Nonlinear aeroelastic analysis of a T-tail with a split rudder incorporating structural nonlinearity

Limit cycle oscillations hold significant importance for their potential impact on the performance and durability of aeroelastic systems. In this paper, the nonlinear aeroelastic behavior of a T-tail with a split rudder is investigated. The hinges between the vertical fin and rudders are modeled by two torsion springs with bilinear nonlinearity. An aerodynamic model in the time domain with gust loads is obtained via the rational function approximation method. To effectively address the structural nonlinearity problem and enhance computational efficiency, a reduced-order aeroelastic model for response analysis based on modal coordinates is constructed using the fictitious mass approach. Numerical simulations demonstrate that the coupling of vertical fin bending and upper rudder flapping creates bending–flapping modes, which notably reduce the T-tail flutter velocity. An increase in hinge stiffness results in suppression of the coupling mode. Nonlinear behavior analysis reveals that a turning point occurs at the linear flutter velocity, signifying a transition in the vibrational mode of the T-tail. The upper rudder serves as the predominant factor contributing to the nonlinear vibration, while the lower rudder introduces additional complexity to the vibrational behavior. These findings may offer valuable theoretical insights for mitigating the impact of unfavorable vibration through design.