Theoretical and experimental study on dynamic characteristics of V-shaped beams immersed in viscous fluids: From small to finite amplitude

In this paper, an underwater vibration model is developed to depict the dynamic characteristic of V-shaped beams for both small and finite amplitude vibrations by considering the fluid-structure interactions between the complicated geometry and viscous fluids. The gap to width ratio in beam's cross-section is introduced to describe the geometry of the V-shaped beam. For small amplitude vibrations, a complex hydrodynamic function in terms of the gap to width ratio and the frequency parameter is presented to characterize the fluid-structure interactions according to the 2-D fluid dynamics simulations. Besides, a 3-D numerical simulation is performed to verify the proposed computational approach and hydrodynamic function in the 2-D analysis. As the vibration amplitude increases, the 2-D fluid dynamics simulations are further conducted to investigate the effects of amplitude parameter on the flow physics. Therefore, a revised hydrodynamic function governed by the interplay of the frequency parameter, the gap to width ratio and the amplitude parameter is presented to model the hydrodynamic force for finite vibration amplitude accounting for nonlinear damping effects. Moreover, the experimental verifications on both small and finite amplitude vibrations of several V-shaped beams with different geometrical sizes are carried out. It illustrates that the presented model is capable of capturing the nonlinear damping phenomenon occurred at finite oscillation amplitudes and is generally able to predict the underwater vibrations of V-shaped beams with both small and finite amplitude.