Selective buckling via states of self-stress in topological metamaterials

TL;DR

This paper introduces a topological approach to design metamaterials with localized buckling regions, leveraging states of self-stress that are robust and indistinguishable from the surrounding material, demonstrated through analytical, numerical, and experimental methods.

Contribution

It presents a novel topological method for sculpting localized buckling in metamaterials using states of self-stress, with robustness against structural perturbations.

Findings

Localized buckling regions can be engineered using topological states of self-stress.

These regions are robust and indistinguishable from the surrounding material.

Experimental validation confirms the effectiveness of the topological design.

Abstract

States of self-stress, tensions and compressions of structural elements that result in zero net forces, play an important role in determining the load-bearing ability of structures ranging from bridges to metamaterials with tunable mechanical properties. We exploit a class of recently introduced states of self-stress analogous to topological quantum states to sculpt localized buckling regions in the interior of periodic cellular metamaterials. Although the topological states of self stress arise in the linear response of an idealized mechanical frame of harmonic springs connected by freely-hinged joints, they leave a distinct signature in the nonlinear buckling behaviour of a cellular material built out of elastic beams with rigid joints. The salient feature of these localized buckling regions is that they are indistinguishable from their surroundings as far as material parameters or connectivity of their constituent elements are concerned. Furthermore, they are robust against a wide range of structural perturbations. We demonstrate the effectiveness of this topological design through analytical and numerical calculations as well as buckling experiments performed on two- and three-dimensional metamaterials built out of stacked kagome lattices.