From Elementary Units Towards Optimized Large-Scale Structures: Design and Validation of a Finite-Size Labyrinthine Metamaterial for Elastic and Acoustic Wave Control
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Our work deals with a metamaterial consisting of periodically arranged labyrinthine unit cells. Based on the geometry of the unit cell, we propose three designs of finite-size specimens with different raw materials and out-of-plane thicknesses. The design procedure aims to maximize the band gap while making use of simulation techniques based on Bloch-Floquet analysis coupled with finite element (FE) method. An experimental test campaign is conducted in order to assess the capacity of the designed specimens to mitigate vibrations. The experiments reveal a band gap in the low- to mid-frequency range. Furthermore, the mechanical average transfer function as well as the acoustic sound transmission loss at normal incidence of the small-scale sandwich-structure specimens are obtained. Numerical models of the specimens are used to validate the experiments and explore additional vibro-acoustic load cases. We propose straightforward solutions to optimize the vibro-acoustic design of one specimen for applications in vibration mechanics and a sound insulating panel. Further investigations will be focused on optimized large scale structures in which metamaterial building blocks are positioned selectively. Since the computational effort to simulate structures that involve different length scales is very high, we intend to use enriched continuum models like the relaxed micromorphic model [1,2]. Acknowledgements The European Commission supported this work with ERC Consolidator Grant META-LEGO [No 101001759]. References [1] J. Voss, G. Rizzi, P. Neff, and A. Madeo. Modeling a labyrinthine acoustic metamaterial through an inertia-augmented relaxed micromorphic approach. Mathematics and Mechanics of Solids, p 10812865221137286, 2022. [3] P. Demetriou, G. Rizzi, and A. Madeo. Reduced relaxed micromorphic modeling of harmonically loaded metamaterial plates: investigating boundary effects in finite-size structures. Archive of Applied Mechanics, 2023.
