Design Of Circular Vibration Penetration Lunar Soil Sampler And Study Of Sampling Quality And Efficiency

Along with the successful conclusion of the third phase of China’s lunar exploration project,the Chang’e 5 lunar probe successfully obtained 1731 g of lunar soil and returned to Earth.However,the lunar soil sample is prone to blockage in the sampling tube,resulting in high penetration resistance,low sampling rate,and destruction of the lunar soil layer sequence structure.In order to improve the quality and efficiency of lunar soil sampling,this paper proposes a method to reduce the disturbance and increase the efficiency of lunar soil sampling based on the lunar soil liquefaction characteristics.Using the lunar soil liquefaction characteristics as the main line,the flow characteristics of lunar soil particles under the circumferential vibration of the sampling tube are elaborated by using the Discrete Element Method simulation technique,and a comprehensive evaluation model of lunar soil sampling quality and efficiency is constructed.The principle prototype of circumferential vibration penetration type lunar soil sampler is developed,and the experimental study of lunar soil sampling qualitative performance is carried out as follows:To construct a load mechanics model between the lunar soil sampling tube and the lunar soil,analyze the resistance variation characteristics of the inner wall,outer wall and port of the sampling tube,and find out the causes of poor quality and efficiency of the sampling.We propose a method to reduce the disturbance and increase the efficiency based on the liquefaction characteristics of the lunar soil,and analyze the feasibility of the method from the theoretical level.A curvature-based evaluation method is proposed to evaluate the structure of lunar soil layer sequence,and a comprehensive evaluation model is built to evaluate the quality and efficiency of lunar soil sampling by combining the minimum penetration force,the rate of change of lunar soil density and the sampling rate required for sampling.Plackett-Burman experimental design method and Central Composite Design(CCD)experimental design method are used to optimize the lunar soil contact mechanics parameters and conduct parameter matching tests.The EDEM simulation technique is used to analyze the loading mechanics between the lunar soil and the lunar soil sampling tube,to model and analyze the evaluation method of lunar soil laminar sequence structure based on the curvature characteristics,and to analyze the feasibility of the sampling method based on the lunar soil liquefaction characteristics from the simulation level.Discrete element simulation experiments are conducted to analyze the influence of circumferential vibration parameters on the liquefaction performance of the particles;the three-dimensional morphology of irregular lunar soil particles is mathematically described to study the influence of irregular particle morphology on the liquefaction performance of the particles;simulation experiments are conducted to match the macroscopic wall friction coefficient and microscopic friction coefficient of the sampling tube to analyze the influence of the friction coefficient of the lunar soil sampling tube on the liquefaction performance of the particles.A prototype of circumferential vibration sampling principle is developed and simulated lunar soil sampling experiments with different circumferential vibration parameters are carried out.The simulated lunar soil samples with layer sequence structure are prepared and compared with the hydrostatic penetration lunar soil sampling test to verify the rationality of the new lunar soil sampling scheme proposed in this paper,and to study the influence of the circumferential vibration parameters on the sampling quality and efficiency.