Assessment of truss-based modular structures in the wingbox structural design of commercial aircraft

Disruptive projects and technologies have been presented with the aim of improving and reducing structural weight during aircraft design. With the replacement of fossil fuel by electric propulsive systems, and consequently with the removal of fuel tanks from the wing's inner structure, it is possible to rethink and develop new ways to optimize and reduce its weight. Therefore, based on the Common Research Model's wingbox, this work aims to showcase the effectiveness of a truss-based inner structure in fulfilling this objective in commercial aircraft, bringing a new structural design approach, where the conventional inner structures, such as ribs, spars, and stringers are replaced solely by a truss-based structure, and its joints are represented by mass elements. The static analysis of the structure is performed using a solver with NASTRAN, which in turn is integrated into a particle swarm optimization that will optimize the design variables of the optimization problem. Design variables include the outer radius and thickness of each truss element of the structural mesh. The possibility of removing unnecessary elements is also evaluated, while still ensuring the minimum aerodynamic profile necessary to form the wing. The wingbox structure is then optimized in search of the lowest structural weight considering stress constraints. The results, verified by a buckling post-analysis, show that truss-based modular structures can be a good strategy in structural wing designs, in terms of modularity and reduction of weight.