Nonlinear analysis of the interaction of the nose landing gear and the fuselage of an aircraft with the perspective of a real-time dynamic substructuring test

When taking off or landing, pilots sometimes experience oscillations in the cockpit. It is known that the nose landing gear - which is situated right under the cockpit - is prone to self-excited vibrations at certain velocities. Therefore, an explanation for the cockpit vibrations can be the dynamic interaction between the nose landing gear and the aircraft body. This interaction, however, can be bi-directional, that is, the fuselage dynamics may also influence the dynamics of the landing gear. In order to study this coupling and clarify the mutual interaction, a mathematical model is developed. By means of nonlinear techniques it is revealed that the interaction may be significant in both directions, and that the system behaviour depends strongly on the modal characteristics of the fuselage. Considering system parameters providing significant interaction, the model is used to study the feasibility of a real-time dynamic substructuring test.