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Structural Engineering and Mechanics
  Volume 8, Number 6, December 1999 , pages 579-589
DOI: https://doi.org/10.12989/sem.1999.8.6.579
 


Sub-degrees of freedom method with perturbation procedure for reduction of eigenvalue computation
Liu XL

 
Abstract
    A new way to reduce the eigenvalue computation effort in structural dynamics is presented in this paper. The degrees of freedom of a structure may be classified into groups that are termed as sub-degrees of freedom. The eigenvalue analysis is performed with each of sub-degrees of freedom so that the computing time is much shortened. Since the dynamic coupling between sub-degrees of freedom is selected to be small and it may be considered as a perturbation, the perturbation algorithm is used to obtain an accuratae result. The accuracy of perturbation depends on the coupling between sub-degrees of freedom. The weaker the coupling is, the more accurate the result is. The procedure can be used to simplify a problem of three dimensions to that of two dimensions or from two dimensions to one dimension. The application to a truss and a space frame is shown in the paper.
 
Key Words
    structural dynamics, eigenvalue computation, reduction, sub-degrees of freedom, perturbation
 
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