Vibration response analysis of blade-disk dovetail structure under blade tip rubbing condition

Abstract

A cyclic sector corresponding to blade-disk structure with dovetail connection (1/38 blade-disk) is studied and the finite element (FE) model of this structure is established based on ANSYS software. A revised normal rubbing force model is developed and a pulse force model is established to simulate the local rubbing phenomenon between the blade and elastic casing based on the revised model. The effects of the rubbing under different rotating speeds and penetration depths on the blade vibration response and contact behaviors of dovetail interface are analyzed. The results show that the rubbing will cause amplitude amplification phenomenon when the multiple frequency components are close to the first bending and first torsion natural frequencies. The arch bending of the blade caused by blade-tip rubbing can be identified by evaluating the displacement and stress of the blade in the radial direction ( y-direction). The dynamic stress in the process of rubbing gradually changes from alternation between tension and compression stress to the tension stress with the increasing rotating speed. Maximum contact sliding distance may change dramatically when the rubbing force is greater than the centrifugal force. With the increase of rotating speed, the contact pressure increases under the centrifugal force and its fluctuation under rubbing is smaller at higher rotating speeds.