Research On Penetrating Characteristics Of A Creepy-boring Penetrator

This topic comes from the in-advanced program of “Human-Machine CombinedDetection Scheme” in China's manned space area. The program is aimed at obtainingthe data of geological composition, physical and chemical properties, temperatureprofile of lunar regolith at an expected depth for a long time. For this mission, a schemeof creepy-boring and detecting system have been proposed after investigating therelevant information of extraterrestrial detection in the world. The system consists ofcreepy-boring penetrator and device on the moon surface. On the help of device on themoon surface, creepy-boring penetrator is able to penetrate regolith by using theprinciple of peristaltic movement. After arriving at desired depth, inner sensors wereused to detection. This paper mainly focuses on the penetrating characteristics of thecreepy-boring penetrator.This paper analyzed the crawling motion principle and built the movement model of thecreepy-boring penetrator. A relationship between load and displacement of lunar regolithsubsidence was built by using the foundation subsidence theory in soil mechanics. Themaximum penetrating depth of the creepy-boring penetrator could be predicted after putting thedisplacement into the movement model. Penetrating ability of creepy-boring penetrator wasevaluated by the maximum depth.Mohr coulomb failure criteria and passive Rankine's earth pressure theory were usedto build the drill cutting load model. Referring traditional screw conveying theory andscrew extrusion theory, screw conveying load model was built. These two load modelcould be theoretical foundation for the structure design and power matching of the drilland screw. Discrete Element Method (DEM) was combined with theory to analyzefilling characteristics of soil in the cache area. On the basis of the filling characteristics,load of cache area was predicted. This could guide the structure design of the cachearea.This subject developed the creepy-boring penetrator prototype and its test system.Drill cutting experiments and screw transporting experiments were conducted torespectively verify and modify the theoretical model of drill cutting load and screwtransporting load theoretical model. Filling characteristics and load model of cache areawere analyzed by the extra moment acted on the screw. The extra moment was producedby the accumulation of lunar regolith in the cache area. Besides that, the anchoringperformance of the anchoring mechanism was also test by the experiments.