DEM modelling of cone penetration tests in lunar soil

This paper presents numerical investigations of the cone-penetration test (CPT) in lunar soil via a modified 2D Discrete Element Method (DEM). The Van der Waals forces were included in the DEM particle contact model to simulate the cohesive interactions in the lunar environment. In addition, the rolling resistance model was used to account for the high inter-particle friction angle resulted from particle angularity. A series of DEM biaxial tests were performed to investigate the mechanical properties of lunar soil. The obtained results from the DEM biaxial tests indicate that the mechanical behaviour of lunar soil is different from that of terrestrial soil due to the inter-particle cohesive forces and low gravity on the Moon. In tests, the grains near the penetrometer have experienced intense loading and unloading with complex displacement paths. In the meantime, the granular velocity, stress and strain fields were also changed during the penetration process. This study reveals that the lunar soil has relatively small friction and strength when compared with the terrestrial soil.