An Equivalent Multi-mass System of a Flexible Airplane

For the case in which the rigid mode and the first n modes of a flexible airplane are considered,the body of the airplane is defined as a multi-mass equivalent system and the calculation formulas of the parameters of the system are derived,which presents a model for testing/verifying landing impact load,landing work etc.under the influence of fuselage vibrations and also presents a simple and clear equivalent system for landing gear design analysis.The formula for calculating the landing work,displacement at the wing tip,the shears and bending moments of the wing of a flexible airplane are also given.From an overall point of view,structure deformation of airplane must be considered and optimization design must be used in landing gear design of a flexible airplane.