Effect of Different Test Setup Configurations on the Identification of Modal Parameters from Digital Image Correlation

Over the past few years, the application fields for digital image correlation (DIC) have significantly broadened and are now extensively used not only for material characterization and deformation analysis but also for vibration and dynamic testing. The key advantage over more traditional technologies such as accelerometer- or laser-based measurement is the fact that all points of interest can be measured at once or over a limited number of repetitions without mass loading the structure or having to deal with complex cabling scenarios. While qualitative analysis, such as operational deflection shapes, proved to be very successful and straightforward, performing classical modal analysis on frequency response functions between a load cell signal and the deformations obtained by applying digital image correlation still requires extra care when setting up the experiments. In this paper, the effect of different cameras, camera settings, excitation levels, and speckle pattern on the modal parameters of a simple plate structure will be investigated and compared with classical acceleration measurement. The results will also be compared with numerical simulations where the accuracy of the mode shapes can be easily and quantitatively assessed.