Special Session 47: 

On the asymptotic form of solutions of the Tadjbakhsh-Odeh`s variational problem

Minoru Murai
Osaka City University
Japan
Co-Author(s):    Shoji Yotsutani
Abstract:
Let $\Gamma$ be a plane closed elastic curve with length $L>0.$ We denote the arc-length and the curvature by $s$ and $\kappa(s)$, respectively. Let ${\mathcal A}(\Gamma)$ be the signed area of the domain bounded by $\Gamma$. We consider the variational problem: Find a curve $\Gamma$ (the curvature $\kappa(s)$) which minimize the functional $\displaystyle {1 \over 2} \int_{0}^{L} \kappa(s)^{2} ds+p{\mathcal A}(\Gamma)$ subject to $\displaystyle \int_{0}^{L} \kappa(s)ds=2 \pi$, where $p$ is a given positive constant. This variational problem was first considered by Tadjbakhsh-Odeh to study the equilibrium states of an elastic inextensible ring under a uniform pressure $p>0$. S.Okabe showed the asymptotic form of solutions of the Euler-Lagrange equation for sufficient large $p$ and derived the second variation. He showed the uniqueness and the profile of the minimizer for sufficiently large $p$. In this talk, we will give new proofs of the asymptotic form of solutions of the Euler-Lagrange equation for sufficient large $p$.