  In this article, a novel explicit approach for designing complex thin-walled
structures based on the Moving Morphable Component (MMC) method is proposed,
which provides a unified framework to systematically address various design
issues, including topology optimization, reinforced-rib layout optimization,
and sandwich structure design problems. The complexity of thin-walled
structures mainly comes from flexible geometries and the variation of
thickness. On the one hand, the geometric complexity of thin-walled structures
leads to the difficulty in automatically describing material distribution
(e.g., reinforced ribs). On the other hand, thin-walled structures with
different thicknesses require various hypotheses (e.g., Kirchhoff-Love shell
theory and Reissner-Mindlin shell theory) to ensure the precision of structural
responses. Whereas for cases that do not fit the shell hypothesis, the
precision loss of response solutions is nonnegligible in the optimization
process since the accumulation of errors will cause entirely different designs.
Hence, the current article proposes a novel embedded solid component to tackle
these challenges. The geometric constraints that make the components fit to the
curved thin-walled structure are whereby satisfied. Compared with traditional
strategies, the proposed method is free from the limit of shell assumptions of
structural analysis and can achieve optimized designs with clear load
transmission paths at the cost of few design variables and degrees of freedom
for finite element analysis (FEA). Finally, we apply the proposed method to
several representative examples to demonstrate its effectiveness, efficiency,
versatility, and potential to handle complex industrial structures.
