Euler-Bernoulli beams with contact forces: existence, uniqueness, and numerical solutions

TL;DR

This paper establishes the existence and uniqueness of solutions for a contact force-influenced Euler-Bernoulli beam model and demonstrates how numerical solutions via fixed-point iterations converge to the true solution.

Contribution

It provides new theoretical results on solution existence and uniqueness, and introduces a numerical method with proven convergence for contact force problems in Euler-Bernoulli beams.

Findings

Unique solutions exist for the boundary value problem.

Discrete solutions via finite difference are also unique.

Fixed-point iterations effectively solve the absolute value equation.

Abstract

In this paper, we investigate the Euler-Bernoulli fourth-order boundary value problem (BVP) $w^{(4)}=f(x,w)$, $x\in \intcc{a,b}$, with specified values of $w$ and $w''$ at the end points, where the behaviour of the right-hand side $f$ is motivated by biomechanical, electromechanical, and structural applications incorporating contact forces. In particular, we consider the case when $f$ is bounded above and monotonically decreasing with respect to its second argument. First, we prove the existence and uniqueness of solutions to the BVP. We then study numerical solutions to the BVP, where we resort to spatial discretization by means of finite difference. Similar to the original continuous-space problem, the discrete problem always possesses a unique solution. In the case of a piecewise linear instance of $f$, the discrete problem is an example of the absolute value equation. We show that solutions to this absolute value equation can be obtained by means of fixed-point iterations, and that solutions to the absolute value equation converge to solutions of the continuous BVP. We also illustrate the performance of the fixed-point iterations through a numerical example.