Study On The Influence Of Particle Size On The Penetration Characteristics Of Star Soil

The particulate media in the surface layer of unknown extraterrestrial soil exhibit both integrity and granularity.Therefore,their penetrating characteristics often manifest in particle responses at both macroscopic and microscopic scales.Understanding the interaction between the two scales is a necessary condition for exploring the properties of extraterrestrial soil.However,the scale effects of penetrating unknown soil particles lack a real testing environment,and the microscopic responses between discrete particles are hard to obtain.Therefore,using particle diameter as the primary physical variable of extraterrestrial soil,simulation experiments were conducted through the FEM-DEM coupling method to study the effect of particle size on the multi-scale penetration characteristics.The interaction relationship between particle size properties and penetration characteristics was obtained,which is of reference value for future physical inversion work on extraterrestrial soil penetration detection.Research has been carried out in the following areas:Firstly,a FEM-DEM coupled numerical simulation method was used to construct a simulation model for soil-penetration.Based on the key micro-parameters in the simulation,mathematical analyses were conducted on the movement model between discrete particles and the coupling model between particles and projectiles.The impact of parameters was identified,and it was found that the micro-friction coefficient had the greatest influence on the model.Through experiments with different projectile types to adjust the parameters and refine the model,the focus was placed on the penetration characteristics that balance macro and micro scales: information on projectile motion(penetration depth,acceleration),projectile instability,penetration impact craters,and force chain characteristics.Subsequently,penetration simulation experiments were carried out with different particle sizes of the star soil.Using experimental validation and fitting with the Poncelet formula,the correlation between star soil particle size properties and each penetration characteristic was obtained.The corresponding conclusions are: the information of projectile motion changes significantly with particle size;at the macro scale,two indicators are proposed to reasonably evaluate the stable motion of the projectile body,and provide the velocity parameters for the offset position of the projectile body inside the particles.At the micro scale,through the study of the influence relationship of the force chain,the three functional relationships between particle size and force transfer velocity are obtainedFinally,the overload information was studied as a key characteristic,and combined with the particle size comparative experimental stage analysis,overload was studied with the added layer sequence experiment.The influence of particle size on acceleration signal is summarized,and it can also be indirectly proved that acceleration has certain inversion value for signal interpretation,and it is expected that the particle properties contained in the acceleration information can be further reasonably separated in the future.