Classically, inertial measurements (accelerometer and gyroscope signals) or optical methods (DIC, SDIC, or LDV) have been used to monitor the structural response of flexible structures under fluid loads. Unfortunately, these methods are hampered by non-harmonic motions (in the former case) and by a lack of clear optical access (in the former).
It is therefore desirable to have, as experimentalists, a robust tool to monitor the deformations of flexible aerospace and marine structures under arbitrary loading conditions and under testing conditions that may preclude line-of-sight – such as in multi-phase flows.
I designed, built, and validated an original sensor for inferring 3D deformations on wing-like structures. The sensors are low-cost, simple to build, and field-replaceable/repairable. Shape sensing is performed using simple polynomial fitting and integration, and can run in real time (at rates of ~100 Hz).
The sensors have been used in my flexible hydrofoil experiments to measure static and dynamic motions, and to perform on-line mode-shape identification.
By providing accurate inferences of static and dynamic deflections of flexible lifting surfaces, the sensors provide reliable access to data not previously available outside of ideal laboratory enviornments.
Future applications include real-time monitoring of time-domain and modal responses of marine lifting surfaces, aerospace structures, and propeller blades.