Aeroelastic Behavior of Chiral Lattice Airfoils: Experimental and Finite Element Analysis Assessment of Passive Morphing under Aerodynamic Loading

open_access
Open Access
Author:
Ghabashi, Riyad
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Tamy Guimaraes, Thesis Supervisor
Margaret Louise Byron, Thesis Honors Advisor
Keywords:
passive morphing
reconfigurable structures
aeroelastic response
additive manufacturing
Metamaterials
passive morphing
reconfigurable structures
aeroelastic response
additive manufacturing
Abstract:
Morphing airfoils offer a promising pathway toward improving aerodynamic efficiency by allowing controlled shape change under varying flow conditions. Unlike conventional rigid airfoils, morphing structures can respond to aerodynamic loading through structural deformation. This thesis investigates the influence of chiral lattice core structure on the passive morphing behavior of airfoils, with emphasis on the relationship between structural compliance and aerodynamic performance. Two hexachiral lattice configurations with ligament-to-node ratios of L/R = 0.6 and L/R = 0.9 were designed and integrated into a scaled Eppler 420 airfoil geometry. Rigid-core airfoils fabricated from PLA and TPU were also produced to serve as baseline references. All specimens were manufactured using additive manufacturing techniques. Structural behavior is examined through FEA point-load simulations to assess compliance and deformation trends under concentrated loading. Aerodynamic performance is evaluated experimentally in a wind tunnel using a custom-built force balance to measure lift and drag at zero angle of attack (AoA) across a range of freestream velocities. The results demonstrate that lattice topology influences both structural and aerodynamic responses. While point-load simulations indicate that the lower-density L/R = 0.9 lattice is more compliant under localized loading, wind-tunnel measurements, on the other hand, show higher lift generation for the L/R = 0.6 configuration. This apparent mismatch highlights the distinction between local structural compliance and global flow-induced deformation. It further motivates the need to consider relative density normalization when comparing structural and aerodynamic trends, as differences in lattice density can lead to contrasting interpretations of compliance depending on the loading condition. Addressing this distinction is essential for forming clearer connections between point-load simulations and wind-tunnel measurements. Overall, this work shows that passive lattice structures alone can meaningfully influence aerodynamic behavior, even at small geometric scales. This thesis establishes a framework for interpreting how lattice geometry affects deformation and lift generation. The findings provide a validated baseline for future studies focused on density-normalized lattice designs, improved geometric scaling, and the eventual integration of active morphing mechanisms.