Geometric dependence of curvature-induced rigidity

TL;DR

This study investigates how the geometry of thin elastic sheets influences the balance between curvature-induced rigidity and gravity-driven buckling, revealing complex behaviors like non-monotonic deflections and hysteresis.

Contribution

It introduces a combined experimental, numerical, and theoretical approach to understand the geometric effects on rigidity and buckling in elastic sheets, highlighting the role of shape and curvature.

Findings

Sheet geometry significantly affects deflection and stability.

Non-monotonic deflections observed with increasing sheet length.

Hysteretic bistability regions depend on shape and curvature.

Abstract

Bending the edge of a thin elastic material promotes rigidity far from its clamped boundary. However, this curvature-induced rigidity can be overwhelmed by gravity or other external loading, resulting in elastic buckling and large deformations. We consider the role of body geometry on this competition using experiments, numerical simulations, and reduced-order models. Finite element simulations are performed using a model nonlinear hyperelastic material, and a theoretical framework is proposed that incorporates small lateral curvatures, large longitudinal rotations, and a varying cross-sectional width. A particular focus is on the comparison between rectangular and triangular sheets, and trapezoidal sheets in between. Sheet geometry affects downward tip deflection by changing the relative importance of the sheet's weight and the rigidity provided by curvature, often in subtle ways. In extreme cases, non-monotonic deflection is observed with increasing sheet length, and a region of hysteretic bistability emerges, becoming more pronounced with rectangular sheets and large imposed curvatures. These findings demonstrate the profound impact of geometry on the competition between curvature-induced rigidity and gravity-induced deformation in thin elastic materials.