scholarly journals Identification and influence factors analysis of blade crack mistuning in hard-coated blisk based on modified component mode mistuning reduced-order model

2020 ◽  
pp. 146134842097138
Author(s):  
Kunpeng Xu ◽  
Xianfei Yan ◽  
Dongxu Du ◽  
Wei Sun
Keyword(s):  
Crack Length ◽  
Influence Factors ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order ◽  
Crack Location ◽  
Vibration Localization ◽  
Identification Method ◽  
Bending Modes ◽  
Blade Crack

Blade crack will cause severe mistuning of hard-coated blisks, which will lead to vibration localization. To identify crack mistuning and analyze influence factors, in this study, a mistuning identification method of blade cracks in hard-coated blisks is presented based on modified component mode mistuning reduced-order model, in which the hard-coated blisk with blade crack is decomposed into a substructure of tuned hard-coated blisk and a substructure of coated blade with cracks. Crack mistuning of each coated blade can be obtained by a single identification calculation. After verifying the rationality of this identification method, the influence factors of blade crack mistuning are analyzed. The influence factors include the crack location on the coated blade (cracks occurring only in coating or only in blade substrate or both in blade substrate and coating), crack length, crack position in the radial direction of the blisk, and modal data type of coated blisk used for mistuning identification calculation. The research results show that, with the increase of crack length, the mistuning of crack occurring only in the coating does not increase continuously but decreases firstly and then increases. For the first bending modes, the closer the blade crack is to the blade root, the larger the mistuning is. For the second bending modes, the blade crack located at the position of maximum modal displacement will produce large mistuning. For hard-coated blisk with blade crack, these crack mistuning variation rules are of great significance to the dynamic analysis and the determination of the crack location.

Vibration reduction optimization of the mistuned bladed disk considering the prestress

2017 ◽  
Vol 233 (1) ◽  
pp. 226-239 ◽  
Author(s):  
Hongyuan Zhang ◽  
Huiqun Yuan ◽  
Wenjun Yang ◽  
Tianyu Zhao
Keyword(s):  
Finite Element ◽  
Optimization Algorithm ◽  
Synthesis Method ◽  
Reduced Order Model ◽  
Component Mode Synthesis ◽  
Order Model ◽  
Blade Vibration ◽  
Reduced Order ◽  
Vibration Localization ◽  
Bladed Disk

Ignoring the effect of prestress can increase the gap between the actual results and research results, which is not conducive to improve the vibration localization of bladed disk system and the finite element calculation. To improve the vibration localization and computational efficiency, the prestressed component mode synthesis method (PCMSM) was adopted to establish the finite element reduced-order model considering prepress. Since the main calculation precision of the prestressed component mode synthesis method was the mode truncation number, calculation was made to the eigenfrequency of different mode truncations; the contrast and analysis were made to the calculation result of blisk model, minimum mode truncation number under the above calculation precision was obtained, and freedom of the model was greatly reduced. The finite element reduced-order model was collocated to make an analysis of the vibration response characteristics of mistuned bladed disk. From the aforementioned analysis, the maximum amplitude of mistuned bladed disk was not only associated with the mistuning value of blade but also related to the frequency of adjacent blade; on the basis of such a rule, the finite element reduced-order model was adopted to raise an optimization algorithm for the blade vibration reduction and arrangement. Results have revealed that the optimization algorithm has made an adequate consideration of both model precision and calculation speed. The maximum dimensionless amplitude of blade vibration under three mistuning patterns and upon optimization is greatly reduced by 32.8%, 30.1%, and 28%. The localization factor of blade vibration under three mistuning patterns and upon optimization is greatly reduced by 64%, 68.5%, and 57.2%. The optimization algorithm based on the prestressed component mode synthesis method gets the optimization value by not more than 15 iterations. The optimization algorithm has greatly reduced the amplitude of the blade and obviously dampened vibration localization of the bladed disk system.

scholarly journals Bolt loosening detection in a jointed beam using empirical mode decomposition–based nonlinear system identification method

2019 ◽  
Vol 15 (9) ◽  
pp. 155014771987565 ◽  
Author(s):  
Chao Xu ◽  
Chen-Chen Huang ◽  
Wei-Dong Zhu
Keyword(s):  
System Identification ◽  
Nonlinear System ◽  
Nonlinear System Identification ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order ◽  
System Identification Method ◽  
Identification Method ◽  
Mode Decomposition ◽  
Bolt Loosening

In this work, a state-of-art nonlinear system identification method based on empirical mode decomposition is utilized and extended to detect bolt loosening in a jointed beam. This nonlinear system identification method is based on identifying the multi-scale dynamics of the underlying system. Only structural dynamic response signals are needed to construct a reduced-order model to represent the system concerned. It makes the method easy to use in practice. A new bolt loosening identification procedure based on the constructed system nonlinear reduced-order model is proposed. A new damage feature to indicate bolt loosening is presented. Experimental works are carried out to validate the proposed method. The results show that the proposed damage detection method can detect bolt loosening effectively, and the proposed damage feature values increase with the increase of bolt torques. The damage feature calculated from the response solution of the reduced-order model can give robust and sensitive indication of bolt loosening.

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