Modular compliant cube with anisotropic nonlinear responsiveness

Compliant mechanisms are a class of mechanical structures in which rigid joints are replaced by flexible components. With its simplified structure and high resilience, the flexible joints bring high precision, low cost and easy maintenance to the compliant mechanisms. However, mainstream compliant mechanisms respond linearly to external excitation via small elastic deformations (< 10%) and cannot expand their sizes and work collectively. Here, we propose an inverse design strategy which generating a family of modular compliant cubes (MCC) with a wide range of elastic deformations (25%~65%) from arbitrary cubic geometry. We found these cubes exhibited mechanical softening undergoing compression stimulus. Further, we built mechanical metamaterials as well as flexible robots by assembling MCCs. These metamaterials were hyperelastic, anisotropic, compressable. The modular flexible robot was metre-scale, free of complex pipelines and traversed complex scenarios on demand. We expect this strategy provide insights into the application of compliant mechanisms in large scale interdisciplinary applications.