Dynamic behavior and modeling of icy lunar regolith subjected to dynamic loading

The icy lunar regolith (ILR) in the permanently shadowed regions (PSRs) of the lunar poles is an important lunar water resource for humans, which can be efficiently explored in situ by using a high-speed kinetic penetrator. The dynamic mechanical properties of ILR need priority research since they are related to the ballistics and overload of the penetrator. Based on ILR occurrence form and microscopic composition analyses, four types of ILR simulant (ILRS) specimens with typical water contents are prepared in the present study according to the principle of similar mineral composition and physical state. The dynamic mechanical properties of the ILRS specimens are investigated by combining the results of split Hopkinson pressure bar (SHPB), quasi-static unconfined compression, and variable angle shear (VAS) tests. The results show that the loading strain rates alter the microcrack number and expansion rate of the specimens, which in turn significantly affects their damage mode, dynamic uniaxial compressive strength (DUCS) and toughness ratio. Finally, based on the relationship between stress and strain in the SHPB tests, the damage properties of the ILRS under dynamic loading are analyzed, and a segmental constitutive model is provided by combining it with the Drucker-Prager strength theory. The research results could form the basis for subsequent penetrator structure design and ballistic prediction.