A study of high-velocity penetration on icy lunar regolith simulants

Understanding the mechanical response of a high -speed penetrator penetrating icy lunar regolith (ILR) is essential for designing penetrators in lunar permanently shadowed regions and interpreting the detection data from the device. Experimental research on the penetrators is limited in engineering due to the difficulties in preparing large-scale icy lunar regolith simulants (ILRS). Such limitation urges the need to construct a theoretical model and verify a numerical simulation model based on the scaled-down penetration experimental results, which provide insights into the mechanical response of penetrator penetrating ILR. Projectile penetration experiments were conducted on ILRS targets with four typical water content levels in a cryogenic chamber at 110 K. The experimental results show that the ILRS with higher water content exhibits greater brittleness and a faster crack growth rate. Consequently, the diameters of cratering and scabbing areas are augmented on the target surface upon projectile penetration. Moreover, increased mechanical strength decreases the plugging height on the ILRS targets. Based on the projectile residual velocities, the equivalent target strength parameter R were calculated and fitted to a functional relationship with the uniaxial compressive strength. RHT model parameters were calibrated using the test results of the dynamic and static mechanical properties of the simulants. Numerical simulation of projectile penetration into semi-infinite and thick targets were conducted using the calibrated model. The simulation results demonstrate high consistency with the experimental and theoretical calculations, indicating the effectiveness of the constitutive model in describing the mechanical response of the ILRS under projectile penetration.