Sensitivity analysis of the aeroelastic stability of a composite wing-box with uncertain material properties

Global sensitivity analysis is undertaken for the aeroelastic stability of a composite wing in order to assess sensitivity to uncertain material properties. The wing is idealised as a thin-walled beam. A Gaussian process is fitted to aeroelastic instabily speed using Bayesian inference, and used as an emulator which may be run with considerably less computational effort. Multiple emulators are required because the critical instability speed is non-smooth. Uncertainties are introduced to the ply orientations and moduli of the upper and lower flanges of the beam, and 'lamination parameters' are used to prevent the input dimension from growing with the number of plies. Sensitivity indices are determined using Monte Carlo integration. Results show that uncertainty in ply orientation typically contributes significantly to the output variance; however, uncertainty cannot be neglected in the other inputs since the instability speed is highly sensitive to different moduli for different layups.