P4I-3 A Magnified Lamb Wave Source Based on the Resonant Cavity of Phononic-Crystal Plates

In this paper, we analyzed Lamb wave generation based on the resonant cavity of a phononic-crystal plate. The phononic-crystal plate is composed of circular steel cylinders which form a square lattice in an epoxy plate and the resonant cavity is created by arranging defect inside the periodic structure. The dispersion and eigenmodes of acoustic waves are analyzed by the finite-difference time-domain method. By exciting the specific resonant mode in an asymmetric cavity, the enlarged displacement field is observed which propagates away from the cavity. The asymmetric cavity shows a directional propagation and the magnified ratio of Lamb wave can be two-order larger than the normal one.