Component mode synthesis for high frequency acoustics

In this paper a Component Mode Synthesis (CMS) method using characterstic constraint (CC) modes is developed for finding the natural frequencies of large acoustic cavities with high modal density. The cavity under consideration is a periodic structure. Since conventional FE techniques require large number of elements due to the high modal density, two new formulations using Chebyshev polynomial and trigonometric shape functions are proposed. These result in significantly smaller number of elements. The accuracy and computational efficiency is clearly demonstrated here. the cavity is divided into subcavities; each subcavity has been analyzed using finite element method and they are coupled using normal modes and constrained modes of subcavities. Characteristic constrained modes (CC modes) are used for reducing the large number of constraint modes.