The Preparation And Performance Analysis Of High Compactness Simulated Planet Soil Under The Condition Of Planetary Lander Equipment's Drilling Samples And Landing

Deep space exploration is one of the important criteria of a national scientific research and military strength,so in recent decades,more and more countries put forward the strategic objectives of deep space exploration.China is no exception.After the completion of the first phase,the second phase of the lunar exploration project,next is expected to launch returnable lunar lander and carry out related research in 2017,and then plans to launch returnable Mars detectors around 2030,which will provide an important experimental basis for the origin of the solar system and the search for extraterrestrial life.In the process of landing of the planet probe,the mechanical parameters of the landing point directly determine to the lander whether can safely land on the surface of the planet.In addition,whether the sampling shovel can successfully acquire the samples of the planet on the surface of the planet is also closely related to the parameters of the star's surface.Therefore,the study of the mechanical properties of the star is very important.Based on the previous experiments,a set of simulated star preparation equipment and testing methods have been developed for simulated landing of the planet lander and drilling.The self-made simulated star preparation equipment can simulate the relative density of simulated hits to 99%,so as to meet the requirements of simulated planet soil under the limited condition of drilling.Due to the high compactness of the simulated planet soil under the condition of extreme drilling,it is difficult to measure the effective numerical value of the simulated planet soil by normal penetrating resistance testing equipment.Therefore,this paper provides a new type of simulated planet soil penetrating resistance detection equipment.This device will quickly detect the penetration resistance of simulated planet soil under extreme drilling conditions,which will help improve the reliability of planet soil's simulation.On this basis,EDEM was used to simulate the detection process of penetration resistance measuring device on simulated planet soil.Through the comparative analysis,the simulation data results are in good agreement with the experimental data,which provides an effective research method for the further study of the mechanical properties of the planet soil.In the aspect of specific experimental detection,the penetration resistance and cohesion and internal friction angle of JLU5 series simulated lunar soil were systematically determined.The detection of seven kinds of particle size of the JLU5 simulated lunar penetration resistance reveals that the penetration resistance is very large when the relative density is 99%.If the penetration depth is 25 mm,the penetration resistance value can reach 100 Mpa.Comparing the laboratory soil samples with the actual simulated lunar soil mechanics parameters,it is found that the laboratory soil's compactness is much higher.Based on the analysis of the shear characteristics of JLU5 series,it is concluded that the cohesion of most of the simulated lunar soil is in the range of 20 kPa ~ 60 kPa,and the internal friction angle is mostly in the range of 50 ° ~ 70 °.These mechanical parameters will provide a strong basis for the design of the planet drilling devices.In this paper,we focus on the simulation of soil used to Martian landing based on the determination of mechanical parameters.And the interaction between the landing pad and the simulated Martian soil during the landing process was simulated by the impact test of the foot pad model.Data analysis shows that the larger area of the foot pad for the soft landing of the planet lander,the smaller depth of the subsidence,and the greater impact acceleration.Therefore,the greater foot pads,more difficult the lander sink to the Martian,and more easily to damage the equipment carried by lander.In addition,the instantaneous velocity between the foot pads with the simulated Martian soil also affects the depth of the subsidence and the impact acceleration.So it should try to reduce the impact speed during the soft landing process.According to determination of JLU5 Mars-4,we get the variation range of friction coefficient is 0.39 ~ 0.56 and the mean value is 0.46.The change of bearing strength is 6.3kpa ~ 22.5kpa,which all of the parameters satisfy the expected requirement.In order to determine the accuracy of the results of the simulated planet soil,this paper simulates the planet soil penetration resistance of simulated soil based on DEM.And compared with the experiment values,the simulation results are basically consistent.This indicates that the actual measured value of simulated planet soil penetrating resistance is very reliable.This paper systematically describes a new method of simulating and testing the planet soil.We can quickly and efficiently carry out the simulated soil of the limited conditions,and rapidly measure mechanical parameters by this new method.This will provide a basic technical guarantee for the design of the soft landing part of the planet detector and the development of the planet soil collector.