Accurate and reliable damping identification techniques are needed to assess stability margin with the development of advanced rotor systems of helicopters. This paper focuses on identifying damping from transient time domain test data. The determination of damping from a transient response can be reduced to determination of the decay envelope. The Hilbert Transform is an envelope detector that can produce envelope signal of a transient response. However, it is effective for only single degree of freedom (or single mode) systems. The Fourier Series Base Moving Block (FSMB) method can also produce envelope, furthermore, it has frequency localization characteristics, which means it can be used to study a single mode in a spectrally dense environment. But the FSMB has relatively poor performance when the modal frequencies are closely spaced especially if the damping level is high. A hybrid damping identification algorithm is developed which exploits the advantages of both methods. This hybrid method can identify damping in the presence of spectrally close modes. Simulation shows that the algorithm can provide accurate damping estimation and robustness to spectrally close modes and noise. It is successfully applied to hover stand test of a bearingless rotor employing chordwise bending torsion coupled composite flexbeams, as well as forward flight test data.


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    Title :

    Time domain damping identification in helicopter rotor systems


    Contributors:
    Zhao, Y. (author) / Wereley, N.M. (author)


    Publication date :

    2001


    Size :

    15 Seiten, 16 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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