Boundary-profile-dependent dispersion and attenuation of quasi-Lamb waves in graphene-like corrugated waveguides

Quasi-Lamb waves (QLWs) propagating in periodically corrugated structures exhibit remarkable bandgap characteristics and have attracted considerable interest for elastic-wave manipulation. In this work, the propagation and attenuation behaviors of QLWs in graphene-like corrugated waveguides with different structural symmetries are systematically investigated through finite-element simulations and laser ultrasonic experiments. Two waveguides with distinct boundary profiles derived from a common hexagonal parent geometry are designed and fabricated to examine the influence of boundary-profile transformation on quasi-Lamb-wave propagation. Dispersion relations, transmission spectra, pressure-field distributions, and frequency–wavenumber maps are analyzed and compared. The results show that both structures exhibit low-frequency bandgaps associated with Bragg scattering induced by periodic geometric modulation. Significant differences are observed in the high-frequency range, where the C 6 v-symmetric trapezoidal waveguide exhibits multiple attenuation bands, whereas the C 2 v-symmetric triangular waveguide supports only one dominant attenuation band. Spatially resolved transmission maps further reveal the progressive suppression of wave propagation inside the periodic structures and clearly visualize the evolution of attenuation along the propagation direction. Good agreement between numerical predictions and experimental measurements confirms the effectiveness of boundary-profile-based modulation of quasi-Lamb-wave attenuation characteristics. The present study provides useful guidance for the design of elastic-wave structures with tunable transmission characteristics and potential applications in vibration isolation, wave filtering, and acoustic sensing.