@inproceedings{KuehhornGolze, author = {K{\"u}hhorn, Arnold and Golze, Mark}, title = {An Improved Sandwich Theory for a Better Prediction of the Wrinkling Phenomenon}, series = {Proceedings of the Fifth World Congress on Computational Mechanics, Vienna, Austria, July 7 - 12, 2002, held at Vienna University of Technology}, booktitle = {Proceedings of the Fifth World Congress on Computational Mechanics, Vienna, Austria, July 7 - 12, 2002, held at Vienna University of Technology}, address = {Vienna}, isbn = {3-9501554-0-6}, abstract = {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 K{\"u}hhorn 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.}, language = {en} } @inproceedings{KuehhornGolze, author = {K{\"u}hhorn, Arnold and Golze, Mark}, title = {Thickness flexible theory with generalized core warping for plane sandwich-structures}, abstract = {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 K{\"u}hhorn 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.}, language = {en} } @inproceedings{GolzeKuehhorn, author = {Golze, Mark and K{\"u}hhorn, Arnold}, title = {CFK-/GFK-Auslegung am Beispiel eines Modellfl{\"u}gels}, series = {Tagungsband, 14. deutschsprachiges ABAQUS Anwendertreffen, 23. - 24. September 2002 in Wiesbaden}, booktitle = {Tagungsband, 14. deutschsprachiges ABAQUS Anwendertreffen, 23. - 24. September 2002 in Wiesbaden}, publisher = {ABACOM Software GmbH}, address = {Aachen}, abstract = {{\"O}konomische und {\"o}kologische Bed{\"u}rfnisse verlangen von modernen Konstruktionen sowohl eine hochintegrative Bauweise als auch eine massive Gewichtseinsparung. Dies f{\"u}hrt zu neuen Leichtbaukonstruktionen mit einem stetig zunehmenden Anteil an Faserverbundl{\"o}sungen. Die hierbei er{\"o}ffnete M{\"o}glichkeit, kraftfluß- und beanspruchungsgerecht auszulegen, erschließt sich erst vollst{\"a}ndig durch die sichere Anwendung moderner FE-Programme wie beispielsweise ABAQUS. Nutzt man dar{\"u}ber hinaus die M{\"o}glichkeit der flexiblen Script-Programmierung, so lassen sich wirkungsvolle Effizienzsteigerungen durch die gezielte Erstellung spezifischer Eingabemen{\"u}s und Ausgaberoutinen erreichen. Dieser Beitrag veranschaulicht an Hand eines ausgef{\"u}hrten und getesteten CFK-Modellfl{\"u}gels unter Biegebeanspruchung, die Vorgehensweise bei Verwendung von ABAQUS und der Script-Sprache Python.}, language = {de} } @article{KuehhornKlaukeGolze, author = {K{\"u}hhorn, Arnold and Klauke, Thomas and Golze, Mark}, title = {Simulation und Verifikation der sukzessiven Bruchabfolge eines CFK-Bauteils mittels neuartiger Bruchkriterien}, language = {de} } @article{KuehhornBeirowKlaukeetal., author = {K{\"u}hhorn, Arnold and Beirow, Bernd and Klauke, Thomas and Golze, Mark}, title = {Simulation der Mistuningeffekte von Hochdruckverdichter-Schaufelscheiben zur Bestimmung kritischer Schwingungen in Flugtriebwerken}, language = {de} } @inproceedings{BeirowKuehhornGolzeetal., author = {Beirow, Bernd and K{\"u}hhorn, Arnold and Golze, Mark and Klauke, Thomas}, title = {Strukturdynamische Untersuchungen an Hochdruckverdichterschaufelscheiben unter Ber{\"u}cksichtigung von Mistuningeffekten}, series = {Modalanalyse und Identifikation, Verfahren und Anwendungen bei dynamischen Systemen, Tagung Wiesloch, 25. und 26. Mai 2004}, booktitle = {Modalanalyse und Identifikation, Verfahren und Anwendungen bei dynamischen Systemen, Tagung Wiesloch, 25. und 26. Mai 2004}, publisher = {VDI-Verlag}, address = {D{\"u}sseldorf}, isbn = {3-18-091825-X}, pages = {351 -- 372}, language = {de} } @misc{KuehhornBeirowSchrapeetal., author = {K{\"u}hhorn, Arnold and Beirow, Bernd and Schrape, Sven and Golze, Mark and Kn{\"o}pke, Martin}, title = {Simulation fluidged{\"a}mpfter Strukturschwingungen mittels partitionierter Fluid-Struktur-Kopplung}, series = {Forum der Forschung}, volume = {9}, journal = {Forum der Forschung}, number = {18}, issn = {0947-6989}, pages = {79 -- 86}, language = {de} } @misc{deSilvaKuehhornGolze, author = {de Silva, Tina and K{\"u}hhorn, Arnold and Golze, Mark}, title = {Homogenization of thin structured sheet metals by using FEM}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {12}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {1}, doi = {10.1002/pamm.201210104}, pages = {227 -- 228}, language = {en} } @misc{BeirowGolzePopig, author = {Beirow, Bernd and Golze, Mark and Popig, Frederik}, title = {Vibration Reduction of a Steam Turbine Wheel by Means of Intentional Mistuning}, series = {Advances in Mechanism Design III : Proceedings of TMM 2020}, journal = {Advances in Mechanism Design III : Proceedings of TMM 2020}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-83593-4}, issn = {2211-0984}, doi = {10.1007/978-3-030-83594-1_8}, pages = {73 -- 82}, abstract = {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.}, language = {en} } @inproceedings{BeirowKuehhornGolzeetal., author = {Beirow, Bernd and K{\"u}hhorn, Arnold and Golze, Mark and Klauke, Thomas}, title = {Experimentelle Untersuchungen des strukturdynamischen Verhaltens von Hochdruckverdichterschaufeln in Integralbauweise (Blisks) mittels Laser-Doppler-Vibrometrie}, language = {de} } @article{KuehhornBeirowGolzeetal., author = {K{\"u}hhorn, Arnold and Beirow, Bernd and Golze, Mark and Studener, Johannes}, title = {Strukturmechanische Analyse einer Triebwerksverdichter-Schaufelscheibe}, abstract = {Die Verbesserung von Kalibriermethoden f{\"u}r Hochdruckverdichterstufen in ausgef{\"u}hrter Integralbauweise verlangt von den Ingenieuren ein detaillierteres Verst{\"a}ndnis der strukturdynamischen Zusammenh{\"a}nge dieses komplexen Bauteils. Als Ausgangsbasis werden zun{\"a}chst f{\"u}r das perfekte Normdesign bei Ausnutzung der vorliegenden zyklischen Rotationssymmetrie numerische Ergebnisse vorgestellt. Dabei stehen bez{\"u}glich des Schwingverhaltens die Kopplungseffekte zwischen Scheibe und Schaufeln im Mittelpunkt, wobei experimentelle Untersu-chungen am realen Bauteil erg{\"a}nzend hinzugezogen werden. Zuk{\"u}nftig wird in einem weiteren Schritt im Rahmen erheblich aufwendigerer Berechnungen mit der Ber{\"u}cksichtigung von Imperfektionen hinsichtlich der filigranen Schaufeln die Rotationssymmetrie aufgegeben und somit die Basis f{\"u}r eine gezielte Beeinflussung des Schwingverhaltens infolge von Mistuning - Effekten geschaffen.}, language = {de} } @inproceedings{BeirowKuehhornGolzeetal., author = {Beirow, Bernd and K{\"u}hhorn, Arnold and Golze, Mark and Parchem, Roland and Johann, E.