Additive Manufacturing Process-Induced Wing Skin Deformation and Effects on Aerodynamic Performance

Abstract

The objective of this study is to characterize the trade space for the structural design of small uncrewed aerial vehicle wings fabricated using Material Extrusion Additive Manufacturing, specifically the trade-off between maintaining the wing external shape while minimizing its internal structure. Beam bending analysis shows that the structural requirements associated with flight loads are easily met with a single perimeter extrusion monocoque construction, however this approach leads to large, unsupported, thin-walled structures that can deform during the build process, creating a potential need for additional structure to maintain wing shape. To characterize the relationship between structure/weight and wing deformation, wing sections were fabricated with varying internal structures for two airfoil shapes. Weight and 3-D laser measurements were taken of the printed parts to capture the final as-built geometry. The as-built geometries were then compared to the as-designed geometries to quantify the deformation, and a coupled viscous-inviscid flow solver was used to determine the aerodynamic effects. The results indicate that while significant aerodynamic performance penalties exist for the monocoque construction, a small amount of well-placed internal structure provides sufficient improvement at minimal weight penalty. Results also showed that less internal structure is required to minimize deformation for an airfoil with larger initial curvature.