• Schedlinski C. et al.:
    "Computational Model Updating of Structural Damping and Acoustic Absorption for Coupled Fluid-Structure-Analyses of Passenger Cars"

    Proceedings of the Noise and Vibration Engineering Conference, ISMA 2008, Leuven, Belgium, 2008

    To validate structural Finite Element models, test data, e. g. from an experimental modal analysis, may be utilized in order to update mass and stiffness parameters. For frequency response calculations, however, proper modeling of structural damping mechanisms must be achieved as well to obtain acceptable estimates of the overall response levels. Going even further towards fluid-structure-analyses, the absorption behavior of the cavity boundary and of interior components (seats etc.) need to be respected.

    In this paper a modeling strategy for damping and absorption is presented that is based on computational optimization and model updating techniques. For the structural part, individual structural damping is assigned to the individual components and subsequently updated utilizing test data obtained from classical modal analysis testing (force excitation). For the acoustic absorption the approach is extended such that individual absorption coefficients can be addressed. The test data utilized here come from acoustic tests with volume source excitation.

    By means of a real car body the single steps of the strategy will be highlighted, and it will be shown that very encouraging results can be obtained even for very complex systems.

    (PDF-Datei 2279 KB)

  • Wagner F. et al.:
    "Computerunterstützte Dämpfungsidentifikation einer Rohkarosserie mit Anbauteilen auf Basis gemessener Frequenzgänge"

    Proceedings VDI-Konferenz Schwingungsdämpfung 2007, VDI-Berichte Nr. 2003, 2007

    In dieser Veröffentlichung wird eine Methode zur computerunterstützten Identifikation von Dämpfungsparametern auf Basis gemessener Frequenzgänge vorgestellt. Dabei wird die Leistungsfähigkeit der Methode am Beispiel einer Rohkarosserie mit Anbauteilen gezeigt, welche im Rahmen des Arbeitskreises 6.1.19 "Strukturoptimierung Akustik" der deutschen Automobilindustrie untersucht wird.

    (PDF-Datei 916 KB)

  • Schedlinski C. et al.:
    "Modellierung der Flanschverbindungen von Verbrennungsmotorkomponenten unter Berücksichtigung von Mikroschlupf"

    Proceedings VDI-Konferenz Schwingungsdämpfung 2007, VDI-Berichte Nr. 2003, 2007

    Diese Veröffentlichung behandelt die Modellierung von Zusammenbauten von Gehäusebauteilen eines Verbrennungsmotors. Bei diesen Zusammenbauten findet man eine Vielzahl an Flanschverbindungen, die zum Steifigkeits- und Dämpfungsverhalten des Gesamtverbandes beitragen. Am Beispiel eines Vierzylinderverbrennungsmotors wird eine Finite Elemente Modellierungstechnik vorgestellt, die auf eine korrekte Abbildung der Flanschregion zwischen Zylinderkurbelgehäuse und Kurbelwellengrundlagerdeckel zielt. Speziell wird eine numerische Methode gezeigt und angewendet, die die nichtlinearen Dämpfungs- und Steifigkeitseigenschaften des Systems berücksichtigt. Die Ergebnisse der numerischen Analyse werden ferner mit experimentellen Daten verglichen, um die Wirksamkeit der Methode zu demonstrieren.

    (PDF-Datei 1346 KB)

  • Schedlinski C., Genzo A., Läer B. and Panning L.:
    "Modeling of Assembled Combustion Engine Parts under Consideration of Micro Slip Effects in the Connection Flanges"

    Proceedings of the Noise and Vibration Engineering Conference, ISMA 2006, Leuven, Belgium, 2006

    This paper addresses the modeling of assembled combustion engine parts. Here multiple flange connections are found that contribute to the stiffness and damping characteristics. By example of a four cylinder combustion engine a finite element modeling technique will be introduced which focuses on a suitable and proper representation of the flange regions between crankcase and crankshaft main bearing cap. Especially, a numerical method will be presented and applied that accounts for the nonlinear damping and stiffness characteristics of the system. The numerical analysis results will be compared to experimental data in order to prove the effectiveness of the method.

    (PDF-Datei 592 KB)

  • Schedlinski, C. et al.:
    "Test-Based Computational Model Updating of a Car Body in White"

    Sound and Vibration, Volume 39/Number 9, September 2005

    To validate finite-element models, test data from experimental modal analyses may be utilized. The model data must be highly accurate since they form the basis for subsequent validation efforts. An integrated validation strategy is presented that takes into account the complete process chain from model-based test design through modal testing, data evaluation, test/analysis correlation to computational model updating. By means of a real car body in white, the single steps of the validation strategy are highlighted, and it is shown that very encouraging results can be obtained even for very complex systems.

    (online verfügbar bei http://www.SandV.com)

  • Böswald, M. et al.:
    "Computational Model Updating and Validation of Aero-engine Finite Element Models Based on Vibration Test Data"

    IFASD 2005, Munich, Germany, 28. June-01. July 2005

    In this paper, an overview and some selected details are given on a general procedure to improve large order structural dynamic models of aero-engines. Because of the complexity of typical whole engine models (WEM) a special model validation strategy is required to account for the large number of finite element (FE) model parameters which may be uncertain in a WEM. A three-step strategy is proposed which is based on three subsequent levels of model validation. In the first step, model validation is carried out on component model level, whereas in the second step, sub-assembly models are validated with emphasis on updating joint parameters, and in the final step, model validation is carried out on the whole engine assembly level where only a few uncertain joint parameters need to be adjusted. Typical problems encountered during computational model updating are addressed, among those, the selection of effective updating parameters. An extension of the classical model updating techniques is presented which aims at extending the prediction capability of the model into the large vibration amplitude regime where non-linear behavior is likely to occur. This is achieved by identifying non-linear joint stiffness and damping parameters by application of a non-linear model updating approach based on measured non-linear frequency response data.

    (PDF-Datei 512 KB)

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