Characteristic Constraint Modes for Component Mode Synthesis

Yung-Chang Tan,Matthew P Castanier,Christophe Pierre

doi:10.1115/detc99/vib-8187

Abstract

Abstract In this paper, a technique is presented for improving the efficiency of the Craig-Bampton method of Component Mode Synthesis (CMS). An eigenanalysis is performed on the partitions of the CMS mass and stiffness matrices that correspond to the so-called constraint modes. The resultant eigenvectors are referred to as “characteristic constraint modes,” since they represent the characteristic motion of the interface between the component structures. By truncating the characteristic constraint modes, a CMS model with a highly-reduced number of degrees of freedom may be obtained. An example of a cantilever plate is considered. It is shown that relatively few characteristic constraint modes are needed to yield accurate approximations of the lower natural frequencies. This method also provides physical insight into the mechanisms of vibration transmission in complex structures.

Highlights

W HEN modeling the dynamics of a complex structure, it is often impractical to perform a nite element analysis of the entire structure
In Component mode synthesis (CMS), the dynamics of a structure are described by selected sets of normal modes of the individual component structures, plus a set of static vectors that account for the coupling at each interface where component structures are connected
This paper introduceda techniquefor reducingthe size of a Craig– Bampton CMS2,5 model by improving the representation of the interface between component structures

Summary

Characteristic Constraint Modes for Component Mode Synthesis

To cite this version: Matthew Castanier, Yung-Chang Tan, Christophe Pierre. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. Yung-Chang Tan, and Christophe Pierre University of Michigan, Ann Arbor, Michigan 48109-2125. When the characteristic constraint modes are truncated, a CMS model with a highly reduced number of degrees of freedom may be obtained. It is shown that relatively few characteristic constraint modes are needed to yield accurate approximationsof the lower natural frequencies. This method yields physical insightinto the mechanisms of vibration transmission in complex structures, and it provides an excellent framework for the ef cient calculation of power ow.

Introduction

Component Mode Synthesis and Constraint Modes

NC N

Findings

Conclusions