Tensegrity-inspired sandwich metamaterial for reprogrammable stiffness and impact mitigation

Metamaterials are renowned for their unique properties, but most have fixed properties once fabricated. Tensegrity metamaterials offer tunable mechanical properties by adjusting prestress, making them excellent for load-bearing and energy absorption. However, tensegrity structures’ inherent self-equilibrium and stability demand complex geometries with irregular angles and pre-tensions, restricting convenient fabrication. To address those limitations, we propose a tensegrity-inspired sandwich metamaterial (TSM), which preserves the stress redistribution capability of standard tensegrity structures, yet can be easily fabricated. The design comprises an elastic membrane sandwiched by two spiked plates, with the membrane in tension and the spikes in compression. The TSM can be reprogrammed to achieve a wide range of static and dynamic responses by adjusting the preloading distance between the two plates. In particular, the TSM achieves a tuning of energy dissipation efficiency within the range of 20%-56% and the tuning of mitigation rate in the range of 0.136-0.204 by a single layer. This study provides a pathway for creating effective and reprogrammable energy-absorbing metamaterials for impact mitigation systems, allowing for active control of static and dynamic responses.