Lightweight optimization of locally reinforced sandwich cell units in air rudders under thermo-mechanical coupling

Hypersonic vehicles operate under severe aerodynamic-thermal coupled loading conditions during flight. The air rudder, as a key component for attitude control, is also subjected to significant aerothermal loads and therefore requires both high stiffness and lightweight characteristics. In this study, a unit cell of the air-rudder sandwich structure is selected as the research object. Structural parameter analysis under thermo-mechanical coupling is conducted, and a radial basis function surrogate model is then constructed, and the pointer algorithm is employed for structural optimization to reveal the interaction mechanisms among structural parameters. Results indicate that the skin thickness is the key parameter controlling deformation resistance. Increasing the skin thickness improves the cell stiffness and enhances the cooperative effects of variables such as radial ribs. As the projected cell area increases, the coupling effect among structural parameters becomes stronger. The optimized cellular configurations obtained under five constraint conditions validate these findings. Different performance objectives correspond to distinct optimal designs, achieving a weight reduction of 8.25%-28.29% while maintaining deformation resistance, thereby providing a basis for further high-performance design of air-rudder sandwich structures.