Flying-wing aircraft, typified by the X-56A, experience flutter due to both an instability inherent to tailless configurations and the necessity for aerodynamically efficient high-aspect-ratio wings. Seeking to reduce the barriers to entry for testing flutter-suppression technologies for these aircraft within the controlled environment of wind-tunnel testing, a three-dimensionally printed wind-tunnel flutter model was developed. Leveraging advantages in stiffness control over traditional fabrication techniques through multimaterial three-dimensional printing, the model demonstrated that conventional internal topologies can be achieved while still achieving a predictable flutter response within the limitations of a low-speed wind tunnel. A case study via aeroelastic analysis identified a valid half-span model design. Fabrication challenges including discontinuous stiffness requirements and part sizes larger than available printer build-tray dimensions were overcome via novel techniques that maintained the desired modal response. Specifically, repetitive interpenetrating fastening features eliminated the need for traditional fasteners and elastomeric breaks maintained a continuous aerodynamic surface despite discontinuous stiffness requirements. The model, as fabricated, showed good agreement with the predicted values via a modal assurance criterion of greater than 0.89 for the first three modes and a flutter speed within 15% of the predicted value, realizing the first fully three-dimensionally printed wind-tunnel flutter model.
Multi-Material Printed Wind-Tunnel Flutter Model
AIAA Journal ; 56 , 2 ; 793-807
2017-10-31
15 pages
Article (Journal)
Electronic Resource
English
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