Image credit: Pravinkumar Ghodake
Stretching of the Gaussian pulse in a layered nonlinear elastic metamaterial designed as an alternative layer of a linear and nonlinear elastic metallic material. The widths of linear and nonlinear layers are kept the same and that unit cell is repeated nearly 200-500 times. Note that, as the impedance of linear and nonlinear layers is the same, if material nonlinearity is not considered, no stretching and no higher harmonics, it’s just a linear wave propagation study. The widths of the layers are varied by maintaining the total length of the metamaterial same as shown in the image (?/?, ?, ??). Due to multiple local resonances, harmonic scattering, and cumulative harmonic generation, such an effect is observed. At ?/? width of a single layer, the wave received at the other end of the nonlinear metamaterial maintains its shape and generates higher harmonics. At ? width of a single layer, local harmonic resonance and harmonic scattering dominate more resulting in stretching of the wave. As the width of the single-layer increases to ??, the bulk wave gets delayed in the time domain due to cumulative harmonic generation.
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