Structural Damping Identification for Mistuned Bladed Disks and Blisks

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Darren E. Holland ◽  
Bogdan I. Epureanu ◽  
Sergio Filippi
Keyword(s):  
Complex Systems ◽  
Complex Structure ◽  
Cyclic Symmetry ◽  
Structural Damping ◽  
Bladed Disks ◽  
Bladed Disk

To accurately predict the dynamics of most structures, a representation of damping must be used. This paper focuses on structural damping and the identification of structural damping for complex systems with cyclic symmetry such as bladed disks and integrated (one-piece) bladed disks (blisks) with mistuning. The damping identification methodology is demonstrated together with two measurement filters for a complex structure, namely an integrated bladed disk with stiffness mistuning.

Comparative Performance of Isotropic and Composite Bladed Disks

1989 ◽  
Author(s):  
P. Seshu ◽  
V. Ramamurti
Keyword(s):  
Steady State ◽  
Shell Element ◽  
Cyclic Symmetry ◽  
Bladed Disks ◽  
Comparative Performance ◽  
Composite Blade ◽  
Bladed Disk ◽  
Plate And Shell ◽  
Representative Model ◽  
Symmetry Method

Abstract Using a 3-noded, multilayered anisotropic triangular plate and shell element combined with cyclic symmetry method, a comparison has been drawn on the steady state as well as free vibration behaviour of isotropic and composite bladed disks, taking into account all the geometric and material complexities. Results are presented for a representative model for three cases – isotropic bladed disk, isotropic disk-composite blade, and composite bladed disk.

scholarly journals Validation of a Modal Work Approach for Forced Response Analysis of Bladed Disks

2021 ◽  
Vol 11 (12) ◽  
pp. 5437
Author(s):  
Lorenzo Pinelli ◽  
Francesco Lori ◽  
Michele Marconcini ◽  
Roberto Pacciani ◽  
Andrea Arnone
Keyword(s):  
Forced Response ◽  
Response Analysis ◽  
Test Case ◽  
Cyclic Symmetry ◽  
Bladed Disks ◽  
Low Pressure Turbine ◽  
Bladed Disk ◽  
Forcing Function ◽  
Bladed Rotor ◽  
Good Agreement

The paper describes a numerical method based on a modal work approach to evaluate the forced response of bladed disks and its validation against numerical results obtained by a commercial FEM code. Forcing functions caused by rotor–stator interactions are extracted from CFD unsteady solutions properly decomposed in time and space to separate the spinning perturbation acting on the bladed disk in a cyclic environment. The method was firstly applied on a dummy test case with cyclic symmetry where the forcing function distributions were arbitrarily selected: comparisons for resonance and out of resonance conditions revealed an excellent agreement between the two numerical methods. Finally, the validation was extended to a more realistic test case representative of a low-pressure turbine bladed rotor subjected to the wakes of two upstream rows: an IGV with low blade count and a stator row. The results show a good agreement and suggest computing the forced response problem on the finer CFD blade surface grid to achieve a better accuracy. The successful validation of the method, closely linked to the CFD environment, creates the opportunity to include the tool in an integrated multi-objective procedure able to account for aeromechanical aspects.

scholarly journals A Comparison between Two Reduction Strategies for Shrouded Bladed Disks

2018 ◽  
Vol 8 (10) ◽  
pp. 1736
Author(s):  
Alessandro Sommariva ◽  
Stefano Zucca
Keyword(s):  
Degrees Of Freedom ◽  
Computational Effort ◽  
Life Assessment ◽  
Test Cases ◽  
Cyclic Symmetry ◽  
Bladed Disks ◽  
Reduced Order ◽  
Sector Model ◽  
Bladed Disk ◽  
Reduction Strategies

Shrouded bladed disks exhibit a nonlinear dynamic behavior due to the contact interfaces at shrouds between neighboring blades. As a result, reduced order models (ROMs) are mandatory to compute the response levels during the design phase for high cycle fatigue (HCF) life assessment. In this paper, two reduction strategies for shrouded bladed disk reduction are presented. Both approaches rely on: (i) the cyclic symmetry of the linear bladed disk with open shrouds to perform only single sector calculations, (ii) the Craig–Bampton (CB) method to reduce the number of physical degrees of freedom (dofs). The two approaches are applied to a set of test cases in order to evaluate and compare their accuracy and the associated computational effort. Although both approaches allow for generating accurate ROMs, it is found that the numerical efficiency of the two methods depends on the ratio of the number of nodes at the inter-sector interfaces over the number of inner nodes of the elementary sector model.

