Forced Response of Mistuned Bladed Disks: Quantitative Validation of the Asymptotic Description

Khemiri, Oualid; Martel, Carlos; Corral, Roque

doi:10.2514/1.b34631

Cited by 11 publications

(11 citation statements)

References 23 publications

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“…where N a is now the number of active modes, that is, the number of modes that have frequencies close to the frequency of the forced mode (see [7,8]). The key idea from the AMM is that the important thing is not the total number of blades but the number of modes with frequencies similar to that of the forced mode; these are the only modes that the small mistuning can couple and combine to produce an increase of the forced response.…”

Section: Introductionmentioning

confidence: 99%

“…The analyses available in the literature of the forced response of a mistuned rotor with aerodynamic damping typically perform statistical explorations and optimizations on full FEM models and reduced order models [11,12,14,16]. The purpose of this paper is to analyze the effect of mistuning using the AMM methodology [17,7,8]. The resulting AMM is a very reduced model that gives information about the basic mechanisms that play a role in the mistuned response.…”

Section: Introductionmentioning

confidence: 99%

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Maximum mistuning amplification of the forced response vibration of turbomachinery rotors in the presence of aerodynamic damping

Martel

Sánchez-Álvarez

2017

Journal of Sound and Vibration

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Mistuning can dangerously increase the vibration amplitude of the forced response of a turbomachinery rotor. In the case of damping coming from aerodynamic effects the situation is more complicated because the magnitude of the damping changes for the different travelling wave modes of the system. This damping variability modifies the effect of mistuning, and it can even result in a reduction of the mistuned forced response amplitude below that of the tuned case (this is not possible in the usual case of constant material damping). In this paper the Asymptotic Mistuning Model (AMM) methodology is used to analyze this situation. The AMM is a reduced order model that is systematically derived from the mistuned bladed disk full model using a perturbative procedure based on the small size of the mistuning and the damping. The AMM allows to derive a very simple expression for an upper bound of the maximum amplification factor of the vibration amplitude that the system can experience (an extension of the well known Whitehead 1966 result to include the effect of non-uniform aerodamping). This new upper bound gives information on the mechanisms involved in the amplification/reduction of the mistuned response: (i) the number of modes participating in the response, and (ii) the ratio between the aerodamping of the directly forced mode and that of the of the rest of the modes. A FEM of a mistuned bladed disk is also used to verify the AMM predictions for several different forcing configurations, and both results show a very good quantitative agreement.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Maximum mistuning amplification of the forced response vibration of turbomachinery rotors in the presence of aerodynamic damping

Martel

Sánchez-Álvarez

2017

Journal of Sound and Vibration

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“…However, FMM ROMs are only accurate for analysis near flat isolated families. The asymptotic model of mistuning [28][29][30] generalizes the concept and extends the applicability FMM by relaxing assumptions regarding dominance of blade motion in the tuned system modes, seeking to instead approximate which tuned modes actively contribute the most to the mistuning components assuming small mistuning and damping in the modes.…”

Section: Dynamic Reduction and Probabilisticmentioning

confidence: 99%

“…The effects of mistuning were studied widely, and a number of different ROMs were proposed for linear mistuned blisks. These include modifications of general linear reduction methods such as Craig-Bampton component mode synthesis (CB-CMS) [17][18][19][20][21][22], as well as more specialized techniques developed especially for blisks such as subset of normal modes (SNM) [23], fundamental model of mistuning (FMM) [24], component mode mistuning (CMM) [25][26][27], and asymptotic model of mistuning [28][29][30]. Alternatives for linear systems with parametric variations include parametric reduced order models [31,32].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Modeling and Projection-Based Reduction Methods for Bladed Disks With Nonlinear Frictional and Intermittent Contact Interfaces

Mitra

Epureanu

2019

Applied Mechanics Reviews

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Turbine bladed disks or blisks, which constitute critical components of most modern turbomachinery, are known for their complex vibratory behavior. The nonlinear dynamics observed in most operational regimes of blisk with contact interfaces are dominated by one of two typical contact behaviors. Frictional contacts are dominated by Coulomb friction forces, while intermittent contacts are characterized by multiple separation events. Other factors such as the dispersion in material or geometric properties across blades, known as mistuning, also affect the dynamics significantly. Presently, probabilistic analysis is the widely accepted design methodology to account for mistuning, which is unknown prior to manufacture. Thus, reduced order modeling of these blisks is essential as high fidelity models are prohibitively expensive for such simulations. This paper provides a technical discussion of dynamic modeling and reviews projection-based techniques used for creation of reduced models of blisks with contacts.

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“…Khemiri, et al [6] investigated the effect of small mistuning numerically using their asymptotic mistuning model that was successfully used by Martel, et al [7] and Martel and Corral [8].…”

Section: Introductionmentioning

confidence: 99%

Detection of Blade Mistuning in a Low Pressure Turbine Rotor Resulting from Manufacturing Tolerances and Differences in Blade Mounting

Schönleitner¹,

Traussnig²,

Marn³

et al. 2015

JMEA

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For a serious prediction of vibration characteristics of any structure, a detailed knowledge of the modal characteristic is essential. This is especially important for bladed turbine rotors. Mistuning of the blading of a turbine rotor can appear due to manufacturing tolerances or because of the blading process itself due to unequal mounting of the blades into the disk. This paper investigates the mistuning of the individual blades of a low pressure turbine with respect to the effects mentioned above. Two different rotors with different aerodynamic design of the blades were investigated. The blades were mounted to the disk with a so-called hammer head root which is especially prone to mounting irregularities. For detailed investigations, the rotor was excited with a shaker system to detect the forced response behavior of the individual blades. The measurements were done with a laser vibrometer system. As the excitation of rotor structure was held constant during measurement, it was possible to detect the line of nodes and mode shapes as well. It could be shown that the assembly process has an influence on the mistuning. The data were analyzed and compared with numerical results. For this, different contact models and boundary conditions were used. The above described characterization of modal behavior of the rotor is the basis for the upcoming aeroelastic investigations and especially for the blade vibration measurements of the rotor, turning with design and off-design speeds.

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Forced Response of Mistuned Bladed Disks: Quantitative Validation of the Asymptotic Description

Cited by 11 publications

References 23 publications

Maximum mistuning amplification of the forced response vibration of turbomachinery rotors in the presence of aerodynamic damping

Maximum mistuning amplification of the forced response vibration of turbomachinery rotors in the presence of aerodynamic damping

Dynamic Modeling and Projection-Based Reduction Methods for Bladed Disks With Nonlinear Frictional and Intermittent Contact Interfaces

Detection of Blade Mistuning in a Low Pressure Turbine Rotor Resulting from Manufacturing Tolerances and Differences in Blade Mounting

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