Effects of Inhomogeneous Subgrade Settlement to Aircraft Vibration and Its Control Standard

The runway in mountainous areas usually passes across different geological unit and has the form of filled and excavated subgrade. It is of great significance to study the effect of the runway settlement to aircraft vibration. An airplane taxiing model of six degree of freedom which can consider the effect of aerodynamic lift was established to research the influence of settlement amplitude, wavelength and taxiing velocity to aircraft vibration under typical settlement model of inhomogeneous subgrade. The results show that the impact coefficient for posterior main landing gear tire force and root mean square of weighed centroid acceleration increase linearly with the increase of settlement amplitude. Both values have the increasing tendency with the taxiing velocity increasing or the wavelength decreasing. Based on security and passenger comfort, the settlement control standard for inhomogeneous subgrade was proposed. The calculated results can have a positive significance to the settlement control or maintenance of runway in mountainous areas.