Approximate Modal Coupling of Multi Degree of Freedom Substructures

Primary and Secondary Systems
  • B. Zastrau
Conference paper


This contribution treats the approximate calculation of the eigenfrequency variation of complex structures due to slight changes of system properties or the attachment of multiply supported MDOF secondary substructures. Starting from simple mechanical assumptions like negligible changes of the eigen- modes of the primary structure an energy concept using the Rayleigh quotient and the energy balance of systems with forced vibration is developed. The accurateness of the proposed method is demonstrated by comparison with finite element results and measured eigenfrequencies of the combined system.


Combine System Forced Vibration Primary System Finite Element Result Secondary System 
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  1. 1.
    Bohlen, S.: Messung der erzwungenen BiegeSchwingungen einer Balkenstruktur mit angekoppeltem Zwei-Freiheitsgrad-Zusatzsystem. Mitteilung aus dem Institut für Mechanik, UniBwH (1985) I’ 1–10.Google Scholar
  2. 2.
    Gaul, L.; Zastrau, B.; Bohlen, S.: Analytische Näherung und Messung der Eigenfrequenzen, Eigenformen und Dämpfung gekoppelter Strukturen. VDI-Berieht Nr.536 (1984) 289–307.Google Scholar
  3. 3.
    Igusa, T.; Der Kiureghian, A.: Dynamic Characterization of Two-Degree-of- Freedom Equipment-Structure Systems. J. of Eng. Mec. Vol.111 (1985) 1–19.CrossRefGoogle Scholar
  4. 4.
    Sackman, J.L.; Der Kiureghian, A.; Nour-Omid, B.: Dynamic Analysis of Light Equipment in Structures. J. of Eng. Mec. Vol.109 (1983) 73–89.CrossRefGoogle Scholar
  5. 5.
    Zastrau, B.: Zur Eigenfrequenzschätzung für gekoppelte Strukturen aus dominantem Grundsystem und allgemeiner Equipmentstruktur bei beliebiger Verbindung. Mitteilung aus dem Institut für Mechanik, UniBwH (1985) VIII:1–37.Google Scholar

Copyright information

© Springer Japan 1986

Authors and Affiliations

  • B. Zastrau
    • 1
  1. 1.Institute for MechanicsUniversity of Federal Armed ForcesHolstenhofweg, 2000 Hamburg 70Federal Republic of Germany

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