RESEARCH ON PREDICTION & PREVENTION OF VIBRATION IN STRUCTURES IN CONTACT WITH WATER

大型水下壳体结构可作为LNG储罐和海洋研究实验室。我们已经对未来这种新结构进行了部分可行性研究。由于抗静水压力的强度，水下壳体结构的形状是轴对称的。由于我国地震频发，我们特别关注海底结构的动力特性。通过实验和数值分析研究了垂直固定在水平基座上的圆柱壳的动力特性。采用有限元法和边界元法编制了数值分析程序。日本最近发展了高速船舶，以实现交通方式的转变。局部结构与湍急的水流接触，水流诱发振动或不稳定振动会对结构造成破坏。本文研究了与水接触的平板的动力不稳定性。利用开发的数值代码，明确了相对速度的临界速度。

Large underwater shell structures can be used as LNG storage tanks and research laboratories for reserch on oceans. We have performed a part of feasibility study on such new structures in the future. The shape of the underwater shell structures is axisymmetric because of the strength against the hydrostatic pressure. Especially we focused on the dynamic characteristics of the structures under the sea because our country syfers from frequent erthquakes. We examined the dynamic characteristics of a cylindrical shell fixed vertically on a horizontal base by experiments and numerical analysis. Numerical code for the analysis has been developed by use of FEM and BEM.High speed ships have recently developed in Japan for the purpose of traffic modal shift. The local structures are in contact with rapid flow of water and can be damaged by flow induced vibration or unstable vibration. In the present study dynamic instability of a flat plate in contact with water has been studied. We make clear the critical velocity of relative speed by use of developed numerical code.