Multi-parameter bifurcation analysis of shimmy in a new configuration dual-wheel nose landing gear

For the heavy loads and lateral mounting limitations of modern military aircraft, a fully parameterized mathematical model is established based on a new dual-wheel nose landing gear configuration. Nonlinear dynamic analysis reveals the regulatory mechanism of the front and rear wheel caster length parameters and load distribution parameter on the evolution of shimmy oscillation modes. The model comprehensively considers the torsional and lateral bending motion modes of the landing gear and introduces the lateral deformation coupling effects of the tire-ground contact. The focus is on the impact of the front and rear wheel caster length and load distribution parameter on the system’s stability in the parameter plane. Based on the two-parameter bifurcation analysis, it was found that increasing the front caster length ef and decreasing the rear caster length er reduce the torsional shimmy region, but at the same time lower the threshold for lateral bending shimmy. In addition, allocating a moderate portion of the vertical load to the front wheel is beneficial for controlling shimmy, whereas excessive allocation may trigger premature onset of lateral bending shimmy. This study provides a theoretical basis for caster length matching, load distribution, damping control, and shimmy suppression in the design of new dual-wheel landing gear configurations based on bifurcation theory.