ICCM Conferences, The 8th International Conference on Computational Methods (ICCM2017)

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Flutter frequency based on bending - torsion coupling theory
Xin Zheng, Yu-Bin LIU, Pu CHEN, Feng SHEN, Sheng-Jun ZHANG, Xiang-Rong FU

Last modified: 2017-06-30

Abstract


In the series of aeroelastic problems caused by the load of the aircraft, the avoidance of the flutter problem has become an extremely important part of the aircraft design due to the abruptness and destructiveness of the accident cauesed by it. The aeroelastic flutter damage is caused by the interaction among inertial, elastic and aerodynamic forces,thus the vibration of the structure becomes considerable significance when the mechanism of flutter is studied. This paper establishes a method which can forcast the general value range of flutter frequency by the following two steps,namely 1)Based on the theory of frequency superposition,a highly simplified theory proposed that the critical state of the flutter concerning coupling between bending and torsional vibrations, this paper chooses the cantilever panel structure as a main object of the analysis, and controls the chord length and the root chord length as single variable separately. By the establishing and simulating the flutter procedures, This paper studies the correlation between the flutter mode and the bending - torsional coupling modes of the wing model under different geometric parameters. A convenient and effective method for calculating the flutter frequency is provided, and the calculation error is compared and analyzed to verify the reliability of the analysis results. 2) Considering the flexible characteristics of the elastic support in the selection of node positions together with its agility to descript a intricate mechanical state of a structure, subjoined two spring supports to the original model to simulated flutter statement. Finding out a specific value for the stiffness of the spring,that makes its first-order vibration mode frequency corresponds to the original model flutter value. This approximation model simulates the flow-solid coupling state caused by the additional aerodynamic force in the flutter problem. The research content provides a relatively effective forecasting method for the initial selection of the parameters before flutter analysis, and also provides some reference value for the simplification of the internal mechanism of the flutter problem.


Keywords


Bending - torsion coupling theory; Flutter frequency; Equivalent spring model;

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