}, title = {Experimentelle und numerische Untersuchungen hinsichtlich einer Festigkeitsauslegungsoptimierung von Hochdruck-Verdichter-Schaufelscheiben unter besonderer Ber{\"u}cksichtigung von Mistuningeffekten}, series = {Deutscher Luft- und Raumfahrtkongress 2003, M{\"u}nchen, 17. bis 20. November 2003, Bd. 2}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2003, M{\"u}nchen, 17. bis 20. November 2003, Bd. 2}, publisher = {DGLR}, address = {Bonn}, pages = {1495 -- 1504}, language = {de} } @inproceedings{KlaukeKuehhornGolzeetal., author = {Klauke, Thomas and K{\"u}hhorn, Arnold and Golze, Mark and Villwock, J. and Lenk, Olaf}, title = {Finite-Elemente-Anwendung neuerer Faserverbund-Bruchkriterien und deren Verifizierung mittels CFK-Bauteilpr{\"u}fung}, series = {Deutscher Luft- und Raumfahrtkongress 2003, M{\"u}nchen, 17. bis 20. November 2003, Bd. 1}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2003, M{\"u}nchen, 17. bis 20. November 2003, Bd. 1}, publisher = {Dt. Ges. f{\"u}r Luft- und Raumfahrt}, address = {Bonn}, pages = {113 -- 120}, language = {de} } @misc{KlaukeKuehhornBeirowetal., author = {Klauke, Thomas and K{\"u}hhorn, Arnold and Beirow, Bernd and Golze, Mark}, title = {Numerical Investigations of Localized Vibrations of Mistuned Blade Integrated Disks (Blisks)}, language = {de} } @misc{BeirowGolzePopig, author = {Beirow, Bernd and Golze, Mark and Popig, Frederik}, title = {Application of Intentional Mistuning to Reduce the Vibration Susceptibility of a Steam Turbine Wheel}, series = {ASME 2022 Turbomachinery Technical Conference \& Exposition (GT2022)}, journal = {ASME 2022 Turbomachinery Technical Conference \& Exposition (GT2022)}, abstract = {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.}, language = {en} } @incollection{BeirowGolzePopig, author = {Beirow, Bernd and Golze, Mark and Popig, Frederik}, title = {Vibration Reduction of a Steam Turbine Wheel by Means of Intentional Mistuning}, series = {Advances in Mechanism Design III}, booktitle = {Advances in Mechanism Design III}, editor = {Beran, Jaroslav and B{\´i}lek, Martin and V{\´a}clav{\´i}k, Miroslav and Žabka, Petr}, publisher = {Springer International Publishing}, address = {Heidelberg}, isbn = {978-3-030-83593-4}, issn = {2211-0984}, doi = {10.1007/978-3-030-83594-1_8}, pages = {73 -- 82}, abstract = {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.}, language = {en} } @incollection{SchrapeKuehhornGolze, author = {Schrape, S. and K{\"u}hhorn, Arnold and Golze, Mark}, title = {Simulation fluidged{\"a}mpfter Strukturschwingungen durch partitionierte Fluid-Struktur-Kopplung mittels MpCCI}, language = {de} } @article{SchrapeKuehhornGolze, author = {Schrape, S. and K{\"u}hhorn, Arnold and Golze, Mark}, title = {Simulation fluidged{\"a}mpfter Strukturschwingungen mittels partitioniertem Kopplungssatz via MpCCI}, series = {NAFEMS-Magazin}, volume = {2}, journal = {NAFEMS-Magazin}, number = {4}, pages = {41 -- 49}, language = {de} } @incollection{SchrapeKuehhornGolze, author = {Schrape, S. and K{\"u}hhorn, Arnold and Golze, Mark}, title = {Simulation of fluid damped structural vibrations}, series = {Proceedings, 7th MpCCI User Forum, February 21st and 22nd 2006, at Schloss Birlinghoven, Sankt Augustin, Germany}, booktitle = {Proceedings, 7th MpCCI User Forum, February 21st and 22nd 2006, at Schloss Birlinghoven, Sankt Augustin, Germany}, address = {Sankt Augustin}, pages = {112 -- 121}, language = {en} } @inproceedings{BeirowKuehhornGolze, author = {Beirow, Bernd and K{\"u}hhorn, Arnold and Golze, Mark}, title = {Experimental and Numerical Investigations of High pressure Compressor Blades Vibration Behavior Considering Mistuning}, language = {en} } @article{KuehhornGolze, author = {K{\"u}hhorn, Arnold and Golze, Mark}, title = {Thickness flexible sandwich theory for the common description of global and local effects}, language = {en} }