返回舱着陆姿态和动力响应的DEM-FEM耦合分析

针对返回舱安全着陆问题，采用陆面颗粒离散元模型（discrete element model, DEM）与返回舱壳体有限元模型（finite element method, FEM）相耦合的方法，对返回舱回收着陆过程的动力特性进行数值分析，并与试验结果进行对比，验证计算结果的正确性。分析讨论垂直和倾斜2种着陆姿态的返回舱结构应力分布，从冲击能量的角度讨论陆面颗粒对其缓冲作用。对影响返回舱回弹响应的主要因素进行分析并提出相应的改进方法。结果认为：陆面颗粒是返回舱着陆冲击能量吸收的主体，且倾斜着陆时陆面颗粒吸能占比更加显著；当陆面颗粒之间的摩擦因数较小或返回舱质量较大时，返回舱着陆的回弹速度相对较小。

DEM-FEM coupling analysis on landing attitude and dynamic response of re-entry capsule

As to the safety landing problem of the re entry capsule, the numerical analysis on the dynamic characteristics of the re entry capsule during re entry and landing is carried out using coupling method of land particle discrete element model (DEM) and re entry capsule finite element model (FEM). The dynamic characteristics of the re entry capsule landing are compared with the experimental results, and the correctness of the computational results are verified. The structure stress distribution of the re entry capsule landing vertical and with oblique postures are discussed, and the buffering effect of surface granules on the re entry capsule structure is discussed in the terms of impact energy. The main factors affecting the rebound response of the re entry capsule are analyzed, and the corresponding improvement methods are proposed. The results show that the land surface granules are the main part of the impact energy absorption of the re entry capsule, and the proportion of energy absorbed by land surface granules is more significant when landing in inclined direction; when the friction factor of land surface granules is smaller and the mass of re entry capsule is larger, the rebound velocity of the re entry capsule is relatively smaller.