A nongraphical obstacle problem for elastic curves

Abstract

We study an obstacle problem for the length-penalized elastic bending energy for open planar curves pinned at the boundary. We first consider the case without length penalization and investigate the role of global minimizers among graph curves in our minimization problem for planar curves. In addition, for large values of the length-penalization parameter $\lambda>0$, we expose an explicit threshold parameter above which minimizers touch the obstacle, regardless of its shape. On contrary, for small values of $\lambda>0$ we show that the minimizers do not touch the obstacle, and they are given by an explicit elastica.