TY - CHAP A1 - Kühhorn, Arnold A1 - Golze, Mark T1 - An Improved Sandwich Theory for a Better Prediction of the Wrinkling Phenomenon T2 - Proceedings of the Fifth World Congress on Computational Mechanics, Vienna, Austria, July 7 - 12, 2002, held at Vienna University of Technology N2 - An advanced design of sandwichstructures does not only require the knowledge of the global stress- and deformation behavior, but also the knowledge of the local effects, such as load singularities and the loss of stability caused by the short wave wrinkling of one (bending) or both (pressure) sandwich skins.Based on the nonlinear theory for sandwich shells with seven kinematic degrees of freedom, introduced from Kühhorn and Schoop an improved theory for plane sandwich shells with eight degrees of freedom will be presented, enabling a much better representation of the sandwich core behavior.Due to consideration of quadratic core thickness and linear core shear strain as well as longitudinal core deformation an improved prediction of the wrinkling behavior is succeeded even for thick cores and thin skins.The kinematic quantities as well as the nonlinear-differential equations and the simplified equations of first order theory resulting from them are given.Finally applying the well known classical problems of stability loaded by pressure and bending, the efficiency of this 8 DOF-theory ist demonstrated. A comparison with a detailed finite element (plain strain) calculation shows the high quality of these results.The presented sandwich theory characterized by eight degrees of freedom enables the calculation of nearly all essential sandwich phenomena even for thick cores. KW - Sandwich KW - Thickness flexible KW - Wrinkling KW - Stability KW - Platetheory Y1 - 2002 SN - 3-9501554-0-6 CY - Vienna ER - TY - CHAP A1 - Kühhorn, Arnold A1 - Golze, Mark T1 - Thickness flexible theory with generalized core warping for plane sandwich-structures N2 - An advanced design of sandwichstructures does not only require the knowledge of the global stress- and deformation behavior, but also the knowledge of the local effects, such as load singularities and the loss of stability caused by the short wave wrinkling of one (bending) or both (pressure) sandwich skins.Based on the nonlinear theory for sandwich shells with seven kinematic degrees of freedom, introduced from Kühhorn and Schoop an improved theory for plane sandwich shells with eight degrees of freedom (position vector r, director d, and intensity factors az1, az2 for including core flexibility) will be presented, enabling a much better representation of the sandwich core behavior.Due to consideration of quadratic core thickness and linear core shear strain as well as longitudinal core deformation an improved prediction of the wrinkling behavior is succeeded even for thick cores and thin skins.The kinematic quantities as well as the nonlinear-differential equations achieved from the principle of virtual work and the simplified equations of first order theory resulting from them are given.Finally applying the well known classical problems of stability loaded by pressure and bending, the efficiency of this 8 DOF-theory is demonstrated. A comparison with a detailed finite element (plain strain) calculation shows the high quality of these results.The presented sandwich theory characterized by eight kinematic degrees of freedom is valid for arbitrary displacements, rotations and moderat strains enables the calculation of nearly all essential sandwich phenomena even for thick cores. KW - sandwich KW - thickness flexible KW - wrinkling KW - stability Y1 - 2002 ER - TY - CHAP A1 - Golze, Mark A1 - Kühhorn, Arnold T1 - CFK-/GFK-Auslegung am Beispiel eines Modellflügels T2 - Tagungsband, 14. deutschsprachiges ABAQUS Anwendertreffen, 23. - 24. September 2002 in Wiesbaden N2 - Ökonomische und ökologische Bedürfnisse verlangen von modernen Konstruktionen sowohl eine hochintegrative Bauweise als auch eine massive Gewichtseinsparung. Dies führt zu neuen Leichtbaukonstruktionen mit einem stetig zunehmenden Anteil an Faserverbundlösungen. Die hierbei eröffnete Möglichkeit, kraftfluß- und beanspruchungsgerecht auszulegen, erschließt sich erst vollständig durch die sichere Anwendung moderner FE-Programme wie beispielsweise