New FRF based methods for substructure decoupling

Abstract

Substructuring methods are well known and are widely used in predicting dynamics of coupled structures. In theory, there is no reason why the same techniques could not be used in a reverse problem of predicting the dynamic behavior of a particular substructure from the knowledge of the dynamics of the coupled structure and of all the other substructures. However, the reverse problem, known as decoupling, usually requires matrix inversions, and therefore even small measurement errors may easily affect the accuracy of such methods. In this study two new FRF based approaches are presented for decoupling. The methods proposed require coupled system FRFs at coordinates that belong to the known subsystem as well as the measured or calculated FRFs of the known subsystem alone. Formulations are based on the reverse application of the structural coupling method proposed in a previous publication co-authored by one of the authors of this paper. The performances of the proposed methods are demonstrated and then compared with those of some well-known recent methods in the literature through a case study.