Archive | 2021
Editorial: Cutting-Edge Metastructures: Micro-Architected and Active Metamaterials
Abstract
The present Research Topic collects articles dealing with the optimal design, the realization and the testing of meta-structures capable of achieving dynamic high-performance. The common thread linking these articles is using metamaterials concepts to conceive intriguing internal architecture for wave propagation control. Due to their interdisciplinary nature and their broad range of applications, metamaterials have increasingly inspired researchers of different communities. In the last years, mathematicians, physicists, engineers, and material scientists have mobilized massive effort to move the limits beyond state-of-the-art to realize extreme materials. Charming behaviors such as filtering, wave-guiding, negative refraction, cloaking, seismic protection, noise reduction and band-gap control have been demonstrated to be possible theoretically, via numerical simulations and by real experiments. Different techniques have been developed for achieving such exotic effects. A nonexhaustive list of these includes i) mass, inertia and stiffness modifications, ii) the use of local inertial or Helmholtz resonators or gyroscopes elements embedded into lattice or continuum materials, iii) the use of a multi-field electro-mechanical coupling via piezoelectric active phases. Within this framework, the current research topics of the articles provide a new perspective for using the metamaterial idea to achieve phenomena such as cloaking, seismic protection, dynamic wave propagation attenuation, and wave localization. The present collection includes six research articles and one review article. The review article by Yakovleva et al., provides an overview of the main theories used to describe the response of microstructured elastic solids subjected to dynamic loads. Some examples of wave propagation in structured elastic media are presented, such as applying metamaterial concepts to describe the dynamics of real-life bridges. Particular emphasis is given to the reliability of theoretical models, derived considering an infinite structure, to describe dynamic of finite span elements. The links between flexural metamaterials, metasurfaces, and predictive seismic assessments are discussed through the case study of a region affected by an earthquake. The performance of large-scale metamaterials in seismic protection and noise reduction is discussed by Varma et al.. Here the focus is on investigating the effect of some parameters, such as microstructure geometry, orientation, constraints and constituent materials, in opening band gaps at low frequency regimes. The numerical analysis show that not only steel but also concrete inclusions can lead to large wave attenuation. A design of a protective barrier for civil engineering constructions is proposed and discussed. Potential applications in seismic shielding and wave scattering reduction have the outcomes reported in the article by Rossi et al.. This work is devoted to investigating some relevant issues encountered in the Edited and reviewed by: Alberto Corigliano, Politecnico di Milano, Italy