Vibration Localization Analysis of Bladed Disk with Grouped Blades

2010 ◽  
Vol 139-141 ◽  
pp. 2307-2311
Author(s):  
Ai Lun Wang ◽  
Bo Hai Sun ◽  
Jin Bo Chen
Keyword(s):  
Natural Frequency ◽  
Vibration Localization ◽  
Bladed Disk ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Periodic Groups ◽  
Localization Analysis ◽  
Random Mistuning ◽  
Nature Frequency ◽  
Grouped Blades

Vibration localization of bladed disk turns to be much complex when a number of blades are assembled into periodic groups. This work focused on natural frequency distribution and modal localization of bladed disks with grouped blades based on the lumped parameter models, and effects of the blade number in each group on natural frequency were studied. Then Monte Carlo method was applied to analyze the sensitivity of modal localization to the random mistuning of blade stiffness. The results show that the number of blades in each group influences the nature frequency of bladed disk with grouped blades, and modal localization of tuned bladed disk with grouped blades is found in the closely spaced modal region. Moreover, compared to the bladed disk with free blades, the modal localization of bladed disk with grouped blades is much less sensitive to random mistuning of blade stiffness.

Theoretical Study of the Vibration Suppression on a Mistuned Bladed Disk Using a Bi-periodic Piezoelectric Network

2018 ◽  
Vol 35 (1) ◽  
pp. 17-28 ◽  
Author(s):  
Lin Li ◽  
Pengcheng Deng ◽  
Jiuzhou Liu ◽  
Chao Li
Keyword(s):  
Vibration Suppression ◽  
Robustness Analysis ◽  
Forced Response ◽  
Lumped Parameter Model ◽  
Modal Assurance Criterion ◽  
Vibration Localization ◽  
Bladed Disk ◽  
Lumped Parameter ◽  
Random Mistuning ◽  
Response Amplification

AbstractThe paper deals with the vibration suppression of a bladed disk with a piezoelectric network. The piezoelectric network has a different period (so called bi-period) from that of the bladed disk and there is no inductor in it. The system is simulated by an electromechanical lumped parameter model with two DOFs per sector. The research focuses on suppressing the amplitude magnification or reducing the vibration localization of the mistuned bladed disk. The dynamic equations of the system are derived. Both mechanical mistuning and electrical mistuning have been taken into account. The Modified Modal Assurance Criterion (MMAC) is used to evaluate the vibration suppression ability of the bi-periodic piezoelectric network. The Monte Carlo simulation is used to calculate the MMAC of the system with the random mistuning. As a reference, the forced responses of the bladed disk with and without the piezoelectric network are given. The results show that the piezoelectric network would effectively suppress amplitude magnification induced by mistuning. The vibration amplitude is even smaller than that of the tuned system. The robustness analysis shows that the bi-periodic piezoelectric network can provide a reliable assurance for avoiding the forced response amplification of the mistuned bladed disk. The amplified response induced by the mechanical mistuning with standard deviation 0.2 can be effectively suppressed through the bi-periodic piezoelectric network.

Intentional Mistuning Design Space Reduction Based on Vibration Energy Flow in Bladed Disks

2004 ◽  
Author(s):  
Sang-Ho Lim ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
Energy Flow ◽  
Design Space ◽  
Flow Analysis ◽  
Design Guidelines ◽  
Vibration Energy ◽  
Bladed Disk ◽  
Space Reduction ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Random Mistuning

Intentional mistuning is the deliberate incorporation of blade-to-blade parameter variations in the nominal design of a bladed disk. Previous studies have shown that this is a promising strategy for mitigating the damaging effects of unintended, random mistuning. In this paper, the mechanisms of intentional mistuning are studied by investigating the relation between blade response and vibration energy flow in lumped parameter models. Based on key observations from the energy flow analysis, a few design guidelines are proposed that drastically reduce the design space for intentional mistuning patterns. Thus, an optimization may be performed on the reduced design space or skipped altogether, yielding dramatic reductions in computational costs. The guidelines are validated by extensive Monte Carlo simulations for the lumped parameter models as well as for a finite-element-based reduced-order model of an industrial rotor. It is shown that the reduced design space includes optimal or near-optimal intentional mistuning patterns.

scholarly journals Effects of Crack on Vibration Characteristics of Mistuned Rotated Blades

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Hailong Xu ◽  
Zhongsheng Chen ◽  
Yongmin Yang ◽  
Limin Tao ◽  
Xuefeng Chen
Keyword(s):  
Natural Frequency ◽  
Vibration Amplitude ◽  
Crack Detection ◽  
Vibration Characteristics ◽  
Lumped Parameter Model ◽  
Crack Model ◽  
Breathing Crack ◽  
Vibration Localization ◽  
Lumped Parameter ◽  
Amplitude Increase

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.

