Laser vibrometry and videogrammetry are two techniques suitable for testing large, low mass flexible structures. Laser vibrometry is a mature technology while videogrammetry is a relatively new non-contact measurement technology. This paper demonstrates the potential for using videogrammetry as a tool for modal identification of membrane structures. For this study a 2-m, four-quadrant solar sail model was used. First, a comparison between a two-camera, 1008 x 1018 pixel videogrammetry system and a scanning laser vibrometer is presented. Modes between 1-5 Hz are identified for one quadrant of the 2-m solar sail model. The two techniques yield similar shapes for five modes. Second, whole field measurements are presented and used to quantify the measurement uncertainty. For this videogrammetry system, the measurement precision was approximately 0.02 mm. Thus, to achieve good signal to noise it is desirable to have at least 2 mm of motion at all measurement points on the 2 m sail. Finally, full field measurements of the static shape of the sail membrane are presented.
Modal identification of membrane structures with videogrammetry and laser vibrometry
2003
11 Seiten, 10 Quellen
Conference paper
English
Modal Identification of Membrane Structures with Videogrammetry and Laser Vibrometry
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