Modeling And Analysis Of Tiltrotor Whirl Flutter Based On Lagrange Equations Of The Second Kind And Transient Perturbation Method

Abstract

This paper establishes a modeling and analysis framework for tiltrotor whirl flutter based on Lagrange equations of the second kind and the transient perturbation method. A multibody dynamic model is constructed and progressively validated through key subcomponent comparisons, including the gimballed rotor and semispan wing, showing strong agreement with experimental data. The framework accurately predicts the damping trends of the Maryland TiltRotor Rig across different rotor and wing configurations. Additionally, the study confirms that freewheeling mode yields lower damping than constant-speed mode, even under identical collective pitch settings, and identifies the critical roles of wing and blade stiffness, wing-pylon angle, and wing sweep in determining system stability, where reduced wing stiffness may lead to instability, blade stiffness significantly influences chord damping, the wing-pylon angle alters damping trends in different modes, and wing sweep has opposite effects on beam and chord mode damping. The proposed method provides a validated and reliable tool for analyzing tiltrotor aeroelastic behavior and offers guidance for stability-oriented design optimization.