Fiber-Optics-Based Aeroelastic Shape Sensing

This paper presents a numerical and experimental wind tunnel study of aeroelastic shape sensing using fiber-optic sensors. Strain measurements via both discrete and distributed dynamic fiber-optic sensing technologies were used to estimate a wing's deformed shape and modal displacements using a strain-to-displacement transformation algorithm. The performance of the fiber-optic sensors and the algorithm were tested in a set of validation tests, in which the displacement response to static loads and to initial conditions was recovered and compared with that from a reference motion tracking cameras system. Excellent match of the responses validated the capabilities of the sensing configuration. The wing was tested in the wind tunnel in static conditions as well as in dynamic conditions close to and at flutter. Fiber-optics strains data were used to recover the deformed shape at static conditions, which was compared with that from aeroelastic analysis. At flutter, strain data were used to compute the wing's dynamic response and extract the flutter speed, frequency, and complex flutter mode. These were compared with aeroelastic flutter analysis and were found to be in good agreement. Overall, the study has experimentally demonstrated that strain-based aeroelastic shape sensing, both static and dynamic, is feasible and provides accurate deformations and modal responses even when based on sparse strain measurements, and when the modes used for the strain-to-displacement transformation are not the exact eigenmodes of the aeroelastic system.