Impact mitigation generated by localized softness on a 3D-printed topological lattice

Topological mechanics can exhibit localized softness through geometrically programmed unit cells, and a promising application of this property is impact mitigation. We experimentally demonstrate efficient impact mitigation achieved through localized softness in a topological lattice, where the lattices are fabricated via 3D printing of hinged structures, and their force responses under dynamic loading are measured. The introduced soft surface produces a plateau in the force–displacement response, thereby suppressing peak forces relative to the hard surface and enhancing energy absorption efficiency. These soft responses are consistent with the predicted zero-mode counts. Furthermore, the design relies solely on periodic structures rather than material and geometrical gradation, preserving modularity and simplifying fabrication. These results indicate that localized topological mechanics can effectively tune contact compliance and mitigate impact loads, offering an efficient strategy for impact attenuation.