The Stability Analisys of Rotor System Using Substructure Synthesis Method

Abstract

Component Mode Synthesis method (CMS) is applied to the stability analysis evaluated by logarithmic decrement in order to reduce the calculating time. But usual CMS cannot be applied the rotor system that consists of bearings, seals and impellers, because inertia, stiffness and dammping matrices of the rotor system are umsymmetric matices. So this study propose two improved CMS methods. The one of them uses the mode calculated from the symmetric parts of the inertia and stiffness matrices. The other uses the complex mode calcurated from the unsymmetric inertia and stiffness matrices. The logarithmic decrement is calculated from the reduced matrices and the complex mode calculated from reduced matrices. And numerical examples compared with FEM demonstrate the excellence of these new methods.