Exploiting large elastic bistability in prestressed metal shells for adaptive dual-mode energy-absorbing metamaterials

Energy-absorbing materials and structures based on metal plasticity are widely deployed in many applications. However, the irreversible destructiveness of plasticity challenges the development of reusable and adaptive metal energy-absorbing materials. Here, we introduce reusable elastic bistability into metal structures and create an energy-absorbing metamaterial that can be fully recovered and reused under low impact and efficiently absorb energy under high impact. By prestress processing, large elastic bistability is produced in metal shells to gain higher reusable specific absorption than soft material-based bistable structures. The metamaterials architected by these shells can sequentially perform decoupled bistable and plastic deformation to absorb energy and showcase two energy-absorbing modes, "pure bistable" and "bistable + plastic" modes, realizing adaptively switchable reusability and high absorption capacity. This design is programmable and applicable to different metals. This work paves the way to design intelligent energy-absorbing materials with metals.