微重力环境轮下月壤运动状态细观分析

Microscopic study on dynamic behavior of lunar regolith under driving wheel in microgravity circumstance

通过离散元软件PFC2D模拟微重力环境下刚性轮在月壤上行驶状态,并选取轮下5个典型颗粒和半径为5cm的1个圆形区域进行监测,细观分析了光滑轮下月壤颗粒运动轨迹、速度分布和孔隙率的动态变化过程。仿真结果表明:光滑轮下月壤颗粒轨迹可分为前推、下压和回弹3阶段;有刺轮下颗粒轨迹可以分为2类,第1类颗粒位于车轮外圆之外,其轨迹与光滑轮下颗粒轨迹类似,第2类颗粒位于车轮的基圆与外圆之间,轨迹可分为下压、上抛、下落阶段;当滑转率在0～100%之间时,轮下月壤颗粒有2个流动破坏区,即向前的流动区和向后的流动区;车轮通过月壤上方时,孔隙率下降,车轮驶过后,在颗粒间弹力作用下孔隙率略有回升,但整体小于通过前。

That rigid wheel passed lunar regolith was simulated by discrete element method （DEM）, 5 typical particles and a area with a radius of 5 cm were elected, and the particle tracks, speed distributions and the dynamic process of the porosity ratio of lunar regolith under driving wheel in microgravity circumstance were analyzed. The result shows that the tracks can be separated into push, press and rebound parts when lunar regolith particles are under smooth wheel. They can be separated into two kinds when lunar regolith particles are under lug-wheel. When the particles are outside the circularity, the tracks are similar to that under smooth wheel. When the particles are inside the circularity, the tracks can be separated into press, toss and drop parts. Lunar regolith under driving wheel has ahead and retral floating areas when the slip ratio is between 0 to 100%. The porosity ratio of lunar regolith descends when the wheel passing, and then it has some rebound after the wheel passing, but as a whole it is less than that before the passage. I tab, 11 figs, 11 refs.