Vibration of ring-stiffened circular cylinders under external water pressure

The paper describes a theoretical and an experimental investigation into the free vibration of three ring-stiffened circular cylinders subjected to various values of uniform external pressure. The experimental procedure involved a novel device, which was suitable for ferrous metals. The theoretical method involved the finite element method for both the structure and the fluid, where in the case of the latter, the wave equation was solved. The results showed that the resonant frequencies decreased with increasing values of external pressure, especially when the vibration eigenmode had the same shape as the static buckling mode.