TY - CHAP A1 - Klauke, Thomas A1 - Kühhorn, Arnold A1 - Liang, Luo A1 - Kober, Markus A1 - Sieghart, D. A1 - Führer, M. A1 - Viehweger, Bernd A1 - Fritzsche, Christoph A1 - Sarradj, Ennes T1 - Entwicklung eines 3-Blatt-CFK-Verstellpropellers für Ultraleichtflugzeuge N2 - Deutscher Luft- und Raumfahrkongress 2010, 31.08. - 02.09.2010, Hamburg Y1 - 2010 ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold T1 - Auslegung und Optimierungsprozess einer Tragstruktur in Faserverbundbauweise unter Berücksichtigung moderner Versagenskriterien Y1 - 2009 ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Klauke, Thomas T1 - Auslegung einer Flanschverbindung aus faserverstärktem Kunststoff durch Optimierung der Faserorientierungen und Schichtdicken mit Hilfe von Altair HyperStudy unter Verwendung eines Wirkebenenbruchkriteriums als Nebenbedingung Y1 - 2007 ER - TY - CHAP A1 - Kober, Markus A1 - Klauke, Thomas A1 - Kühhorn, Arnold A1 - Lenk, Olaf T1 - Einbindung eines modernen Wirkebenenbruchkriteriums für faserverstärkte Kunststoffe in eine Parameteroptimierung mit Altair HyperStudy Y1 - 2006 ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Klauke, Thomas A1 - Lenk, Olaf T1 - Topology-Optimized Intermediate Casing of Aero Engine and Comparative Evaluation of Titanium and Composite Architecture in Terms of Load Capacity and Weight Reduction T2 - Proceedings of the ASME Turbo Expo 2008, presented at the 2008 ASME Turbo Expo, June 9 - 13, 2008, Berlin, Germany, Vol. 5, part A Y1 - 2008 SN - 978-0-7918-4315-4 N1 - GT2008-50644 SP - 69 EP - 79 PB - ASME CY - New York, NY ER - TY - GEN A1 - Kober, Markus A1 - Kühhorn, Arnold T1 - Development of optimized washer-shape for damage-free load application to composites T2 - Composite Structures Y1 - 2010 SN - 0263-8223 VL - 92 IS - 9 SP - 1985 EP - 1991 ER - TY - CHAP A1 - Kober, Markus T1 - HyperWorks im Einsatz in der Lehre Y1 - 2009 ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold T1 - Development of optimized washer shape for damage-free load application to composites Y1 - 2009 ER - TY - CHAP A1 - Klauke, Thomas A1 - Kühhorn, Arnold A1 - Kober, Markus T1 - Application of a Newer Inter-Fiber-Failure Criteria on CFRPs in Aero Engine Development Y1 - 2010 ER - TY - CHAP A1 - Stelldinger, Enrico A1 - Kühhorn, Arnold A1 - Kober, Markus T1 - Otimization of a Carbon-fiber-reinforced Plastic Composite Structure using the Example of a Wing Rigger KW - Optimization KW - Composite KW - Wing Rigger Y1 - 2011 ER - TY - GEN A1 - Kober, Markus A1 - Kühhorn, Arnold T1 - Comparison of different failure criteria for fiber-reinforced plastics in terms of fracture curves for arbitrary stress combinations T2 - Composites Science and Technology KW - Failure Criteria KW - Fibre Reinforced Plastic Y1 - 2012 U6 - https://doi.org/10.1016/j.compscitech.2012.08.007 SN - 0266-3538 VL - 72 IS - 15 SP - 1941 EP - 1951 ER - TY - CHAP A1 - Zuchlinski, André A1 - Kühhorn, Arnold A1 - Kober, Markus A1 - Wehrenpfennig, Lutz T1 - Kombinierte Topologie- und Parameteroptimierung des Aufhängungssystems von heckinstallierten Turbofantriebwerken T2 - 61. Deutscher Luft- und Raumfahrtkongress 2012, 10. - 12. September 2012, Estrel Berlin KW - Hecktriebwerksaufhängung KW - Optimierung Y1 - 2012 N1 - Beitrag DLRK 2012-281168 PB - Dt. Ges. für Luft- und Raumfahrt CY - Bonn ER - TY - THES A1 - Kober, Markus T1 - Ein Beitrag zur strukturmechanischen Optimierung realer Bauteile in metallischer und Faserverbundbauweise unter Verwendung von wirkebenenbasierten Bruchkriterien KW - Optimierung KW - Verbundbauweise KW - Bruchkriterien Y1 - 2011 SN - 978-3-86387-085-0 PB - Mensch und Buch CY - Berlin ER - TY - GEN A1 - Mahler-de Silva, Tina A1 - Kühhorn, Arnold A1 - Kober, Markus T1 - Developing a Simplified Surrogate Model for Structured Sheet Metals with Numerical and Experimental Comparisons T2 - Proceedings in applied mathematics and mechanics : PAMM N2 - It is important to steadily refine lightweight designs with regard to saving resources and energy in common with good economic efficiency. Thin structured sheet metals offer significantly improved component stiffnesses in addition to an upgraded buckling behavior compared to flat, unstructured sheet metals. By using a distortion energy based homogenization method it is possible to develop a mechanical surrogate model which describes effective mean properties. The accurate selection of symmetric and periodic boundaries enables to determine the required parameters. The conditions are contemplated on elementary cells whose structural mechanical behavior is representative for the elastic behavior of large structures. By doing this, the amount of elements can be reduced and thus the calculating time of large components can considerably be saved. For an efficient surrogate model it is required to analyze and compare numerical with experimental investigations. Some different versions of optimization will be tested to get better approximation of the data. KW - Structured Sheet Metals Y1 - 2013 UR - http://onlinelibrary.wiley.com/doi/10.1002/pamm.201310045/abstract N1 - GAMM 2013, 84th Annual Scientific Conference, Novi Sad , 18. - 22. März 2013 VL - 13 IS - 1 SP - 99 EP - 100 ER - TY - GEN A1 - Zolochevsky, Alexander A1 - Sklepus, Sergiy A1 - Galishin, Alexander A1 - Kühhorn, Arnold A1 - Kober, Markus T1 - A Comparison between the 3D and the Kirchhoff-Love Solutions for Cylinders under Creep-Damage Conditions T2 - Technische Mechanik KW - creep deformation Y1 - 2014 UR - http://www.ovgu.de/ifme/zeitschrift_tm/2014_Heft2/04_Zolochevsky_et_al.pdf VL - 34 IS - 2 SP - 104 EP - 113 ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Stelldinger, Enrico A1 - Keskin, Akin T1 - Considerations About the Necessary Mesh Density of Bearings in Detailed Finite Element Models T2 - ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, Volume 7B: Structures and Dynamics Düsseldorf, Germany, June 16–20, 2014, Paper GT2014-25624 N2 - In order to predict properly the behavior of very complex mechanical models, much focus needs to be done on the level of model details as well as the techniques used to predict component movements based on mechanical and thermal loads. In particular bearings and joints play a significant role in big model assemblies such as aero-engines where most of the structures are modeled by solid elements rather than using traditional shell or beam elements. This approach is very complex and expensive in terms of computational effort however can lead to increased simulation accuracy when done properly. This publication will answer questions related to the modeling techniques required for detailed bearings (not only rotor bearings) and joints of an aero-engine application where these components are not idealized or simplified, i.e. the ball in a ball joint is meshed by solid elements. The investigation will discuss the question about the number of elements needed to mesh a ball joint in such a way that a correct rotation is possible. If the mesh is too coarse, a rotation would be impossible due to the faceting of the rotating parts. It will be shown that a proper rotation depends on a correct relation between the radius of the inner ball, the gap size of the bearing and the number of nodes in the circumferential direction. For this relation an analytical formula has been derived and successfully tested at some examples. Furthermore, some finite element codes offer the possibility of smoothed contact surfaces. These options improve the situation but they might cause issues too. For this reason these smoothed contact options are also considered under the aspects mentioned above. Copyright © 2014 by Rolls-Royce Deutschland Ltd & Co KG KW - Density KW - Bearings Y1 - 2014 SN - 978-0-7918-4577-6 U6 - https://doi.org/10.1115/GT2014-25624 PB - ASME ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Kästner, Benjamin A1 - Keskin, Akin T1 - Evaluation of the Stress and Displacement Behavior of Different LS-Dyna Element Types in Combination with Different Anti-Hourglassing Formulations and Initial Element Deformations T2 - Kurzfassungen der Vorträge, 13. LS-DYNA Forum 2014, 6. - 8. Oktober 2014, Bamberg Y1 - 2014 SN - 978-3-9816215-1-8 PB - DYNAmore GmbH CY - Stuttgart ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Stelldinger, Enrico A1 - Keskin, Akin T1 - Identification of Stiffness Parameters of a Simplified Aero-Engine Mount System by Using a Higher Fidelity Model of the Mount System T2 - Kurzfassungen der Vorträge, 13. LS-DYNA Forum 2014, 6. - 8. Oktober 2014, Bamberg Y1 - 2014 SN - 978-3-9816215-1-8 PB - DYNAmore GmbH CY - Stuttgart ER - TY - GEN A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Rademann, Jörg A1 - Mück, Bernhard T1 - Nonlinear topology optimization of centrifugally loaded aero-engine part with newly developed optimality-criteria based algorithm T2 - Aerospace Science and Technology N2 - In this paper a successful topology optimization of a centrifugally loaded aero-engine part is presented. For the topology optimization, which is a nonlinear problem due to several contact regions, a self-developed topology optimization algorithm in combination with a commercial FE-solver is used. The goal of the optimization was the reduction of stresses in the structure. ©2014 Rolls-Royce Deutschland Ltd & Co. KG. Published by Elsevier Masson SAS. All rights reserved. KW - Topology optimization KW - Optimality criteria KW - Aero-engine KW - Centrifugal loading Y1 - 2014 UR - http://www.sciencedirect.com/science/article/pii/S1270963814001783 U6 - https://doi.org/10.1016/j.ast.2014.09.005 VL - Vol. 39 SP - 705 EP - 711 ER - TY - GEN A1 - Stelldinger, Enrico A1 - Kühhorn, Arnold A1 - Kober, Markus T1 - Experimental evaluation of the low-velocity impact damage resistance of CFRP tubes with integrated rubber layer T2 - Composite Structures N2 - The impact performance of structural components made of fibre-reinforced plastic is often one of the limiting