Vibration Characteristics of Rotating Thin Disks—Part II: Analytical Predictions

Khorasany, Ramin M.H.; Hutton, Stanley G.

doi:10.1115/1.4005810

Cited by 3 publications

(1 citation statement)

References 18 publications

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“…Khorasany and Hutton [4] numerically investigated the effect of geometrical nonlinearity on the frequency characteristics of a spinning disk. They discretized the governing equations of motion, found the equilibrium solutions, and then linearized the governing equations around these solutions.…”

Section: Introductionmentioning

confidence: 99%

Flutter Instability Speeds of Guided Splined Disks: An Experimental and Analytical Investigation

Mohammadpanah

Hutton

2015

Shock and Vibration

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Guided splined disks" are defined as flat thin disks in which the inner radius of the disk is splined and matches a splined arbor that provides the driving torque for rotating the disk. Lateral constraint for the disk is provided by space fixed guide pads. Experimental lateral displacement of run-up tests of such a system is presented, and the flutter instability zones are identified. The results indicate that flutter instability occurs at speeds when a backward travelling wave of a mode meets a reflected wave of a different mode. Sometimes, the system cannot pass a flutter zone, and transverse vibrations of the disk lock into that flutter instability zone. The governing linear equations of transverse motion of such a spinning disk, with assumed free inner and outer boundary conditions, are derived. A lateral constraint is introduced and modeled as a linear spring. Rigid body translational and tilting degrees of freedom are included in the analysis of the total motion of the spinning disk. The eigenvalues of the system are computed numerically, and the flutter instability zones are defined. The results show that the mathematical model can predict accurately the flutter instability zones measured in the experimental tests.

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Section: Introductionmentioning

confidence: 99%

Flutter Instability Speeds of Guided Splined Disks: An Experimental and Analytical Investigation

Mohammadpanah

Hutton

2015

Shock and Vibration

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Vibration Characteristics of Rotating Thin Disks—Part I: Experimental Results

Khorasany¹,

Hutton

2012

Journal of Applied Mechanics

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Analysis of the linear vibration characteristics of unconstrained rotating isotropic thin disks leads to the important concept of "critical speeds." These critical rotational speeds are of interest because they correspond to the situation where a natural frequency of the rotating disk, as measured by a .stationary observer, is zero. Such speeds correspond physically to the speeds at which a traveling circumferential wave, of shape corresponding to the mode shape of the natural frequency being considered, travel around the disk in the absence of applied forces. At such speeds, according to linear theory, the blade may respond as a space fixed stationary wave and an applied space fixed dc force may induce a resonant condition in the disk response. Thus, in general, linear theory predicts that for rotating disks, with low levels of damping, large responses may be encountered in the region of the critical speeds due to the application of constant space fixed forces. However, large response invalidates the predictions of linear theory which has neglected the nonlinear stiffness produced by the effect of in-plane forces induced by large displacements. In the present paper, experimental studies were conducted in order to measure the frequency response characteristics of rotating disks both in an idling mode as well as when subjected to a space fixed lateral force. The applied lateral force (produced by an air jet) was such as to produce displacements large enough that non linear geometric effects were important in determining the disk frequencies. Experiments were conducted on thin annular disks of different thickness with the inner radius clamped to the driving arbor and the outer radius free. The results of these experiments are presented with an emphasis on recording the effects of geometric nonlinearities on lateral frequency response. In a companion paper (Khorasany and Hutton, 2010, "Vibration Characteristics of Rotating Thin Disks-Part II: Analytical Predictions," ASME J. Mech., 79(4), p. 041007), analytical predictions of such disk behavior are presented and compared with the experimental results obtained in this study. The experimental results show that in the case where significant disk displacements are induced by a lateral force, the frequency characteristics are significantly influenced by the magnitude of forced displacements.

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A novel mathematical model for the design of the resonance mechanism of an intentional mistuning bladed disk system

Kan

Xing

2022

Mech. Sci.

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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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Vibration Characteristics of Rotating Thin Disks—Part II: Analytical Predictions

Cited by 3 publications

References 18 publications

Flutter Instability Speeds of Guided Splined Disks: An Experimental and Analytical Investigation

Flutter Instability Speeds of Guided Splined Disks: An Experimental and Analytical Investigation

Vibration Characteristics of Rotating Thin Disks—Part I: Experimental Results

A novel mathematical model for the design of the resonance mechanism of an intentional mistuning bladed disk system

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