Resumo:
Research on composite materials has gained prominence due to their excellent mechanical
properties combined with low weight, attracting various engineering fields such as
aerospace, naval, automotive, and industrial engineering. Historically, challenges involving
composite materials include understanding their characteristics, controlling quality,
and optimizing properties. With the advancement of computational capacity, the finite element
method has become an essential tool for predicting the behavior of these materials
under different boundary conditions. This specific study focuses on thin-walled cylinders
composed of 10-layer shells with various delaminations. Each tube was subjected to three
types of analyses: modal, static, and buckling. The detailed analysis of these delaminated
structures aims to understand how delamination parameters affect structural performance,
allowing the development of more failure-tolerant designs. The parameters considered for
simulating delamination include: z (height of the delamination in the ellipse), b (major
axis of the ellipse), r (ratio between the major and minor axes of the ellipse), θ (angle of
inclination of the ellipse), α (severity of the delamination), and n (layer of the thin wall
with the delamination). A total of 1000 tests were conducted for each type of analysis
with the same delaminations. The responses obtained—natural frequency, inverse Tsai
Wu index, and eigenvalue—did not show a significant correlation among themselves, except
for a good internal correlation of the eigenvalues. To better understand the impact
of each variable on the obtained responses, the Sobol index, a global sensitivity analysis
technique, was used. This analysis helped identify the most critical parameters influencing
each type of response. The results indicate that, although there is no direct and universal
correlation among all the analyzed responses, a detailed understanding of the influence
of each delamination parameter can guide the development of more robust and resilient
designs. The findings of this study are valuable for materials engineering, contributing to
advances in the safety and efficiency of composite structures. Finally, the thesis concludes
that the use of modal, static, and buckling analyses combined with sensitivity analysis is
an effective approach to evaluate and improve the performance of delaminated composite
structures, providing important insights for future projects and research in the field.