Bifurcation of elastic curves with modulated stiffness

TL;DR

This paper studies the equilibrium shapes of closed elastic curves with variable stiffness, introducing a density-dependent model and analyzing bifurcations through analytical and numerical methods.

Contribution

It develops a generalized elastica model with density-dependent stiffness and a density gradient term to analyze bifurcations of solutions.

Findings

Bifurcation structure of elastic curves with modulated stiffness identified

Analytical and numerical solutions demonstrate shape transitions

Model extends classical elastica to heterogeneous stiffness scenarios

Abstract

We investigate the equilibrium configurations of closed planar elastic curves of fixed length, whose stiffness, also known as the bending rigidity, depends on an additional density variable. The underlying variational model relies on the minimization of a bending energy with respect to shape and density and can be considered as a one-dimensional analogue of the Canham-Helfrich model for heterogeneous biological membranes. We present a generalized Euler-Bernoulli elastica functional featuring a density-dependent stiffness coefficient. In order to treat the inherent nonconvexity of the problem we introduce an additional length scale in the model by means of a density gradient term. We derive the system of Euler-Lagrange equations and study the bifurcation structure of solutions with respect to the model parameters. Both analytical and numerical results are presented.