Lightweight design of a bolt-flange sealing structure based on topology optimization

To date, sealing structures have been widely used in aerospace vehicles. This paper presents a normalized and systematic procedure realizing lightweight design for a square bolt-flange sealing structure of a rocket engine. To measure the sealing behavior, the contact force on the sealing interface is obtained by a nonlinear analysis of node-to-node contact. The topology optimization is established to achieve sufficient contact forces in the sealing area by acquiring the Kreisselmeier-Steinhauser (KS) function to condense multiple contact force constraints into a global sealing constraint. A three-field projection scheme is also adopted to obtain a clear result and a semi-analytical perturbation scheme is proposed to realize the sensitivity calculation. Then, the square flange cover is optimized by the proposed optimization framework and a lightweight design with a clear load-carrying path is obtained. The optimized design is reconstructed and further optimized in detail. Compared with several traditional designs, it shows better leakproofness under inner liquid pressure, which can be directly fabricated by additive manufacturing and used in the rocket engine. The optimization procedure is proved effective and practical in designing sealing structures for aerospace vehicles.