Hydrodynamic damping enhancement by implementing a novel combined rigid-elastic heave plate

Heave plates are structural components used for reducing the vibrations caused by environmental forces on marine and offshore structures by changing the hydrodynamic properties. The fact that the added mass increase via heave plates does not always lead to the structural response reduction underscores the role of damping in maintaining the vibration amplitude within allowable limits. In the present experimental study, a novel combined rigid-elastic design is used to improve the damping through the velocity increase in the elastic part and added mass creation in the central rigid part. The desired percentage of total added mass and damping can be adjusted by changing the rigid-to-elastic parts diameter ratio, which is the main scope of this experimental research. Frequency of vibration, which affects the elastic edge excited mode shapes, also affects the forming of the vortex shedding. Experimental tests show that the frequency increase generally causes high damping performance provided that the excited mode shapes are axisymmetric, which strongly depends on equivalent stiffness and mass.