航速及定常流场对航行船体结构水弹性力学特性的影响

本文侧重于研究航速对船舶结构水弹性力学响应的影响。     

基于Level-set法的液体晃荡与弹性液舱耦合作用研究

对基于Level-set法模拟液舱液体晃荡的数值模型进行了改进,实现了对大幅晃荡引起的抨击载荷的模拟.运用水弹性力学理论论述了液体晃荡与弹性液舱耦合作用的分析方法,建立了相应的水弹性力学方程.数值算例与实验结果的比较验证了对抨击载荷模拟的正确性;通过对晃荡载荷引起的结构响应的计算分析,得出一些关于结构响应特性的重要结论.     

极大型海洋浮体结构的流固耦合分析

本文研究了两种多模块极大型海洋浮体结构的流固耦合问题。采用弹性连接多刚体系统模型，利用三维线性水弹性力学理论，获得了系统在各种浪向下运动和连结件动应力响应的理论预报。     

水弹性力学在SWATH船体结构振动响应分析中的应用研究

文章以三维水弹性力学理论为基础,对小水线面双体船的船体振动响应特性进行了分析,预报了该船体在航行时受发电机激励下的振动响应,并与实船测量结果进行了对比,结论表明三维水弹性力学方法在船体受机械激励作用下对于船体振动响应的预报是有效的,可应用于工程设计。     

结构刚度变化对箱式超大型浮体结构水弹性响应的影响

结构刚度改变会导致结构固有频率变化和结构广义刚度的变化。必然会对结构在波浪中的水弹性响应产生影响，本文在某箱式超大型浮体结构单位幅值正弦规则波和不规则波水弹性响应计算的基础上，假定结构质量分布不变，研究了结构刚度变化对箱式超大型浮体结构水弹性响应的影响。得到了一些有价值的结论。     

基于完全耦合算法的绕水翼流固耦合特性研究

基于完全耦合算法对绕二维NACA0009水翼流固耦合特性进行了数值模拟研究。采用Theodorsen模型和Munch模型对刚性和弹性水翼的水弹性响应进行了数值计算,分析了流体与结构的相互作用关系,研究了影响结构水弹性响应和流固耦合特性的因素。研究结果表明:考虑了流体黏性的Munch模型与基于势流理论的Theodorsen模型对气动弹性响应的数值计算结果基本一致,而Theodorsen模型由于没有考虑流体黏性在一定程度上低估了结构的水弹性响应。结构的惯性、阻尼和刚度力矩与流体的相应附加载荷均处于同一数量级,故流体与结构的相互作用不可忽略,尤其对于弹性水翼,流体的惯性、附加阻尼作用增大,流固耦合算法的数值稳定性对流固耦合特性的计算结果影响将更大。外部激励频率为非共振频率时,结构的刚度作用是影响水弹性响应的主要因素,外部激励频率为共振频率时,流体的附加阻尼和附加刚度作用减弱,除结构的刚度作用外,流体与结构的惯性作用对水弹性响应和流固耦合特性的影响也较大。     

船舶水弹性力学理论的研究进展

船舶水弹性力学理论在过去近三十年中取得了长足的进步,尤其是三维水弹性理论已被广泛应用于船舶与海洋工程领域的流固耦合问题中。全面地回顾了国内外船舶水弹性力学理论及试验研究的历史与现状,将水弹性力学理论分为二维线性、三维线性、二维非线性、三维非线性等几类,以波浪中航行船舶的水弹性力学理论研究与应用为重点,依次进行了介绍。在船舶水弹性试验方面,着重介绍了国内在整体弹性船模试验研究中取得的进展。     

三维水弹性分析中不规则频率消除及在船舶上的应用

三维水弹性力学是求解浮体和波浪流固耦合作用的重要方法,在求解时存在不规则频率的问题,这些不规则频率的存在会对高频波激振动响应的判断和二阶波浪力的精确计算产生影响。论文采用在水线面建立网格和扩展边界积分方程的方法来消除不规则频率。通过圆柱形浮体的计算,验证该方法在三维水弹性响应计算中的有效性。在此基础上,将该方法应用于一艘散货船,对比了不规则频率处理前后的水动力系数,并给出了船体的水弹性响应。计算结果表明,将不规则频率消除方法应用于三维水弹性响应的计算,可以获得更好的结果,显著改善不规则频率点处的水弹性响应。     

