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Potential and Limitations of the Modal Characterization of a Spacecraft Bus Structure by Means of Active Structure ElementsTheoretical and experimental studies have been performed to investigate the potential and limitations of the modal characterization of a typical spacecraft bus structure by means of active structure elements. The aim of these studies has been test and advance tools for performing an accurate on-orbit modal identification which may be characterized by the availability of a generally very limited test instrumentation, autonomous excitation capabilities by active structure elements and a zero-g environment. The NASA LARC CSI Evolutionary Testbed provided an excellent object for the experimental part of this study program. The main subjects of investigation were: (1) the selection of optimum excitation and measurement to unambiguously identify modes of interest; (2) the applicability of different types of excitation means with focus on active structure elements; and (3) the assessment of the modal identification potential of different types of excitation functions and modal analysis tools. Conventional as well as dedicated modal analysis tools were applied to determine modal parameters and mode shapes. The results will be presented and discussed based on orthogonality checks as well as on suitable indicators for the quality of the acquired modes with respect to modal purity. In particular, the suitability for modal analysis of the acquired frequency response functions as obtained by excitation with active structure elements will be demonstrated with the help of reciprocity checks. Finally, the results will be summarized in a procedure to perform an on-orbit modal identification, including an indication of limitation to be observed.
Document ID
19990009909
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Grillenbeck, Anton M.
(Industrieanlagen-Betriebsgesellschaft m.b.H. Ottobrunn, Germany)
Dillinger, Stephan A.
(Industrieanlagen-Betriebsgesellschaft m.b.H. Ottobrunn, Germany)
Elliott, Kenny B.
(NASA Langley Research Center Hampton, VA United States)
Date Acquired
August 19, 2013
Publication Date
October 1, 1998
Publication Information
Publication: 20th Space Simulation Conference: The Changing Testing Paradigm
Subject Category
Electronics And Electrical Engineering
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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