Vibration Suppression of Mistuned Coupled-Blade-Disk Systems Using Piezoelectric Circuitry Network

2007 ◽  
Author(s):  
Hongbiao Yu ◽  
K. W. Wang
Keyword(s):  
System Analysis ◽  
Vibration Suppression ◽  
Effective Means ◽  
Forced Response ◽  
Bladed Disks ◽  
Disk Model ◽  
Vibration Localization ◽  
Bladed Disk ◽  
Random Mistuning ◽  
Blade System

In this research, piezoelectric networking is investigated as an effective means for vibration suppression of mistuned bladed disk systems. Due to mistuning (i.e., imperfections in blade properties), bladed disks in turbo-machinery often suffer from vibration localization. In such cases, the vibration energy is confined to a small number of blades and forced response can be drastically increased when the structure is under engine order force excitation. To suppress the excessive vibration caused by localization, a piezoelectric networking concept has been proposed and analyzed for a multi-blade system in a previous study by the authors [1]. This research further extends the investigation with focus on circuitry design for a complex bladed disk model with the consideration of coupled blade-disk dynamics. A new multi-circuit piezoelectric network is designed and analyzed for multiple-harmonic vibration suppression of bladed disks. An optimal network is derived analytically based on system analysis. The performance of the network for bladed disks with random mistuning is examined using Monte Carlo simulation. The effects of variations (mistuning and detuning) in circuit parameters are also studied. Finally, a method to improve system performance and robustness is discussed.

A Mistuning Sensitivity Suppression Method of Bladed Disk

2012 ◽  
Vol 479-481 ◽  
pp. 1350-1354
Author(s):  
Yi Xuan Li ◽  
Chuang Shao ◽  
Zhi Jun Zhang
Keyword(s):  
Element Model ◽  
Vibration Response ◽  
Modal Shape ◽  
Free System ◽  
Response Characteristics ◽  
Bladed Disk ◽  
Lumped Parameter ◽  
Random Mistuning ◽  
Suppression Method ◽  
Shape Characteristics

Based on the lumped parameter modal, the modal shape characteristics of the tuned free bladed disk and the random mistuned bladed disk was studied. It can be concluded that the vibration energy is evenly distributed in the tuned free system, but in the mistuned system, the modal localization dose exist. And the localization degree gets stronger while the mistuning strength is bigger .Then based on the finite element model of a bladed disk. The intentional mistuning technology’s role in reducing the sensitivity of the bladed disk to random mistuning was studied in this paper. The blades vibration response characteristics and the intentional mistuning technology was also studied through magnification factor for amplitude and localization factor. The result shows that the mistuning sensitivity level can be reduced by adding the quantity of intentional mistuning, and intentional mistuning has an important meaning to reduce the adverse effect of the random mistuning to the blades vibration response.

Effects of Harmonic Intentional Mistuning on the Free Response of Bladed Disks

1999 ◽  
Author(s):  
Michael E. Brewer ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
Forced Response ◽  
Lumped Parameter Model ◽  
Free Response ◽  
Bladed Disks ◽  
Nodal Diameter ◽  
Bladed Disk ◽  
Lumped Parameter ◽  
Engine Order ◽  
Bladed Disk Assembly ◽  
Random Mistuning

Abstract In this paper, the free response of bladed disks with intentional mistuning is considered in detail. A simple lumped-parameter model of a bladed disk is employed. Intentional mistuning is included by applying a sinusoidal variation to the nominal blade stiffnesses. It is shown that if the intentional mistuning harmonic number and the number of blades have a common integer factor greater than one, then the eigenvalue problem reduces to a set of smaller problems. It is found that the ratio of intentional mistuning strength to the interblade coupling strength is a key parameter for the free response. As this ratio increases, the modes become localized. More importantly, the modes of the intentionally mistuned system have several non-zero nodal diameter components, in contrast to the tuned system which has pure nodal diameter modes. Furthermore, if only random mistuning is present, each mode of the bladed disk assembly still retains a strong nodal diameter component. However, the modes of the system with intentional mistuning and random mistuning tend to have more evenly distributed nodal diameter components. This shows why intentional mistuning can be effective in reducing the maximum blade forced response for engine order excitation.

Lumped parameter models for two-ventricle and healthy and failing extracardiac Fontan circulations

2021 ◽  
Author(s):  
Matthew G Doyle ◽  
Marina Chugunova ◽  
S Lucy Roche ◽  
James P Keener
Keyword(s):  
Single Ventricle ◽  
Left Ventricular ◽  
Sensitivity Analyses ◽  
Surgical Strategies ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Fontan Failure ◽  
Existence Of Periodic Solutions ◽  
Mathematical Definitions ◽  
Extracardiac Fontan

Abstract Fontan circulations are surgical strategies to treat infants born with single ventricle physiology. Clinical and mathematical definitions of Fontan failure are lacking, and understanding is needed of parameters indicative of declining physiologies. Our objective is to develop lumped parameter models of two-ventricle and single-ventricle circulations. These models, their mathematical formulations and a proof of existence of periodic solutions are presented. Sensitivity analyses are performed to identify key parameters. Systemic venous and systolic left ventricular compliances and systemic capillary and pulmonary venous resistances are identified as key parameters. Our models serve as a framework to study the differences between two-ventricle and single-ventricle physiologies and healthy and failing Fontan circulations.

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