TY - CHAP A1 - Keskin, Akin A1 - Swoboda, Marius A1 - Flassig, Peter Michael A1 - Dutta, Amit Kumar A1 - Bestle, Dieter T1 - Accelerated Industrial Blade Design Based on Multi-Objective Optimization Using Surrogate Model Methodology T2 - Proceedings of the ASME Turbo Expo 2008, presented at the 2008 ASME Turbo Expo, June 9 - 13, 2008, Berlin, Germany, Vol 6., Part C KW - Optimization KW - Blade Design Y1 - 2008 SN - 978-0-7918-4316-1 SP - 2339 EP - 2349 PB - ASME CY - New York, NY ER - TY - CHAP A1 - Keskin, Akin A1 - Dutta, Amit Kumar A1 - Bestle, Dieter T1 - Modern Compressor Aerodynamic Blading Process using Multi-objective Optimization T2 - Proceedings of the ASME Turbo Expo 2006, presented at the 2006 ASME Turbo Expo, May 6 - 11, 2006, Barcelona, Spain, Vol. 6, Part B Y1 - 2006 SN - 0-7918-4241-X SP - 1209 EP - 1216 PB - ASME CY - New York, NY ER - TY - CHAP A1 - Keskin, Akin A1 - Bestle, Dieter T1 - A Method for Using Multi-objective Optimization within the Rolls-Royce meanline Prediction Process Y1 - 2005 ER - TY - CHAP A1 - Dutta, Amit Kumar A1 - Flassig, Peter Michael A1 - Bestle, Dieter A1 - Keskin, Akin A1 - Swoboda, Marius T1 - Validierung optimierter Verdichterschaufeln mit Hilfe der 3D-CFD T2 - Deutscher Luft- und Raumfahrtkongress 2008, Darmstadt, 23. bis 25. September 2008, Bd. 2 Y1 - 2008 N1 - DLRK 2008-081222 SP - 1023 EP - 1033 PB - Dt. Ges. für Luft- und Raumfahrt CY - Bonn ER - TY - CHAP A1 - Keskin, Akin A1 - Przewozny, Hans A1 - Gräsel, Jürgen A1 - Saxer, Andre A1 - Swoboda, Marius T1 - A full parametric model for turbo machinery blade design and optimisation Y1 - 2004 ER - TY - CHAP A1 - Bestle, Dieter A1 - Keskin, Akin A1 - Otto, Dierk T1 - Process Integration and Automation for optimal Design Y1 - 2006 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 - 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 T1 - Instability problems in implicit transient FEM simulations of fast rotating elastic structures - Description of the phenomenon and possible solutions T2 - Proceedings of NAFEMS DACH Conference 2018, Bamberg, May 14-16, 2018 Y1 - 2018 SN - 978-1-910643-14-3 SP - 48 EP - 52 PB - NAFEMS Deutschland, Österreich, Schweiz GmbH CY - Grafing ER -