Enhancing nose landing gear shimmy performance using torsional inerter-based dynamic vibration absorber

During aircraft taxiing process of takeoff and landing, the landing gear often experiences shimmy phenomenon subjected to external disturbance, which threatens the aircraft handling and safety, and should be controlled in practical engineering. This paper proposes four types of torsional Inerter-based Dynamic Vibration Absorber (IDVA) based on the series and parallel configurations of the inerter-spring-damper system, and applies them in the Nose Landing Gear (NLG) to improve the shimmy performance. The dynamic model of the NLG using torsional IDVA is established, the two-parameter and single-parameter bifurcation diagrams are obtained to show the shimmy region and Limit Cycle Oscillation Amplitude (LCOA) using the bifurcation theory combined with numerical continuation algorithm, a comparison of its shimmy performance is made against with the original NLG and NLG using torsional DVA. The structural parameters of the torsional IDVA are studied for their effects on NLG shimmy performance, with the genetic optimization algorithm being used to optimize its structural parameters. The results show that using the torsional IDVA in the NLG significantly reduces the Torsional Shimmy (TS) region, slightly decreases the Lateral Shimmy (LS) region, and enlarges the stable region; also narrows the TS and LS forward speed ranges, and decreases the maximum LCOA of both TS and LS, it obtains a better shimmy suppression performance than the torsional DVA. Selecting a smaller inertance and a larger auxiliary spring stiffness for the IDVA is better for improving the NLG shimmy performance. Furthermore, when the NLG occurs shimmy, compared with the original NLG, the optimized torsional IDVA using the genetic optimization algorithm reduces the TS, TLS and LS regions by 33.45%, 22.24% and 8.74%, respectively, and expands the stable region by 14.79%, which exhibits a superior shimmy suppression performance.