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  • Experimental modal analysis...
    Javh, Jaka; Slavič, Janko; Boltežar, Miha

    Journal of sound and vibration, 11/2018, Volume: 434
    Journal Article

    High-speed camera measurements are increasingly being used in modal analysis to instantaneously measure full-field structural responses by extracting the displacement information from images using digital-image-correlation and other optical-flow methods. High-speed cameras capable of filming full frame at high frame rates can be very expensive and produce image resolutions of only approximately 1 mega pixel, which is why this research aims at measuring and identifying the full-field response using cheaper, still-frame cameras with a higher image and intensity resolution, such as digital single-lens reflex (DSLR) and mirrorless cameras. Using spectral optical flow imaging (SOFI) full-field operational shapes can be acquired using still-frame cameras. This study demonstrates the hybrid modal-parameter identification of full-field mode shapes using an accelerometer and a DSLR camera for responses far above the DSLR camera's frame rate (demonstrated up to 1 kHz). Display omitted •Spectral Optical Flow Imaging (SOFI) is used to measure full-field dynamic responses.•Using SOFI, responses up to 1000 Hz were measured with a consumer DSLR camera.•Apparent motion between frames was discovered, likely caused by the shutter.•Due to the mechanical shutter operation, video was shot instead of separate frames.•A hybrid modal parameter identification combining SOFI and a point sensor is introduced.