Mechanics of Low Dimensional Biomimetic Scale Metamaterials

Combination of topology and material could play an important role in giving rise to nontraditional behavior in mechanical structures and is a typical strategy in nature. Topology is concerned with the geometrical and spatial properties of the objects, which are preserved under continues mechanical deformation of the object such as stretching, bending, twisting, etc. In this work, we focus on structures based on fish scale inspired surface topology. The utilized idea for surface topology is a bioinspired design on the substrate of biological scale-covered systems. Scales are a path breaking evolutionary adaptation that accompanied vertebrate evolution for the past 500 million years. Fish scales are inherently lightweight with diverse shapes, sizes, materials, and distribution, and they provide remarkable architecture-material enhancement, typical of metamaterials. Here we provide a perspective on mechanical behavior of fish scale inspired structures and quantify the origins of some of their striking mechanical properties that include nonlinear and directional strain stiffening in both bending and twisting, dual nature of friction which combines both resistance as well as adding stiffness to motion. We will provide derivation of mathematical laws that govern structure-property relationships that can help guide design. The response of biomimetic scale under twisting, bending and combined load is tailorable through the geometric arrangement and orientation of the scales. Also, the analytical models have been validated by the finite element analysis. We outline and explain the progress in understanding the complexities of these structures in global and local deformation modes and conclude by offering future perspectives and challenges