DEM thermal simulation of bit and object in drilling of lunar soil simulant

The bit and object thermal problem was investigated in this study with particular regard to the drilling of lunar soil simulant. The discrete element method (DEM) was used to establish a thermal model of the simulant that considered convection, radiation, and geometry. Parameter calibration of the DEM heat transfer model was undertaken, and drilling experiments were performed under normal pressure to verify the model. Thermal simulations of the drilling of the lunar soil simulant under normal pressure and in a vacuum were also conducted, and very good agreement was observed between the simulation and experimental results. The temperature rise of the lunar soil simulant was found to be much less during drilling in a vacuum compared to drilling under normal pressure for comparable temperatures of the drill bit. And in a vacuum, lunar soil simulant had little effect on heat dissipation from the drilling tool.