An active damping method using blended velocity feedback for the reduction of sound transmission through a simplified aircraft double panel is considered The system is composed by a 3 x 3 array of decentralized feedback control units Each unit is composed by an electrodynamic actuator reacting between the two panels and velocity sensors at the points where the actuator is connected with the source and radiating panels The outputs of the source and radiating panel velocity sensors are weighted by factors alpha and 1 - alpha, respectively The two weighted outputs are subtracted and combined into the error signal Stability and performance of the 3 x 3 system of velocity feedback loops is considered as a function of the velocity weighting factor used Metrics of the feedback-loop stability, which is the inverse of the maximum stable feedback gam delta0 in this case, strongly depend on the velocity weighting factor used In fact, there is a critical value of the velocity weighting factor. For subcritical values of the velocity weighting factor, the open-loop sensor-actuator frequency response functions exhibit low-frequency phase lags, which compromise the stability, and decrease the available gain margin. However, if velocity weighting factors larger than the critical one are used, the lowfrequency phase lags vanish and the available gain margin increases. Still, the maximum stable feedback gain is limited due to the sensor fundamental resonance, which causes high-frequency phase lags and, therefore, negative real parts of the open-loop sensor-actuator frequency response function. By varying the velocity weighting factor between 0 and 1 it is possible to improve the performance of the active control system. In particular, the low-frequency sound radiation decreased with the increase of the velocity weighting factor. Consequently, large reductions of the radiated sound power were recorded at the lowest resonance of the smart double panel, varying between 12 and 18 dB, depending on the case studied. When the sound radiation of the double panel with no transducers mounted was compared with the sound radiation of the double panel with transducers, large passive mass and damping effects were observed in the broad frequency band.


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    Title :

    Smart double panel for the sound radiation control: Blended velocity feedback


    Additional title:

    Intelligente Doppelschale zur Schallabstrahlungsregelung: Gemischte Geschwindigkeitsrückkopplung


    Contributors:

    Published in:

    AIAA Journal ; 49 , 6 ; 1123-1134


    Publication date :

    2011


    Size :

    12 Seiten, 14 Bilder, 2 Tabellen, 18 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English





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