, Fröhlich, Henning, additional, Velic, Ana, additional, Fraser, Scott, additional, Kemp, Bruce E., additional, Seebohm, Guiscard, additional, Völkl, Harald, additional, and Lang, Florian, additional

Published
2011
Full Text
View/download PDF

35. Regulation of renal tubular glucose reabsorption by Akt2/PKBβ

Author

Kempe, Daniela S., primary, Siraskar, Gulab, additional, Fröhlich, Henning, additional, Umbach, Anja T., additional, Stübs, Michael, additional, Weiss, Florian, additional, Ackermann, Teresa F., additional, Völkl, Harald, additional, Birnbaum, Morris J., additional, Pearce, David, additional, Föller, Michael, additional, and Lang, Florian, additional

Published
2010
Full Text
View/download PDF

36. Akt/PKB‐sensitive proximal tubular glucose and phosphate transport

Author

Föller, Michael, primary, Kempe, Daniela S., additional, Siraskar, Gulab, additional, Fröhlich, Henning, additional, Ackermann, Teresa F., additional, Siraskar, Balasaheb, additional, Völkl, Harald, additional, Judenhofer, Martin, additional, Pichler, Bernd, additional, Leavens, Karla F., additional, Birnbaum, Morris J., additional, Pearce, David, additional, and Lang, Florian, additional

Published
2010
Full Text
View/download PDF

37. SGK1-sensitive renal tubular glucose reabsorption in diabetes

Author

Ackermann, Teresa F., primary, Boini, Krishna M., additional, Völkl, Harald, additional, Bhandaru, Madhuri, additional, Bareiss, Petra M., additional, Just, Lothar, additional, Vallon, Volker, additional, Amann, Kerstin, additional, Kuhl, Dietmar, additional, Feng, Yuxi, additional, Hammes, Hans-Peter, additional, and Lang, Florian, additional

Published
2009
Full Text
View/download PDF

39. Reduced intestinal and renal amino acid transport in PDK1 hypomorphic mice

Author

Rexhepaj, Rexhep, primary, Grahammer, Florian, additional, Völkl, Harald, additional, Remy, Christine, additional, Wagner, Carsten A., additional, Sandulache, Diana, additional, Artunc, Ferruh, additional, Henke, Guido, additional, Nammi, Srinivas, additional, Capasso, Giovambattista, additional, Alessi, Dario R., additional, and Lang, Florian, additional

Published
2006
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results