The Extreme Mechanics of Viscoelastic Metamaterials

TL;DR

This paper reviews how viscoelasticity influences the extreme mechanical responses of flexible metamaterials, highlighting the importance of dissipation in dynamic scenarios and potential for new functionalities through patterning.

Contribution

It introduces the role of viscoelasticity and dissipation in the behavior and design of flexible mechanical metamaterials, emphasizing dynamic and patterning effects.

Findings

Viscoelasticity affects buckling and snapping behaviors.

Dissipation influences the dynamical response of metamaterials.

Patterning viscoelastic properties enables rate-dependent functionalities.

Abstract

Mechanical metamaterials made of flexible building blocks can exhibit a plethora of extreme mechanical responses, such as negative elastic constants, shape-changes, programmability and memory. To date, dissipation has largely remained overlooked for such flexible metamaterials. As a matter of fact, extensive care has often been devoted in the constitutive materials' choice to avoid strong dissipative effects. However, in an increasing number of scenarios, where metamaterials are loaded dynamically, dissipation can not be ignored. In this review, we show that the interplay between mechanical instabilities and viscoelasticity can be crucial and can be harnessed to obtain new functionalities. We first show that this interplay is key to understanding the dynamical behaviour of flexible dissipative metamaterials that use buckling and snapping as functional mechanisms. We further discuss the new opportunities that spatial patterning of viscoelastic properties offer for the design of mechanical metamaterials with properties that depend on loading rate.