Blade Root Joint Modelling and Analysis of Effects of Their Geometry Variability on the Nonlinear Forced Response of Tuned and Mistuned Bladed Disks

2020 ◽  
Author(s):  
Adam Koscso ◽  
E. P. Petrov
Keyword(s):  
Harmonic Balance Method ◽  
Forced Response ◽  
High Fidelity ◽  
Contact Interactions ◽  
Bladed Disks ◽  
Element Mesh ◽  
Disk Model ◽  
Bladed Disk ◽  
Nonlinear Contact ◽  
Manufacturing Tolerances

Abstract One of the major sources of the damping of the forced vibration for bladed disk structures is the micro-slip motion at the contact interfaces of blade-disk joints. In this paper, the modeling strategies of nonlinear contact interactions at blade roots are examined using high-fidelity modelling of bladed disk assemblies and the nonlinear contact interactions at blade-disk contact patches. The analysis is performed in the frequency domain using multiharmonic harmonic balance method and analytically formulated node-to-node contact elements modelling frictional and gap nonlinear interactions. The effect of the number, location and distribution of nonlinear contact elements are analyzed using cyclically symmetric bladed disks. The possibility of using the number of the contact elements noticeably smaller than the total number of nodes in the finite element mesh created at the contact interface for the high-fidelity bladed disk model is demonstrated. The parameters for the modeling of the root damping are analysed for tuned and mistuned bladed disks. The geometric shapes of blade roots and corresponding slots in disks cannot be manufactured perfectly and there is inevitable root joint geometry variability within the manufacturing tolerances. Based on these tolerances, the extreme cases of the geometry variation are defined and the assessment of the possible effects of the root geometry variation on the nonlinear forced response are performed based on a set of these extreme cases.

scholarly journals Sensitivity and Forced Response Analysis of Anisotropy-Mistuned Bladed Disks With Nonlinear Contact Interfaces

2019 ◽  
Author(s):  
Adam Koscso ◽  
E. P. Petrov
Keyword(s):  
Harmonic Balance Method ◽  
Computational Effort ◽  
Forced Response ◽  
Response Analysis ◽  
Nonlinear Friction ◽  
Material Anisotropy ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Nonlinear Contact ◽  
Blade Model

Abstract A new method has been developed for the analysis of nonlinear forced response of bladed disks mistuned by blade anisotropy scatter and for the forced response sensitivity to blade material anisotropy orientations. The approach allows for the calculation of bladed disks with nonlinear friction contact interfaces using the multi-harmonic balance method. The method uses efficient high-accuracy model reduction method for the minimization of the computational effort while providing required accuracy. The capabilities of the developed methods are validated and demonstrated using a two-blade model. A thorough study of the influence of the material anisotropy mistuning and its sensitivity on the characteristics of the forced response is carried out using finite element modes of anisotropy mistuned realistic bladed disk with nonlinear friction joints of blade roots and shroud contacts. The dependency of the nonlinear forced response on excitation level and contact pressure values has been carried out for anisotropy mistuned bladed disks.

scholarly journals Blade Manufacturing Tolerances Definition for a Mistuned Industrial Bladed Disk

2004 ◽  
Author(s):  
Evange´line Capiez-Lernout ◽  
Christian Soize ◽  
Jean-Pierre Lombard ◽  
Christian Dupont ◽  
Eric Seinturier
Keyword(s):  
Industrial Application ◽  
Three Dimensional ◽  
Forced Response ◽  
Nonparametric Model ◽  
Dispersion Parameters ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Geometric Tolerances ◽  
Centrifugal Stiffening ◽  
Manufacturing Tolerances

This paper deals with the characterization of the blade manufacturing geometric tolerances in order to get a given level of amplification in the forced response of a mistuned bladed-disk. It is devoted to an industrial application in order to validate the theory previously developed [1] and in order to show that this theory is suited to any industrial bladed-disks. It should be noted that the development of an adapted methodology for solving the inverse problem, in order to characterize the manufacturing tolerances, is an important challenge for industries in this area. Let us recall that this theory is based on the use of a nonparametric probabilistic model of random uncertainties in the blade [2]. The dispersion parameters controlling the nonparametric model are estimated as a function of the geometric tolerances. Such an identification is carried out in a computational context by using the numerical Monte Carlo simulation and by using the reduced model method presented in [3]. The industrial application is devoted to the mistuning analysis of a 22 blades wide chord fan stage. Centrifugal stiffening due to rotational effects is also included. The results obtained validate the efficiency and the reliability of the method on three dimensional bladed disks.

