Discrete Element Modeling of Vicksburg Sand and Lunar Simulant

The modeling of mobility and excavation on mars and the moon requires a thorough understanding of the planetary regolith. In this work, a discrete element (DEM) based model of a triaxial cell was created that closely represents the complex processes and properties of granular media. This model relies on a triangular lattice membrane covered triaxial cell for determining the macroscopic properties of the modeled granular material as well as a fast and efficient contact detection algorithm for a variety of grain shapes. This enables direct comparison to an actual triaxial test of the proposed material. We compare simulations and experiments using Vicksburg sand that can be closely replicated by poly-ellipsoidal (asymmetrical ellipsoidal) grains in the model. Then we compare experimental triaxial tests done on lunar simulant (JSC-1a) to DEM triaxial simulations. This comparison gives us a basis to begin scaling DEM grain size, shape and size distributions to practical values for extraterrestrial mobility and excavation modeling.