A locally resonant metamaterial layer for enhanced filtering and attenuation of elastic surface waves
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In this study, we explore the feasibility of designing resonant layers composed of locally resonant metamaterials coupled to elastic half-spaces to control the propagation of vertically and horizontally polarized surface waves. The resonant layer is realized through a periodic arrangement of multiple layers of sub-wavelength resonators embedded in the host material [1]. An analytical model is developed to derive dispersion relations capable of predicting the dynamic characteristics of the resonant layer within the frequency range of interest. In parallel, numerical simulations are conducted to validate the analytically derived dispersion relations and evaluate the surface wave attenuation performance of the resonant layer. Finally, a small-scale prototype of the resonant layer is fabricated and experimentally tested utilizing the Laser Doppler vibrometry technique to validate the numerical and analytical predictions. The combination of analytical, numerical, and experimental analyses highlights the generation of a narrow bandgap near the operational frequency range of embedded resonators. Within this bandgap frequency range, the propagation of surface waves is effectively impeded. We demonstrate that the proposed resonant layer with a single row of embedded resonators can successfully capture the dynamics of a locally resonant metasurface, namely, thin resonant layers attached to the free surface of elastic waveguides. A parametric study of the design parameters of locally resonant metamaterials reveals that increasing the thickness of the resonant layer extends the frequency range of the bandgap, thereby enhancing the effectiveness of attenuating incoming surface waves [1]. In summary, our developed framework provides a practical and efficient approach for designing and fabricating locally resonant metamaterials with desirable filtering capabilities. ACKNOWLEDGEMENT This work has received funding from the Italian Ministry of Education, Universities, and Research (MUR) for the ELeMEnT project under grant agreement SOE_0000157. REFERENCES [1] F. Zeighami, A. Palermo, A. Marzani, Rayleigh waves in locally resonant metamaterials, International Journal of Mechanical Sciences,195, 106250, 2021.