MS Plan A Defense: Experimental Investigation of Thin-Walled Cylindrical Cantilever Beams Undergoing Vortex-Induced Vibrations

Clara Encke
Master’s Student
Department of Ocean and Resources Engineering
University of Hawai’i at Mānoa

**This defense will be held both in person (POST 723) and over Zoom**
Meeting ID: 989 0662 3277
Passcode: ClaraMS
https://hawaii.zoom.us/j/98906623277

In this study, we experimentally investigate the dynamic response of three low mass ratio hollow cylindrical cantilever beams experiencing vortex-induced vibrations. We conducted experiments using three polycarbonate cylinders with low mass ratios of 0.761, 0.830 and 0.922, respectively. Motion analysis was performed using two high-speed cameras, and motion tracking was facilitated by UV lights for better image quality. Our findings indicate that the IL: CF frequency ratios conform to the conventional 2:1 frequency ratio. However, we also observed 1:1 and 3:1 frequency ratios at low and high reduced velocities. These were accompanied by predominantly small positive and negative lift coefficients in phase with velocity values. The amplitude response aligns with previous literature, although our study reveals that the in-line amplitudes reach higher values due to the cylinders’ low mass and damping ratios. We also observed that both cylinders exhibited higher in-line amplitudes at reduced velocities below 3. The results of this study provide important insights for optimizing the design and performance of cylindrical offshore structures.