Flexibility-based component mode synthesis: or is it possible to break impasse in mode selection and convergence uncertainties ?

At LMSSC, Cnam, Paris, March 25th 2002
K.C. Park
Professor, Department of Aerospace Engineering Sciences and Center for Aerospace Structures,
University of Colorado, Boulder, USA

Existing component mode synthesis methods, while attractive for their practicality and heuristic soundness, cannot claim convergence as the Rayleigh-Ritz theory can. Recently, new demands for high accuracy much beyond two or three digits in the modeling of emerging vibration problems such as micro-mechanical systems, has motivated us for the development of high-fidelity component mode synthesis procedures. In this lecture, we present several new component mode synthesis techniques based on the flexibility-based partitioned equations of motion for structures. For each approximation, a corresponding substructural mode selection expression is identified, which can be used for a rational mode selection criterion for each substructure. The present methods can be implemented as a hierarchy-free algorithm for reducing the interface degrees of freedom as opposed to a tree-structure architecture required by the Craig-Bampton method for parallel computations. Numerical experiments show that the present flexibility-based component mode synthesis procedure outperforms stiffness-based methods, including the Craig-Bampton method, for simple plates and a ring modeled with 160,000 DOFs.

Laboratoire de Mécanique des Structures et des Systèmes Couplés - LMSSC