ANÁLISE TERMOMECÂNICA UTILIZANDO ELEMENTOS FINITOS DE CASCA ISOPARAMÉTRICOS

Abstract

This work introduces an integrated methodology for thermomechanical analysis, applying specific isoparametric finite elements for shells. These elements are developed through direct isoparametric formulation, aimed at both flat and curved shell elements, and are based on the theory of degenerated solids. The constitutive model used for these elements is founded on the von Mises plasticity equations, utilizing Mandel notation to facilitate the effective implementation of tensorial constitutive equations. The developed formulations are detailed extensively, aiming for deep understanding and applicability in future research. The validation of the proposed finite element is conducted through four examples from the literature that have analytical solutions. For the coupled thermomechanical approach, validation and comparison are done with another four examples, of which two have analytical solutions and two are modeled using Abaqus software. The verification of the constitutive model is conducted through four additional examples: the first two are based on literature results, while the last two are modeled in Amaru software. In all scenarios, the results demonstrate good agreement with the analytical solutions and with the data obtained through finite element software. In conclusion, three case studies are presented. The first numerically simulates experimental results of temperature and stress for a pressure vessel. The second addresses a hypothetical simulation to examine a flare section, considering the thermomechanical effect combined with material nonlinearity (plasticity), including the verification of von Mises stress along the length of the structure under different temperature levels. Finally, the last case study analyzes a pillar subjected to fire, comparing the results obtained through computational modeling with those found in the literature. It is concluded that the proposed methodology, validated through analytical examples and case studies, proved effective in accurately representing stresses and deformations under mechanical and thermal loads. The treatment of the drilling effect was efficient for the presented examples. The use of the von Mises plasticity model, combined with Mandel notation, facilitated computational implementation, allowing complex simulations with precision and efficiency. The case study results confirmed the approach’s applicability in various scenarios, highlighting its usefulness for structural analyses in severe environments.