@inproceedings{GerschSchulzKral, author = {Gersch, Sebastian and Schulz, Carsten and Kral, Christopher}, title = {Verifizierung der Prozessstabilit{\"a}t einer konstruierten WAAM-Anlage zum Induzieren von Eigenspannungen in generativ gefertigten Strukturen}, series = {9. Mitteldeutsches Forum - 3D-Druck in der Anwendung: 29. Juni 2022, Jena}, booktitle = {9. Mitteldeutsches Forum - 3D-Druck in der Anwendung: 29. Juni 2022, Jena}, doi = {10.35096/othr/pub-5600}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-56006}, abstract = {Heutzutage werden Strukturen h{\"a}ufig aufwendig konstruiert und nachtr{\"a}glich mithilfe von numerischen Verfahren optimiert. Dennoch kommt es zu erheblichen Sch{\"a}den infolge von Erm{\"u}dungsbr{\"u}chen bei wechselnd beanspruchten Bauteilen. Ein Großteil dieser Sch{\"a}den hat den Ursprung in den im Inneren herrschenden Spannungszust{\"a}nden, den sogenannten Eigenspannungen. Diese Eigenspannungen heben sich innerhalb des Bauteils auf und f{\"u}hren zu keiner Formabweichung des Bauteils, weswegen diese Spannungen in Form und Lage nur schwer detektierbar sind und sich h{\"a}ufig negativ auf die Betriebsfestigkeit von Strukturen auswirken. Mithilfe neuartiger numerischer Methoden k{\"o}nnen thermomechanische Simulationen angefertigt und Verformungen, sowie Spannungszust{\"a}nde abgeleitet werden. Durch diese Optionen ergeben sich neue Anwendungen, die das Potenzial von Fertigungsverfahren in Hinblick auf die Ausnutzung spezieller Eigenschaften neu er{\"o}ffnen. Durch die geschickte Anwendung und Vernetzung der Simulation mit der Fertigung k{\"o}nnen Eigenspannungen gezielt in Lage und Richtung schon w{\"a}hrend der Produktion des Bauteils eingebracht werden. Im theoretischen Vergleich zu konventionell gefertigten Bauteilen entstehen Strukturen, die hinsichtlich ihrer Bauteillebensdauer optimiert sind.}, language = {de} } @inproceedings{HerrmannSchaefferLehmannetal., author = {Herrmann, David and Schaeffer, Leon and Lehmann, Lukas and B{\"o}hm, Valter and Rieffel, John}, title = {Basic Investigations on a Compliant 2D Tensegrity Grid for the Use in Soft Robotic Applications}, series = {2024 6th International Conference on Reconfigurable Mechanisms and Robots (ReMAR), 23-26 June 2024, Chicago, IL, USA}, booktitle = {2024 6th International Conference on Reconfigurable Mechanisms and Robots (ReMAR), 23-26 June 2024, Chicago, IL, USA}, publisher = {IEEE}, isbn = {979-8-3503-9596-9}, doi = {10.1109/ReMAR61031.2024.10619926}, pages = {652 -- 657}, abstract = {The use of compliant tensegrity grids in soft robotic applications is a promising research topic. By using these grids, systems with large shape and stiffness change ability can be realized. In this paper, different tensegrity grid variants, consisting of rigid members indirectly connected via compliant tensioned members, are presented. A selected grid variant is analyzed in more detail for shape adaptation. Therefore the use of the grid as end effector in form-fit grippers is selected as a specific application case. Covariance Matrix Adaptation Evolution Strategies are used to optimize actuators for two given shape function variants and an evaluation is carried out.}, language = {en} } @inproceedings{LaumerSchmidtStichel, author = {Laumer, Tobias and Schmidt, Michael and Stichel, Thomas}, title = {Influence of temperature gradients on the part properties for the simultaneous laser beam melting of polymers}, series = {Proceedings of Laser in Manfacturing Conference 2015, June 22 - June 25, 2015 Munich, Germany}, booktitle = {Proceedings of Laser in Manfacturing Conference 2015, June 22 - June 25, 2015 Munich, Germany}, organization = {German Scientific Laser Society (WLT e.V.)}, abstract = {By Laser Beam Melting of polymers (LBM), parts with almost any geometry can be built directly out of CAD files without the need for additional tools. Thus, prototypes or parts in small series production can be generated within short times. Up to now, no multi-material parts have been built by LBM, which is a major limitation of the technology. To realize multi-material parts, new mechanisms for depositing different polymer powders as well as a new irradiation strategy are needed, by which polymers with different melting temperatures can be warmed to their specific preheating temperatures and be molten simultaneously. This is achieved by simultaneous laser beam melting (SLBM). In the process, two different materials are deposited next to each other and preheated a few degrees below their melting temperatures by infrared emitters and laser radiation (λ = 10.60 µm), before in the last step the two preheated powders are molten simultaneously by an additional laser (λ = 1.94 µm). So far, multi-material tensile bars have been realized and analyzed regarding their boundary zone between both materials. The experiments showed that the temperature gradients in the boundary zone and along the building direction seem to be of great importance for the process stability and the resulting part properties. Therefore, a detailed analysis of the occurring temperature gradients during the process is needed to identify adequate process adjustments regarding the temperature controlling. To analyze the temperature gradients, thermocouples positioned inside the powder bed are used. By varying the temperature of the building platform, the influence of different temperature gradients on the resulting part properties is shown.}, language = {en} }