舰船纵向有限振幅响应的探讨

本文用水弹性力学方法在频域中的探讨舰船在波浪激励下的纵向有限振幅响应问题。流体自由表面仍采用线性假设，舰船的物面条件则利用相运动及切片理论进行式展开，在频率域中得到一串响应方程组，其一阶响应方程组与线性水弹性力学的结果完全相同。     

海上超大型储油船的水弹性频域分析

超大型储油船是海上浮式储油基地的主要组成结构,对其进行水弹性响应分析是保障储油基地安全的一个重要环节,在势流理论的基础上采用特征函数展开法求解流场速度势以及底板水动压力分布,采用一组简单的正弦振型函数,将结构的水弹性响进行模态叠加,然后代入结构水弹性运动方程求解结构的水弹性响应,讨论不同波长对结构水弹性响应的影响。     

6750箱集装箱船非线性波激振动和颤振响应分析

本文采用三维时域非线性水弹性方法分析了一艘6750箱集装箱船的水弹性响应以及运动和垂向弯矩特征。通过考虑入射波力、静水恢复力、砰击效应的非线性,研究了在恶劣海况下船体的非线性运动和垂向弯矩响应,同时分析了波激振动及颤振对垂向弯矩的影响。数值计算结果表明:(1)非线性入射波力对运动的影响较小,但是对垂向弯矩的影响较大,使得其有明显的倍频成分,同时中垂弯矩显著大于中拱弯矩。另外,非线性入射波力也引起了明显的非线性波激振动;(2)非线性静水恢复力对运动和载荷的影响均较大,但是没有引起明显的非线性响应。非线性计算的垂荡响应小于线性结果,而纵摇和垂向弯矩响应大于线性结果;(3)砰击效应对运动的影响较小,但对垂向弯矩的影响较大,砰击效应引起了显著的船体弹性高频振动,增大了载荷幅值,但是其引起的合成中垂和中拱幅值相差不大;(4)非线性水动力的作用主要引起垂向弯矩的倍频响应,包括倍频可能引起的二节点垂向弯矩弹性共振,而砰击效应主要引起船体二节点垂向弯矩共振;(5)本文的非线性水弹性响应计算结果与Kim给出的数值计算结果吻合很好。     

支撑条件对浮动式厚弹性板水弹性行为的影响分析（英文）

The hydroelastic response of very large floating structures(VLFS) under the action of ocean waves is analysed considering the small amplitude wave theory. The very large floating structure is modelled as a floating thick elastic plate based on TimoshenkoMindlin plate theory, and the analysis for the hydroelastic response is performed considering different edge boundary conditions.The numerical study is performed to analyse the wave reflection and transmission characteristics of the floating plate under the influence of different support conditions using eigenfunction expansion method along with the orthogonal mode-coupling relation in the case of finite water depth. Further, the analysis is extended for shallow water depth, and the continuity of energy and mass flux is applied along the edges of the plate to obtain the solution for the problem. The hydroelastic behaviour in terms of reflection and transmission coefficients, plate deflection, strain, bending moment and shear force of the floating thick elastic plate with support conditions is analysed and compared for finite and shallow water depth. The study reveals an interesting aspect in the analysis of thick floating elastic plate with support condition due to the presence of the rotary inertia and transverse shear deformation. The present study will be helpful for the design and analysis of the VLFS in the case of finite and shallow water depth.     

基于离散模块梁单元水弹性理论的复杂连接处建模方法

[目的]在离散模块?梁单元(DMB)水弹性理论框架下,提出针对连接形式复杂的超大型浮体结构(VLFS)的新的建模方法,并与已有方法进行对比分析.[方法]首先,概述基于DMB的水弹性分析方法,给出求解连续VLFS结构在波浪作用下的动力响应步骤;然后,针对VLFS复杂连接处进行建模,通过定义连接处的刚度矩阵,对与连接处相邻...     

