Video-based operational modal analysis of slender mechanical structures with neutral axis estimation via barycenter calculation

International audience ; This paper presents an innovative adaptation of Operational Modal Analysis (OMA) by employing the concept of the barycenter to analyze dynamic behaviors in mechanical systems through video signal processing. Although this method is framed as a new contribution to the field of modal analysis, it is essential to recognize that its applicability is primarily confined to slender structures. Unlike conventional OMA methods reliant on numerical simulations or accelerometer measurements, this technique presents a non-contact, non-invasive measurement approach. It simultaneously captures multiple points across a wide field of view, ensuring robust measurements. The methodology was tested on a cantilever beam exposed to white Gaussian noise, with the beam recorded at 2048 frames per second to capture its dynamic response. The high-contrast environment facilitated image processing, while Laser Doppler Vibrometry (LDV) measurements served as a reference for validating the results. The proposed video-based OMA methodology demonstrated promising accuracy in capturing the system's dynamic behaviour by providing a more accessible and efficient alternative to traditional OMA techniques. Additionally, an analysis of the robustness of results concerning lighting conditions and video noise is conducted, along with a discussion on algorithmic complexity. Refinement of image processing algorithms and a broader application of this methodology to various mechanical systems and structures are proposed as important future objectives.