Research On Penetrating Load Characteristics Of Hammer-driven Penetrator For Lunar Exploration

With the development of deep space exploration, scientific investigation goes deep into the interior of extraterrestrial bodies. Extraterrestrial subsurface regolith contains abundant geological and environment information which can reveal the extraterrestrial bodies’ origin and evolution. As a small, light and low-power unmanned autonomous penetrator, the hammer-driven penetrator is an effective means of detecting subsurface lunar regolith. In order to improve penetration capability, this paper mainly focuses on studying the penetrating load characteristics of the hammer-driven penetrator.Based on the physical and mechanical properties of lunar regolith, the impact compaction principle was analyzed. The hammer-driven penetrator was simplified as a “mass-spring” system according to its mechanical composition. By analyzing the movement process and energy transfer law within a penetrating cycle, the main factors affecting the penetration depth were summarized.Mohr coulomb failure criteria and the limited balance condition were used to build the penetrating load model of the penetration head. Then, we quantified the relevant parameters to study the influence of configuration parameters on the penetrating load, which is the theoretical foundation for geometry optimization of the penetration head. Based on the passive Rankine’s earth pressure theory, the friction load model of shell was built for guiding the structure design.Then, a system for testing the penetrating load of penetrator was developed. Penetration heads with different configuration parameters were penetrated into simulated lunar regolith to verify and modify the theoretical model. Besides that, the influence of the shell configuration parameters on the penetrating load was analyzed by experiment. Parametric optimization was conducted by analyzing the load model and the test results comprehensively.We matched the “mass-spring” system parameters to improve the penetration capability. To verify the parameters, multi-body dynamics simulation was conducted. Then, the influence of the low-gravity environment on the penetrating performance was studied. Following the lightweight, compact design principles, we developed a hammer-driven penetrator prototype. Using the high-speed camera, the dynamic law of penetrator was revealed. Last, the penetration capability of the prototype was verified by the test system.