Real-time tunable negative stiffness mechanical metamaterial

Real-time tunable mechanical metamaterial is an emerging field attracting great attention. It enables a wide range of mechanical properties but is hard to design and fabricate due to its complexity. Here, a pneumatically actuated tunable negative stiffness mechanical metamaterial with real-time tunable properties is presented. Numerical simulations and experiments were both employed to investigate the proposed real-time tunable negative stiffness mechanical metamaterial. Research results demonstrate that multistage pattern-transformation can be realized through the pneumatic actuation. Uniaxial compression and vibration tests reveal the influence of the inner air pressure on the metamaterial's basic mechanical properties and the vibration isolation performance, respectively. Additionally, real negative stiffness behavior and high energy absorption efficiency are achievable for the proposed metamaterial. This study can be a reference to relevant researches on tunable mechanical metamaterials, and presents a new path for designing real-time tunable negative stiffness mechanical metamaterials.