properties during the design process. To improve the damage resistance regarding transverse low-velocity impact loading, a rubber layer (KRAIBON®) is integrated into the composite laminate of tubular carbon/epoxy specimens. Numerous impact tests, using two different rubber compounds and three different layups, are carried out. The specimens are impacted using a modified Charpy pendulum. Force–time histories have been used to determine the damage threshold load. To visualise damage such as delaminations and inter-fibre failures, the impacted samples have been examined using microsectioning. It is shown that a significant improvement in impact damage resistance can be achieved by integrating a rubber layer into a carbon/epoxy laminate. KW - Composites KW - Tubes KW - Low-velocity impact KW - Damage resistance Y1 - 2016 U6 - https://doi.org/10.1016/j.compstruct.2015.11.069 SN - 0263-8223 IS - 139 SP - 30 EP - 35 ER - TY - GEN A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Mück, Bernhard T1 - Topologieoptimierung eines fliehkraftbelasteten Triebwerkbauteils mit einfach zu implementierendem Algorithmus unter Berücksichtigung mehrerer Zielfunktionen T2 - NAFEMS-Magazin : Zeitschrift für numerische Simulationsmethoden und angrenzende Gebiete KW - Topologieoptimierung Y1 - 2015 UR - http://www.nafems.org/publications/magazin/archive/ SN - 2311-522x IS - 35 SP - 56 EP - 66 ER - TY - CHAP A1 - Keskin, Akin A1 - Kober, Markus A1 - Stelldinger, Enrico A1 - Kühhorn, Arnold A1 - Böhm, Holger A1 - Hornig, Andreas A1 - Hufenbach, Werner T1 - On the quantification of errors of a pre-processing effort reducing contact meshing approach : AIAA 2015-0408 T2 - 53rd AIAA Aerospace Sciences Meeting 2015, Kissimmee, Florida, USA, 5 - 9 January 2015, held at the AIAA SciTech Forum 2015, vol. 4 Y1 - 2015 SN - 978-1-5108-0117-2 U6 - https://doi.org/10.2514/6.2015-0408 SP - 3113 EP - 3124 PB - Curran CY - Red Hook, NY ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Keskin, Akin T1 - Implicit Time Integration Schemes for the FEM Simulation of Fast Rotating Structures T2 - WCCM XII & APCOM VI (World Congress on Computational Mechanics & Asia Pacific Congress on Computational Mechanics), Seoul, South Korea, 23.-29. Juli 2016 N2 - Due to the demand of more and more detailed FEM simulation results of whole aero-engine models, the number of DOF of such models (Fig. 1) increases dramatically. Although the available computational power for the solution of such highly nonlinear, dynamic boundary value problems also increased during the last years, the overall computational time of these high-fidelity models for the simulation of a few milliseconds of the running engine is in the order of several weeks even on high performance clusters with thousands of CPU cores. Typically, for such highly dynamic FEM computations explicit time integration schemes are used in order to solve the equations of motion. To keep such a numerical integration stable, the time step size may not exceed a certain critical time step size. Unfortunately, the critical time step size of an explicit time integration algorithm for the engine models under consideration is in the order of 10-8. This means that the simulation of a running engine over a time span of a few seconds results in a computational time of several years with clusters, which are available nowadays. Therefore, implicit time integration schemes, which are unconditionally stable and allow much bigger time steps, have to be used. Since in an implicit integration, in contrast to an explicit one, an equilibrium iteration is always necessary, the computational costs for an implicit time step are much higher than for an explicit time step. Almost all commercial FE codes use the classical Newmark implicit time integration scheme. It will be shown that this algorithm fails especially for the simulation of fast rotating structures if bigger time steps are used. This is demonstrated at the example of academic examples as well as for more realistic rotor models. To overcome the problems of the Newmark integration, a 3-Point-Newmark- Euler-Backward integration scheme [1,2] has been selected, which consists of alternating Newmark and 3-Point-Euler-Backward steps. The additional interpolation information for the Euler-step is provided by the previous Newmark step. This integration procedure has been implemented and successfully applied to the FEM simulation of fast rotating structures, which will be also demonstrated during the presentation. Y1 - 2016 UR - http://wccm2016.org/data/WCCM_Proceeding_v2.1.pdf UR - http://wccm2016.org/wp/pdf/150917.pdf ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Keskin, Akin A1 - Singh, Kai Navtej T1 - Challenges and opportunities of thermomechanical FEM simulations of high fidelity aero-engine models by implicit time-integration T2 - Proceedings of ISABE 2017, ISABE-2017-22568, Manchester, September 3.-8., 2017 Y1 - 2017 UR - https://isabe2017.org/ PB - ISABE ER -