Research On The Impact Type Penetrator And Its Mechanical Properties During Penetrating Lunar Regolith Profile

Planetary exploration is an important means of studying the evolution and formation of planets.China Chang'e V lunar exploartion project will adopt drilling and surface sampling methods to acqurie the lunar soil and return its back.Compared with sampling the soil and return its back for analysis,the hammer-driven type penetrating in situ detection has some advantages in unlimited penetraing depth,small mass of shape nose,low cost of exploration,and small power consumption,etc.Since hammer-driven type penetrator can penetrate to a certain depth in planetary soil and realize the scientific exploration of planetary soil's mechancial parameters,it is more suitable for the in situ exploration of the Moon,Mars,and asteroid.Limited by the operating power,the impact energy and other factors,there are still many technical shortcomings for the penetration device in the implementation of the in situ planetary soil's penetrating exploration.In this paper,the lunar soil profile penetrating project is selected as the engineering background.By closely combing the mechanical properties of the lunar soil profile and the quality,energy and the scale of the the detector,a hammer-driven type lunar soil profile penetrator has been proposed.In order to maximize the penetrating efficiency,this research on the general characteristics of the penetrator in the lunar soil profile,the efficiency transmission of the impact and other common problems are carried out.Finally,a high efficiency,low power consumption,lightweight impact penetrator has been developed.Based on the principle of space replacement in the process of penetrating process,the interaction between the penetrator and the lunar soil was analyzed to obtain the soil extruding stress zone,the soil elastic recovery zone and the law of the stress diffusion in the in situ lunar soil and its boundary conditions.By analyzing the influence of the submerged approach and its structural parameters on the distribution of stress field in the lunar soil,the void variation regulation during the penetrator piercing process,the penetrating resistance,and the penetration boundary,etc.,are acquired thereby,which lays the foudation for determinating the design index and the mechanical modeling.This paper proposed a structural scheme of the energy storage type impact penetrator with a rope driven mechanism,which has some advantages of simple structure and high energy transfering efficiency,etc.The interacted mechanical model of penetrating into the lunar soil has been established and the influence on the penetrating load with different penetrator's structural parameters are analyzed then.The optimized structural parameters are selected finally.Besides,the optimization of the mass and the stiffness matching in the core elements of the penetrator is carried out under the limited impacting power.By neglecting the influence of the impact interface,the best matches between the mass and the stiffness values of the core elements are obtained under the given boundary conditions.In order to study the particle flowing and stress distribution in the penetrating process,the simulation model of the flowing field of the lunar soil and the penetrator was established.By analyzing the effect on the resistance force by the parmaters in contact model in simulation,suitable contact model parameters were selected then,and the parameters' matching of the simulated lunar simulants' constitutive model were completed then.By conducting the combination simulation between the EDEM software and the ADAMS software,the penetrating process has been realized.For the cone-type penetrator's piercing process,the around particles' moving regulation are acquired by analyzing above lunar soil's flowing characteristics.Also,the stress influences area of lunar soil particle under different structural shape nose can provide a support for the preapration of simulated lunar soil simulants.By adopting the 3D vibration compacting method,several different types of lunar soil profile simulants were prepared by using the relative density as the evaluation index to make sure the consistency of soil's mechanical properties along the depth profile.After then,the hammer-driven type penetrator prototype has been developed,which were used to conduct the lunar soil simulant impacting experiments.By applying the high-speed camera system to record the real-tme impacting speed,the optimal impact power efficiency parameter matching vaule were acquired.Finally,the impacting efficiency experiments under the horizontal and vertical ultimate attitudes were conducted to verify the effectiveness of the theoretical analysis and structural design.