arXiv subjects

Plastiras Demetriou

Publications and source records attributed to Plastiras Demetriou.

4 recordsLinked to original sources

arXiv2026

Multiple Band-Gaps through the Coupling of Unit Cells from the Same Metamaterial: the Dual Cell method

This study investigates how the coupling of two unit cells belonging to the same mechanical metamaterial into a dual unit cell configuration, can produce a new metamaterial with enhanced wave attenuation capabilities. For two metamaterials, two different unit cell coupling configurations are examined in 2D (side by side and chessboard), with particular emphasis on maintaining a plane crystallographic group of high symmetry, in order to simplify band structure calculations given the complexity of the geometry. It is shown that for specific configurations and choices of unit cell, multiple directional and/or omnidirectional band-gaps can appear, some of which can exhibit enhanced attenuation. The way in which these band-gaps emerge is described through applying the same procedure on 1D spring mass chains. Results support the idea that any band-gap metamaterial could have a much more efficient version which can be constructed purely from its own unit cells.

physics.app-ph↗

arXiv2026

Transmissibility, boundary-guided waves, and representative unit cell choice in finite-sized metamaterials

The implications of selecting different unit cells are often overlooked in both direct studies of microstructured materials and their homogenized equivalents. Investigating the effects of unit cell selection is crucial not only for understanding boundary phenomena but also for identifying which finite-sized metamaterial performs best for a given purpose (e.g., achieving zero or minimal transmissibility in the band-gap range). This study examines how the choice of a representative unit cell in periodic metamaterials influences boundary effects and, consequently, the transmissibility of finite-size samples, while providing a strategy based on eigenfrequency calculations that enables a priori optimization.

physics.optics↗

arXiv2025

Effective interface forces to model boundary effects in a finite-size metamaterial through the reduced relaxed micromorphic model

We use the reduced relaxed micromorphic model (RRMM) to capture the effective "bulk" dynamical response of finite size metamaterial specimens made out of a Labyrinthine unit cell. We show that for small finite-size specimens, boundary effects can play a major role, so that the RRMM needs an enrichment to capture the metamaterial's bulk response, as well as the boundary effects. A benchmark test is introduced to show that different metamaterial/ homogeneous material interfaces can drive completely different responses even if the bulk metamaterial remains the same. We show with no remaining doubts that the concept of "interface forces" must necessarily be introduced if one wants to model finite-size metamaterials in a homogenized framework.

physics.app-ph↗

arXiv2023

Reduced relaxed micromorphic modeling of harmonically loaded metamaterial plates: investigating boundary effects in finite-size structures

In this paper, we propose an approach for describing wave propagation in finite-size microstructured metamaterials using a reduced relaxed micromorphic model. This method introduces an additional kinematic field with respect to the classical Cauchy continua, allowing to capture the effects of the underlying microstructure with a homogeneous model. We show that the reduced relaxed micromorphic model is not only effective for studying infinite-size metamaterials, but also efficient for numerical simulations and analysis on specimens of finite size. This makes it an essential tool for designing and optimising metamaterials structures with specific wave propagation properties. The proposed model's efficiency is assessed through numerical simulations for finite-size benchmark problems, and shows a good agreement for a wide range of frequencies. The possibility of producing the same macroscopic metamaterial with different but equivalent unit cell "cuts" is also analysed, showing that, even close to the boundary, the reduced relaxed micromorphic model is capable of giving accurate responses for the considered loading and boundary conditions.

physics.app-ph↗