Research on the analysis of hydro-elastic behavior of a very large mobile offshore structure in waves and its anti-motion

本文主要研究了以下三个方面的内容：1.水动力分析计算机程序的研制对超大型移动式海洋结构物水弹性理论进行了回顾，并编制了计算机程序。这段代码使用p-FFT方法，可以在实际的CPU时间内处理数十种弹性模式和大约100,000个流体动力面板。此外，为了简化结构数据的输入输出和弹性振型的计算，采用了流行的商业程序MSC NASTRAN和MSC PATRAN的结合。开发了这些商业程序与流体力学程序之间的接口。从理论上讲，该程序的特点是保持了结构离散化和水动力离散化的一致性，从而满足兴波阻尼器和振型阻尼器之间的能量守恒。2.计算机程序的验证对程序进行了详细的收敛测试，结果表明该程序具有足够的收敛能力，可以进行足尺结构的计算。利用粘性阻尼器的实验数据，研究了粘性阻尼器的减振效果。将数值计算结果与NIES试验数据进行了比较，结果表明数值计算结果具有足够的精度。3.超大型移动式海洋结构物分析的建立总结了总体结果，提出了VLMOS的概念。利用这一概念对航海和发电进行了仿真。通过仿真验证了本研究提出的方法对超低功耗MOS的概念设计是有效的。

The following 3 topics have been mainly studied.1.Developement of a computer code for the analysis of hydrodynamic behaviorReview of the hydroelastic theory for a very large mobile offshore structure and the development of a computer code have been carried out. This code uses the p-FFT method, which enables to handle dozens of elastic modes with about 100,000 hydrodynamic panels in a practical CPU time. In addition, in order to simplify the input and output of the structural data and elastic modes computation, the combination of MSC NASTRAN and MSC PATRAN, which are popular commercial codes, is used. The interface between these commercial codes and the hydrodynamic code also has been developed. From the theoretical aspect, the code features that the consistency between the structural discretization and the hydrodynamic discretization is maintained so that the energy conservation between the wave making damping and the modal damping is satisfied.2.Validation of the computer codeA detailed convergence test of the code has been carried out and it is find that the code has enough convergence to carry out the computation of full scale structure. The effect of viscous damping has been investigated with the experimental data of the viscous damping. Comparisons between the numerical results and experimental data by NIES have been carried out, and it is confirmed that the numerical results have enough accuracy.3.Establishment of the analysis of the very large mobile offshore structureSummarizing overall results a concept of VLMOS has been presented. Using this concept for the simulation of navigation and electric power generation has been carried out. Through the simulation, it is confirmed that the methodology developed in this research is valid for conceptual design of VLMOS.