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

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Hongbiao Yu ◽  
K. W. Wang
Keyword(s):  
Piezoelectric Transducer ◽  
Vibration Suppression ◽  
Structural Vibration ◽  
Bladed Disks ◽  
Disk Model ◽  
Bladed Disk ◽  
Engine Order ◽  
Optimal Network ◽  
Random Mistuning ◽  
Engine Components

For bladed-disk assemblies in turbomachinery, the elements are often exposed to aerodynamic loadings, the so-called engine order excitations. It has been reported that such excitations could cause significant structural vibration. The vibration level could become even more excessive when the bladed disk is mistuned, and may cause fatigue damage to the engine components. To effectively suppress vibration in bladed disks, a piezoelectric transducer networking concept has been explored previously by the authors. While promising, the idea was developed based on a simplified bladed-disk model without considering the disk dynamics. To advance the state of the art, this research further extends the investigation with focus on new circuitry designs for a more sophisticated and realistic system model with the consideration of coupled-blade-disk dynamics. A novel multicircuit piezoelectric transducer network is synthesized and analyzed for multiple-harmonic vibration suppression of bladed disks. An optimal network is derived analytically. The performance of the network for bladed disks with random mistuning is examined through Monte Carlo simulation. The effects of variations (mistuning and detuning) in circuit parameters are also studied. A method to improve the system performance and robustness utilizing negative capacitance is discussed. Finally, experiments are carried out to demonstrate the vibration suppression capability of the proposed piezoelectric circuitry network.

scholarly journals High-Fidelity Sensitivity Analysis of Modal Properties of Mistuned Bladed Disks Regarding Material Anisotropy

2018 ◽  
Author(s):  
Adam Koscso ◽  
Guido Dhondt ◽  
E. P. Petrov
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Coordinate Systems ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Material Orientation

A new method has been developed for sensitivity calculations of modal characteristics of bladed disks made of anisotropic materials. The method allows the determination of the sensitivity of the natural frequencies and mode shapes of mistuned bladed disks with respect to anisotropy angles that define the crystal orientation of the monocrystalline blades using full-scale finite element models. An enhanced method is proposed to provide high accuracy for the sensitivity analysis of mode shapes. An approach has also been developed for transforming the modal sensitivities to coordinate systems used in industry for description of the blade anisotropy orientations. The capabilities of the developed methods are demonstrated on examples of a single blade and a mistuned realistic bladed disk finite element models. The modal sensitivity of mistuned bladed disks to anisotropic material orientation is thoroughly studied.

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 Vibration Parameters Estimation by Blade Tip-Timing in Mistuned Bladed Disks in Presence of Close Resonances

2020 ◽  
Vol 10 (17) ◽  
pp. 5930
Author(s):  
Saeed Bornassi ◽  
Christian Maria Firrone ◽  
Teresa Maria Berruti
Keyword(s):  
Frequency Response ◽  
Optimization Technique ◽  
Numerical Test ◽  
Parameters Estimation ◽  
Least Square ◽  
Response Curves ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Resonance Frequencies ◽  
Blade Tip

The present paper is focused on the post processing of the data coming from the Blade Tip-Timing (BTT) sensors in the case where two very close peaks are present in the frequency response of the vibrating system. This type of dynamic response with two very close peaks can occur quite often in bladed disks. It is related to the fact that the bladed disk is not perfectly cyclic symmetric and the so called “mistuning” is present. A method based on the fitting of the BTT sensors data by means of a 2 degrees of freedom (2DOF) dynamic model is proposed. Nonlinear least square optimization technique is employed for identification of the vibration characteristics. A numerical test case based on a lump parameter model of a bladed disk assembly is used to simulate different response curves and the corresponding sensors signals. The Frequency Response Function (FRF) constructed at the resonance region is compared with the traditional Sine fitting results, the resonance frequencies and damping values estimated by the fitting procedure are also reported. Accurate predictions are achieved and the results demonstrate the considerable capacity of the 2DOF method to be used as a standalone or as a complement to the standard Sine fitting method.

