Lamb wave propagation in coupled-resonator elastic waveguides
Résumé
Waveguides based on linear chains of coupled cavities have been shown theoretically to allow very strong wave con nement and low group
velocity transmission. In this work, we observe experimentally for the rst time highly con ned propagation of Lamb waves along coupled-
resonator elastic waveguides (CREWs). We also observe that sharp 90° bends can be included to form phononic circuits.
Numerical simulations are conducted using the FE method in order to understand better the experimental results. A supercell technique is
used to investigate the dispersion relation and eigenmodes of CREWs. Traction-free boundary conditions are set on the top and bottom
surfaces and inside the holes, and periodic Bloch boundary conditions are applied on the other boundaries. Displacements are also measured using a Polytec PSV-500 scanning vibrometer.
We investigate experimentally Lamb wave propagation in coupled-resonator elastic waveguides (CREWs) formed by a chain of cavities in a
two-dimensional phononic crystal slab with cross holes. A waveguide and a wave splitting circuit with exact 90° bends are designed,
fabricated and measured. Elastic Lamb waves are excited by a piezoelectric patch attached to one side of the phononic slab and detected
using a scanning vibrometer. Strongly confined guidance along waveguides and splitting at waveguide junctions are clearly observed.
Numerical simulations are conducted to obtain the band structure of the waveguides and the transmission of the circuits. They are found to
be in excellent agreement with experimental results and allow the identi cation of the involved resonant cavity modes. The work in this
paper has implications for the design of innovative phononic devices.