This paper has focused on the analysis and performance evaluation of semiactive, Coulomb friction lead-lag dampers. Both adaptive and selective damping strategies were investigated. Simulations were run in both ground resonance and forward flight to assess the use of friction as an energy dissipation mechanism to control the ground resonance instability and provide adequate lead-lag damping levels. The following conclusions can be drawn from this study: 1) Through identification of modal decay rates, it was demonstrated that the energy dissipation capacity of the proposed friction damper increases with increasing normal force levels. Furthermore, the proposed concept is able to match or exceed the damping levels of the presently installed hydraulic dampers on the UH-60 aircraft. 2) The ability to adapt the damping level of the proposed device enables the concept of damping on demand. For flight conditions requiring lower energy dissipation levels, it becomes possible to lower the damping forces in the damper, as well as those applied to the blade and hub, resulting in lower stress levels and potential weight savings. In the second part of this paper, the concept of selective damping was investigated. Whereas many dampers are designed to absorb as much energy as possible, the purpose of rotorcraft lead-lag dampers is to control the rotor regressive lag mode. The concept of selective damping is to target energy dissipation to the regressive lag mode while minimally affecting the other modes. Selective algorithms were proposed and implemented within a simplified analytical framework. The following conclusions can be drawn from this exploratory study: 1) Selectivity does enhance the performance of lead-lag dampers. In fact, when using selectivity, it is possible to stabilize a system that would be unstable when using a passive damper of identical dashpot constant. 2) While the potential of selective damping has been demonstrated, this concept faces numerous drawbacks that might prevent its practical implementation. Indeed, selectivity requires increased actuation and controller complexity; furthermore, fail safe operation considerations might drive the design to a configuration where selectivity provides little advantage over less complex designs. Clearly, further studies would be required to obtain fully satisfactory designs.


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    Titel :

    Semiactive coulomb friction lead-lag dampers


    Weitere Titelangaben:

    Halbaktive auf Coulombscher Reibung basierende Schwenkbewegungsdämpfer


    Beteiligte:

    Erschienen in:

    Journal of the American Helicopter Society ; 55 , 1 ; 012005/1-012005/12


    Erscheinungsdatum :

    2010


    Format / Umfang :

    12 Seiten, 14 Bilder, 1 Tabelle, 45 Quellen




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch




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