A New Method for Dynamic Analysis of Mistuned Bladed Disks Based on the Exact Relationship Between Tuned and Mistuned Systems

2002 ◽  
Vol 124 (3) ◽  
pp. 586-597 ◽  
Author(s):  
E. P. Petrov ◽  
K. Y. Sanliturk ◽  
D. J. Ewins
Keyword(s):  
Dynamic Analysis ◽  
Frequency Response Function ◽  
New Method ◽  
Test Cases ◽  
Finite Element Models ◽  
Bladed Disks ◽  
Sector Model ◽  
Bladed Disk ◽  
Parametric Studies ◽  
Exact Relationship

A new method for the dynamic analysis of mistuned bladed disks is presented. The method is based on exact calculation of the response of a mistuned system using response levels for the tuned assembly together with a modification matrix constructed from the frequency response function (FRF) matrix of the tuned system and a matrix describing the mistuning. The main advantages of the method are its efficiency and accuracy, which allow the use of large finite element models of practical bladed disk assemblies in parametric studies of mistuning effects on vibration amplitudes. A new method of calculating the FRF matrix of the tuned system using a sector model is also developed so as to improve the efficiency of the method even further, making the proposed method a very attractive tool for mistuning studies. Various numerical aspects of the proposed method are addressed and its accuracy and efficiency are demonstrated using representative test cases.

Modal Controllability and Observability of Bladed Disks and their Dependency on the Angular Velocity

2005 ◽  
Vol 11 (6) ◽  
pp. 801-828 ◽  
Author(s):  
René H. Christensen ◽  
Ilmar F. Santos
Keyword(s):  
Angular Velocity ◽  
Rotor Blades ◽  
Parametric Vibration ◽  
Mode Shapes ◽  
Sensors And Actuators ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Centrifugal Stiffening ◽  
Vibration Coupling ◽  
Controllability And Observability

Rotating bladed disks are characterized by time-variant mathematical models presenting vibration coupling among rotor lateral motion and blade flexible motion. Moreover, they present parametric vibration modes and the blade natural frequencies may change depending on the angular velocity due to centrifugal stiffening. Consequently, the degree of controllability and observability of bladed disks also becomes time-varying, dependent on angular velocity, and a difficult task to analyze. In this paper we present a methodology for analyzing the modal controllability and observability of a bladed disk, based on time-variant modal analysis. The method takes into account time-variant parametric vibration mode shapes, and quantitative measures of modal controllability and observability are calculated. Numerical results show that, in order to control blade and shaft vibrations of a tuned bladed disk, by means of active control, blade-based as well as shaft-based sensing and actuation are required to monitor and control all vibration levels. If rotor blades are properly mistuned, the results show that disk as well as blade vibrations are monitorable and controllable by using only shaft-based sensing and actuation. The analysis shows why the mistuned disk becomes theoretically controllable and observable, via the presence of parametric mode shape components. Finally, the results show that the levels of controllability and observability depend significantly on the angular velocity, no matter the number of applied sensors and actuators used or their positioning.

Hot Isostatic Pressing of Ti6Al4V Alloys Monolithic Bladed Disks

2014 ◽  
Vol 496-500 ◽  
pp. 279-283 ◽  
Author(s):  
Peng Ju Xue ◽  
Yan Wu ◽  
Qing Song Wei ◽  
Yu Sheng Shi
Keyword(s):  
Tensile Strength ◽  
Hot Isostatic Pressing ◽  
Fracture Morphology ◽  
Bladed Disks ◽  
Isostatic Pressing ◽  
Bladed Disk ◽  
Near Net Shape ◽  
Near Net Shaping ◽  
Net Shaping ◽  
Parts Manufacturing

Near-net-shaping hot isostatic pressing (NNS-HIP) method was used for once-forming complex monolithic Ti6Al4V alloy bladed disks manufacturing. The complex monolithic bladed disks were formed successfully in a near-net-shape manner using the proposed HIP mold scheme in this study. The results showed that there were fine and homogeneous strip α+β phases and no obvious pores or cracks were detected. A "layered" phenomenon was observed in as-built part microstructure. The tensile strength value of specimens from the NNS-HIP bladed disks in the same furnace reached 900MPa, which was higher than the values of parts manufactured using casting and forging processes. The fracture morphology analysis showed that the sample had a ductile fracture. This study provides a reference to the NNS-HIP for the bladed disk parts manufacturing.

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