月壤的钻取采样离散元动态行为研究

Dynamically behavioral research of lunar soil drilling and sampling by DEM

月壤为离散介质,其力学行为不仅受外部因素影响,而且受月壤颗粒形状之间相互作用和约束因素影响,一般连续介质力学难以模拟其力学特性,而离散元法作为一种分析离散介质的数值方法,可用来模拟器具与月壤相互作用的力学行为.基于前苏联Luna-24月面钻取采样过程力学机理分析,首先对钻取运动过程进行分析,然后应用PFC3D离散元软件,构建离散元月壤模型,通过赋予颗粒接触刚度、摩擦系数、粘结系数等定义月壤本构模型,仿真钻取过程,对比钻取消耗能量和钻进阻力.计算结果表明螺距和转速对钻取消耗能量和钻进阻力影响较大,螺距越大,转速越高,钻取消耗能量和钻进阻力越大,且与螺距和转速呈线性关系.研究结果可为月表采样机构的设计与优化提供借鉴.

Lunar soil,as a kind of discrete mediums, whose mechanical behavior is not just affect- ed by external factors, but by the interactions and constraints between the soil particles. The me- chanical property of continuous mediums is difficult to simulate, and the discrete element method （DEM） as a numerical way to the analysis of discrete medium can be used to simulate the mechan- ical behavior between devices and the lunar soil. This paper was based on the former analysis of the drilling process on moon＇s surface by Soviet Luna-24. Analyzing the process of drilling and building the lunar soil modal with the discrete element software PFC3D was the first step, then we defined the lunar soil＇s constitutive model by giving the particle contact stiffness, coefficient of friction, adhesion coefficient and so on. We contrasted the energy consumption and drilling re- sistance by stimulating the process of drilling. The results show that the screw pitch and rotate speed have great impact on the energy consumption and drilling resistance. The bigger the screw pitch is and the higher the speed is, the larger the energy consumption and drilling resistance are, and they have a linear relation. The results are conducive to the lunar surface sampling mechanism＇s design and optimization.