Uncertainty Quantification in Modal Shape Sensing of a High-Aspect-Ratio Wing

Kurzfassung

Shape sensing based on strain measurements is a promising approach for monitoring flexible aircraft structures when direct displacement measurements are not available. Modal shape sensing using experimentally identified mode shapes is particularly attractive for aeroelastic applications, since it captures real boundary conditions and operational effects more realistically than numerical models. Experimentally identified mode shapes are however affected by measurement noise and operational variability, introducing uncertainty into the displacement reconstruction. This work investigates how uncertainties in measured strains and identified mode shapes propagate into modal shape sensing estimates for a 5 m high-aspect-ratio wing-like structure. Experimental investigations are conducted on the test specimen under two different loading configurations: force-controlled loading using a compliant actuation chain and static loading by added tip masses. Experimentally identified modes are used for displacement reconstruction, and analytical uncertainty propagation methods are applied to quantify the resulting displacement estimation uncertainty. The results show that displacement reconstruction errors below 2 % can be achieved at the wing tip. While strain measurement uncertainty is negligible for the investigated setup, variability in the identified mode shapes significantly affects reconstruction reliability, if short measurement durations are used in the modal identification.