An experimental approach to improve controllability in test rigs using passive components

Paper in proceeding, 2012

The first step in successful vibration testing is to calculate input signals such that the test rig accurately replicates the reference signal. The Time Waveform Replication (TWR) method, or augmentations of it, is often used to this end. TWR and similar methods most often result in a test output which closely replicates, or tracks, the reference signal; however, if there are eigenmodes of the test specimen in the desired frequency range of the test which are uncontrollable, it can be shown that the output error cannot be removed beyond the uncontrollable state’s contribution to the reference trajectory. For those specific cases, a method to improve tracking by the use of passive control components designed using a validated finite element (FE) model of the test specimen has been previously proposed by the authors. In this article we propose instead an experimental approach, based on state-space substructure synthesis, to passive control components design for improved tracking in controllability-lacking test rigs.