Design of enhanced load-bearing and energy-absorbing negative stiffness metastructure for elastic wheels of lunar rovers

To address the vibration control challenges faced by deep-space exploration planetary rovers under extreme planetary surface conditions, a design method for an enhanced load-bearing and energy-absorbing metastructure based on a negative stiffness series system is proposed, leading to the development of a novel high-performance elastic wheel. By constructing a theoretical model of the negative stiffness series system and integrating a composite “rigid-flexible” limiting strategy, a synergistic mechanism for load-bearing and energy-absorbing enhancement is achieved. Without increasing the number of series units or compromising structural load-bearing capacity, the energy absorption performance of the system is significantly improved. Based on this mechanism and combined with key design indicators for lunar rover wheels, a highly compact metastructure wheel spoke consisting of only four layers of negative stiffness units in series is designed. The metastructure achieves a damping loss factor of 0.316 and the proportion of components unrelated to material plastic energy dissipation is 69.6%. A complete wheel prototype is constructed by integrating eight such spokes. Test results show that under loads of 5 and 8 kg, the standard deviation of longitudinal fluctuation at the wheel axle during normal rolling is only 0.37% and 1.17% of the wheel diameter, respectively. After crossing obstacles with heights ranging from 100 to 150 mm, the vibration attenuation time is less than 1 s. The findings of this study provide a new approach for the design of elastic wheels for planetary rovers and offer valuable insights for the development of compact low-frequency vibration control systems in fields such as transportation, national defense, and smart manufacturing.