On the Vertical Vibration of Elastic Bodies Immersed in Water : A Note on the Method of Calculation of Ship Hull Vibration

Abstract

This paper presents a calculation method of natural frequencies of an elastic body vibrating in water. In the analysis using added virtual mass, it is necessary to use the actual mode shape in order to estimate accurately the added virtual mass. In this paper, the modified J-values for ellipsoid of revolution, circular cylinder and elliptical cylinder are derived by using actual mode shapes obtained from experiments. Calculated natural frequecies obtained by this method are in good agreement with those by model tests. Furthermore, another calculation method on coupled vibration of an elastic body and water is presented using the Rayleigh-Ritz method. This method is shown to be an effective tool for the analysis of flexural vibration of an elastic body immersed in water with a high accuracy.