Analysis and test research on influencing factors of drilling and coring quantity of lunar soil simulant

During the design of drilling and coring mechanism for lunar exploration, a coring method based on a flexible tube can obtain slim continuous sample core, which enables high coring rate and preserves the stratification information of the subsurface samples. Since the complex movement of lunar soil particles during the flexible tube coring, there is no systemic method to analyze the factors that determine the coring quantity. The flowage of the lunar soil particles in flexible tube was analyzed and the coring model of the flexible tube based on the theory of limit equilibrium was established. The mechanical boundary conditions of the model were interactions between lunar soil and coring drill tools and among each part of lunar soil. The coring model described the dynamic process of lunar soil flowing from the outside of coring drill tools into the flexible tube. A numerical prediction method for coring rate was proposed based on the coring model. Drilling parameters, lunar soil properties and drill tool structure were analyzed as key influencing factors of coring rate. A verifying test with simulant of lunar soil HIT-LS1# and drill tools HIT-2 was implemented on a simulated drilling test-bed. The average error between the test results and the predicted results is less than 5%.