MSc Thesis Defense: Emre YILDIRIM, DEVELOPMENT AND EXPERIMENTAL VALIDATION OF A NOVEL SHAPE SENSING STRATEGY FOR COMPOSITE AIRCRAFT WINGS USING INVERSE FINITE ELEMENT METHOD AND FBG SENSORS
DEVELOPMENT AND EXPERIMENTAL VALIDATION OF A NOVEL SHAPE SENSING STRATEGY FOR COMPOSITE AIRCRAFT WINGS USING INVERSE FINITE ELEMENT METHOD AND FBG SENSORS
Emre YILDIRIM
Manufacturing Engineering, MSc. Thesis, 2025
Thesis Jury
Assoc. Prof. Adnan Kefal (Thesis Supervisor)
Asst. Prof. Dr. Bekir Dizman
Prof. Dr. Ahmet Ergin
Date & Time: December 18th, 2025 – 02:30 PM
Place: FENS L062
Keywords : Aircraft wing, fiber-reinforced composite, single sensor based inverse finite element method (SSB-iFEM), experimental mechanics, shape sensing
Abstract
A single sensor based inverse finite element method (iFEM) framework is developed and experimentally validated for the real-time deformation reconstruction of a complex, tapered composite aircraft wing with an airfoil cross-section. The shape-sensing capabilities of this framework are validated using both numerical modeling and experimental strain data. The approach utilizes an enhanced iFEM formulation capable of modeling the complex, non-prismatic geometry of an airfoil, which is a significant advancement over simplified beam models. A key novelty of this methodology is the use of a sparse instrumentation network with Fiber Bragg Grating (FBG) sensors located on only a single surface, which addresses a critical implementation barrier of traditional back-to-back sensor configurations. The structural analysis utilized a hollow NACA 64010 profile, which was deliberately selected to provide large, measurable deflections to rigorously test the sparse, single-sided formulation. The high accuracy of a high-fidelity Finite Element Model (FEM) was first successfully demonstrated by comparing its strain predictions to experimental measurements, thereby establishing it as a reference. Then, the predictive capabilities of the iFEM framework were explored on the manufactured composite wing using the experimental FBG strain measurements from two distinct static load scenarios: Load-I (pure bending) and Load-II (coupled bending-torsion). The quantitative comparison revealed an exceptionally high level of accuracy, with reconstructed maximum deflection errors averaging only 0.6% for the pure bending case and 2.0% for the complex bending-torsion case. Finally, the demonstrated robustness of the single sensor based iFEM, even when extrapolating over a significant, un-instrumented region of the wing, validates its potential as a practical and intelligent structural monitoring solution for next-generation aircraft.