A STUDY OF COMPONENT MODE SELECTION USING MOMENT MATCHING APPROACH

Abstract eng:
Model reduction methods increase the effectiveness of dynamic analysis in various engineering fields such as aerospace, electronic and even in biomechanial engineering. The component mode synthesis (CMS) technique, especially the Craig-Bampton (CB) method is one of the most popular and widely used model reduction method. The CB method selects a few specific modes (dominant modes), and constructs a transformation matrix consisting of the dominant modes. Finally, engineers can obtain an equation of motion of a reduced model constructed by the transformation matrix of the CB method and the size of the reduced model is much smaller than that of the original model. If the dominant modes are included appropriately, accurate reduced model can be obtained that has the important dynamic characteristics of the original model. Then, key point is to distinguish the dominant modes from whole substructural modes. To solve this problem, various criterions have been suggested and these methods are called mode selection methods. In this study, we focused on the CMSχ method developed by Liao et al at 2007 and proposed new mode selection method by improving the original CMSχ method; CMSχ+ method. The main principle of the original CMSχ method is moment-matching approach. The assumption of this technique is that minimizing the difference of moment vectors of the global and reduced model can lead to construct robust reduced model. We induced new formula that has better accuracy than the original method by removing some approximations which were used in the Liao's original paper to simplify the induction procedure. For example, forces applied to the substructural part were ignored and only forces applied to the interface boundary part is considered appropriately, to simplify the derivation procedure. However, these approximations cannot reflect the characteristics of the model properly, therefore we developed a new formula with removing the approximations. The newly proposed method, CMSχ+ method shows significantly improved performance in free and fixed boundary conditions and it is demonstrated by several numerical examples.

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