Vibrations of Impellers : Part 3. An Analysis of Coupled Vibrations between a Disk and Blades using a Reduced Impedance Method

Abstract

A reduced impedance method is proposed in order to analyze vibrations of complex mechanical structures. Natural frequencies and modes of coupled vibrations between a disk and blades of an impeller can be analyzed using this method. In this method a total structure is considered as an assembly of some sub-structures, and reduced impedance matrices on combined regions in each sub-structure are calculated and are composed together to make dynamic equations of the total system. On the other hand, the natural frequencies of impellers are obtained experimentally with piezo electric elements and non-contacting type displacement meters. Natural modes of them are observed by the holographic technique with argon gas laser beams. The results of the theoretical analysis are in good agreement with the experimental ones.