Soft Topological Metamaterials with Pronounced Polar Elasticity in Mechanical and Dynamic Behaviors

We realize soft topological mechanical metamaterials with pronounced polar elastic responses (i.e., softer on one edge than the other) in both the quasistatic and dynamic regimes. Numerical simulations and experimental results confirm the presence of directional dependence in metamaterial response at low and high strain rates, despite the use of lossy elastomer as bulk media. The metamaterials exhibit means to tailor the location of topologically protected uniaxial mechanical stiffnesses by virtue of both loading orientation and geometric changes to the lattice architecture. High-speed video recordings show strong topologically protected asymmetric wave propagation for the soft metamaterials subjected to impact. The results indicate a class of metamaterial architectures possessing polar elastic behavior and confirm the persistence of the response in lossy media.