Discrete Element Modeling of Strength Properties of Johnson Space Center (JSC-1A) Lunar Regolith Simulant

This paper simulates the three-dimensional axisymmetric triaxial compression of JSC-1A lunar regolith simulant under lunar and terrestrial gravity environments under a wide range of confining pressures and relative densities. To accomplish this, the discrete element method (DEM), using Particle Flow Code In Three-Dimensional (PFC3D) software, was employed. The paper focuses on the peak and the critical state (CS) friction angles, which were predicted in the ranges of 35.4°–82.7° and 31.2°–79.8°, respectively, depending on the specimen density and confining pressure. A significant increase in peak and CS friction angles was predicted at near-zero confining pressure. The DEM results validated an empirical model that relates the peak friction angle with the CS friction angle, relative density, and mean effective stress at the CS. Comparison of DEM results with lunar in situ measurements of friction angle, from Apollo missions and other extraterrestrial laboratory experiments under a microgravity environment, shows a favorable agreement.