Willis metamaterial on a structured beam
Willis coupling is the analogy of electromagnetic bianisotropy in elastic waves. Here, we provide a realization on flexural waves.
Source illusion for flexural waves
Metasurface based on space-coiling unit cells for elastic waves. Source illusion with target phase profile = original excitation + phase discontinuity by metasurface
Phys. Rew. Lett. 119, 034301 (2017)
Meaning of an acoustic negative index
Resonating breathing mode to negative modulus and resonating oscillating mode to negative density.
This double negativity gives a negative index
Phys. Rev. E 70, 055602(R) (2004)