Abstract
The outstanding obstacle to estimate vibration level is, it is well known, that the precise damping of fluid and structure can not be estimated because the mechanism of the damping is not explicated. Therefore it is necessary to investigate the phenomena of damping caused by fluid viscosity, and the authors proposed a theory of added damping matrix based on dissipation energy caused by fluid viscosity. To verify the validity of the damping matrix, more experimental data was necessary.
In this paper, some experiments on the dependency of dissipation energy on vibrational displacement are shown, and the important result, which we may approximate the damping of fluid to linear damping matrix in the vibration problem, is verified. Comparing some calculations and experiments, the following are declared. In case of infinite depth of water, using ν (kinematic viscosity coefficient) as νω (virtual kinematic viscosity coefficient), the calculation and experimental results agree well on the dissipation energy, in the result νω is not so important. In case of shallow water, νω must be used, and if νω estimated from the dissipation energy by experiment is used, the frequency response curve can be reproduced.
