A reusable and rate-independent energy-absorbing metamaterial

This work reports a new strategy for designing reusable and rate-independent energy-absorbing metamaterials. Combining finite element simulations, asymptotic post-buckling analysis, and experiments, we discover that as the width-to-length ratio increases, a hyperelastic column subjected to uniaxial compression can undergo continuous buckling, snapping-through buckling, snapping-back buckling, or creasing. Harnessing the hysteretic snapping-through or snapping-back buckling of wide hyperelastic columns, we build a class of metamaterial that is capable of energy dissipation and shock attenuation. The metamaterial shows a long working distance under loading, and instantaneously recovers its original shape upon unloading, but forming a large hysteresis between loading and unloading. Such an energy-absorbing metamaterial is reusable, self-recoverable and rate-independent. By tuning the design parameters or applying a pre-load, we can tailor the peak force, the dissipated energy, and even the monostability of the metamaterial. Our study opens a new avenue to the design of reusable energy-absorbing materials for personal safety, packaging, and aircraft and vehicles crashworthiness.