Spectral-based direct multi-substructure analysis of mechanical system vibration response

A new spectral-based multi-substructure theory is formulated to compute the frequency responses of mechanical systems that are subdivided into multiple inter-connected substructures. The proposed approach employs the free substructure frequency response functions at the coupling, response and excitation coordinates of interest to construct the complete system model using a single efficient coupling step. Even though this proposed approach is conceptually similar to the conventional transfer path analysis, it is more extensive because of the capability to analyze structural systems with arbitrary numbers of substructures and coupling coordinates. Hence, the proposed methodology can be applied to treat complex multi-substructure mechanical structures commonly found in automotive and aerospace systems. In the present study, several lumped parameters mass-spring-damper systems are analyzed to validate the proposed theory. The comparison results show excellent agreement between the multi-substructure predictions and the single complete system calculations.