The aeromechanical stability of a helicopter with an elastically coupled composite bearingless rotor in forward flight is investigated. A finite element based structural analysis including the effects of transverse shear, torsion related out-of-plane warping, and warping restraint is incorporated into the University of Maryland Advanced Rotorcraft Code (UMARC). The out-of-plane warping model is developed using a fourth order polynomial over the cross section area. The effects of restrained warping are incorporated by modifying the torsional stiffness distribution along the blade. Three soft in-plane bearingless rotor configurations, including bending-torsion structural couplings are analyzed. The analysis covered free flight propulsive trim, blade steady periodic response, and stability of the perturbed rotor-body system. Elastic pitch-lag couplings caused by the ply layup of the flexbeam have a significant effect on the vibratory response, hub loads, and aeroelastic stability of a bearingless rotor. Negative pitch-lag elastic couplings have a stabilizing effect on the regressive lag mode in hover and forward flight. The stability margin is increased by as much as 250 percent.
Aeroelastic analysis of a composite bearingless rotor in forward flight using an improved warping model
Die aeroelastische Analyse eines lagerlosen Verbundrotors beim Vorwärtsflug unter Anwendung eines verbesserten Verwölbungsmodelles
Journal of the American Helicopter Society ; 40 , 3 ; 80-91
1995
12 Seiten, 15 Bilder, 4 Tabellen, 30 Quellen
Aufsatz (Zeitschrift)
Englisch
British Library Conference Proceedings | 1993
|British Library Conference Proceedings | 1994
|Aeromechanical stability of a bearingless composite rotor in forward flight
Tema Archiv | 1993
|