3D Discrete element method modeling of the cone penetration test in lunar regolith simulant with various internal friction angles

The mechanical behavior of lunar regolith is highly influenced by its diverse mechanical properties, which are critical for geotechnical engineering activities during lunar exploration missions. Cone Penetration Test (CPT) serves as a key method to investigate these properties, while numerical simulation provides an effective approach for replicating the lunar conditions. In this study, the Discrete Element Method (DEM) was employed to simulate CPT on lunar regolith simulants with varying internal frictional angles (from 33.6° to 49.7°), achieved by simulating the interlocking force among particles to reflect the natural regolith properties at different depths. Microscale analysis revealed that specimens under terrestrial gravity exhibit stronger particle interactions and volumetric strain compared to lunar gravity, although the macroscopic shear strength remains minimally affected. During the CPT process, the variation of contact force, particle displacement, and velocity is concentrated around the cone, with the affected area expanding as the shape parameter increases. The penetration results show that cone tip resistance ([Formula: see text]) increases approximately linearly in the initial stage before stabilizing, while side frictional resistance ([Formula: see text]) reaches its peak value in the beginning stage and then declines gradually. Both [Formula: see text] and [Formula: see text] increase with the strength of the specimen, with values approximately 19.1% higher for [Formula: see text] and 17.1% higher for [Formula: see text] under terrestrial gravity compared to lunar gravity. This study offers a reference for future lunar surface experiments and geotechnical assessments.