Analysis of mistuned cyclic systems using mistune modes

摘要

The bladed disk assembly, a prime example of a cyclic system, forms an important component of modern turbomachinery. Vibrations of the blades leads to fatigue damage and limits their service life. Analysis of these systems is complicated by the combination of coupling of blade dynamics with mistuning of the blade properties. The present study of mistuned cyclic systems encompasses a complete model of a bladed disk assembly which includes multiple degrees-of-freedom per blade, aerodynamic coupling, and structural coupling. A systematic analysis of this model allows the determination of the effect of mistune pattern, along with excitation mode, on the forced response amplitudes of the blades. The main motivation of this study is to gain a better understanding of the dynamics of cyclic systems. Through this understanding, better designs of these components will be possible. The concept of mistuning modes is introduced to provide a generalized method of describing the mistuning of bladed disk assemblies. Perturbation analyses reveal which constant interblade phase angle modes will contribute to the response as a result of given mistune modes and excitation modes. Results generated through a computational study demonstrate the range of validity of the perturbation approaches.