Thermal simulation of drilling into lunar rock simulant by discrete element method

Abstract

This study investigated the thermal problem of drilling into a lunar rock simulant. A thermal model involving radiation and heat transfer involved a geometry for drilling into the lunar rock simulant was established using discrete element method (DEM). Drilling experiments were performed in a vacuum to verify the model. Thermal simulations of drilling into the lunar rock simulant in a vacuum with and without lunar soil simulant were conducted, and very good agreement was observed between the simulation and experimental results. The simulation results showed that the lunar soil temperature during drilling in a vacuum simulant was much less than that of the lunar rock simulant, and lunar soil simulant had little effect on heat dissipation from the drilling tool. A drilling procedure intervention strategy for the thermal safety of drilling tools was investigated. It was found from the intervention process based on DEM that the temperatures of the drilling tool were within a safe range, and the time duration for heat dissipation was usually much longer than the time required for temperature increase.