Negative extensibility metamaterials: Occurrence and design-space topology

Abstract

A negative extensibility material structure pulls back and contracts when the external tensile load reaches a certain critical level. In this paper, we reveal basic mathematical features of the nonlinear strain energy function responsible for this unusual mechanical property. A systematic discussion leads to a comprehensive phase diagram in terms of design parameters for a simple unit cell structure that provides a panoramic view of all possible nonlinear mechanical behaviors. A negative extensibility region clearly is identified in the diagram. The sought property is seen to be rare, occurring only for a very narrow range of the design parameters. Nonetheless, due to the simplicity of the studied structure we suggest that the negative extensibility should be a more common phenomenon than previously thought. It can appear in simple bistable cells made of only several linearly elastic links, although at some peculiar combinations of their properties. These bistable unit cells can be used to design periodic mechanical metamaterials whose examples are shown as well as innovative architectural metastructures.

Structural and optical characteristics determined by the sputtering deposition conditions of oxide thin films

“…The application of oxide thin films is quite diverse due to their excellent properties [1][2][3][4][5], such as dielectric properties [6][7][8] for the production of metamaterials [9]. Metamaterials applied in the field of space science come with a new dimension of microstructural representation of advanced functional materials [10,11]. Metamaterial structures are of significant interest not only in space science but also in the fields of public security and sensors [9][10][11].…”

“…Metamaterials applied in the field of space science come with a new dimension of microstructural representation of advanced functional materials [10,11]. Metamaterial structures are of significant interest not only in space science but also in the fields of public security and sensors [9][10][11]. Materials with dielectric properties, such as SiO 2 and ZnO, are used to build devices with metasurface structures whose properties can be observed in the visible spectrum.…”

Structural and optical characteristics designed by sputtering deposition conditions of the oxide thin films

“…Metamaterials applied in the field of space science come with a new dimension of microstructural representation of the advanced functional materials [10,11]. Materials with dielectric qualities, such as SiO2 and ZnO, are used to make devices with metasurface structures in the broad visible spectral domain.…”

Anomalous strain energy transformation pathways in mechanical metamaterials

“…The science of mechanical metamaterials emerged at the interface of applied mechanics and materials engineering, inspired by the earlier research in optics, acoustics and electromagnetism [1–11], to explore opportunities for materials with exotic mechanical properties rarely found in the nature. The modern research in mechanical metamaterials encompasses design, theoretical, experimental and computational studies of material systems with negative Poisson's ratio [12–14], negative bulk modulus [15,16], negative longitudinal stiffness and compliance [17–21], reverse Saint–Venant's effect [22] and other anomalous elastic properties. Interesting properties of the metamaterials are defined mostly by their internal structure, topology and geometric architecture rather than chemical composition.…”

“…properties rarely found in the nature. The modern research in mechanical metamaterials encompasses design, theoretical, experimental and computational studies of material systems with negative Poisson's ratio [12][13][14], negative bulk modulus [15,16], negative longitudinal stiffness and compliance [17][18][19][20][21], reverse Saint-Venant's effect [22] and other anomalous elastic properties. Interesting properties of the metamaterials are defined mostly by their internal structure, topology and geometric architecture rather than chemical composition.…”