Last modified: 2021-06-22
Abstract
Vibration and elastic-wave manipulations at sub-wavelength scale have been realized by using acoustic/elastic metamaterials. However, most of the existing metamaterial designs are still suffering from fundamental limitations including large volume, narrow operating bandwidth and unadjustable functionalities. How to realize efficient elastic-wave and vibration control in a compact-footprint, broadband and tunable strategy has been a challenge. In this report, a series of elastic metamaterials and metasurfaces are introduced for broadband vibration-suppression and extraordinary wavefront manipulation. Specifically, a double zero-index metamaterial is proposed to achieve two separated elastic-wave Dirac-like cones at the Brillouin zone center, which is further applied for wave-front shaping and perfect tunnelling. Furthermore, requiring neither active control nor nonlinear effect, a couple of diatomic metamaterials and ultrathin lossless metasurface are designed for highly efficient asymmetric-transmission within a wide frequency range. Also, combining the shape memory effect and programmable design, a 4D printed metamaterial concept is further proposed for self-adaptive bandgap shift and programmable waveguide channels. The efficient, robust and broadband capabilities of tailoring vibration and elastic-wave in compact and lightweight meta-structures are systematically verified by theoretical analysis, numerical simulation and experimental measurements. The proposed designs pave feasible ways for noise and vibration control in elastodynamics.