ABAQUS. Nutzt man darüber hinaus die Möglichkeit der flexiblen Script-Programmierung, so lassen sich wirkungsvolle Effizienzsteigerungen durch die gezielte Erstellung spezifischer Eingabemenüs und Ausgaberoutinen erreichen. Dieser Beitrag veranschaulicht an Hand eines ausgeführten und getesteten CFK-Modellflügels unter Biegebeanspruchung, die Vorgehensweise bei Verwendung von ABAQUS und der Script-Sprache Python. KW - CFK KW - GFK KW - FEM KW - ABAQUS KW - Faserverbundauslegungen KW - Python Y1 - 2002 PB - ABACOM Software GmbH CY - Aachen ER - TY - JOUR A1 - Kühhorn, Arnold A1 - Klauke, Thomas A1 - Golze, Mark T1 - Simulation und Verifikation der sukzessiven Bruchabfolge eines CFK-Bauteils mittels neuartiger Bruchkriterien KW - CFK-Bauteile KW - Bruchkriterien KW - Simulation Bruchabfolge Y1 - 2003 ER - TY - JOUR A1 - Kühhorn, Arnold A1 - Beirow, Bernd A1 - Klauke, Thomas A1 - Golze, Mark T1 - Simulation der Mistuningeffekte von Hochdruckverdichter-Schaufelscheiben zur Bestimmung kritischer Schwingungen in Flugtriebwerken KW - Mistuningeffekte KW - Blisks Y1 - 2004 ER - TY - CHAP A1 - Beirow, Bernd A1 - Kühhorn, Arnold A1 - Golze, Mark A1 - Klauke, Thomas T1 - Strukturdynamische Untersuchungen an Hochdruckverdichterschaufelscheiben unter Berücksichtigung von Mistuningeffekten T2 - Modalanalyse und Identifikation, Verfahren und Anwendungen bei dynamischen Systemen, Tagung Wiesloch, 25. und 26. Mai 2004 KW - Verdichterschaufelscheiben KW - Mistuningeffekte Y1 - 2004 SN - 3-18-091825-X SP - 351 EP - 372 PB - VDI-Verlag CY - Düsseldorf ER - TY - GEN A1 - Kühhorn, Arnold A1 - Beirow, Bernd A1 - Schrape, Sven A1 - Golze, Mark A1 - Knöpke, Martin T1 - Simulation fluidgedämpfter Strukturschwingungen mittels partitionierter Fluid-Struktur-Kopplung T2 - Forum der Forschung Y1 - 2005 SN - 0947-6989 VL - 9 IS - 18 SP - 79 EP - 86 ER - TY - GEN A1 - de Silva, Tina A1 - Kühhorn, Arnold A1 - Golze, Mark T1 - Homogenization of thin structured sheet metals by using FEM T2 - Proceedings in applied mathematics and mechanics : PAMM KW - Structured Sheets KW - FEA Y1 - 2012 UR - http://onlinelibrary.wiley.com/doi/10.1002/pamm.v12.1/issuetoc U6 - https://doi.org/10.1002/pamm.201210104 N1 - GAMM 2012, 83rd Annual Scientific Conference, Darmstadt, 26. - 30. März 2012 VL - 12 IS - 1 SP - 227 EP - 228 ER - TY - GEN A1 - Beirow, Bernd A1 - Golze, Mark A1 - Popig, Frederik T1 - Vibration Reduction of a Steam Turbine Wheel by Means of Intentional Mistuning T2 - Advances in Mechanism Design III : Proceedings of TMM 2020 N2 - A last stage steam turbine wheel is analyzed with the objective to alleviate the flutter susceptibility by employing intentional mistuning (IM). In particular, the operation at nominal speed under part-load conditions may cause unfavorable flow conditions facilitating flow separation. In consequence, negative aerodynamic damping ratios occur for the first bending mode family in some circumstances. Employing intended alternate mistuning of adequate magnitude has proved to be a promising measure to stabilize rotors in terms of avoiding self-excited vibration phenomena. From the manufacturing point of view, this two-blade design is advantageous as well and hence, chosen here as a first measure to attenuate flutter susceptibility. Two prototypes of bladed disks series have been made, which are exhibiting small but unavoidable deviations from the design intention due to manufacturing. The real blade alone frequencies have been identified within foregoing experimental investigations. Numerical modal analyses carried out for the prototypes as manufactured finally reveal that there is an additional positive contribution of random mistuning in terms of further enhancing the least aerodynamic damping ratio. Another promising and robust IM pattern is found by using generic algorithms to optimize the least aerodynamic damping ratio yielding stable conditions at any time as well. Moreover, it shows that IM combined with random mistuning also mitigates the maximum forced response at part-speed conditions. KW - Intentional mistuning KW - Blade vibration KW - Flutter KW - Forced response KW - Optimization KW - Aeroelastics Y1 - 2022 SN - 978-3-030-83593-4 SN - 978-3-030-83594-1 U6 - https://doi.org/10.1007/978-3-030-83594-1_8 SN - 2211-0984 SN - 