Study On Impact Reflection Wave Of Three Typical Simulated Lunar Soil

Sampling and return of the lunar surface is an important part of the lunar exploration activity.The main goal of the unmanned autonomous sampling task of the lunar surface in China is to obtain and return to the earth a sample of lunar soil that is 2m deep and has continuous bedding information below the lunar surface.Due to the peculiarity of the formation process of lunar soil,lunar soil has different physical and mechanical properties from the earth's soil.Different lunar soil materials at the bottom of the drilling tool will affect the drilling and sampling work.Taking the outer diameter of the sampling drilling tool and the diameter of the inlet as reference standards,lunar soil is divided into three types: representative small-scale homogeneous lunar soil,critical-scale granular lunar soil,and large-scale lunar rock,representing three types of drills,respectively.Into working condition.By conducting impact tests and simulations on three simulated lunar soils,the propagation characteristics of reflected waves in drilling tools are studied.This paper provides a reference for the identification of lunar soil conditions at the bottom of the drilling tools during unmanned autonomous sampling.Based on the theory of elastic mechanics,material mechanics and wave dynamics,the interaction model of drilling tools and lunar soil under impact is established.According to the distribution of lunar soil particle size distribution,lunar soil drilling and core-coring conditions are divided into homogeneous lunar soil,critical-scale particles and rocks.The equation of the relationship between the speed of stress wave propagation in the drilling tool and the stress change under impact is derived and analyzed.The corresponding relationship between the two is explained,the principle and characteristics of stress wave propagation between different media interfaces are explained,and the propagation law of stress waves between different media interfaces is obtained.Using the finite element software to simulate the impact process of the drilling tool in contact with lunar soil,the research work of no-load impact,homogeneous lunar soil impact,critical-scale particle impact and moon rock impact were carried out respectively,and the stress wave reflection wave was obtained in The propagation law in different configurations of drilling tools,the simulation results show that with the increase of the initial impact velocity,the amplitude of stress wave propagation in the drilling tool also increases correspondingly,the two are in a linear relationship,and the impact velocity does not affect the waveform in the drilling tool Curves;studies on the effect of three drill tool configurations on the amplitude and waveform of stress wave propagation,the results show that the hollow drill tool and the outer spiral configuration of the drill tool have little effect on the propagation of stress waves in the drill tool;homogeneous reflection waves It is basically the same as the reflected wave waveform curve,and the amplitude of the transmitted wave is extremely small;the attenuation of the reflected wave amplitude of the critical-scale particles and the simulated moonstone is obvious and the attenuation of the critical-scale particles is the largest.The three ratios of the reflected wave amplitudes can clearly distinguish the three materials.Based on the compaction method,the density of homogenous simulated lunar soil and critical-scale particles simulated lunar soil are increased to be within the range of true lunar soil density.The lunar soil drilling sampling platform was used to perform impact tests on three simulated lunar soils.By processing the impact displacement data of drilling tools collected by high-speed cameras,the propagation of stress incident waves and reflected waves in the simulated lunar soils was analyzed.By comparing and analyzing the simulated stress-time curve and the test data curve,it can be seen that the two curves have the same trend.The three simulated lunar soils of the experiment have obvious differences in the amplitude ratio of the stress wave and the reflected wave.There are obvious differences in the reflected wave waveform.The amplitude of the reflected wave of the homogeneous lunar soil is the largest,and the simulated amplitude of the critical scale granular lunar soil is the smallest.Consistent.