DOUBLE COMPATIBLE MODE SYNTHESIS OF SYMMETRIC STRUCTURES WITH C_nGROUP

The success of implementing the mode analysis in the structural integrity research depends to a large extent on the ability to extract normal modes of the structures.In this paper,a new technique is proposed to combine the group theory algorithm and double compatible substructure method for analyzing rotationally symmetric(C_n)structures.In this method,only one sector(1/n part of a structure)is taken and considered so as to obtain the normal modes of the whole structure.But for a large complicated structure,this sector still contains a lot of degrees of freedom(DOF)and is not suitable for direct solution by finite element method.For this reason a substructure method-double compatible mode synthesis method is employed.This technique enhance the extraction efficiency with the accuracy ensured by considerable reduction of synthetic scale through elimination of interface DOF,a numerical example is given to illustrate the merits of the presented technique.