2211-0992 SP - 73 EP - 82 PB - Springer CY - Cham ER - TY - CHAP A1 - Beirow, Bernd A1 - Kühhorn, Arnold A1 - Golze, Mark A1 - Klauke, Thomas T1 - Experimentelle Untersuchungen des strukturdynamischen Verhaltens von Hochdruckverdichterschaufeln in Integralbauweise (Blisks) mittels Laser-Doppler-Vibrometrie KW - Blisks KW - Integralbauweise Y1 - 2004 ER - TY - JOUR A1 - Kühhorn, Arnold A1 - Beirow, Bernd A1 - Golze, Mark A1 - Studener, Johannes T1 - Strukturmechanische Analyse einer Triebwerksverdichter-Schaufelscheibe N2 - Die Verbesserung von Kalibriermethoden für Hochdruckverdichterstufen in ausgeführter Integralbauweise verlangt von den Ingenieuren ein detaillierteres Verständnis der strukturdynamischen Zusammenhänge dieses komplexen Bauteils. Als Ausgangsbasis werden zunächst für das perfekte Normdesign bei Ausnutzung der vorliegenden zyklischen Rotationssymmetrie numerische Ergebnisse vorgestellt. Dabei stehen bezüglich des Schwingverhaltens die Kopplungseffekte zwischen Scheibe und Schaufeln im Mittelpunkt, wobei experimentelle Untersu-chungen am realen Bauteil ergänzend hinzugezogen werden. Zukünftig wird in einem weiteren Schritt im Rahmen erheblich aufwendigerer Berechnungen mit der Berücksichtigung von Imperfektionen hinsichtlich der filigranen Schaufeln die Rotationssymmetrie aufgegeben und somit die Basis für eine gezielte Beeinflussung des Schwingverhaltens infolge von Mistuning - Effekten geschaffen. KW - FEM-Simulation KW - Experimentelle Modalanalysen KW - Kopplungseffekte Y1 - 2002 ER - TY - CHAP A1 - Beirow, Bernd A1 - Kühhorn, Arnold A1 - Golze, Mark A1 - Parchem, Roland A1 - Johann, E. T1 - Experimentelle und numerische Untersuchungen hinsichtlich einer Festigkeitsauslegungsoptimierung von Hochdruck-Verdichter-Schaufelscheiben unter besonderer Berücksichtigung von Mistuningeffekten T2 - Deutscher Luft- und Raumfahrtkongress 2003, München, 17. bis 20. November 2003, Bd. 2 KW - Festigkeitsauslegungsoptimierung KW - Hochdruck-Verdichter-Schaufelscheiben KW - Mistuningeffekte Y1 - 2003 SP - 1495 EP - 1504 PB - DGLR CY - Bonn ER - TY - CHAP A1 - Klauke, Thomas A1 - Kühhorn, Arnold A1 - Golze, Mark A1 - Villwock, J. A1 - Lenk, Olaf T1 - Finite-Elemente-Anwendung neuerer Faserverbund-Bruchkriterien und deren Verifizierung mittels CFK-Bauteilprüfung T2 - Deutscher Luft- und Raumfahrtkongress 2003, München, 17. bis 20. November 2003, Bd. 1 KW - FEM KW - Faserverbund KW - CFK-Bauteilprüfung Y1 - 2003 SP - 113 EP - 120 PB - Dt. Ges. für Luft- und Raumfahrt CY - Bonn ER - TY - GEN A1 - Klauke, Thomas A1 - Kühhorn, Arnold A1 - Beirow, Bernd A1 - Golze, Mark T1 - Numerical Investigations of Localized Vibrations of Mistuned Blade Integrated Disks (Blisks) Y1 - 2009 ER - TY - GEN A1 - Beirow, Bernd A1 - Golze, Mark A1 - Popig, Frederik T1 - Application of Intentional Mistuning to Reduce the Vibration Susceptibility of a Steam Turbine Wheel T2 - ASME 2022 Turbomachinery Technical Conference & Exposition (GT2022) N2 - Intentional mistuning (IM) is employed on a last stage turbine wheel to alleviate both the flutter susceptibility and maximum forced response. Primarily, operations at nominal speed under part-load conditions may cause unfavorable flow conditions facilitating flow separation. As a consequence, the original design intention with identical blades features negative aerodynamic damping ratios with respect to the first bending mode family. In order to prevent any self-excited vibration phenomena, intentional alternate mistuning is utilized to increase the least aerodynamic damping ratio as far as it takes a positive value and hence, to contribute to a stabilization of the rotor. For the purpose of numerically analyzing the vibration behavior, reduced order models are built up, which are based on modal reduction techniques, namely the subset of nominal system modes (SNM) [1] and the fundamental mistuning model (FMM) [2]. These types of models conveniently allow for considering both, different mistuning distributions in terms of probabilistic analyses and the aeroelastic interaction by means of prescribing aerodynamic damping ratios and aeroelastic natural frequencies of the tuned counterpart or aerodynamic influence coefficients, respectively. A detailed study is presented regarding the correction of frequency