Fig. 1

Numerical simulation and experiment results of elastic wave localization that leverages the defect band splitting phenomenon of a phononic crystal with double defects (4, 7). a A schematic illustration (left) of in-phase and out-of-phase localized behaviors at each frequency of split defect bands and a snapshot (right) of one fabricated specimen. b Formation of five defect bands in the band gap, ranging from 56.55 kHz to 62.51 kHz, and the highlighted target defect band of 59.65 kHz presenting the monopole-like defect mode shape. c Splitting of the five defect bands presented in b into ten defect bands due to coupling between the double defects (4, 7), and the highlighted target defect bands of 59.51 kHz and 59.85 kHz. (d, e) Numerically and (f, g) experimentally demonstrated the defect band splitting phenomenon via comparison of the normalized out-of-plane displacement frequency responses functions in the cases of single and double defects (4, 7), respectively