Use of Special Ritz Vectors in Dynamic Substructure Analysis

Abstract

A numerical method is presented for the dynamic response analysis of large structural systems that are modeled as substructures. The method is similar to the component mode synthesis technique; however, the generation of the substructure modes is very efficient since the eigenvectors of the substructures are not evaluated. In addition, the characteristics of the loading are used in the algorithm, which can result in improved accuracy with the use of fewer vectors. The purpose of the method is to efficiently evaluate the dynamic displacements and forces within complex structures subjected to a particular type of loading. The technique does produce approximate modeshapes and frequencies; however, this is not the basic purpose of the method. The efficiency and accuracy of the method has previously been demonstrated for the direct dynamic analysis of complete structures. In this paper the method is extended to systems of substructures in which local substructure Ritz vectors are used to reduce the number of dynamic degrees of freedom. The basic algorithm is summarized for substructure application and simple examples are studied by the use of different models.