Non-symmetric stiffness of origami-graphene metamaterial plates

Mechanical metamaterials exhibit exceptional mechanical properties that originate from their topological design. In the current study, we designed a novel metamaterial which incorporates origami-graphene with single crystal copper matrix. Unlike classical auxetic materials which have void phase, the proposed origami-graphene based metamaterials appear to be solid in the microscopic scale, and the origami-graphene metamaterial plates may have relative stronger stiffnesses. Based on the molecular dynamics (MD) simulations, we confirmed that the elastic properties of origami-graphene/Cu metamaterials are anisotropic, size-dependent, and temperaturedependent, and the in-plane Poisson's ratios are negative. More important, we discovered that the stiffness of the origami-graphene/Cu metamaterial plates is non-symmetry in the phase of linear elasticity.