Stability and dynamical analysis of whirl flutter in a gimballed rotor-nacelle system with a smooth nonlinearity

Abstract Whirl flutter is an aeroelastic instability that affects aircraft with propellers/rotors. With their long and flexible rotor blades, tiltrotor are particularly susceptible. known to have destroyed in the best case it constitutes a fatigue hazard. The complexity of whirl analysis increases significantly addition nonlinearities, due more complex dynamical behaviours emerge as result. Most stability analyses current literature grounded linear theory, preventing full discovery nonlinearities’ effects. Continuation bifurcation methods (CBM) may instead be used fully appreciate analyse effects presence nonlinearities. Previous CBM-based work on nonlinear gimballed hub rotor-nacelle models, representing those found aircraft, capable parametric regions declared safe by analysis. Furthermore, was they including limit cycle oscillations, quasi-periodic behaviour even chaos, though implications such has not been explored. This paper investigates impact smooth structural nonlinearity basic model, compared its baseline stiffness version. A 9-DoF model quasi-steady aerodynamics, wing blades can move both cyclically collectively flapping lead-lag motions, producing gimbal flap-like behaviour, adopted from existing literature. introduced blade CBM find new created nonlinearity. Time simulations, Poincaré sections spectral were then investigate various found. turn allowed recommendations made concerning preferable and/or hazardous parameter combinations use designer.