Using single-axis multipoint connection approach for coupling test and finite element model in the frequency based substructuring method

Adopting dynamic substructuring methods to predict the dynamic behaviour of a combined structure is a common practice in the field of structural dynamics. This method has the capability and versatility to combine different sources of data; experimental and analytical, via the frequency based substructuring (FBS) method. This paper investigates the dynamic behaviour of a structure with doubled bolted joints using the frequency based substructuring (FBS) method. In the analysis the substructures are combined in the frequency domain, and the frequency response functions of the substructures are analytically derived and experimentally measured. However, the accuracy of the FBS method is highly dependent on experimental rotational degrees of freedom (DOF) which are always found to be very difficult to measure accurately. Therefore, a new approach - namely single-axis multipoint connection through which the need for the rotational DOF in the FBS method can be neglected entirely is presented in this study. The actual test structure used in this study is an assembled structure consisting of two substructures, a simple beam (numerical model) and an irregular plate steel (experimental model) structure. The FRFs of both substructures are combined via the FBS method. This study reveals that the use of the FBS method with the proposed approach is capable of representing the experimental frequency function response accurately even without rotational degrees of freedom data.