Simulation of On-Orbit Modal Identification.

Kurzfassung

Modularly designed large orbital systems cannot be tested as a total structure on earth. Size, zero-g design and the existing atmosphere conflict with traditional structural dynamic qualification. In order to avoid the associated problems with terrestrial testing some form of on-orbit testing is likely to be used. This paper focuses on two objectives: (1) a brief discussion of hardware concerns, particularly under space conditions and (2) the demonstration of one specific software tool for on-orbit modal testing. Results extracted with the Ibrahim Time Domain method from noisy responses of an analytical structure are presented. Challenges of the used problem for system identification are: a frequency bandwidth enclosing two orders of magnitude, two frequency clusters and one mode with relatively high damping. With few exceptions, all results are within predefined "assessment margins" of 2 % for frequencies and 10 % for damping and mode shapes.