Abstract
In order to exactly evaluate the complex behavior of compound structures constructed from many sub-structures, such as nuclear reactors, the following considerations will be important : treating them as ground-structure coupling systems; analyzing by 3-dimensional FEM; and evaluating the properties of each sub-structure. We have used the Component Mode Method as the method which aimed at the efficient modal analysis of the total system by evaluating the properties of and the coupling relations between sub-structures. By rearranging the theory of the Component Mode Method as the process of the coordinate transformation of an equation of vibration, and from the numerical solutions, the following results are obtained : The transformation matrix T=RΦ summarizes the whole process of component structure analysis, where matrix R indicates both direct and indirect coupling relations between components caused by their stiffnesses, while Φ corresponds to those caused by the masses. Besides, R shows the effects of the components to be connected, and Φis affected by those already connected. Consequently, the generalyzed mass matrix M^*, obtained by the congruence transformation of mass matrix M by T, shows the coupling relations between the components' modes. This is confirmed by the numerical solution of a 3-dimensional frame model. If the degree of freedom is not reduced when analyzing each component structure, the results obtained from the eigen value analysis coincide with those obtained from directly analyzing the total system. This is confirmed by the numerical solution of a plane frame model.
