Structural optimized mechanical metamaterial for multi transient high-g impact suppression and self-monitoring

For extreme high-g mechanical impact of vehicle personnel and penetrating munition fuze, specific protections in terms of simultaneous high energy absorption performance, high recoverability and real-time alarming are urgent demands. Currently, Bistable symmetric curved beam structure (BCBS) mechanical metamaterial is promising route that can balance energy absorption performance and recoverability, but still remain the threat of excessive negative stiffness. Here, beyond BCBS metamaterial, we propose a novel mechanical metamaterial of elliptical sandwich curved beam structure (ESCBS), which utilize the stiffness complementarity of elliptical rings and curved beams. Besides, the ESCBS metamaterial has a self-filtering effect on the violently destructive high-frequency components of mechanical impacts due to its low natural frequency. Thus, the ESCBS metamaterial enhances the energy absorption performance (above 50 % decrease in impact peak) and recoverability(above 90 % structural integrity) under extreme strong mechanical impacts (up to 25000 g). Further, to realize self-monitoring and alarming, an endogenous triboelectric self-powered sensor is constituted inside the ESCBS metamaterial via polyurethane foam penetration without any space or energy cost. Thus, the proposed ESCBS metamaterial can serve as a representative metamaterial for safe and intelligent vehicle personnel helmets and fuze systems, and is expected to have a broad commercial application in future.