The design method of ultra-long pressure-resistant ring-stiffened cylindrical shells based on variable stiffness basic unit

Objective This study aims to enhance the mechanical properties and lightweight level of ultra-long pressure-resistant ring-stiffened cylindrical shell structures and address the optimization design challenges of ring-stiffened cylindrical shells under large length-to-diameter ratios.

Methods The mechanical properties of ring-stiffened cylindrical shells under different length-to-diameter ratios were analyzed by combining theoretical and finite element methods. The equal stiffness cylindrical shell was optimized using an optimization algorithm, and a rational adjustment strategy for characteristic stress limit values was proposed. Based on the optimization scheme of the equal stiffness cylindrical shell, a variable stiffness cylindrical shell with a length-to-diameter ratio of 5 was designed and used as a basic unit to propose a design method for ultra-long ring-stiffened cylindrical shells based on the variable stiffness basic unit.

Results The constructed design scheme for the ultra-long ring-stiffened cylindrical shell achieved an average overall weight reduction of 1.07% compared with the equal-stiffness lightweight scheme, while the critical pressure for global instability increased by 1.49% on average.

Conclusions The proposed construction method based on the variable stiffness basic unit is simple and fast, providing a useful reference for the lightweight design of ultra-long ring-stiffened cylindrical shell structures.