The proposed terramechanics modeling software presents novel methods to simulate irregular agglutinate shapes in lunar soil and evaluate their interaction with wheeled rovers on the lunar surface. The method combines automated agglutinate generation in a Discrete Element Method (DEM) numerical framework to produce irregular grain shapes composed of bonded particles. Additional factors are introduced in the model to study soil mechanics properties relevant to ISRU and exploration missions targeted at the lunar poles including terrain generation with reduced soil compaction.
Unlike previous lunar DEM terramechanics models which incorporate both individual particles to represent agglutinates, the proposed software allows the interlocking of irregular agglutinate shapes which act to increase angle of repose, shear strength, and abrasiveness of the soil.
The product of the Phase I project will include automated generation of irregular grain shapes in DEM, coupling of DEM with the Finite Element Method to simulate a wheel and deeper soil layers, and terrain generation routines to allow for variable compaction within the DEM soil layers. These efforts will lead to standalone terramechanics modeling software in Phase II whose mechanical response will be calibrated to results obtained in laboratory experiments.
The primary NASA application of the proposed terramechanics software is the analysis of soil-wheel interactions for conditions found at the lunar poles. These developments allow robust, low-cost analysis of rover designs aimed at ISRU and exploration missions at lunar polar regions. Parametric inputs in the software allow testing of complex wheel geometries under a range of potential terrain and soil mechanics conditions. With realistic modeling of agglutinates, the software brings increased accuracy for the mechanical response of lunar soil.
The terramechanics software presents significant commercial opportunity in the design and evaluation of tracked and wheeled vehicles. Tire manufacturers and vehicle designers in automobile and mining industries can use the software to improve current designs or invent new ones. Many opportunities exist for military branches of the government in the design and testing of expeditionary vehicles.