Free-Play Nonlinearity Aeroelastic Studies on a T-Tail with a Segmented Rudder

Free-play nonlinearity widely exists in the connections of aircraft control surfaces, which is an important factor causing complex nonlinear oscillations inflight. The limit cycle oscillation (LCO) induced by the free-play nonlinearity in the T-tail with a segmented rudder is an important challenge in aircraft design. In this study, a mathematical model describing the nonlinear behavior of the T-tail aeroelastic system is established based on the fictitious mass (FM) method. Based on this mathematical model, the motion pattern of the T-tail is investigated and the evolution of its LCO is elucidated. The precision of the FM method is verified by the direct method. Nonlinear stiffness in the segmented rudder hinge joints results in intricate LCO both below and above the linear flutter velocity. The transition of nonlinear responses is characterized by different types of motion as the velocity increases. The sudden increase in the oscillating amplitude indicates a shift in the LCO pattern. The evolution of the vibration frequency transitions from a single frequency to frequency doubling. The presence of free-play nonlinearity can expedite the onset of instability while simultaneously suppressing divergent motion. The aeroelastic characteristics of the T-tail with free-play nonlinearity in the segmented rudder hinge joints exhibit intricate complexities, rendering them of utmost importance for practical engineering applications.