Fig. 3

Visualization results of the in-phase and out-of-phase monopole-like defect mode shapes inside the double defects of Phononic crystals: a–c time-harmonic wave propagation behaviors in numerical simulations for the single defect case at 59.65 kHz and the double defect case at 59.51 and 59.85 kHz, respectively. d–g Experimentally scanned out-of-plane operating deflection shapes for the single defect case and the double defect case (4, 7), (4, 8), and (4, 9), respectively