Bibliografie tematyczne: „Structural mistuning”

1

Wei, S. T., and C. Pierre. "Localization Phenomena in Mistuned Assemblies with Cyclic Symmetry Part I: Free Vibrations." Journal of Vibration and Acoustics 110, no. 4 (1988): 429–38. http://dx.doi.org/10.1115/1.3269547.

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An investigation of the effects of small structural irregularities on the dynamics of nearly periodic structures with cyclic symmetry is presented. The system studied may be regarded as a simple model of a continuously shrouded blade assembly accounting for one structural mode per blade. A key aspect of the approach is the use of perturbation methods that lead to a physical insight into the effects of mistuning. The study shows that the sensitivity to mistuning depends primarily upon the ratio of mistuning strength to coupling strength. For a small mistuning to coupling ratio, the mistuned system behaves like a perturbation of the corresponding tuned system, in which case mistuning has a relatively small effect on both the free and forced responses. On the other hand, for a large mistuning to coupling ratio (i.e., weak coupling), the mistuned system behaves like a perturbation of the corresponding decoupled mistuned system, in which case small mistuning dramatically changes the dynamics of the system. This paper, Part I, investigates the effects of small mistuning on the free response of the system. Specifically, it is shown that strong mode localization and eigenvalue loci veering phenomena occur in the weakly coupled system when mistuning is introduced. The effects of mistuning on the forced response are studied in the companion paper, Part II (Wei and Pierre, 1987).

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2

Fu, Zhi Zhong, and Yan Rong Wang. "Mistuning and Structural Coupling Effects on Flutter of Turbomachinery Blades." Applied Mechanics and Materials 482 (December 2013): 311–14. http://dx.doi.org/10.4028/www.scientific.net/amm.482.311.

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A fast numerical method based on aeroelastic eigenvalue analysis is applied to study the effects of mistuning on the aeroelastic stability of turbomachinery blades in which the structural coupling is included by a simplified method and an influence coefficient method is employed to deal with the unsteady aerodynamic effects. Results show that there exists an optimal mistuning amount at which the system has the best aeroelastic stability. Structural coupling almost has no effects on aeroelastic stability of a tuned system. But the benefit of alternate frequency mistuning to aeroelastic stability is inhibited drastically when structural coupling is introduced into the bladed disk system.

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3

Kenyon, J. A., J. H. Griffin, and D. M. Feiner. "Maximum Bladed Disk Forced Response From Distortion of a Structural Mode." Journal of Turbomachinery 125, no. 2 (2003): 352–63. http://dx.doi.org/10.1115/1.1540118.

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A method is presented for obtaining maximum bladed disk forced response from distortion of a structural mode. It is shown that maximum response from mode distortion in a bladed disk occurs when the harmonic components of a distorted mode superimpose in a certain manner, causing localization of the mode and strong response in a particular blade. In addition, it is shown that the response of an intentionally mistuned system with maximum response does not change significantly when small random mistuning is added to the system. A method is described for calculating the structural mistuning necessary to obtain the distorted mode that gives maximum response. The theory is validated numerically.

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4

Kenyon, J. A., and J. H. Griffin. "Forced Response of Turbine Engine Bladed Disks and Sensitivity to Harmonic Mistuning." Journal of Engineering for Gas Turbines and Power 125, no. 1 (2002): 113–20. http://dx.doi.org/10.1115/1.1498269.

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The mistuned forced response of turbine engine bladed disks is treated using harmonic perturbations in the properties of a continuous ring. A continuous shear spring is attached to the ring in which the stiffness is allowed to vary along the ring annulus. The modes of such a structure with a single harmonic mistuning pattern are shown to obey the Mathieu equation, which is solved to obtain the natural frequencies and modes of the mistuned system. The forced response of the system is then examined to determine the sensitivity of the system to small mistuning. The model is extended to include multiple harmonics, allowing for the possibility of general mistuning. An expression for the maximum amplitude magnification due to small mistuning is developed by showing that high response is caused by distortion of the structural modes. A method to intentionally mistune systems for maximum forced response is demonstrated, and numerical results demonstrate the accuracy of the analytical prediction. The intentionally mistuned system response is shown to be robust with respect to small random mistuning. Such a result might be useful for designing a test rotor for screening new bladed disk designs or for establishing the root cause of fatigue problems.

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5

Mignolet, Marc P., Wei Hu, and Ioan Jadic. "On the Forced Response of Harmonically and Partially Mistuned Bladed Disks. Part I: Harmonic Mistuning." International Journal of Rotating Machinery 6, no. 1 (2000): 29–41. http://dx.doi.org/10.1155/s1023621x0000004x.

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This series of two papers focuses on the determination and clarification of the characteristics of the forced response of bladed disks that exhibit a mistuning pattern that is either harmonic or partial. Harmonic mistuning refers to single wavelength variations in structural properties along the disk while partial mistuning is associated with blade characteristics that are random in a specific sector and tuned elsewhere. The results of this analysis demonstrate that many features of the response of these simple systems match not only qualitatively but also quantitatively their counterparts on randomly mistuned bladed disks. Relying on these similarities, simple and reliable approximations of the localization factor and of the mean response are easily derived that exemplify the usefulness of harmonic and partial mistuning patterns. Finally, it is demonstrated both theoretically and by comparison with simulation results that the maximum amplitude of response of a disk closely follows a Weibull-type distribution in all coupling situations, from very weak to very strong.

