Abstract: The effect of aircraft structure flexibility on the shock-absorber behavior of landing gears is discussed.The dynamic model and ahalyticl method of the shock strut system can cerning the effect of flexible aircraft are established. Applications hvae shown that the aircraft structure flexibility can decrease the overloat and displacement of the shock strut system, especially,for the main landing gears of large and middle size airplanes.Therefore,considering the aircraft strcture flexibility can not only predict the ground loads of aircraft correctly,but also is of important value to the parameter design of landing gears.

Key words: vibration modes, landing gear, landing impact