The aeroelastic stability, response and loads in forward flight is investigated analytically for composite rotor blades with straight and swept tips. The blade is modeled by beam type finite elements. A single finite element is used to model the swept tip. The nonlinear equations of motion are derived using Hamilton's principle and based on a moderated deflection theory. Arbitrary cross-sectional shape, generally anisotropic material behavior, transverse shears and out-of-plane wrapping are included in the blade model. The analysis is applied to composite blades with two-cell, soft-in-plane, hingeless configuration. Numerical results illustrating the influence of composite ply orientation, tip sweep and anhedral on trim, hub loads, blade response and stability are presented. Vibratory hub loads are moderately influenced by composite apply angle variation while tip sweep and anhedral have pronounced effect on hub loads. Lag mode stability is sensitive to the composite ply orientation. The combined effect of swept tip and composite construction on hingeless blades is quite subtle, due to the nonlinear nature of the problem and thus it can not be predicted by a superposition of the individual effects.
Aeroelastic stability, response and loads of swept tip composite rotor blades in forward flight
Aeroelastische Stabilität, Schwingungsverhalten und Belastungen von gebogenen Spitzen von Flügelblättern aus Verbundwerkstoff beim Vorwärtsflug
1994
20 Seiten, 26 Bilder, 1 Tabelle, 29 Quellen
Aufsatz (Konferenz)
Englisch