Vibration Characteristics of Rotating Mistuned Bladed Disks considering the Coriolis Force, Spin Softening, and Stress Stiffening Effects

Shuai Wang,Bin Zi,Changjun Zheng,Chuanxing Bi

doi:10.1155/2019/9714529

Abstract

Bladed disks of engine rotors usually operate at harsh conditions of high rotating speeds, which may lead to nonnegligible rotordynamic effects, including Coriolis force, spin softening, and stress stiffening effects. These effects on the vibration of mistuned bladed disks are seldom discussed in available investigations. In this paper, the vibration characteristics of rotating mistuned bladed disks are addressed by considering these rotordynamic effects. First, finite element (FE) models of bladed disks are used to obtain the governing equations of motion, and an efficient method for getting the stress stiffening matrix of sector model is developed. Then, the effective component-mode mistuning method (CMM) is employed to create compact, yet accurate, reduced-order models (ROMs). Finally, the models are validated and used to study the influences of Coriolis force, spin softening, and stress stiffening effects on the vibration of bladed disks with frequency mistuning factors. Numerical results show that these rotordynamic effects could significantly affect the vibrations of mistuning bladed disks, especially in the ranges of high speed, and should be carefully considered during analysis.

Highlights

E realistic operating conditions of bladed disks may contain complex coupling between structure, flow field, and rotordynamic effects
Bladed disks of engine rotors tend to operate at rotating conditions with high speeds, which may lead to significant rotordynamic effects, including Coriolis force, spin softening, and stress stiffening effects
The individual influences of Coriolis forces, spin softening, and stress stiffening effects on the forced responses of tuned and mistuned bladed disk are presented by considering these factors in sequence

Summary

Mathematical Formulation

It is difficult to deal with such matrix during analysis, as a list of Ks(Ω) at different speeds should be obtained beforehand when the forced response within a certain range of speed is of interest With respect to this issue, the parametrization method developed by Sternchuss [26] is employed . In order to illustrate the different influences of Coriolis force, spin softening, and stress stiffening effects on the vibration of mistuned bladed disks, these three effects are considered in sequence in subsequent analysis. These three effects exist simultaneously in rotating structures and should all be taken into account to obtain accurate vibration characteristics. The retained terms in equation (13) are determined according to the case of interest and should be consistent with those in equation (5)

Model Validation

Numerical Results

Conclusions