mistuning magnitudes in terms of considering the impact of centrifugal stiffening, which plays a significant role in case of long low pressure turbine blades featuring high aspect ratios. Since alternate IM cannot be implemented perfectly, every bladed wheel as manufactured will exhibit small but unavoidable structural deviations from the design intention, which are known as random mistuning. To ensure the robustness of the IM solution in terms of positive aerodynamic damping ratios at any time, comprehensive probabilistic analyses are conducted with respect to superimposing random structural mistuning at first. Secondly, the impact of varying mistuning magnitude is analyzed. Thirdly, the robustness towards aerodynamic mistuning is investigated by means of small variations of aeroelastic influence coefficients and consequently, the inter blade phase angle dependent aerodynamic damping curves. Moreover, it becomes apparent that alternate IM superimposed with both, random structural and aerodynamic mistuning also mitigates the maximum forced response at part-speed conditions. Y1 - 2022 UR - https://asme-turboexpo.secure-platform.com/a/solicitations/167/sessiongallery/10144/application/82208 ER - TY - CHAP A1 - Beirow, Bernd A1 - Golze, Mark A1 - Popig, Frederik ED - Beran, Jaroslav ED - Bílek, Martin ED - Václavík, Miroslav ED - Žabka, Petr T1 - Vibration Reduction of a Steam Turbine Wheel by Means of Intentional Mistuning T2 - Advances in Mechanism Design III N2 - A last stage steam turbine wheel is analyzed with the objective to alleviate the flutter susceptibility by employing intentional mistuning (IM). In particular, the operation at nominal speed under part-load conditions may cause unfavorable flow conditions facilitating flow separation. In consequence, negative aerodynamic damping ratios occur for the first bending mode family in some circumstances. Employing intended alternate mistuning of adequate magnitude has proved to be a promising measure to stabilize rotors in terms of avoiding self-excited vibration phenomena. From the manufacturing point of view, this two-blade design is advantageous as well and hence, chosen here as a first measure to attenuate flutter susceptibility. Two prototypes of bladed disks series have been made, which are exhibiting small but unavoidable deviations from the design intention due to manufacturing. The real blade alone frequencies have been identified within foregoing experimental investigations. Numerical modal analyses carried out for the prototypes as manufactured finally reveal that there is an additional positive contribution of random mistuning in terms of further enhancing the least aerodynamic damping ratio. Another promising and robust IM pattern is found by using generic algorithms to optimize the least aerodynamic damping ratio yielding stable conditions at any time as well. Moreover, it shows that IM combined with random mistuning also mitigates the maximum forced response at part-speed conditions. KW - steam turbine KW - vibration KW - intentional mistuning Y1 - 2022 SN - 978-3-030-83593-4 SN - 978-3-030-83596-5 U6 - https://doi.org/10.1007/978-3-030-83594-1_8 SN - 2211-0984 SN - 2211-0992 SP - 73 EP - 82 PB - Springer International Publishing CY - Heidelberg ER - TY - CHAP A1 - Schrape, S. A1 - Kühhorn, Arnold A1 - Golze, Mark T1 - Simulation fluidgedämpfter Strukturschwingungen durch partitionierte Fluid-Struktur-Kopplung mittels MpCCI KW - Fluid-Struktur-Kopplung Y1 - 2006 ER - TY - JOUR A1 - Schrape, S. A1 - Kühhorn, Arnold A1 - Golze, Mark T1 - Simulation fluidgedämpfter Strukturschwingungen mittels partitioniertem Kopplungssatz via MpCCI JF - NAFEMS-Magazin KW - fluidgedämpfte Strukturschwingungen Y1 - 2006 VL - 2 IS - 4 SP - 41 EP - 49 ER - TY - CHAP A1 - Schrape, S. A1 - Kühhorn, Arnold A1 - Golze, Mark T1 - Simulation of fluid damped structural vibrations T2 - Proceedings, 7th MpCCI User Forum, February 21st and 22nd 2006, at Schloss Birlinghoven, Sankt Augustin, Germany KW - fluid structures Y1 - 2006 SP - 112 EP - 121 CY - Sankt Augustin ER - TY - CHAP A1 - Beirow, Bernd A1 - Kühhorn, Arnold A1 - Golze, Mark T1 - Experimental and Numerical Investigations of High pressure Compressor Blades Vibration Behavior Considering Mistuning KW - vibration Y1 - 2005 ER -