Energy absorbing capability of kneeling landing gear for new type armed helicopters during crash process (II): Theoretical model analysis

The finite element method (FEM) was adopted to analyze the dynamic plastic response and the energy absorbing capability of a landing gear associated with a fuselage represented by an effective mass system of the rigid truss undergoing the hard landing impact vertically to the ground with an initial velocity of 6 m/s. The model is based on practical armed helicopters. During the primary design stage, how to simply and effectively estimate the energy absorbing capability of the helicopter structural components and how to establish the corresponding rule of reasonably distributing the impact energy to the components are extremely important. This paper is focused on the simple theoretical model of using the spring-mass system based on Lagrange differential equations to approximate estimate the partitioning of the energy absorbing by the landing gear during the hard landing process. The changes of the kinetic energy of the helicopter and the impact curve of the main attenuation oleo cylinder have been given. Finally, a comparison between the results obtained from the FEM technique and present theoretical model is made.