사각탱크를 구성하는 탄성판의 진동특성

Abstract

Rectangular tanks in contact with fluid are used in various fields of civil, mechanical and marine engineering. Especially in the marine engineering, resonance from exciting force of an engine and propeller causes fatigue damages of tanks. Vibration characteristics of these tanks in contact with fluid are significantly affected by added mass of fluid. Therefore, it is very important to estimate the added mass effect to predict vibration of the tank structures. However, it is difficult to estimate exactly the effect of added mass because of a fluid-structure interaction problem, free surface, vibration modes of structural panels and the depth of water. Rectangular and cylindrical tanks in contact with fluid have been studied by Chiba(2000) and etc(2000). Bae(2003) analyzed the plates using FEM(finite element method) and fluid region using BEM(boundary element method). Lakis(2008) experimented two cases. One case is the horizontal plate and another is the perpendicular plate. Bae(2010) analyzed a various of tanks which are the same length and height. He changed breadth, thickness, water level, and boundary conditions. The goal of this paper is to compare one tank with 2-bay tank to find out different characteristics of the tanks. Each vibration mode of panels is calculated to consider structural coupling effects between side plates of a deep 2-bay tank and added mass changing the breadth, thickness, and boundary condition of the tank. A numerical tool using finite elements in plates and boundary elements in fluid region is used to analyse the three dimensional tank structure in contact with fluid.