Ground Calibration and Airborne Physical-Consistency Assessment of Composite-Wing Sectional Loads Using Fiber Bragg Grating Sensors

This study develops a fiber Bragg grating (FBG)-based method for identifying sectional loads on a full-scale RX1E-A composite aircraft wing. Thirty-two load-sensitive FBGs were installed at four spanwise sections. Multi-case ground loading with different spanwise distributions and chordwise positions was used to generate coupled combinations of bending moment, shear force, and torque. Multichannel linear models were calibrated using 89 measured samples from Cases 1 to 9 and independently evaluated using interpolation-oriented Cases 10–11 and limited-extrapolation Cases 12–13. Electrical strain gauges were used only for auxiliary ground-response comparison. The calibration NRMSE ranges were 0.454–1.087% for bending moment, 1.213–3.351% for shear force, and 0.526–1.306% for torque. Across the independent cases, the maximum section-level NRMSEs were 1.949%, 7.251%, and 2.484%. The fixed models were subsequently applied to a nominally identical flight-test wing without airborne refitting. During a pull-up maneuver with a maximum normal load factor of 2.058, the reconstructed bending-moment and shear-force increments exhibited continuous responses, extrema close to the load-factor peak, and a physically reasonable decrease from the wing root toward the tip.