Since lunar soil is a typical granular material and the microgravity environment can not be simulated easily in experiments on earth, the distinct element method (DEM) appears to be a very efficient method to analyze such problems. In this paper, first, a new contact model between particles for lunar soil is proposed, which takes into account particle rolling resistance and van der Waals forces between lunar soil particles, and then is implemented into DEM. By adjusting values of the parameters of the contact model, the basic mechanical characteristics of the DEM sample (e.g. the angle of internal friction, cohesion) can be numerically obtained which match the typical values of lunar regolith on the lunar surface. Second, the numerical simulation of tire-soil bin test was carried out and the interaction between the driving wheel of lunar rover and lunar soil was analyzed under lunar microgravity environment and terrestrial environment by DEM. The force and movement characteristics of the lugged rigid driving wheel, the stress and deformation of soil were analyzed. The results indicate that in lunar environment, the resistance of the wheels and the energy consumption will be less than that on earth but the slip ratio and settlement will be greater. So it will be more risky for lunar rover to travel on lunar surface than on earth.
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