Structural Dynamics Identification by Means of Multi-Axial Base Excitation - Theory and Application -

Kurzfassung

Dynamic qualification of spacecraft structures usually are performed on special vibration test facilities applying single or multi-axial base excitation. The same test set-up allows for the identification of the structural dynamics properties of the tested structure if suitable identification methods are employed. Here, the theory and the basic principles of structural dynamics identification by multi-axial base excitation are described. Starting with the fundamental dynamic equations the specifics of base excitation are explained as well as the relationships of relative kinematics. Questions of controllability are discussed. The determination of the relevant dynamic excitation and the structural responses is described. The requirement of a multi-axial test facility for an appropriate identification is explained under consideration of its special advantages and limitations. A survey of identification approaches developed at DLR Göttingen is given. The practical application of a frequency domain identification of two different structures is described. Exemplary results are discussed and an outlook is given.