ON A COMPONENT MODE SYNTHESIS METHOD AND ITS APPLICATION TO INCOMPATIBLE SUBSTRUCTURES

Component Mode Synthesis (CMS) methods are substructuring techniques f requently employed in structural dynamics. A given structure is subdiv ided into components or substructures which are analyzed independently for natural frequencies and for mode shapes. The substructure mode sh apes are then assembled to give frequencies and mode shapes of the ori ginal structure. In this paper, we construct a substructure interface impedance operator and present a spectral analysis that demonstrates t hat the method of Craig and Bampton (CB) is the most 'natural' CMS met hod. Next, we consider the CB method for assembling heterogeneous subs tructures and recast it into a hybrid variational formulation. We deve lop finite element procedures for 'gluing' non-conforming and incompat ible finite element substructure models, and discuss their computation al aspects. The result is a Hybrid Craig-Bampton (HCB) method that is a finite element refinement of the 'intermediate structure' concept in troduced by Hale and Meirovitch, and which can be used as an interface reduction method. It is illustrated with the eigen analysis of hetero geneous and homogeneous finite element models of a High Speed Civil Tr ansport (HSCT) aircraft.