Pre-compressed beam-based multistable mechanical metamaterials with programmable loading and unloading deformation sequences

In this work, we propose four types of pre-compressed beam-based multistable mechanical metamaterials and use a combination of theoretical, simulation and experimental methods to systematically explore the effects of pre-compression and initial configurations on their mechanical properties. We found that curved beams with identical initial configurations but different pre-compressions have the same negative stiffness value, but their peak forces differ. Furthermore, the results demonstrate that applying pre-compression is a more effective programming strategy than geometric modulation for altering the stability of the beams. We also demonstrate that pre-compressed multistable mechanical metamaterials can robustly program unloading deformation sequences while maintaining consistent loading orders, thereby enabling the concealment of certain stable configurations. The proposed pre-compressed beam-based mechanical metamaterials offer potential benefits in mechanical computing and information encryption, paving the way for expanding the design concepts and application prospects of multistable mechanical metamaterials.