ScholarWorks@숙명여자대학교

초록

Independent tuning of material properties enables the exploration of physically unattainable wave characteristics, providing a central strategy for advanced wave control. While such strategies have been applied to volumetric (longitudinal) waves, their extension to shear (transverse) waves remains limited due to fundamental physical challenges, namely that the particle motion is orthogonal to the wave vector, making mass–stiffness decoupling inherently elusive. The key novelty of this study lies in the unique design concept that enables independent control of the material parameters governing shear waves. Here, we present an elastic metasurface that achieves independent control of vertical mass density and shear modulus by employing dedicated substructures within each unit cell. The mass-controlling substructure can amplify its effective mass without affecting stiffness, while the stiffness-controlling substructure weakens its effective stiffness without altering mass, thereby realizing the desired effective mass-stiffness properties. This simultaneous but independent manipulation strategy of mass and stiffness is the key to realizing impedance matching and arbitrarily reduced phase velocity required to form a high-transmission shear wavefront in a desired pattern. Numerical and experimental validations confirmed that the proposed control method is effective in beam steering and focusing. Accordingly, this approach not only advances shear-wave control into previously unexplored regimes of material properties but also shows its potential for independent tunability of more complex elastic properties in solids. © 2025 Elsevier Ltd

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