Novel multi-stable mechanical metamaterials for trapping energy through shear deformation

A novel shear induced multi-stable mechanical metamaterial (SMMM), consisting of magnets systems in periodic arrangement, is proposed to trap mechanical energy from impact. The metamaterial's multi-stable and negative stiffness behaviors are determined by the repulsive force between magnets, and the input mechanical energy from impact is transformed to the magnetic potential energy and locked in the magnets systems. Through the experiment and theoretical methods, the basic mechanical properties, deformation mechanisms, and the energy trapping capacity of the metamaterial under end shear loading are investigated. Research results indicate that the metamaterials are reusable and rate independent. The metamaterial's mechanical properties are tailorable through the adjustment of the geometric parameters or the change of the magnets system's configuration. Moreover, in order to overcome the metamaterial's direction dependence, a concept, bi-directional SMMM, is proposed with a detailed design philosophy. To our knowledge, this work is first to design SMMM using the magnets system, and report the bi-directional SMMM.