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.

On the Interaction of Multiple Traveling Wave Modes in the Flutter Vibrations of Friction-Damped Tuned Bladed Disks

2016 ◽  
Author(s):  
Malte Krack ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Steady State ◽  
Traveling Wave ◽  
Basins Of Attraction ◽  
Unstable Wave ◽  
Stable Limit ◽  
Lumped Mass ◽  
Limit States ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Wave Forms

The aerodynamic interference between the blades of a bladed disk can lead to self-excited vibrations known as flutter. Flutter vibrations can reach considerable levels and are thus of special concern in the design of turbomachines. The vibrations can be saturated in so-called limit cycles by the nonlinear dissipative effects related to dry friction in mechanical joints. For a given mode family of a tuned bladed disk, the flutter stability depends on the interblade phase angle, and often multiple traveling wave forms are unstable. In spite of this, previous investigations indicated that in the steady state, friction-damped flutter vibrations of tuned bladed disks are dominated by a single traveling wave component. In contrast, we demonstrate that, in fact, multiple traveling wave components may interact in the steady state. To this end, a phenomenological model is studied, which possesses one lumped mass per sector, elastic Coulomb friction inter-sector coupling, and two unstable traveling waves forms. Depending on the location of the complex eigenvalues of the linearized system, the steady-state vibrations are shown to be dominated by either of the two unstable wave forms or exhibit considerable contributions of both. Both periodic and quasi-periodic attractor forms are computed using Fourier methods and validated with direct time integration. Moreover, the basins of attraction of the different stable limit states are analyzed in detail. Remarkably, even if a stable, periodic vibration in a certain traveling wave is attained, a sufficiently strong instantaneous perturbation of the same form can give rise to a transient ending in a limit cycle with a different traveling wave character.

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.

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.

On the Interaction of Multiple Traveling Wave Modes in the Flutter Vibrations of Friction-Damped Tuned Bladed Disks

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Malte Krack ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Steady State ◽  
Traveling Wave ◽  
Initial Conditions ◽  
Limit State ◽  
Experimental Investigations ◽  
Frequency Domain Method ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Theoretical Investigations ◽  
Wave Forms

It is well-known that flutter vibrations of bladed disks can be saturated by dry friction. Previous theoretical investigations indicated that the steady-state, friction-damped flutter vibrations of tuned bladed disks are always dominated by a single traveling wave component, even if multiple traveling wave forms are unstable. This contrasts recent experimental investigations where multiple traveling wave forms were found to participate at steady state. In this paper, we demonstrate that this phenomenon can be explained by nonlinear frictional interblade coupling. To this end, we consider a simple phenomenological model of a bladed disk with frictional intersector coupling and two unstable traveling waves forms. Vibrations occur not only in the form of limit cycle oscillations (periodic) but also in the form of limit torus oscillations (quasi-periodic). It is shown how the limit state depends on the initial conditions, and that the occurrence of multiwave flutter depends on the proximity of the complex eigenvalues of the associated unstable waves. Finally, by computing the limit torus oscillation with a frequency-domain method, we lay the cornerstone for the systematic prediction of friction-saturated flutter vibrations of state-of-the-art bladed disk models.

Reduced-Order Modeling of Bladed Disks With Friction Ring Dampers

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Seunghun Baek ◽  
Bogdan Epureanu
Keyword(s):  
Steady State ◽  
Dry Friction ◽  
Friction Model ◽  
Contact Friction ◽  
Bladed Disks ◽  
Transient Dynamic Analysis ◽  
Reduced Order ◽  
Bladed Disk ◽  
Steady State Responses ◽  
State Responses

