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Shock and Vibration
Volume 2017, Article ID 1785759, 18 pages
https://doi.org/10.1155/2017/1785759
Research Article

Effects of Crack on Vibration Characteristics of Mistuned Rotated Blades

1Science and Technology on Integrated Logistics Support Laboratory, National University of Defense Technology, Changsha, Hunan 410073, China
2State Key Laboratory for Manufacturing and Systems Engineering, Xi’an Jiaotong University, Xi’an, Shanxi 710049, China

Correspondence should be addressed to Zhongsheng Chen; nc.ude.tdun@gnehsgnohznehc

Received 19 October 2016; Accepted 16 January 2017; Published 15 February 2017

Academic Editor: Vadim V. Silberschmidt

Copyright © 2017 Hailong Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Rotated blades are key mechanical components in turbine and high cycle fatigues often induce blade cracks. Meanwhile, mistuning is inevitable in rotated blades, which often makes it much difficult to detect cracks. In order to solve this problem, it is important and necessary to study effects of crack on vibration characteristics of mistuned rotated blades (MRBs). Firstly, a lumped-parameter model is established based on coupled multiple blades, where mistuned stiffness with normal distribution is introduced. Next, a breathing crack model is adopted and eigenvalue analysis is used in coupled lumped-parameter model. Then, numerical analysis is done and effects of depths and positions of a crack on natural frequency, vibration amplitude, and vibration localization parameters are studied. The results show that a crack causes natural frequency decease and vibration amplitude increase of cracked blade. Bifurcations will occur due to a breathing crack. Furthermore, based on natural frequencies and vibration amplitudes, variational factors are defined to detect a crack in MRBs, which are validated by numerical simulations. Thus, the proposed method provides theoretical guidance for crack detection in MRBs.