Low frequency and wide band gap metamaterial with divergent shaped star units: Numerical and experimental investigations

Accomplishing low frequency and wide bandgaps with a single phase metamaterial remains a challenging task. In this work, we propose a single phase acoustic metamaterial having periodically arranged divergent shaped star units and performed numerical simulation to obtain the bandgaps. The simulation results demonstrate that the metamaterial exhibits an uninterrupted and extended bandgap that lies in the low frequency regime. We fabricated the structure based on numerical investigations, and using the experimental technique, elastic wave transmission characteristics have been analyzed. Experimental observations are in good agreement with numerically calculated bandgaps. Moreover, we perform a parametric study on the bandgaps with geometrical parameters like the concave angle and length of divergent ribs of the unit cell.