Numerical analysis on travelability of lunar soil simulant by means of distinct element method

The geometric model of lunar simulant particles was built based on its scanning electron microscopic-photograph (SEM), and a producing strategy for irregular-shape particle assembly was presented. A simplified contact reaction model of lunar particles was created. The relationship between soil macro-mechanical property and its meso-parameters was obtained by means of dimensional analysis and biaxial test simulation by distinct element method (DEM). According to the relationship and triaxial test data of lunar simulant, the model parameters were determined numerically. Wheel-lunar simulant interaction was simulated by DEM under moon gravity, and the soil thrust expression in granular-scale was derived. The dynamic behavior of soil particles was quantitatively analyzed at different slip ratio, and lunar simulant's travelability was qualitatively estimated. Results show that soil thrust increases with higher slip ratio; there are transient period and steady-stage period when wheel travels at high slip ratio, and soil thrust value is bigger in transient period than that in steady-stage period.