The safe lander dynamics is an important part of the lunar landing mission. In this paper, a discrete element method (DEM) for lunar soil is set up, and the finite element method (FEM) for the lander is set up by shell elements and beam elements. The lander is regarded as a multibody system composed of a cabin, legs and footpads, and its motion characteristics are solved by multibody dynamics (MBD). A DEM-FEM-MBD coupling algorithm is developed to simulate the landing process of the lander considering landing mode and buffer mechanism, whose correctness is verified by comparison with a full-scale experiment involving lunar lander on earth. The effects of the mass, landing velocity and attitude of the lander on the safe landing are discussed. The buffering mechanism and influencing factors of lunar soil are analyzed. The results show that the impact force peak and impact depth gradually increase with the increase in the landing velocity and mass of the lander. Two kinds of inclined landing modes are defined and compared with vertical landing. It is found that the force on the landing leg that first contacts the lunar soil is significantly greater than that on the landing leg, that contacts later. The impact force peak on the lander under the two inclined landing modes is similar, but the impact depth of the 1-2-1 mode is significantly greater than that of the 2-2 mode. In the process of landing, lunar soil has the function of buffering dissipation. The energy dissipation rate is affected by the physical characteristics of lunar soil and the mechanical energy of the lander.

安全着陆器动力学是登月任务的重要组成部分。本文建立了月球土壤离散元法（DEM），着陆器有限元法（FEM）建立了壳单元和梁单元。着陆器被视为由机舱、腿和脚垫组成的多体系统，其运动特性通过多体动力学（MBD）求解。考虑着陆方式和缓冲机制，开发了DEM-FEM-MBD耦合算法来模拟着陆器的着陆过程，并通过与月球着陆器在地球上的全尺寸实验对比验证了其正确性。讨论了着陆器的质量、着陆速度和姿态对安全着陆的影响。分析了月壤的缓冲机制及影响因素。结果表明，随着着陆器着陆速度和质量的增加，撞击力峰值和撞击深度逐渐增加。定义了两种倾斜着陆方式，并与垂直着陆进行了比较。发现首先接触月球土壤的着陆腿上的力明显大于后来接触的着陆腿上的力。两种倾斜着陆模式下着陆器的冲击力峰值相似，但1-2-1模式的撞击深度明显大于2-2模式。在着陆过程中，月球土壤具有缓冲耗散的作用。能量耗散率受月球土壤物理特性和着陆器机械能的影响。