Force-sensitive metamaterials for vibration mitigation and mechanical protection

Inspired by the structure of proteins, designed by nature to function as nanoscale shock absorbers, we propose the concept of harnessing structural instabilities to repeatedly filter out forces, e.g. from a vibrating environment, that exceed the permitted level. In the context of engineering applications, such remarkable mechanical protection has only been possible with complicated feedback-control; yet, we show that it can be materialized by means of architected materials that include force-sensitive building blocks, i.e. mechanical units that are carefully designed to undergo reversible morphological changes when forces exceed the permitted level. Experiments with 3D-printed prototypes and computer simulations demonstrate that forces transferred from a vibrating environment do not exceed the design threshold, irrespective of the amplitude or frequency of the vibrations. The design threshold is also maintained under impacts. With today's manufacturing technology, the underlying principles can be implemented at all practical scales, from sub-millimeter size to meters, and the behavior can be tailored per application. (C) 2020 Elsevier Ltd. All rights reserved.