Bioinspired Flexible and Programmable Negative Stiffness Mechanical Metamaterials

Energy-absorbing materials are widely used under certain high-frequency scenarios, such as cargo packaging or sport protection. Though negative stiffness mechanical metamaterials have many distinctive advantages, fairly low strength and poor specific energy absorption unfortunately limit their present industrial applications. Inspired by the excellent cushioning performance of the paw pads of mammals, a novel flexible energy-absorbing negative stiffness mechanical metamaterial is proposed herein. Results show that the presented metamaterial outperforms traditional packaging materials with respect to cushion performance. Moreover, a performance programming strategy is proposed to achieve multistage tuning between large energy absorption and high rebound properties.