Buckling performance optimization of sub-stiffened composite panels with straight and curvilinear sub-stiffeners

This paper studies the buckling behavior of T-shaped composite stiffened panels reinforced by both straight and curvilinear sub-stiffening configurations subjected to compression. First, the simulated buckling response of the T-shaped stiffened composite panel is verified with experimental results from the existing literature. Subsequently, straight and curvilinear I-shaped sub-stiffeners are introduced into the design of the T-shaped stiffened composite panel. The distribution and laminate stacking sequence of straight and curvilinear sub-stiffened composite panels are optimized to improve buckling performance while maintaining a constant weight constraint. Further, a parametric analysis was implemented to assess the influence of the sub-stiffener curvature on the buckling response of the curvilinear grid sub-stiffened composite panel. Results demonstrate that introducing straight and curvilinear grid sub-stiffeners into the T-shaped stiffened composite panel improves buckling performance. Specifically, the introduction of straight sub-stiffeners results in a remarkable improvement of up to 200% in buckling performance, while introducing curvilinear grid sub-stiffeners exhibits an even more noteworthy improvement of up to 260%, which shows the superior design of curvilinear grid sub-stiffeners when compared to straight sub-stiffeners. This investigation delivers valuable insights into the design of sub-stiffened composite panels for improving structural performance, offering significant advantages for industries such as aerospace that require lightweight structures yet are resistant to buckling.