Waveguiding and frequency selection of Lamb waves in a plate with a periodic stubbed surface

In this paper, we numerically and experimentally study the waveguiding of Lamb modes in a thin plate with a periodic stubbed surface and propose a frequency-selection method based on the found complete band gaps of Lamb waves in the periodic structure. In the numerical simulations, we employ finite-element method to analyze the waveguiding effect of a line defect created in the periodic plate structure; and on the experimental side, we utilize a pulsed laser to generate broadband elastic-wave energy and a laser interferometer to receive the wave signals inside the line-defect waveguide. In the experiment, well-confined acoustic energy in the acoustic band gaps is observed. Furthermore, a polyline sharply bent waveguide is designed and used for the frequency selection of Lamb waves. Measurements show that acoustic energy with frequencies in the band gaps can be separated out and guided by the bent waveguiding route. The characteristics of deaf bands found in the experiment are discussed as well.