Rigidity paradox of kirigami arches

TL;DR

This paper reveals that in kirigami arches, strategic cuts can paradoxically increase rigidity, with the effect depending on cut placement, load symmetry, and support distance, validated through experiments and simulations.

Contribution

It uncovers the rigidity paradox in kirigami arches, showing how cuts can enhance stiffness and providing parametric insights into optimal cut placement and load conditions.

Findings

Cut patterns can increase rigidity under various loads.

Rigidity depends on cut location, support distance, and load symmetry.

Experimental results validate numerical predictions.

Abstract

The geometry of bending-active kirigami arches, decorated by cuts and holes, is strongly influenced by the location and geometry of the perforations. This study demonstrates that, in some instances, the geometric stiffening induced by additional cuts can outweigh the weakening effect of material removal, leading to a counterintuitive increase in structural rigidity under a given concentrated load. We present multiple parametric cut patterns to show that rigidity can be increased both under symmetric and asymmetric loads. While the preferred cut location is often near the point of action of the load, asymmetric loading can shift this optimum elsewhere. Moreover, the distance between the supports also plays a crucial role, namely, the rigidity gain vanishes when the supports are too far apart. We found that the rigidity can be increased for both non-perforated and perforated sheets, and there is a non-monotonic relationship between the global porosity and the rigidity of the structure. Numerical predictions are validated against experimental measurements.