On a kinematically exact rod model for thin-walled open section members: incorporating polyconvex constitutive equation

Resumo

In the current work, advances on kinematically exact rod models for thin-walled open section members,

taking into account both primary and secondary cross-sectional warpings, are proposed. Advanced elastic consti-
tutive equations are incorporated in order to enable full bending, compression and torsional strain couplings in the

finite strain regime. The paper extends a previous contribution by the authors (Kassab and Campello [1] ”On a

kinematically exact rod model for thin-walled open section members”, CILAMCE-PANACM-2021) by incorpo-
rating a more advanced constitutive equation, now based on the polyconvex neo-Hookean Simo-Ciarlet’s material.

The older version contemplated only linear elastic and Saint-Venant ́s constitutive equations, which are known for
being unsuited for truly finite strains. Differently from what was performed in a past attempt, all the terms of the
constitutive equation were retained. The model was implemented in PEFSYS, which is an in-house FEM program.
Validation is performed using existing results from the literature as well as solutions obtained with the Ansys’s
shell 281 element.