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Abstract Fish scale-like features on substrates arranged periodically produce peculiar mechanical behavior. These include nonlinear stiffness, anisotropy in deformation, and finally jamming behavior. These smart structures can be fabricated by partially embedding stiffer plate-like segments on softer substrates to create a bi-material system, with overlapping scales. The dynamic response shows remarkable geometrical-material interplay and anisotropies in damping. Especially interesting is the damping behavior that is distinct from typical damping found in mechanical structures which are often approximated as Rayleigh-Damping. Here we discuss some of these dynamic behaviors that include material-geometry distinction in damping, multiple damping scenarios and interplay of dissipation possibilities. We performed experimental analysis and compared the results with simple mathematical laws that govern architecture-dissipation relationships that can help understand the vibrating response of pillar/scale-covered membranes/thin plates. We conclude by noting the applicability these metastructure in structural damping with other forms currently in use in practice. 

Biomimetic scale-covered substrates are architected meta-structures exhibiting fascinating emergent nonlinearities via the geometry of collective scales contacts. Despite much progress in understanding their elastic nonlinearity, their dissipative behavior arising from scales sliding is relatively uninvestigated in the dynamic regime. Recently discovered is the phenomena of viscous emergence, where dry Coulomb friction between scales can lead to apparent viscous damping behavior of the overall multi-material substrate. In contrast to this structural dissipation, material dissipation common in many polymers has never been considered, especially synergistically with geometrical factors. This aspect is addressed here, where material viscoelasticity is introduced via a simple Kelvin–Voigt model for brevity and clarity. The results contrast the two damping sources in these architectured systems: material viscoelasticity and geometrical frictional scales contact. It is discovered that although topically similar in effective damping, viscoelastic damping follows a different damping envelope than dry friction, including starkly different effects on damping symmetry and specific damping capacity. 

Abstract Fish scales inspired materials platform can provide advanced mechanical properties and functionalities. These materials, inspired from fish scales take the form of either composite materials or multi-material discrete exoskeleton type structures. Over the last decade, they have been under intense scrutiny for generating tailorable and tunable stiffness, penetration and fracture resistance, buckling prevention, nonlinear damping, hydrodynamic and camouflaging functions. Such programmable behavior emerges from leveraging their unique morphology and structure-property relationships. Several advanced tools of characterization, manufacturing, modeling and computation have been employed to understand and discover their behavior. With the rapid proliferation of additive manufacturing (AM) techniques, and advancing envelope of modeling and computational methods, this field is seeing renewed efforts to realize even more ambitious designs. We present a review and recapitulation of the state-of-the art in fish scale inspired materials in this paper.