Amplitude reduction optimization of time delay semi-active control for aircraft landing gear shimmy

Abstract

Considering the time delay issue in the process of aircraft landing gear shimmy, the time delay semi-active control is used to achieve the purpose of amplitude reduction optimization. Firstly, in order to eliminate the influence of dimensionality and make the results better describe the objective universal law, after dimensionless treatment of the shimmy equations, the influence of dimensionless lateral bending damping coefficient and lateral bending stiffness coefficient of strut on the shimmy amplitude is analyzed. Then, in order to further reduce the amplitude, the time delay semi-active control term is introduced into the shimmy equations, and a mathematical method for solving the characteristic equation of the time-delay dynamic equation is proposed. Designing optimization criterion limits the amplitude of the first resonance to a small enough range. The time delay semi-active control can achieve good vibration reduction effect in the whole frequency domain and eliminate the second resonance. Finally, it is verified and compared in the frequency domain and time domain, the correctness of the calculation and the superiority of time delay semi-active control are proved.

Vibration Qualification Campaign on Main Landing Gear System for High-Speed Compound Helicopter

“…Both increasing the torsional damping and optimizing the stiffness distribution of the NLG can effectively improve the anti-swing performance, preventing the shimmy [23][24][25]. Several instability suppression strategies have been investigated in recent decades by developing multi-disciplinary formulations and the innovative design of active vibration absorbers [26][27][28][29][30][31][32][33]. Friction-induced vibrations are a major concern in the aircraft braking mechanism.…”