Hydroelastic Analysis of a Flexible Floating Body for the Variation of Incident Wave

As for the hydroelastic response of a flexible floating body, various kinds of simplified analytical and numerical methods based on the different assumption have been developed, however, the most versatile and applicable approach is the three-dimensional hydroelasticity theory. Currently, most studies mainly focused on the wave condition of head seas without taking the differences for the variation of the incident wave angle into account. In this paper, based on the three-dimensional hydroelasticity theory, an investigation into the variation of the hydroelastic response for different incident wave angles is presented; also some comparisons are demonstrated and discussed.     

Connection design for two-floating beam system for minimum hydroelastic response

This paper is concerned with the connection design for a two-floating beam system for minimum hydroelastic response. The frequency domain approach is used for the hydroelastic analysis. The fluid is modelled as an ideal fluid, and the floating beams are modelled by the Euler–Bernoulli beam theory. The boundary element method (BEM) and the finite element method (FEM) are applied to solve the governing equation of the fluid motion and the beam equation of motion, respectively. The study aims to investigate the optimum location and rotational stiffness of the connection for the two-floating beam system with the view to minimize the compliance. The study also investigates the effects of relative beam stiffnesses on the hydroelastic response of the two-floating beam system.     

Hydroelastic analysis of a very large floating plate with large deflections in stochastic seaway

The hydroelasticity of a very large floating plate with large deflections in multidirectional irregular waves is discussed. After a brief introduction on wave loads on a flexible structure, the paper derives the generalised fluid force acting on a floating structure in multidirectional irregular waves. The nonlinear sectional forces induced by the membrane forces in the plate are deduced. The hydroelastic response equations of a floating plate with large deflections in multidirectional irregular waves are established, and a solution method in the frequency domain is discussed including extreme value statistics. A very large floating structure is chosen as an example. The numerical results show that the influence of the membrane forces on the vertical displacements and the bending moments is noticeable but not that large.     

Hydroelasticity based fatigue assessment of the connector for a ribbon bridge subjected to a moving load

In this paper, the prediction of the hydroelastic response of the floating bridge and the fatigue behavior of the connectors is presented. And based on the hydroelastic response analysis of the ribbon bridge, the dynamic alternating load of the connector can be obtained, in that the fatigue behavior analysis of the connector simulated by the solid elements can be conducted by employing the local stress–strain approach. It is revealed that the sequence of the dynamic loads acting on the connectors, the value of various fatigue parameters and the ultimate tensile strength should be sufficiently considered, especially the passing speed of a moving load, so that it can significantly reduce the fatigue damage of the connectors.     

On the hydroelastic behavior of two-dimensional articulated plates

The hydroelastic behavior of two-dimensional articulated plates is investigated analytically within the scope of linear theory. The connectors are modeled by singular line loading and its derivatives. The velocity potential under the free surface and plate is obtained by use of a wave-maker theory. The characteristics of large displacements at the upstream and downstream edges of the plate and the connectors are obtained from the closed-form solutions. It is also shown that the hydroelastic properties are strongly dependent on the stiffness of the connectors and incoming wave frequency. Finally, the method is used to solve for the response of a multi-module articulated plate.     

On the dispersion relation of hydroelastic waves in a plate

This paper deals with the dispersion relation of hydroelastic waves in pontoon-type very large floating structures (VLFS) using a simple beam modeling, where the term hydroelastic waves means propagation of deflection vibrations in VLFS. The purpose of this paper is to show the properties of the hydroelastic waves. The dispersion relation of hydroelastic waves propagating in an infinite plate floating on the water is derived based on the linear water wave theory. The effects of the water depth and of the bending rigidity of the floating plate on the wavelength, phase velocity, and group velocity of the hydroelastic waves are shown theoretically or numerically. Then, the dispersion relation of hydroelastic waves in a finite plate floating on shallow water is investigated. It is shown that the wavelength or the phase velocity of the hydroelastic waves varies with the location in the plate. Received for publication on April 7, 1999; accepted on Aug. 20, 1999