Interface Reduction Methods for Substructuring Analysis of Complex Structural Systems

摘要

Recent developments are presented for the efficient analysis of vibration in large-scale complex structures. The key issues considered are the generation of reduced-order models (ROM) for the fast and accurate prediction of vibratory response in the low- to mid-frequency range, the development of physical sub-structuring approaches for capturing critical power flow paths, and the prediction of the effects of parameter uncertainties and design changes. The new methods developed and the attendant results are presented for an important class of engineering structures, namely ground vehicles. For large-scale finite element models of vehicle structures, an efficient component mode synthesis with a new interface modal reduction method is proposed, which employs modes characterizing the vibration of the interface between components and relies on the filtration of the interface matrices and the constraint modes. By selecting component and interface modes for the frequency range of interest, highly reduced models are obtained with this component-based modeling approach: for example, a 2100-degree of freedom (DOF) ROM is generated in the 0-200 Hz range from a 1.5-million-DOF finite element model of a sport utility vehicle. Then, a forced response analysis is carried out to verify its accuracy for capturing dynamic response, and a power flow analysis is performed to demonstrate its capability for identifying critical power flow paths. A novel representation is adopted to display power flow through the vehicle structure as a two-dimensional "map," which can be used to illustrate the structural paths through which the vibration energy is transmitted from the source to the key response points. Furthermore, recent progress in predicting the effects of parameter uncertainties is highlighted. The presentation concludes with a discussion of the challenges for ongoing and future research in complex structure vibration.