Structural optimization of composite aircraft wing considering fluid–structure interaction and damage tolerance assessment using continuum damage mechanics

This study proposes a physics-based conceptual design methodology for composite aircraft, integrating conceptual aircraft design (CAD) with multiobjective and multidisciplinary design optimization (MOMDO). Furthermore, to ensure damage-tolerant design, damage effects on the optimal design are evaluated using continuum damage mechanics (CDM). Correction factors for wing weight and drag coefficient are introduced in the CAD phase to represent performance improvements achieved through composite materials. These factors are then refined using response surface methods to ensure consistency between CAD and MOMDO results. In MOMDO, the material properties of composites are estimated based on a fiber/resin-scale analysis. Subsequently, through a fluid–structure interaction analysis, the wing planform and airfoil shape are optimized to minimize wing weight and drag coefficient. As a case study, the proposed methodology is applied to a Boeing 737-class mission with carbon-fiber/epoxy composites, yielding correction factors of 0.97 and 0.81 for wing weight and drag coefficient, respectively. CDM-based evaluation of the optimal design reveals that while transverse cracking has limited impact, stiffness degradation owing to fiber breakage is critical. Additionally, the effects of damage are found to be sensitive to the wing geometry.