Bifurcation analysis of a coupled nose landing gear-fuselage system

Under certain conditions during take-off and landing, pilots may sometimes experience quite violent vibrations in the cockpit. Since it is located right above the nose landing gear { which is known to experience self-excited vibrations on the runway { an explanation for those oscillations might be the interaction between the fuselage and the oscillating landing gear. A mathematical model is developed to study a coupled nose landing gear-fuselage system and the in uence of the landing gear dynamics on the fuselage. Bifurcation analysis reveals that the self-sustained oscillations of the landing gear can trigger the considered fuselage mode and the system behaviour strongly depends on the modal characteristics of the fuselage. At a given natural frequency, the smaller the modal mass of the considered fuselage mode, the larger the amplitude of the fuselage vibrations. The in uence of the vertical load exerted on the landing gear is also studied and the analysis confirms the destabilizing effect of larger mass loads.