A STUDY ON HYDROELASTIC RESPONSE OF LARGE-SCALE FLOATING STRUCTURE TO WAVES

提出了一种分析大型浮体结构对波浪的水弹性响应的数值方法。采用边界元法（BEM）计算流体运动，采用有限元法（FEM）分析结构弹性变形。在满足流固界面位移和压力连续性的前提下，结合边界元法和有限元法模拟了波固相互作用。在数值水槽中，通过逐步给出水面高度和水粒子速度在波浪发生边界上的分布来产生波浪，并在时域上计算结构对波浪的动力响应。虽然本研究的分析重点是线性问题，但该方法可以适用于任意波浪条件下的分析。特别地，该方法可用于分析非周期波，如孤立波，而以往的方法在频域上是不适用的。为了验证所提数值方法的有效性和适用性，分别以聚乙烯板和聚丙烯板作为浮体结构模型进行了室内实验。将数值结果与规则波、随机波和孤立波的实验数据进行了比较，验证了数值结果的有效性。实验和数值结果表明，当结构的弯曲刚度或波高与水深比较大时，柔性浮动结构下的孤立波发生裂变。此外，一连串的裂变波像规则波一样传播。本研究中观察到的裂变不同于在自由水面上观察到的所谓孤子裂变，因为裂变波出现在孤子波主体部分的前面。当裂变不发生时，作用在孤立波波峰处的浮动结构上的弯矩与孤立波剖面的预测一致。然而，当孤立波发生裂变时，裂变波波谷处的弯矩要比波峰处的弯矩大得多。这在实际设计中是非常重要的，特别是在加固结构抵御海啸时。少

A numerical method is developed to analyze the hydroelastic responses of large-scale floating structure to waves. A boundary element method (BEM) is applied to evaluate the fluid motion and a finite element method (FEM) to analyze the elastic deformation of structure. By satisfying the continuity of the displacement and pressure on the fluid-structure interface, the BEM and FEM are combined to simulate the wave-structure interaction. Waves are generated in a numerical water flume by giving the water elevation and the water particle velocity distribution over wave generation boundary step-by-step, and the dynamic responses of structure to waves are calculated in a time domain. Although the analysis in this study is focused on the linear problem, this method can be applied to the analysis under arbitrary wave conditions. Especially, this method is available for the analysis of non-periodic waves, such as a solitary wave for which the previous methods in a frequency-domain can not be appl … More ied.In order to examine the validity and applicability of the proposed numerical approach, laboratory experiments are carried out by using polyethylene plate and polypropylene plate as model floating structures. The validity is verified by comparing the numerical results with experimental data of regular wave, random waves and solitary wave.It is found experimentally and numerically that a solitary wave under flexible floating structure fissions when the bending rigidity of structure or the ratio of wave height to water depth is large. Furthermore, a train of the fissioned waves propagate like as regular waves. The fission observed in this study is different from the so-called soliton fission on a free water surface, since the fissioned waves appear in front of the main part of the solitary wave. When the fission does not occur, the bending moment acting on the floating structure at the crest of solitary wave is significant as expected from the profile of solitary wave. However, when the solitary wave fissions, the bending moment at the trough of the fissioned waves become much larger than that at the crest. This is very important in the actual design, in particular in the reinforcement of structure against Tsunami. Less