Design optimization for the entire aircraft structure of civil aircraft with blended-wing-body layout

The Blended-Wing-Body (BWB) layout represents an innovative subsonic transport aircraft design. Drawing inspiration from the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) proposed by National Aeronautics and Space Administration (NASA), this study focuses on a design optimization for the entire structure of a BWB civil aircraft. A PRSEUS-based finite element model was established and subjected to a static analysis. The results indicate a considerable structural strength margin, suggesting potential for lightweight design advancements. Meanwhile, the structural region division techniques were adopted to analyze the sensitivity of the BWB aircraft structure and to sort the parameters affecting its mass. Subsequently, seven surrogate modeling techniques were employed to train a surrogate model for the BWB aircraft structure to analyze the primary factors affecting its prediction accuracy. Among various modeling approaches, the optimal heuristic computation (ES) method demonstrates superior prediction accuracy and enhances the efficiency of optimal solution searches, resulting in a 18.45% mass reduction in the optimized BWB civil aircraft structure. Based on the optimization results of the ES model, a dual-loop optimization strategy was proposed by considering the vibration effects on the BWB aircraft. This strategy facilitates the optimization of the dimensional parameters of the BWB aircraft structure, resulting in substantial 17.83% increase in the first-order natural frequency of the optimized structure. After two rounds of optimization, the mass of the optimized BWB aircraft structure accounted for only 25% of the maximum takeoff mass. Consequently, the proposed optimization strategies present robust applicability and high efficiency, providing a valuable reference for designers and researchers in related fields.