Overview
This project focused on the structural characterisation of a carbon fibre reinforced polymer (CFRP) wing section intended for a UAV platform. The goal was to validate the design against FAR 23-equivalent load cases and identify mass reduction opportunities without compromising structural margins.
Methodology
Geometry was authored in CATIA V5 and imported into ANSYS Mechanical, where layered shell elements represented the ply-by-ply laminate architecture. Load cases included:
- +2.5g positive limit load (pull-up manoeuvre)
- −1.0g negative limit load (pushover)
- Combined torsion and bending (asymmetric gust loading per CS-23 Annex F)
Material properties were derived from coupon-level tensile and interlaminar shear testing, with knockdown factors applied per ECSS-E-HB-32-20.
Optimisation Study
A parametric study varied fibre orientation angles [0° / ±45° / 90°] and ply count across seven spanwise zones. The Tsai–Wu failure criterion was applied throughout. The final optimised layup achieved:
- 19.4% mass reduction versus the baseline symmetric laminate
- All Tsai–Wu failure indices < 0.72 at limit load (requirement: < 1.0)
- First linear buckling eigenvalue: 2.31× (requirement: ≥ 1.5×)
- Tip deflection within certification envelope at all load cases
Critical Design Drivers
Ply drop-off regions emerged as the primary design constraint — stress concentrations at thickness transitions required local reinforcement doublers, partially offsetting the global mass savings achieved through the layup optimisation. Bond line shear in the spar-cap joints was a secondary concern addressed by increased overlap length.
Tools Used
ANSYS Mechanical (FEA), CATIA V5 (geometry), Python (post-processing and automated report generation)
Reflections
Future work should explore topology optimisation of the internal rib structure and investigate the use of tow-steered AFP layups to further tailor stiffness distribution along the span.