Design of elastic metamaterials
This study focused on the design and fabrication of a double negativity and three broadband single negativity elastic metamaterials using a 3D printer. We investigated dispersion curves and dynamic material properties of the metamaterials. Negative phase velocity in the double negativity metamaterial was also demonstrated. For metamaterials with single negativity, three types of broadband metamaterials were designed from parametric studies. A comparison showed that using frame bending/stretching mode is more effective than applying beam bending mode to broaden bandgap. Furthermore, it is found that adding internal resonant components could enlarge the bandgap. The single negativity metamaterials were validated by numerical simulations of dispersion curves and attenuation factors. Moreover, an effective continuum model was derived and utilized to investigate the wave propagation in the elastic metamaterials. The effective continuum model works for long wavelength, and is able to accurately determine the band-gap region. In addition, the applications of double negativity metamaterials such as negative refraction and interface mode conversion were demonstrated using the effective continuum model. Finally, tunable characteristics of metamaterials were employed to select the propagation speed of a pulse. Potential applications such as signal delay were identified and simulated.
Sun, Purdue University.
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