Aircraft Nose Landing Gear Shimmy with Nonlinear Tyre Models

Abstract In this study, an application of a nonlinear tyre model is considered in the analysis of aircraft nose landing gear shimmy. An aircraft single-wheel nose landing gear system is used to analyse the shimmy stability, where the tyre model is designed to account the nonlinear relaxation length by the two-degree-of-freedom model, as well as the nonlinearity of the tyre contact patch. This improvement takes into account the nonlinear relaxation length of the tyre and the time-varying changes in the tyre contact path due to large amplitude vibrations. The system is analysed using nonlinear bifurcation methods, and the results indicate that the nonlinear tyre model exhibits greater amplitude and extends the velocity range for shimmy occurrence. Simultaneously, the bistable region where coupled shimmy oscillations occur also shifts downwards, indicating a greater tendency for coupled oscillations involving lateral bending shimmy oscillations and torsional shimmy oscillations. Moreover, evaluate the differences between two tyre models and the results show that the new nonlinear tyre model can allow for better and more accurate predictions of shimmy behaviour and potential oscillation amplitude based on varying environmental factors. From the perspective of shimmy prediction and prevention, the application of this new model in shimmy analysis enhances aircraft safety redundancy and increases overall safety.