Eduardo M. B. Campello

A Fully Nonlinear Thin Shell Model of Kirchhoff-Love Type

This work presents a fully nonlinear Kirchhoff-Love shell model. In contrast with shear flexible models, our approach is based on the Kirchhoff-Love theory for thin shells, so that transversal shear deformation is not accounted for.

Finite Element analysis of the wrinkling of orthotropic membranes

This work presents a fully nonlinear formulation for the analysis of the wrinkling on orthotropic membranes. Our approach describes the membrane kinematics as a thin shell motion, whose bending stiffness comes naturally from the shell assumptions. We combine the geometrically-exact isotropic shell model of [1],[2] with an orthotropic constitutive equation for the membrane strains (see [3],[4]), so that both bending and typical membrane capabilities are present in a totally consistent way. The strain energy function is split into an isotropic and an orthotropic part, the first one being relative to the shell (hyperelastic) behavior and the latter to the membrane deformations. The model is discretized under the light of the finite element method using the six-node triangular element of [2], and the performance of the formulation is assessed in several numerical examples (see e.g. Fig. 1). Unstructured meshes are deliberately employed whereas small geometrical imperfections are imposed for the wrinkles to be initiated. Experimental data from the membrane tests of [5] are also taken into account for comparison with our results. Open image in new window Fig. 1 Stretching of two orthotrophic membranes. Deformed configurations.

Elastic-plastic analysis of metallic shells at finite strains

The geometrically-exact finite-strain variable-thickness shell model of [1] is reviewed in this paper and extended to the case of metallic elastoplastic shells. Isotropic elasticity and von Mises yield criterion with isotropic hardening are considered. The model is implemented within a triangular finite element and is briefly assessed by means of two numerical examples.

A Unified Approach for the Nonlinear Dynamics of Rods and Shells Using an Exact Conserving Integration Algorithm

A unified formulation is presented in this work for the nonlinear dynamics analysis of rods and shells undergoing arbitrarily large deformations and rigid body motions. Based on our previous works, we develop a special notation and describe both rod and shell kinematics with the same set of expressions. Differences are observed only at the constitutive equation. Important aspects of the above-mentioned works are preserved, such as the special paramete-rization of the rotation field, the concept of stress resultants and the ability to handle nonlinear hyperelastic materials in a totally conserving way. The time integration algorithm developed for the equations of motion follows an energy-momentum approach and results in a fully conserving scheme. The formulation is well-suited for (but not restricted to) finite element approximations and its unified character leads to a straightforward simultaneous implementation of both rod and shell dynamics models within a finite element code. Assessment is made by means of numerical simulations.