Análise numérica do fenômeno de flambagem em barras sob compressão centrada, formadas por materiais compostos, em seções transversais tipo “I” e tubular circular

Abstract

Composite materials have emerged due to the need of developing stronger and lighter materials. They are applied in several engineering branches such as aeronautics, mechanics, naval, civil among others. The present work is dedicated to the use of the Finite Element Method, through the ANSYS software, aiming to predict the behavior of compressed structural elements in relation to buckling, both local and global. Orthotropic composite materials (glass fiber reinforced plastic) are considered, and it is intended to evaluate the influence of geometrical parameters, the lamination sequence, and the orientation of reinforcements, in obtaining critical buckling loads. These critical loads are easily determined for isotropic material profiles, however for composite materials the equations are not trivial and need to be modified and are often developed through correlations with experimental data. In this work, two types of elements were used in numerical modeling: SHELL 181, which uses two-dimensional formulation, and SOLID 46, which uses three-dimensional formulation. This comparison was performed with the purpose of verifying the errors obtained with different modeling strategies, considering experimental data from the literature. Once the modeling strategy was chosen, it was observed that for local buckling modes in “I” beams, the best performance occurs in the case of stacking sequence [SF ROV CSM CSM ROV SF], with SF layers oriented at [45º / -45º] on the tables and [90º / -90º] in the web. For local buckling modes in circular section tubes, the best stacking sequence was also [SF ROV CSM CSM ROV SF], with SF reinforcement at [90º / -90º]. For global modes, the only relevant elastic modulus in the critical load response is the membrane constant parallel to the profile length, since for all cases in wich global modes have manifested, the best SF-type reinforcement angle was [0º / 0º]. For local modes, the relative errors presented between the FEM results and analytical and semi-analytical methods were relatively low only for some narrow variation ranges of SF-angle reinforcement. For global modes, errors are generally smaller, indicating greater agreement between the several data sources available and the numerical results achieved in this work.