The investigation of the dynamic behaviour of a complex assembled structure using the frequency response function based substructuring method

Abstract

The frequency response function based substructuring method (FRF-BSM) for modelling and investigating dynamic behaviour of engineering structures has received much attention in recent years among modal analysts. However, the accuracy and efficiency of the predicted dynamic behaviour of the structures via the method is often found to be different from the test data. The discrepancy is believed to be the result of the coupling types used in the modelling. This paper aims to investigate the potential candidates of coupling types for FRF based substructuring in predicting the dynamic behaviour of a complex assembled structure which consists of a large flat span and two simplified aircraft pylons. Modal tests are performed to measure the dynamic behaviour of the assembled structure and its components. The finite element method is used for constructing analytical models of the assembled structure. The FRF-BSM is then used for the assembly of the span and pylons, and also to predict the dynamic behaviour of the assembled structure using rigid and elastic coupling. The comparison of results revealed that elastic coupling has demonstrated better capabilities to represent the bolted joints in the test structure, which may due to the coupling calculated is reasonably representing the stiffness of the bolted joints.