3D-Printed Sandwich Structures as Aircraft Side Rudders

Sammanfattning

SAAB currently uses sandwich structures in the construction of aircraft rudders. While the existing method performs well, it presents challenges in terms of weight, cost, and producibility. With the rise of additive manufacturing (AM), this thesis investigates how a generic side rudder, lighter or equal in weight to today’s design, can be produced using 3D printing while maintaining structural performance. nTopology, a software tailored for AM, was used to evaluate a wide range of lattice unit cell types through simulations and polymer SLS printing. Several optimization techniques were applied to both the internal lattice and the outer shell. The most promising designs were 3D printed in metal and tested under simulated flight loads. Gyroid and TPMS Diamond were identified as the best-performing structures. The most effective optimization strategy was Field Optimization, which adjusts geometry based on simulation data. The Diamond lattice proved especially suitable due to its symmetry and powder removal capabilities. Testing showed that actual failure loads were significantly higher than predicted, mainly due to limitations in linear simulations that did not capture plastic deformation or stress redistribution. Smaller cells improved buckling resistance and strength. Despite some manufacturing imperfections, optimized prototypes met performance expectations. This work demonstrates the feasibility of using AM for aerospace sandwich structures and serves as a foundation for future work, including the possibility of printing entire rudder or wing sections as single parts, reducing assembly while slightly increasing cost.