A Review of Discrete Element Method (DEM) Particle Shapes and Size Distributions for Lunar Soil

摘要: As part of ongoing efforts to develop models lunar soil mechanics, this report reviews two topics that are important discrete element method (DEM) modeling the behavior soils (such as soils): (1) methods particle shapes and (2) analytical representations size distribution. The choice shape complexity is driven primarily by opposing tradeoffs with total number particles, computer memory, simulation processing time. also dependent on available DEM software capabilities. For example, PFC2D/PFC3D EDEM support clustering spheres; MIMES incorporates superquadric shapes; BLOKS3D provides polyhedra shapes. Most commercial custom supports some type complex beyond standard sphere. Convex polyhedra, clusters spheres single parametric such ellipsoid, polyellipsoid, superquadric, all motivated desire introduce asymmetry into shape, well edges corners, in order better simulate actual granular behavior. An empirical distribution (PSD) formula shown fit desert sand data from Bagnold. Particle JSC-1a obtained a fine analyzer at NASA Kennedy Space Center fitted similar PSD function.