Forced Response of Bladed Disks in Cyclic Symmetry With Underplatform Dampers

2006 ◽  
Author(s):  
Stefano Zucca ◽  
Juan Borrajo ◽  
Muzio M. Gola
Keyword(s):  
Contact Stiffness ◽  
Harmonic Balance Method ◽  
Rigid Bodies ◽  
Forced Response ◽  
Numerical Code ◽  
Algebraic Equations ◽  
Bladed Disks ◽  
Disk Model ◽  
Normal Contact ◽  
Linear Algebraic Equations

In this paper a methodology for forced response calculation of bladed disks with underplatform dampers is described. The FE disk model, supposed to be cyclically symmetric, is reduced by means of Component Mode Synthesis and then DOFs lying at interfaces are further reduced by means of interface modes. Underplatform dampers are modeled as rigid bodies translating both in the radial and in the tangential direction of the engine. Contacts between blade platforms and damper are simulated by means of contact elements characterized by both tangential and normal contact stiffness, allowing partial separation of contact surfaces. Differential equilibrium equations are turned in non-linear algebraic equations by means of the Harmonic Balance Method (HBM). The methodology is implemented in a numerical code for forced response calculation of frictionally damped bladed disks. Numerical calculations are performed to evaluate the effectiveness of both the reduced order model and the underplatform model in simulating the dynamic behavior of bladed disks in presence of underplatform dampers.

On the Individual and Combined Effects of Intentional Mistuning, Coupling and Damping on the Forced Response of Bladed Disks

2008 ◽  
Author(s):  
Changbo Yu ◽  
Jianjun Wang ◽  
Qihan Li
Keyword(s):  
High Cycle Fatigue ◽  
Numerical Study ◽  
Threshold Value ◽  
Forced Response ◽  
Combined Effects ◽  
Bladed Disks ◽  
Disk Model ◽  
Bladed Disk ◽  
Random Mistuning ◽  
The Individual

Random mistuning always exists in bladed disk structures. The maximum blade forced response amplitudes are often much larger than those of their perfectly tuned counterparts, which leads to eventual failure via high cycle fatigue (HCF). Therefore, it is of great importance to predict and, ultimately, to reduce the blade forced response levels as a result of random mistuning. In this paper, intentional mistuning is introduced into a simplified 12-bladed disk model by varying the stiffness of the blades in periodic harmonic patterns. The individual and combined effects of intentional mistuning, coupling and damping are examined in the absence and presence of random mistuning through numerical study. It is found that there is some threshold value of intentional mistuning and coupling that leads to maximum mistuning effects and certain relations among intentional mistuning strength, integer harmonics, coupling and damping can suppress the response levels of mistuned bladed disks, which provides useful guidelines for safe and reliable designs of bladed disk systems.

Analysis of Forced Response for Bladed Disks Mistuned by Material Anisotropy Orientation Scatters

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Chaoping Zang ◽  
Yuanqiu Tan ◽  
E. P. Petrov
Keyword(s):  
Finite Element ◽  
Monte Carlo ◽  
High Accuracy ◽  
Forced Response ◽  
Response Analysis ◽  
High Fidelity ◽  
Fe Model ◽  
Material Anisotropy ◽  
Bladed Disks ◽  
Bladed Disk

A new method is developed for the forced response analysis of mistuned bladed disks manufactured from anisotropic materials and mistuned by different orientations of material anisotropy axes. The method uses (i) sector finite element (FE) models of anisotropic bladed disks and (ii) FE models of single blades and allows the calculation of displacements and stresses in a mistuned assembly. A high-fidelity reduction approach is proposed which ensures high-accuracy modeling by introducing an enhanced reduction basis. The reduction basis includes the modal properties of specially selected blades and bladed disks. The technique for the choice of the reduction basis has been developed, which provides the required accuracy while keeping the computation expense acceptable. An approach for effective modeling of anisotropy-mistuned bladed disk without a need to create a FE model for each mistuning pattern is developed. The approach is aimed at fast statistical analysis based on Monte Carlo simulations. All components of the methodology for anisotropy-mistuned bladed disks are demonstrated on the analysis of models of practical bladed disks. Effects of anisotropy mistuning on forced response levels are explored.

