Research On The Characteristics Of Adaptive Drilling And Coring Into High Compacted Lunar Regolith Simulant

Since the US,the former Soviet Union,and other countries took the lead in lunar exploration in the last century,humans have collected about 382 kg of lunar regolith samples from the moon.By analyzing the collected lunar regolith,we have deepened the understanding of the evolution and formation of the moon.At present,China's lunar exploration project(phase III)is about to be implemented,and lunar regolith samples will also be collected from the moon by means of drilling and surface sampling for scientific testing and analysis in the laboratory on the Earth.Based on China's lunar drilling and coring exploration project(phase III)as the engineering background,the drilling device should solve the challenges of the uncertain mechanical parameters of lunar regolith and achieve the target of low power consumption,high coring ratio,and high adaptability.Hence,this paper proposed a high compaction lunar regolith simulant preparation method based on tamping strengthen.In addition,the drilling and coring characteristics of the lunar regolith simulant has been investigated by the theoretical modelling and experimental validation.Furthermore,the drilling chips' removal performance and the adaptive drilling characteristics have been analyzed.Above research works can technologically support the optimization of drill tool's structure parameters and drilling parameters for next stage of deep space exploration missions.Aiming at the characteristics of subsurface regolith on the moon,this paper proposes a high-density lunar regolith simulant preparation method based on the principle of tamping compaction strengthening,and establishes the dynamic model of lumbar regolith barrel ramming vibration and impact hammer's ramming rebounding.Based on the ideal elastic-plastic model,the effective compaction depth of the lunar regolith simulant's profile was predicted based on the ideal elastoplastic model for the constraint conditions of the lunar soil barrel for drilling and coring tests.The inherent physical law between the plastic limit and the number of tamping action were verified by conducting tamping compaction tests under different tamping numbers.The ring knife method for measuring the soil density verified the effective of the compaction depth prediction results.Based on the rotary cutting mechanical model,the disturbed dilatation model of the in-situ lunar regolith was established,and the physical law of the lunar regolith's physical and mechanical parameters in the disturbance zone changing with the penetration per revolution ratio was obtained.Based on the powder mechanics theory,a lunar regolith's coring ratio prediction model was established.By using the proposed non-contact online monitoring method of drilling and coring characteristics,an orthogonal drilling and coring experiments under different rotation ratio conditions were carried out,revealing that the internal lunar soil core dynamic instability specific changes with drilling parameters.Four typical coring operations are divided and the accuracy of the coring ratio prediction model is verified,which can provide a theoretical basis for drilling parameters optimization.This dissertation proposed to quantitatively describe the cutting flow of the lunar regolith and the state of spiral chip removal by using indicators such as the cutting chip accumulation angle and the spiral groove filling rate.Based on the screw transportation theory,the drilling load model under two typical working conditions was established.The machine vision technology was used to develop experimental study on the characteristics of chip removal during lunar regolith's rotary cutting.By online monitoring the volume parameters of lunar soil accumulation area during drilling,real-time reflection of key indicators affecting the chip removal performance such as spiral chip removal rate.By extracting the quality and volume of lunar soil cutting chips in the spiral groove,the packing density of the spiral flute cuttings can be calculated thereby.It strongly supported the existence of lunar soil squeezing and self-migration during drilling and coring.Lunar regolith simulant drilling tests under multi-dimensional drilling parameters was carried out.It shows that the drilling load model can effectively predict the actual drilling load,and can provide a reliable theoretical and experimental basis for the optimization of drilling parameters in the following section.An adaptive drilling strategy based on real-time drillability identification is proposed.Based on the coring and drilling load model,the influence on the drilling loads and coring ratio by the drilling parameters are analyzed.Based on above analysis,reasonable drilling parameters are optimized.According to the drilling parameters,the drillability grade of the simulated lunar soil sample with certain coverage was divided by the ROP method.The rotation torque and penetrating force were selected as the drilling characteristic signals.A pattern recognition method based on support vector machine was designed and carried out.The parameters are optimized to obtain an identification model that can be applied to drillability grades 1 to 6.The recognition accuracy rate is 95.8%.A closed-loop control strategy based on real-time drillability identification is constructed.High dense type lunar soil,limestone and marble with multiple layers of randomly distributed was planned as a typical drilling object.Real-time identification closed-loop control method is successfully used to achieve adaptive drilling in complex working conditions.Overall,aiming at the technical difficulties of unmanned drilling and sampling on lunar surface,this dissertation carried out works from the aspects of lunar soil simulant preparation technology,the interaction mechanism between drill tool and lunar regolith,the test method of drilling and coring characteristics,and the adaptive drilling strategy to improve the adaptive ability of drilling and sampling mechanism.Above research method and the corresponding research results have important academic significance and engineering application value.