High-Frequency Modal Analysis via Low-Speed DIC: Mitigation of Harmonic Peaks in the FRF

Digital Image Correlation (DIC) is a technique that has seen a growth in popularity for use in modal analysis, due to its full-field, non-contact measurement capabilities. Recent developments in the field are focused on achieving reliable data acquisition at rates of up to 1 kHz using cost effective configurations. This study explores the potential of using a low-speed stereo camera configuration to assess the vibrational response of a structure. A previously implemented technique, which reconstructs down-sampled data collected by time-shifting the trigger of a stereo-camera system [1], resulted in the introduction of harmonic peaks in the frequency response function (FRF) of the test specimen. To identify the underlying causes, a detailed analysis was performed using an exclusionbased approach. In contrast to the prior method, a novel technique was developed to collect down-sampled data by temporally displacing the force signal while maintaining a constant camera acquisition frequency. Preliminary results indicate the need for further investigation, and post-processing algorithms were evaluated to mitigate harmonic peaks, of which the Cepstral filter demonstrated successful attenuation.