Composite metamaterial square grids with sign-flipping expansion coefficients leading to a type of Islamic design

Abstract

A class of 2D metamaterials with sign-switching coefficients of thermal, pressure and moisture expansions is proposed herein—such materials not only change properties with environmental changes, but also reverses between positive and negative. Designed from bimaterial strips and arranged into the form of square grids, changes to environmental conditions transform the square grids into 2D array of 8-pointed stars found in Islamic art and architecture. Results indicate that the bimaterial strip deflection can fit the 8-pointed star when the overall strain is- 0.105. Suppose the general expansion coefficients for both materials in the bimaterial strip (α1, α2) are known, then the required environmental changes for attaining the 8-pointed star array can be determined. The currently proposed metamaterial not only demonstrates its capability of attaining properties with reversible sign, but also achieve aesthetic feature with historical significance.