A Method for Forced Response Analysis of Mistuned Bladed Disks With Aerodynamic Effects Included

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
Gas Flow ◽  
Forced Response ◽  
Response Analysis ◽  
Bladed Disks ◽  
Blade Vibration ◽  
Disk Model ◽  
Mechanical Coupling ◽  
Bladed Disk ◽  
Flexible Disk ◽  
Function Matrix

A method has been developed for high-accuracy analysis of forced response levels for mistuned bladed disks vibrating in gas flow. Aerodynamic damping, the interaction of vibrating blades through gas flow, and the effects of structural and aerodynamic mistuning are included in the bladed disk model. The method is applicable to cases of high mechanical coupling of blade vibration through a flexible disk and, possibly shrouds, to cases with stiff disks and low mechanical coupling. The interaction of different families of bladed disk modes is included in the analysis providing the capability of analyzing bladed disks with pronounced frequency veering effects. The method allows the use of industrial-size sector models of bladed disks for analysis of forced response of a mistuned structure. The frequency response function matrix of a structurally mistuned bladed disk is derived with aerodynamic forces included. A new phenomenon of reducing bladed disk forced response by mistuning to levels that are several times lower than those of their tuned counterparts is revealed and explained.

Identification of the Maximum Responding Blade in Mistuned Bladed Disks

2003 ◽  
Author(s):  
Bing Xiao ◽  
Alejandro J. Rivas-Guerra ◽  
Marc P. Mignolet
Keyword(s):  
Experimental Testing ◽  
Forced Response ◽  
Statistical Analyses ◽  
Maximum Response ◽  
Bladed Disks ◽  
Disk Model ◽  
Bladed Disk ◽  
Two Degree Of Freedom ◽  
Full Disk

This paper focuses on the identification/prediction of the blade exhibiting the largest response in mistuned bladed disks. This information is very important in experimental/testing efforts as it permits the most effective positioning of a few gages to capture the maximum response on the disk. In computational statistical analyses, knowing the highest responding blade is also quite valuable as it may lead to computational savings in the determination of the maximum response. Different strategies are proposed here for the experimental and computational contexts. In the former situation, mistuning is typically unknown but only one or a few disks must be considered. The proposed solution is then to estimate the mistuned blade properties and to rely on this identified bladed disk model to predict the blades that are likely to exhibit the largest responses through exact, full disk solutions. On the contrary, in computational statistical analyses, mistuning is specified but a potentially large number of disks must be analyzed and it is desired to bypass the ensemble of full disk solutions. Accordingly, a novel, computationally very efficient algorithm is proposed for a preliminary estimation of the forced response of mistuned disks from which the blades that are likely to exhibit the largest responses can be predicted. Examples of application on single- and two-degree-of-freedom per blade models and a reduced order model of a blisk demonstrate the reliability of the proposed strategies.

Method for Sensitivity Analysis of Resonance Forced Response of Bladed Disks With Nonlinear Contact Interfaces

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
Large Scale ◽  
High Efficiency ◽  
Peak Frequency ◽  
Forced Response ◽  
Resonance Peak ◽  
Tree Roots ◽  
Bladed Disks ◽  
Response Level ◽  
Bladed Disk ◽  
Nonlinear Contact

An effective method has been developed to calculate the sensitivity of the resonance peak frequency and forced response level to variation of parameters of nonlinear friction contact interfaces and excitation. The method allows determination of the sensitivity characteristics simultaneously with the resonance peak frequency and response level calculated as a function of any parameter of interest and without significant computational expense. Capabilities of the method are demonstrated on examples of analysis of large-scale finite element models of realistic bladed disks with major types of the nonlinear contact interfaces: (i) a blisk with underplatform dampers, (ii) a bladed disk with friction damping at blade fir-tree roots, and (iii) a high-pressure bladed disk with shroud contacts. The numerical investigations show high efficiency of the method proposed.

scholarly journals Sensitivity and Forced Response Analysis of Anisotropy-Mistuned Bladed Disks With Nonlinear Contact Interfaces

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Adam Koscso ◽  
Evgeny Petrov
Keyword(s):  
Reduction Method ◽  
Computational Effort ◽  
Forced Response ◽  
Response Analysis ◽  
Nonlinear Friction ◽  
Material Anisotropy ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Nonlinear Contact ◽  
Blade Model

AbstractA new method has been developed for the analysis of nonlinear forced response of bladed disks mistuned by blade anisotropy scatter and for the forced response sensitivity to blade material anisotropy orientations. The approach allows for the calculation of bladed disks with nonlinear friction contact interfaces using the multiharmonic balance method. The method uses efficient high-accuracy model reduction method for the minimization of the computational effort while providing required accuracy. The capabilities of the developed methods are validated and demonstrated using a two-blade model. A thorough study of the influence of the material anisotropy mistuning and its sensitivity on the characteristics of the forced response is carried out using finite element (FE) modes of anisotropy mistuned realistic bladed disk with nonlinear friction joints of blade roots and shroud contacts. The dependency of the nonlinear forced response on excitation level and contact pressure values has been carried out for anisotropy mistuned bladed disks.

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.

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