Aircraft Nose Landing Gear Shimmy with Nonlinear Tire Models

In this study, an application of a nonlinear tire model is considered in the analysis of aircraft nose landing gear shimmy. An aircraft single-wheel nose landing gear system is used to analyze the shimmy stability, where the tire model is designed to account the nonlinear relaxation length by the two-degree-of-freedom model, as well as the nonlinearity of the tire contact patch. This improvement takes into account the nonlinear relaxation length of the tire and the time-varying changes in the tire contact path due to large-amplitude vibrations. The system is analyzed using nonlinear bifurcation methods, and the results indicate that the nonlinear tire 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 tire models and the results show that the new nonlinear tire model can allow for better and more accurate predictions of shimmy behavior 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 robustness and increases overall safety.