Digital Image Correlation for High-Speed Flywheels

The objective of the present work is to evaluate the suitability of using 3D digital image correlation (DIC) for measuring strains on high-speed flywheels. A two-camera DIC setup was used to characterize the effect of image blur on de-correlation and to measure strains on the surface of three 32-cm diameter plastic disks rotating in air at low speeds (2,000 rpm). In one set of experiments, images were taken at different exposure times to characterize the effect of image blur on de-correlation. It was established that the DIC algorithm yielded errors in strain measurement with approximately ten pixels of image blur. This result serves to establish performance requirements for imaging hardware, scalable to higher rotor speeds. In other sets of experiments, strains were measured on the surface of discs. Measured strains compare well with analytical and finite element analyses.