Mixed Finite Elements for Geometrically Exact Beams using Discontinuous Rotations and Discrete Curvature

Fuente: arXiv
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Hauptverfasser: Humer, Alexander, Steinbrecher, Ivo, Pechstein, Astrid
Format: Preprint
Veröffentlicht: 2026
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author Humer, Alexander
Steinbrecher, Ivo
Pechstein, Astrid
author_facet Humer, Alexander
Steinbrecher, Ivo
Pechstein, Astrid
contents We propose a novel mixed finite-element formulation for geometrically exact (Simo--Reissner) beams that introduces the moment vector as additional independent field. The specific mixed form allows for an element-local, discontinuous approximation of rotations, which is key to a simple and efficient discretization framework. The concept of discrete curvature provides a mathematically consistent treatment of rotation discontinuities. For linear constitutive laws, the mixed form is derived via a Legendre transform of the curvature-related strain energy. Objectivity is retained at the discrete level by interpolating relative rotations through a multiplicative split of the rotation field; path-independence is inherent to the total Lagrangian setting and verified numerically. Several benchmarks demonstrate optimal rates of convergence and accuracy, irrespective of the beam's slenderness and order of approximation. Notably, the lowest-order element entirely avoids rotation interpolation by employing element-constant rotations only.
format Preprint
id arxiv_https___arxiv_org_abs_2605_04573
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Mixed Finite Elements for Geometrically Exact Beams using Discontinuous Rotations and Discrete Curvature
Humer, Alexander
Steinbrecher, Ivo
Pechstein, Astrid
Numerical Analysis
We propose a novel mixed finite-element formulation for geometrically exact (Simo--Reissner) beams that introduces the moment vector as additional independent field. The specific mixed form allows for an element-local, discontinuous approximation of rotations, which is key to a simple and efficient discretization framework. The concept of discrete curvature provides a mathematically consistent treatment of rotation discontinuities. For linear constitutive laws, the mixed form is derived via a Legendre transform of the curvature-related strain energy. Objectivity is retained at the discrete level by interpolating relative rotations through a multiplicative split of the rotation field; path-independence is inherent to the total Lagrangian setting and verified numerically. Several benchmarks demonstrate optimal rates of convergence and accuracy, irrespective of the beam's slenderness and order of approximation. Notably, the lowest-order element entirely avoids rotation interpolation by employing element-constant rotations only.
title Mixed Finite Elements for Geometrically Exact Beams using Discontinuous Rotations and Discrete Curvature
topic Numerical Analysis
url https://arxiv.org/abs/2605.04573