月球着陆器着陆过程的DEM-FEM耦合分析

Landing Process of Lunar Lander Simulated with Coupled DEM-FEM Model

实现月球着陆器的安全软着陆是宇航员、搭载设备、仪器安全以及着陆器后续正常工作的重要保证.论文采用离散元-有限元方法建立月壤与着陆器相互作用的耦合模型,其中月壤采用具有粘结作用的球体离散元单元,着陆器采用壳单元和梁单元组合的有限元模型,与缓冲垫连接的支撑腿采用可压缩弹簧模型,以实现着陆器自身的缓冲功能;为分析着陆于不同月表的过程,建立平坦、斜坡月球表面;针对不同坡度的斜坡月表,研究不同着陆模式下着陆器与月壤的相互作用,分析冲击力峰值的大小与作用时间的关系,并从能量方面讨论和解释大坡度下冲击力峰值小的原因.以上研究为月球着陆器的安全着陆分析提供有益的参考.

The safe landing of a lunar lander is a major guarantee for the safety of astronauts and the carrying equipment and instrument,as well as the subsequent operation of the lander.Studying the landing process of the lunar lander is important for achieving safe landing.In this study,a model coupling the discrete element method(DEM)and the finite element method(FEM)is set up to analyze the interactions between the lunar soil and the lander.In this coupled model,the lunar soil is modeled by discrete spherical elements with bond capacity.The lander is constructed with a combined finite element model consisting of shell elements and beam elements.Meanwhile,a compressible spring model is used for the supporting legs connected with the cushion to realize the buffer capacity.In order to analyze the landing process on various lunar surfaces,different flat and sloped lunar surfaces are simulated,and the interactions between the lander and the lunar soil in different landing modes are studied.Studies have shown that during landing,the impact strength of the lander structure decreases with an increase in slope.When the lander landed on the lunar surface in a singular posture,the 1-2-1mode was slightly less impacted than the 2-2mode.The above results are explained in detail from the energy point of view.In addition,the relationship between the peak impact force and the impact duration is analyzed,and the reasons for the small peak impact force under the high surface slope are discussed in terms of energy.This work serves as a useful reference for the safe landing of lunar landers.