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Abstract
This thesis experimentally investigates the vortex-induced vibrations (VIV) of a flexible cylinder mounted horizontally in uniform cross-flow with fixed-fixed boundary conditions. All experiments are conducted in a high-speed water tunnel. A spring steel beam is embedded within the silicone cylinder, promoting a response primarily in the cross-flow direction. The test article has an aspect ratio equal to 31.02, a mass ratio of approximately 1.6, and is tested with Reynolds number ranging from 2,850 to 19,000. Particular emphasis is placed on investigating the dynamic response at vortex shedding frequencies beyond the cylinder’s fundamental natural frequency. Excitation pertaining to key lock-in events, intermittent amplitude switching, and multi-frequency contributions is studied. Finally, the influence of hysteresis on the lock-in duration and higher-order harmonics is discussed.