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In this paper we show the existence of global minimizers for the geometrically exact, non-linear equations of elastic plates, in the framework of the general 6-parametric shell theory. A characteristic feature of this model for shells is…

Analysis of PDEs · Mathematics 2013-03-11 Mircea Birsan , Patrizio Neff

We analyze geometrically non-linear isotropic elastic shells and prove the existence of minimizers. In general, the model takes into account the effect of drilling rotations in shells. For the special case of shells without drilling…

Analysis of PDEs · Mathematics 2013-03-11 Mircea Birsan , Patrizio Neff

We show the existence of global minimizers for a geometrically nonlinear isotropic elastic Cosserat 6-parameter shell model. The proof of the main theorem is based on the direct methods of the calculus of variations using essentially the…

Analysis of PDEs · Mathematics 2020-09-16 Ionel-Dumitrel Ghiba , Mircea Bîrsan , Peter Lewintan , Patrizio Neff

We present an existence theorem for a large class of nonlinearly elastic shells with low regularity in the framework of a two-dimensional theory involving the mean and Gaussian curvatures. We restrict our discussion to hyperelastic…

Analysis of PDEs · Mathematics 2018-05-18 Sylvia Anicic

We reconsider the geometrically nonlinear Cosserat model for a uniformly convex elastic energy and write the equilibrium problem as a minimization problem. Applying the direct methods of the calculus of variations we show the existence of…

Analysis of PDEs · Mathematics 2014-12-16 Patrizio Neff , Mircea Bîrsan , Frank Osterbrink

We present a new geometrically nonlinear Cosserat shell model incorporating effects up to order $O(h^5)$ in the shell thickness $h$. The method that we follow is an educated 8-parameter ansatz for the three-dimensional elastic shell…

Mathematical Physics · Physics 2020-09-15 Ionel-Dumitrel Ghiba , Mircea Bîrsan , Peter Lewintan , Patrizio Neff

We present a new way to discretize a geometrically nonlinear elastic planar Cosserat shell. The kinematical model is similar to the general 6-parameter resultant shell model with drilling rotations. The discretization uses geodesic finite…

Numerical Analysis · Mathematics 2015-01-29 Oliver Sander , Patrizio Neff , Mircea Bîrsan

Starting from the three-dimensional Cosserat elasticity, we derive a two-dimensional model for isotropic elastic shells. For the dimensional reduction, we employ a derivation method similar to that used in classical shell theory, as…

Analysis of PDEs · Mathematics 2020-01-20 Mircea Bîrsan

A nonlinear shell model is studied in this paper. This is a nonlinear variant of the Budiansky-Sanders linear shell model. Under some suitable assumptions on the magnitude of the applied force, we will prove the existence of a minimizer for…

Analysis of PDEs · Mathematics 2025-02-14 Trung Hieu Giang

We investigate discretizations of a geometrically nonlinear elastic Cosserat shell with nonplanar reference configuration originally introduced by B\^irsan, Ghiba, Martin, and Neff in 2019. The shell model includes curvature terms up to…

Numerical Analysis · Mathematics 2023-08-02 Lisa Julia Nebel , Oliver Sander , Mircea Bîrsan , Patrizio Neff

In the framework of the geometrically nonlinear 6-parameter resultant shell theory we give a characterization of the shells without drilling rotations. These are shells for which the strain energy function $W$ is invariant under the…

Analysis of PDEs · Mathematics 2013-12-10 Mircea Birsan , Patrizio Neff

Cosserat rod theory is the popular approach to modeling ferromagnetic soft robots as 1-Dimensional (1D) slender structures in most applications, such as biomedical. However, recent soft robots designed for locomotion and manipulation often…

Robotics · Computer Science 2025-10-07 Mohammadjavad Javadi , Robin Chhabra

Using a geometrically motivated 8-parameter ansatz through the thickness, we reduce a three-dimensional shell-like geometrically nonlinear Cosserat material to a fully two-dimensional shell model. Curvature effects are fully taken into…

Analysis of PDEs · Mathematics 2019-09-30 Mircea Birsan , Ionel-Dumitrel Ghiba , Robert J. Martin , Patrizio Neff

We consider a recently introduced geometrically nonlinear elastic Cosserat shell model incorporating effects up to order $O(h^5)$ in the shell thickness $h$. We develop the corresponding geometrically nonlinear constrained Cosserat shell…

Analysis of PDEs · Mathematics 2021-09-15 Ionel-Dumitrel Ghiba , Mircea Bîrsan , Peter Lewintan , Patrizio Neff

This paper presents a general, nonlinear isogeometric finite element formulation for rotation-free shells with embedded fibers that captures anisotropy in stretching, shearing, twisting and bending -- both in-plane and out-of-plane. These…

Computational Engineering, Finance, and Science · Computer Science 2023-06-06 Thang Xuan Duong , Mikhail Itskov , Roger Andrew Sauer

Nonconvex functionals with spherical symmetry are studied. Existence of one and radial symmetry of all global minimizers is shown with an approach based on convex relaxation.

Classical Analysis and ODEs · Mathematics 2007-05-23 Stefan Krömer

"It is still not known if the radial cavitating minimizers obtained by Ball [J.M. Ball, Discontinuous equilibrium solutions and cavitation in nonlinear elasticity, Phil. Trans. R. Soc. Lond. A 306 (1982) 557--611] (and subsequently by many…

Complex Variables · Mathematics 2018-05-09 Aleksis Koski , Jani Onninen

Using $\Gamma$-convergence arguments, we construct a nonlinear membrane-like Cosserat shell model on a curvy reference configuration starting from a geometrically nonlinear, physically linear three-dimensional isotropic Cosserat model. Even…

Analysis of PDEs · Mathematics 2023-06-28 Maryam Mohammadi Saem , Ionel-Dumitrel Ghiba , Patrizio Neff

In this paper we derive the linear elastic Cosserat shell model incorporating effects up to order $O(h^5)$ in the shell thickness $h$ as a particular case of the recently introduced geometrically nonlinear elastic Cosserat shell model. The…

Analysis of PDEs · Mathematics 2022-08-10 Ionel-Dumitrel Ghiba , Mircea Birsan , Patrizio Neff

Modelling two-dimensional chiral materials is a challenging problem in continuum mechanics because three-dimensional theories reduced to isotropic two-dimensional problems become non-chiral. Various approaches have been suggested to…

Mathematical Physics · Physics 2018-05-01 Sebastian Bahamonde , Christian G. Boehmer , Patrizio Neff
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