Research On Impact Crushing In Luna Soil Sampling Based On ANSYS/Ls-dyna Numerical Simulation

The lunar soil sampling on the lunar surface is an important task in the lunar exploration project,research shows that massive lunar rocks with different grain sizes are distributed in the lunar soil,which is larger in diameter and hardness than the lunar soil,causing varying degrees of impact and hindrance to the work of drilling and sampling.The sampling mechanism adopts the combination of rotary cutting and percussive drilling to greatly improve the sampling efficiency.The low gravity,near vacuum,extreme temperature difference and other harsh conditions of the lunar environment and the energy saving needs of aerospace engineering all limit the efficiency of the sampling mechanism.In this paper,two kinds of rock materials,red bricks and sandstones with hardness close to that of lunar rocks are selected for testing and simulation,and the impact of the percussive procedure of the drilling mechanism on the efficiency of breaking rocks is studied.Firstly,the hardness test and static load mechanics test were carried out on the selected materials of red brick and sandstone to determine the basic physical and mechanical parameters of the material.Including demarcating the hardness level;measuring physical parameters such as bulk density,water content and porosity;uniaxial compression test to determine compressive strength,elastic modulus and Poisson's ratio;and Brazilian splitting test to determine tensile strength.Then,the dynamic stress-strain curve of the two materials at different strain rates was measured by the Split Hopkinson Pressure Bar experiment,and the destruction under the dynamic impact of rock material was analyzed.The statistical damage model was established to provide evidence to the subsequent numerical simulation.The simulation model of Hopkinson pressure bar test is established in the finite element simulation software ANSYS/LS-DYNA.The HJC constitutive model suitable for brittle rock materials is selected.The measured basic parameters of physical mechanics and empirical formula are used to determine some parameters of the model.Then the numerical simulation is used to fit the stress-strain curve obtained in the dynamic test,and the sensitive parameters of the material model are corrected.Finally,all the material model parameters are determined.As the basis of this paper,it also provides reference for the simulation of these two materials.Finally,the impact mechanism model are established with reference to the real one.The determined constitutive model of the two chosen materials are used to simulate the luna rock.The control experiment is established by grouping,and the rotational speed,impact velocity and different waveform loads are studied and analyzed.The influence of the impact mechanism on the efficiency of crushing different hardness rocks is beneficial to further optimize the impact parameters of the mechanism and improve the ability to impact and break the moonstone.