有限要素法と境界要素法を用いた防橈板の接水振動解析 : 2次元モデルによる防橈材の付加水質量効果

抄録

Recently demand for suppression of vibration in ship structures has increased for amenity and prevention from fatigue damage. Therefore it is very important to predict vibration characteristics of ship structures precisely in advance. Ship structures are in contact with both inner and outer fluid and then added mass effect due to such fluid has to be taken into consideration in vibration analysis. Inner structures of hull module which are contacted with water are so complicated that it may be difficult to analyze the vibration characteristics, especially because transrings, girders and stiffeners are thin walled structures and immersed in water inside of ballast tanks. In this study, two dimensional numerical analysis of natural vibration of stiffened plate in contact with inner fluid is carried out. In order to extend this analysis for three dimensional problem of real hull module easily, boundary element method has been applied to the fluid region and finite element method has been used for the structure region. And interface model to determine the interaction between structure and fluid has been proposed. The numerical results have been proved to be reasonable. Two dimensional vibration problem of stiffened plate with one stiffener has been analyzed and the effect of added mass of water around the stiffener and the region of fluid which affects natural frequencies has been discussed showing natural frequencies, vibration mode configurations and pressure distribution modes. The formulation described here is thought to be able to be extended for three dimensional problem without much difficulty and the analysis is planed to be executed in the succeeding study.