Cut-enabled anisotropic and non-reciprocal elasticity in chiral metamaterials

Abstract

We introduce strategically placed cuts into chiral mechanical metamaterials to achieve strongly anisotropic and static non-reciprocal elasticity in a fully passive architecture. Under loading, the cuts switch between open states that preserve auxetic kinematics and closed contact states that trigger an abrupt stiffness increase, thereby breaking symmetry. By systematically varying the cut topology—the number, placement, and orientation of cuts—we identify regimes with sharp stiffness transitions and pronounced uniaxial and orthogonal non-reciprocity. A topological coding strategy is proposed to program these responses at the unit-cell level. These results establish cut-mediated opening and contact as a general mechanism for designing non-reciprocal mechanical metamaterials.