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6

Mignolet, Marc P., Wei Hu, and Ioan Jadic. "On the Forced Response of Harmonically and Partially Mistuned Bladed Disks. Part II: Partial Mistuning and Applications." International Journal of Rotating Machinery 6, no. 1 (2000): 43–56. http://dx.doi.org/10.1155/s1023621x00000051.

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This series of two papers focuses on the determination and clarification of the characteristics of the forced response of bladed disks that exhibit a mistuning pattern that is either harmonic or partial. Harmonic mistuning refers to single wavelength variations in structural properties along the disk while partial mistuning is associated with blade characteristics that are random in a specific sector and tuned elsewhere. The results of this analysis demonstrate that many features of the response of these simple systems match not only qualitatively but also quantitatively their counterparts on randomly mistuned bladed disks. Relying on these similarities, simple and reliable approximations of the localization factor and of the mean response are easily derived that exemplify the usefulness of harmonic and partial mistuning patterns. Finally, it is demonstrated both theoretically and by comparison with simulation results that the maximum amplitude of response of a disk closely follows a Weibull-type distribution in all coupling situations, from very weak to very strong.

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7

Kan, Xuanen, and Tuo Xing. "A novel mathematical model for the design of the resonance mechanism of an intentional mistuning bladed disk system." Mechanical Sciences 13, no. 2 (2022): 1031–37. http://dx.doi.org/10.5194/ms-13-1031-2022.

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Abstract. Bladed disk systems with advanced functions are widely used in turbo-machineries. However, there are always deviations in physical dynamic properties between blades and blades due to the tolerance and wear in operation. The deviations will lead to vibration localization, which will result in high cycle fatigue and accelerate the damage of the bladed disk system. Therefore, many intentional mistuning patterns are proposed to overcome this larger local vibration. Previous studies show that intentional mistuning patterns can be used to reduce the vibration localization of the bladed disk. However, the determination of the resonance mechanism of the intentional mistuning bladed disk system is still an unsolved issue. In this paper, a novel mathematical model of resonance of an intentional mistuning bladed disk system is established. Mistuning of blades and energy resonance are included in this theoretical model. The method of the mechanical power of the rotating blade for one cycle is applied to obtain the resonance condition. By using this theoretical model, the resonance mechanism of an intentional mistuning bladed disk is demonstrated. The results suggest that the ideal results can be obtained by adjusting the intentional mistuning parameter. This paper will guide the design of the dynamic characteristics of the intentional mistuning bladed disk.

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8

Lalanne, Bernard. "Perturbations Methods in Structural Dynamics and Applications to Cyclic Symmetric Domains." Journal of Engineering for Gas Turbines and Power 127, no. 3 (2004): 654–62. http://dx.doi.org/10.1115/1.1924430.

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The design of components must take into account the irregularities inherent to the manufacturing process. When the structures have close eigenvalues, small mass and stiffness variations or the damping generate strong variations of the eigenmodes: these structures are then not robust. Here, their dynamics has been analyzed by perturbation method, in the dissipative cases and with coupling within a light fluid. A new perturbation method allows first order developments whatever the spectral density may be. Applications to many different vibration problems are presented: aeroelasticity, mode veering problem, maximum amplitude of forced response in cyclic symmetric domains, with detuning and/or mistuning, i.e., the most important reliability problem in turbomachinery. The results of this study provide a new estimation of the amplification factor and damping due to mistuning and aerodynamic coupling.

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9

Kenyon, J. A., and J. H. Griffin. "Experimental Demonstration of Maximum Mistuned Bladed Disk Forced Response." Journal of Turbomachinery 125, no. 4 (2003): 673–81. http://dx.doi.org/10.1115/1.1624847.

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A theory was previously developed for predicting robust maximum forced response in mistuned bladed disks from distortion of a structural mode. This paper describes an experiment to demonstrate the theory. A bladed disk is designed to be sufficiently sensitive to mistuning to obtain maximum response. The maximum amplitude magnification from mistuning is predicted using the theory, 1.918. The bladed disk is intentionally mistuned to obtain the maximum response, and the response to an engine order traveling wave excitation is measured. The measured amplitude magnification is in close agreement with the theory. The robustness of the maximum response is demonstrated.

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10

Liu, Zhanhe, Jinlou Quan, Jingyuan Yang, Dan Su, and Weiwei Zhang. "A High Efficient Fluid-Structure Interaction Method for Flutter Analysis of Mistuned." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 5 (2018): 856–64. http://dx.doi.org/10.1051/jnwpu/20183650856.

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The time cost is very high by direct fluid-structure interaction method for mistuned bladed disk structures, so aerodynamic loads generally are ignored or treated as small perturbations in traditional flutter analysis. In order to analyze the flutter characteristics of mistuned blade rapidly and accurately, this paper presents an efficient fluid-structure interaction method based on aerodynamic reduced order model. system identification technology and two basic assumptions are used to build the unsteady aerodynamic reduced order model. Coupled the structural equations and the aerodynamic model in the state space, the flutter stability of mistuned bladed disk can be obtained by changing the structural parameters. For the STCF 4 example, the response calculated by this method agrees well with the results obtained by the direct CFD, but the computational efficiency is improved by nearly two orders of magnitude. This method is used to study the stiffness mistuned cascade system, and the stability characteristics of the system are obtained by calculating the eigenvalues of the aeroelastic matrix. The results show that the stiffness mistuning can significantly improve the flutter stability of the system, and also lead to the localization of the mode. The mistuning mode, mistuning amplitude and fluid structure interaction can influence the flutter stability obviously.

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