DYNAMIC CONDENSATION WITH SYNTHESIS OF SUBSTRUCTURE EIGENPROPERTIES

For structures divided into substructures which are defined by their eigenproperties, a combination of the node synthesis and condensation techniques is presented to obtain a first few important eigenproperties of the combined system accurately. The accuracy of the calculated modal properties can be increased by iteratively solving an improved and condensed eigenvalue problem. If desired, the higher modal properties can also be obtained by solving a complementry eigenvalue problem associated with the higher modes. The availability of the substructure modes in this approach also provides a very convenient and efficient means of selecting the most appropriate kept degrees of freedom in the condensed eigenvalue problem to expediate the convergence to the correct eigenproperties. The methods for coupling of the substructure eigenproperties obtained with different boundary conditions at the interface are described. Several examples are presented to demonstrate the application of the approach. © 1992.