Exploiting Localized Transition Waves to Tune Sound Propagation in Soft\n Materials

Abstract

Programmable materials hold great potential for many applications such as\ndeployable structures, soft robotics, and wave control, however, the presence\nof instability and disorder might hinder their utilization. Through a\ncombination of analytical, numerical, and experimental analyses, we harness the\ninterplay between instabilities, geometric frustration, and mechanical\ndeformations to control the propagation of sound waves within self-assembled\nsoft materials. We consider levitated magnetic disks confined by a magnetic\nboundary in-plane. The assemblies can be either ordered or disordered depending\non the intrinsic disk symmetry. By applying an external load to the assembly,\nwe observe the nucleation and propagation of different topological defects\nwithin the lattices. In the presence of instabilities, the defect propagation\ngives rise to time-independent localized transition waves. Surprisingly, in the\npresence of frustration, the applied load briefly introduces\ndeformation-induced order to the material. By further deforming the lattices,\nnew patterns emerge across all disk symmetries. We utilize these patterns to\ntune sound propagation through the material. Our findings could open new\npossibilities for designing exotic materials with potential applications\nranging from sound control to soft robotics.\n