An Analysis Of Landing-gear Behavior In Consideration Of Airplane Flexibility

Landing-gear is an important component of the airplane, and the calculation of its performance ensures safe landing. In the conventional design of landing-gears, the airplane is usually assumed as a rigid body. The neglect of airplane flexibility leads to numerical error. In this paper, the effect of airplane flexibility on the landing-gear behavior is discussed.Flexible airplane landing model is established. The dynamic model of the fuselage is established by the application of Lagrange's equation and virtual-work principles. The generalized force on the fuselage includes not only vertical force of the landing-gear and airplane lift, but also the landing-gear moment on the airplane. The dynamic equations and calculation of the forces are presented. The R-K method is used to generalize the equations for numerical calculation of the landing-gear behavior.Based on the model, a software for calculation analysis of landing-gear considering airplane flexibility is developed. The software is an effectual tool for evaluating the performance of landing-gear primarily. It can be used for the calculation of the response of the landing-gear when initial landing condition, feature of the first 5th symmetrical modes, shock-strut performance and tire parameters are given. Landing simulation is also presented by the software.A series of landing-gear responses are calculated by given different generalized mass, the frequency of the modes and the translation of the modes in the station of landing-gear. From an overall point of view, airplane flexibility must be considered and optimization design must be used in landing-gear design of a flexible airplane.