Morphoelastic ribbons: Differential growth-induced curvature and torsion

TL;DR

This paper develops a rigorous 1D morphoelastic ribbon model from 3D elasticity to connect microscopic growth patterns with macroscopic shapes like curvature and torsion, aiding understanding of plant morphogenesis and soft robotics.

Contribution

It introduces a unified, explicit growth-dependent 1D model derived from 3D elasticity, capturing nonlinearities and predicting shape transitions in slender structures.

Findings

Analytical solutions for growth-induced saddle-bending and twisting.

Numerical phase diagrams showing bifurcation thresholds for shape transitions.

Model links microscopic growth to macroscopic morphology explicitly.

Abstract

Natural slender structures, such as plant leaves, petals, and tendrils, often exhibit complex three-dimensional (3D) morphologies-including twisting, helical coiling, and saddle-bending-driven by differential growth. The resulting internal stresses are partially relieved through the development of intrinsic curvature and torsion. The fundamental challenge lies in effectively correlating microscopic growth fields to the macroscopic shapes and mechanical responses of the ribbon structures. However, existing ribbon or shell models struggle to directly link growth gradients to macroscopic curvature and torsion, necessitating a reduced-dimensional framework. This work establishes a unified one-dimensional (1D) morphoelastic ribbon model derived rigorously from 3D finite elasticity theory via a two-step asymptotic dimension reduction. The reduced-order model captures key geometric nonlinearities and finite rotations while retaining explicit dependence on the growth tensor. We obtain analytical solutions for saddle-bending and twisting configurations induced by specific growth gradients. Furthermore, numerical continuation, based on the reduced model, reveals post-buckling transitions into helical morphologies, identifying bifurcation thresholds and constructing phase diagrams. This framework explicitly links growth fields to ribbon curvature and torsion, providing fundamental mechanics insights into the morphogenesis of slender plant organs and offering the potential for bioinspired soft robotics design.