Identification of Modal Parameters from Driven Base Tests.

Abstract

A structural model of a satellite has been employed for vibration tests on two multi-axis vibration simulator (MAVIS) test facilities. The goal was the identification of modal parameters from measured data. Since modal identification from driven base tests can be considered an alternative to common modal survey tests, here the emphasis was placed on the principles and feasibility of such approaches. It was disired to gather experience and to elaborate outlines for future routine applications. Measured test data, consisting of transient time histories and frequency response functions (FRF's), are assessed and the influence of specific test conditions are considered. In the following, an evaluation of frequency domain data is presented, the modal parameter estimation process is outlined, and exemplary results are presented. Measured time histories of the transient excitation are employed for modal parameter estimation with a new time domain technique. The data processing method is explained and the parameter estimation for different time windows is performed. The results show very close agreement with frequency domain data evaluation. Hints for future work aiming at routine application are also given.