Substructuring by a two level dynamic condensation method

One of the problems of substructuring methods using the dynamic condensation or the technique with constrained interfaces is that it conserves all junction degree of freedom (dof) between substructures to achieve the assembly. This can lead to a condensed problem of high dimension when the structure is complex. The method presented in this paper is an improvement of the substructuring by linearized dynamic condensation already proposed by the authors [Bouhaddi and Filled, Comput. Struct. 45, 679-683 (1992)]. It consists of reducing the final condensed problem by a modal projection technique followed by a linearization by frequency bands of each substructure. We present an example of a structure where the initial finite element model (FEM) leads to 4000 dof. The condensed problem is reduced to 40 dof and the first 30 eigenmodes of the complete structure are calculated with a sufficient precision. This example shows the practical interest of the proposed method. Copyright (C) 1996 Elsevier Science Ltd.