Abstract:

Based on Craig-Bampton's fixed-interface mode synthesis method, a direct transformation method for mode synthesis is put forward in the article. This method is much simpler than the methods in current use and can be applied to large scale complex structure mode synthesis or dynamic model condensations. The error with the proposed method is analyzed and the error bound is derived. The relationship between the frequencies of the overall synthesized structure and the number of the remaining principal modes of the substructures is formulated. In order to avoid the treatment of large degrees of freedom on the substructure interfaces, a partitioned algorithm for the direct transformation method is established. In the method the processes of the assembling of the whole stiffness and mass matrices are not needed and the model condensations are only performed on the substructures. Examples are given in the end of the article to show the effectiveness and the stability of the proposed method.

Key words: mode synthesis method, finite element method, dynamic model condensation, eigenvalue, error bounds, subspace iterative method