Table 2.
Summary of AEMMs in terms of desired dynamic property. Their typical band gap principles are highlighted along with the potential engineering applications, challenges, limitations and scalability issues.
| Feature | Band gap principle | Potential application | Challenges | Scalability issues |
|---|---|---|---|---|
| EMD | nonlinearity due to geometric change [101], flexural mode excitation [100], [102], [103], axial and shear rod deformation [103] | vibration attenuation at quasi-static frequency [101], nondestructive evaluation and structural health monitoring [105], wave redirection mechanisms [107], seismic shields [149] | Material damping effect on attenuation values [102], | Friction effect for small-scale nonlinear metamaterial [101], perfect interface coupling assumed in numerical models |
| EYM | Inner resonance due to stiffness contrast [113], interaction between four-link mechanism and lateral resonators [114] | Device for controlling the direction of transmitted elastic waves [113]; wave conversion [114] | Damping effect reflecting on resonance performance [114] | Principle of wave control based on homogenization method, therefore wave length should be larger than unit cell size [113] |
| QZS | Energy transfer from metamaterial to energy source [136], combination of negative- and positive-stiffness structure [133], large deformation of compliant structure [137] | Ultralow vibration isolation (lower than 20 Hz) [136], [139] | Damping effect reduces wave attenuation [139]; enhanced stiffness nonlinearity can degrade wave attenuation [133], [137]; manufacturing imperfections shift band gap [139] | Band gap is only broadened when scaling up the mass and stiffness of the resonator [138] |
| IA | Increase of effective inertia by generating rotational motion from axial motion [145], [146] | Isolate seismic surface waves [144] | Band gap induced by IA is quite narrow [144]; geometry relies on thin structures, requiring stress evaluation [146] | Geometry of the ligaments should be changed to shift the stop band, which may induce different behaviors for distinct scales [146] |
| Double | translational motion of the resonator [108], [123], combination of torsional, bending and compressional resonance [117] | Polarization filtering, abnormal refraction, and mode conversion (elastic switches and seismic waves control) [117], [121], [122], [124]; structural protection [150] | Broad band gap induced by inclusion of more resonators, increasing geometry complexity; complex coupling of longitudinal and shear waves in 2D and 3D problems | Sensitivity of negative refraction to imperfections can be significant when cell size approaches the wavelength of propagating wave [121]; boundary and material inhomogeneity effects on band gap prediction |