An efficient methodology to predict the nonlinear response of bladed disks with a dry friction ring damper is proposed. Designing frictional interfaces for bladed-disk systems is an important approach to dissipate vibration energy. One emerging technology uses ring dampers, which are ringlike substructures constrained to move inside a groove at the root of the blades. Such rings are in contact with the bladed disk due to centrifugal forces, and they create nonlinear dissipation by relative motion between the ring and the disk. The analysis of the dynamic response of nonlinear structures is commonly done by numerical integration of the equations of motion, which is computationally inefficient, especially for steady-state responses. To address this issue, reduced-order models (ROMs) are developed to capture the nonlinear behavior due to contact friction. The approach is based on expressing the nonlinear forces as equivalent nonlinear damping and stiffness parameters. The method requires only sector-level calculations and allows precalculation of the response-dependent equivalent terms. These factors contribute to the increase of the computational speed of the iterative solution methods. A model of a bladed disk and damper is used to demonstrate the method. Macro- and micro-slip are used in the friction model to account for realistic behavior of dry friction damping. For validation, responses due to steady-state traveling wave excitations are examined. Results computed by ROMs are compared with results from transient dynamic analysis (TDA) in ansys with the full-order model. It is found that the steady-state responses predicted from the ROMs and the results from ansys are in good agreement, and that the ROMs reduce computation time significantly.

Coriolis Forces in Forced Response Analysis of Mistuned Bladed Disks

2006 ◽  
Vol 129 (4) ◽  
pp. 730-739 ◽  
Author(s):  
M. Nikolic ◽  
E. P. Petrov ◽  
D. J. Ewins
Keyword(s):  
Primary Objective ◽  
Forced Response ◽  
Mutual Interaction ◽  
Response Analysis ◽  
Bladed Disks ◽  
Coriolis Forces ◽  
Bladed Disk ◽  
Coriolis Effects ◽  
Representative Model ◽  
Significant Factors

The problem of estimating the mutual interaction of the effects of Coriolis forces and of blade mistuning on the vibration characteristics of bladed disks is addressed in this paper. The influence of different degrees of mistuning on forced response and amplification factors are studied in the presence of Coriolis forces and then compared to their non-Coriolis counterparts using a computationally inexpensive, yet representative, model of a bladed disk. The primary objective of the study reported in this paper is to establish whether current mistuned bladed disk analyses should incorporate Coriolis effects in order to represent accurately all the significant factors that affect the forced response levels.

Reduced Order Modeling of Bladed Disks With Friction Ring Dampers

2016 ◽  
Author(s):  
Seunghun Baek ◽  
Bogdan Epureanu
Keyword(s):  
Steady State ◽  
Dry Friction ◽  
Equations Of Motion ◽  
Iterative Solution ◽  
Friction Model ◽  
Contact Friction ◽  
Bladed Disks ◽  
Transient Dynamic Analysis ◽  
Reduced Order ◽  
Bladed Disk

An efficient methodology to predict the nonlinear response of bladed disks with a dry friction ring damper is proposed. Designing frictional interfaces for bladed disk systems is an important approach to dissipate vibration energy. One emerging technology uses ring dampers, which are ring-like substructures constrained to move inside a groove at the root of the blades. Such rings are in contact with the bladed disk due to centrifugal forces, and they create nonlinear dissipation by relative motion between the ring and the disk. The analysis of the dynamic response of nonlinear structures is commonly done by numerical integration of the equations of motion, which is computationally inefficient, especially for steady-state responses. To address this issue, reduced order models (ROMs) are developed to capture the nonlinear behavior due to contact friction. The approach is based on expressing the nonlinear forces as equivalent nonlinear damping and stiffness parameters. The method requires only sector level calculation, and allows pre-calculation of the response-dependent equivalent terms. These factors contribute to the increase of the computational speed of the iterative solution method. A model of a bladed disk and damper, is used to demonstrate the method. Macro- and micro-slip are used in the friction model to account for realistic behavior of dry friction damping. For validation, responses due to steady-state traveling wave excitations are examined. Results computed by ROMs are compared with results from transient dynamic analysis in ANSYS with the full order 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.

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