Hybrid optimization of hierarchical stiffened shells based on smeared stiffener method and finite element method

In this study, Smeared Stiffener Method (SSM) of hierarchical stiffened shells is derived to release the prediction burden of buckling loads. Then, a minimum-weight optimization formulation for hierarchical stiffened shells is developed based on SSM, attempting to demonstrate the higher lightweight potential of hierarchical stiffened shells compared to the traditional ones. Further, the main aim of this paper is to present a hybrid optimization framework of hierarchical stiffened shells including imperfection sensitivity, combining the efficiency of SSM with the accuracy of FEM, since there are currently no closed-form solutions to take imperfections into account accurately. The illustrative example demonstrates that the proposed framework has a higher optimization efficiency and global optimization capability compared to the conventional methods.