Intrinsically polar elastic metamaterials

Abstract

The ability to design and fabricate materials with tailored mechanical properties, combined with immunity to damage, is a frontier of materials engineering. For example, materials which are characterized by elastic properties that depend on the position inside a medium are required in applications where structural stability has to be combined with a soft and compliant surface, like in impact protection and cushioning. A gradient in the elastic properties can be built from a single material, varying gradually the bulk porosity of the material or its geometrical structure. However, if such a gradient is built into the material at production, damage or wearing over time might expose unwanted elastic properties. Here, we implement a design principle for a spatially inhomogeneous material based on topological band-theory for mechanical systems. The resulting inhomogeneity is stable against wearing and even cutting the material in half. We show how, by creating a periodic elastic material with topological properties, one can create an intrinsically polar behavior, where a face with a given surface normal is stiff while its opposing face is soft.

References in corpus (9)

• Topological Boundary Modes in Isostatic Lattices
• Classification of topological phonons in linear mechanical metamaterials
• Chiral effect in plane isotropic micropolar elasticity and its application to chiral lattices
• Transformable topological mechanical metamaterials
• Mechanical Weyl Modes in Topological Maxwell Lattices
• Acoustic type-II Weyl nodes from stacking dimerized chains
• Topological phonons and Weyl lines in 3 dimensions
• It has been a Weyl coming
• Phonon analogue of topological nodal semimetals

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