Dynamic Substructuring in the Medium-Frequency Range

Abstract

There are several methods in linear dynamic substructuring for numerical simulation of complex structures in the low-frequency range, that is, in the modal range. For instance, the Craig-Bampton method is a very efficient and popular method. Such a method, based on the use of the first normal structural modes of each undamped substructure with fixed coupling interface, leads to small-sized reduced matrix models. In the medium-frequency range, that is, in the nonmodal range, and for complex structures, a large number of normal structural modes should be computed with finite element models having a very large number of degrees of freedom. Such an approach is not really efficient and, generally, cannot be carried out. We present a new approach in dynamic substructuring for numerical calculation of complex structures in the medium-frequency range. This approach is still based on the use of the Craig-Bampton decomposition of the admissible displacement field, but the reduced matrix model of each substructure with fixed coupling interface is not constructed using the normal structural modes of each undamped substructure but instead using the eigenfunctions associated with the first highest eigenvalues of the mechanical energy operator relative to the medium-frequency band for each damped substructure with fixed coupling interface. The method and numerical example are presented.