Reserch On The Filling Characteristic Of Luna Soil In Sampling Pipe

The research is base on the third state of China lunar exploration with the background of discrete element theory, the establishment of lunar soil in the micro-mechanical constitutive model that contains particles of lunar soil and lunar soil contact mechanics model of granular flow model. On this basis, respectively, on the study of the lunar soil in hard and soft pipe filling characteristics of the sampling tube were simulated. Pressure using the built-in sampling test platform were simulated with lunar soil sampling tube in the hard and soft sampling tubes filled with experimental study.First, the physical properties of lunar soil and mechanical properties analysis, the isotropic spherical model using simulated lunar soil particles method, a soft-sphere model based on spherical particles of lunar soil and lunar soil contact mechanics model of the mobility of particles model. Particle contact algorithm using the grid search, the establishment of lunar soil particles constitutive model simulation process.Secondly, based on two-dimensional discrete element simulation software PFC2D, hard on the lunar soil sampling tube in the filling characteristics are simulated and analyzed. Reasonable assumption by filling model of lunar soil will be reduced to the piston model, and using the method specified porosity established simulation model of lunar soil particles. According to the simulation results, analysis of the lunar soil particle size on the filling characteristics of the law of the filler particles of lunar soil during the distribution of force chain. Simulation results show that the lunar soil in the hard core tube filling process, there is limit the sampling rates.Again, based on the three-dimensional discrete element simulation software EDEM, on the soft lunar soil sampling tube in the filling characteristics are simulated and analyzed. Methods using the specified size of the simulation model of lunar soil particles, the use of EDEM in the moving plane functions, to establish the sampling tube placed soft model. According to the simulation results, analysis of the sample stratification and sampling rate of information retention. Simulation results show that the sampling tube with soft bedding to keep the information capacity of the sample, and can effectively prevent the formation of force chain, has a high sampling rate.Finally, with the building of sampling pressure experimental platform, the simulated lunar soil in the hard process of filling the sampling tube experiments were performed to analyze the sample diameter and the loading on the filling characteristics of law; and simulated lunar soil in the soft quality sampling tube filling process experiments were performed to verify the sampling tube soft features with high sampling rates. The results coincide with the simulation results.