Mistuning Effects on the Nonlinear Friction Saturation of Flutter Vibration Amplitude

2021 ◽  
Author(s):  
Carlos Martel ◽  
Salvador Rodriguez
Keyword(s):  
Vibration Amplitude ◽  
Nonlinear Friction

scholarly journals Mistuning Effects on the Nonlinear Friction Saturation of Flutter Vibration Amplitude

2020 ◽  
Author(s):  
Carlos Martel ◽  
Salvador Rodríguez
Keyword(s):  
Vibration Amplitude ◽  
Gas Flow ◽  
Travelling Waves ◽  
Computational Cost ◽  
Travelling Wave ◽  
Nonlinear Friction ◽  
Blade Vibration ◽  
Bladed Disk ◽  
Spring System ◽  
Mass Spring

Abstract The blade vibration level of an aerodynamically unstable rotor is a quantity of crucial importance to correctly estimate the blade fatigue life. This amplitude is the result of the balance between the energy pumped into the blades by the gas flow, and the nonlinear dissipation at the blade-disk contact interfaces. In a tuned configuration, the blade displacements can be described as a travelling wave consisting of one fundamental nodal diameter and frequency and its higher harmonics, and the problem can be reduced to the computation of a time periodic solution in just one sector. This simplification is no longer valid for a mistuned bladed disk. The resulting nonlinear vibration of the mistuned system is a combination of several travelling waves with different number of nodal diameters, coupled through mistuning. In this case, the complete bladed disk has to be considered, which requires an extremely high computational cost, and, for this reason, reduced order models (ROM) are required to analyze this situation. In this work, we use a 3 DOF/sector mass-spring system to describe the nonlinear friction saturation of the flutter vibration amplitude of a realistic mistuned bladed disk. The convergence of the solution of the mass-spring system is still quite slow because of the presence of many unstable modes with very similar growth rates. In order to speed-up the simulations a simpler asymptotic ROM is derived from the mass-spring model, which allows for much faster integration times. The simulations of the asymptotic ROM are compared with the measurements obtained in the European project FUTURE, where an aerodynamically unstable LPT rotor was tested with different intentional mistuning patterns.

Identification of Nonlinear Friction Properties in the Conditions of Self-Excited Vibrations

2017 ◽  
Author(s):  
Tomasz Piatkowski ◽  
Miroslaw Wolski ◽  
Przemyslaw Osowski
Keyword(s):  
Friction Coefficient ◽  
Vibration Amplitude ◽  
Sliding Friction ◽  
Friction Model ◽  
Nonlinear Friction ◽  
Kinetic Friction ◽  
Lugre Friction Model ◽  
Excited Vibration ◽  
Froude Pendulum ◽  
Lugre Friction

The paper presents method of the friction coefficient characteristics determination for kinematic pairs in the self-excited vibration conditions occurring in the Froude pendulum. Friction coefficients were calculated by measuring the vibration amplitude of the pendulum. Measurement of this amplitude for kinetic friction coefficient is carried out in the conditions of sliding friction and a static one — when the conditions of stickslip phenomena exist. The proposed method was verified using the LuGre friction model.

scholarly journals Multistage Asymmetric Rotors Coaxial Measurement Stacking Method Based on Minimization of Exciting Force

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1054
Author(s):  
Yongmeng Liu ◽  
Yingjie Mei ◽  
Chuanzhi Sun ◽  
Pinghuan Xiao ◽  
Ruirui Li ◽  
...  
Keyword(s):  
Vibration Amplitude ◽  
High Speed ◽  
Geometric Error ◽  
Exciting Force ◽  
Propagation Model ◽  
Assembly Method ◽  
Geometric Center ◽  
Asymmetric Rotor ◽  
Rotor Equipment ◽  
Geometric Error Measurement

The unbalanced exciting force of high-speed rotary asymmetric rotor equipment is the main factor causing rotor vibration. In order to effectively suppress the vibration of the asymmetric rotor equipment, the paper establishes a multistage asymmetric rotor coaxial measurement stacking method that minimizes the exciting force. By analyzing the propagation process of the centroid of the multistage asymmetric rotor assembly and analyzing the relationship between the geometric center and the centroid of a single asymmetric rotor, a multistage asymmetric unbalanced rotor propagation model based on geometric center stacking is established. The genetic algorithm is used to optimize the unbalance of the multistage asymmetric rotors. Combined with the vibration principle under the exciting force, the vibration amplitude of the left bearing at different rotation speeds under the minimization of the exciting force and the random assembly phase is analyzed. Finally, the experimental asymmetric rotors are dynamically measured, combined with the asymmetric rotors’ geometric error measurement experiment. The experimental results confirm that the vibration amplitude of the assembly phase with the minimum exciting force is smaller than the vibration amplitude under the random assembly phase at three-speed modes, and the optimization rate reached 73.2% at 9000 rpm, which proves the effectiveness of the assembly method in minimizing the exciting force.

Nonlinear energy sink with limited vibration amplitude

2021 ◽  
Vol 156 ◽  
pp. 107625
Author(s):  
Xiao-Feng Geng ◽  
Hu Ding ◽  
Xiao-Ye Mao ◽  
Li-Qun Chen
Keyword(s):  
Vibration Amplitude ◽  
Nonlinear Energy Sink ◽  
Energy Sink ◽  
Nonlinear Energy

The Investigation of the Influence of Structure Parameters on the Friction-Induced Self-Excited Vibration

2011 ◽  
Vol 66-68 ◽  
pp. 933-936
Author(s):  
Xian Jie Meng
Keyword(s):  
Nonlinear Dynamics ◽  
Numerical Method ◽  
Calculation Result ◽  
Dry Friction ◽  
Vibration Amplitude ◽  
The Self ◽  
Structure Parameters ◽  
Dynamics Model ◽  
Excited Vibration ◽  
Nonlinear Dynamics Model

A one degree of freedom nonlinear dynamics model of self-excited vibration induced by dry-friction was built firstly, the numerical method was taken to study the impacts of structure parameters on self-excited vibration. The calculation result shows that the variation of stiffness can change the vibration amplitude and frequency of the self-excited vibration, but can not eliminate it, Along with the increase of system damping the self-excite vibration has the weakened trend and there a ritical damping, when damping is greater than it the self-excite vibration will be disappeared.

scholarly journals Sightline Jitter Minimization and Shaping Using Nonlinear Friction Compensation

2007 ◽  
Vol 1 (3) ◽  
pp. 259-283 ◽  
Author(s):  
David Anderson ◽  
Matt MacDonald ◽  
Paul Ingleby ◽  
Nick Brignall
Keyword(s):  
Friction Compensation ◽  
Nonlinear Friction
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