A Hydroelastic Approach to Ship Vibration Problems

Abstract

A procedure is presented to determine the vibration frequencies and mode shapes of submerged structures. Hamilton's principle is used to formulate the problem, and general sequences of trial functions are introduced to permit the direct extremization of the corresponding energy functional. The fluid-structure interaction is accounted for by restricting the trial functions of the fluid to represent the flow around the immersed body imposed by each trial function of the structure. The trial functions for the fluid are built up from the contributions of triangular constant source elements distributed over the wetted surface of the structure, the accuracy of which in representing a flow is tested on an accelerated sphere. The structure is modeled with finite elements. The accuracy of the hydroelastic procedure is accessed on two examples as compared to experimental data: a cantilever plate and a freely floating ship.