Dynamic responses analysis of a 5 MW spar-type floating wind turbine under accidental ship-impact scenario

Ship impact against offshore floating wind turbine (OFWT) has been identified as one of the major hazards with the development of OFWTs. The dynamic responses of OFWTs under ship impact should be taken into consideration during the design phase. This paper addresses a study on the dynamic responses of an OFWT in ship collision scenarios. Firstly, a mathematical model for external mechanism of ship-OFWT collision scenario is developed. Secondly, this model is combined with an in-house programme, DARwind, which can be used to predict nonlinear dynamic responses of whole OFWT system in time-domain. With the newly combined analysis tool, simulation cases for different scenarios are conducted to investigate the nonlinear dynamic responses of OFWT system, including the cases of still water condition, wave-only condition and wind-wave condition. It is shown that in still water condition, the ship impact will more obviously change the responses of motions and mooring system, compared with those in wave and wave-wind conditions. In the wave-only condition, these motions responses of platform are suppressed by wave effect, but the tower vibration and tower top deformation are sensitive to ship collision. For the wave-wind combined condition, the motions increment in surge and pitch due to ship collision becomes smaller than that of wave-only condition, but yaw motion has a considerable variation compared with those of the other two conditions. Additionally, the blade tip deformation increment due to ship collision are analyzed and it is found that the edgewise tip deformation got more obvious increment than that of flapwise. To further asses the safety of OFWT, the acceleration at nacelle are analyzed because some equipment might be sensitive to acceleration. The analysis results indicate that even though the OFWT structure doesn't get critical damage by ship impact, the equipment inside may still fail to work due to the high value of acceleration induced by ship impact. The research outcomes can benefit the safety design of OFWT in the engineering practice.     

铁路钢管混凝土系杆拱桥动力特性及地震响应分析

以某铁路钢管混凝土系杆拱桥为研究对象,运用有限元分析软件ANSYS建立了其空间杆系有限元 模型,其中拱肋与系梁采用空间梁单元模拟,吊杆采用空间杆单元模拟,对其动力特性进行了分析;在此基础上运用时程分析方法分别计算了该桥在竖向和纵向地震力组合以及竖向和横向地震力组合两种工况下的地震响应,得到了主拱控制截面在两种荷载工况下的最大内力和最大位移响应,对其抗震性能进行了分析评价.结果表明：该铁路系杆拱桥动力特性总体体现为刚性拱桥的动力特征,横桥向刚度相对较弱,竖向地震力作用下的响应较大,应引起设计注意.研究可为同类型的铁路刚性拱桥抗震设计提供理论依据.     

新概念张力腿平台水动力性能分析

张力腿平台对水深具有高度敏感性,随水深变化,垂直面内的运动受到显著影响。对于超深水情况,对张力筋腱的设计提出更高的要求。为了改善这一状况,提出了一种新概念张力腿平台设计方案——Tension Based Tension Leg Platform(TBLP),它可以成倍地增加TLP适用的水深范围。对于已经使用的中等水深下的传统型的TLP,通过增加张力基底,就可以将其使用于更深的海域。针对这一新型TBLP概念,对典型的传统型TLP和TBLP水动力性能进行了初步分析比较,得出TBLP优于常规设计的水动力性能。     

Wave responses of a coastal cargo ship consisting of unit modules

This article discusses the dynamic responses of a coastal cargo ship that consists of unit modules with advance forward speed in waves. We introduce a simple way of connecting the modules that has enough capability to link the modular parts of the ship as a unified whole. The flexible connection consists of male and female rubber fenders with additional pretensioned ropes. This kind of connection system is proposed for use in coastal regions with relatively calm waters wherein the modular ship can move at a moderate speed. The modules are assumed to be rigid compared to the connections. Computations were performed to investigate the vertical elastic responses of four modules connected end-to-end with the assumption that in the simple hinge, no gaps occur in the flexible rubber connections between adjacent modules. A simple method, which is an extension of the computational analysis we reported previously, is presented to study the hydroelasticity and rope tension forces of the modular ship with forward speed in waves. Experiments with a three-dimensional model at Froude numbers of 0 and 0.16 in head waves were performed to evaluate the effectiveness of the calculation method. In the experiments, deflections for each part were measured using calibrated potentiometers. Force transducers were used to measure the rope tension force between the modules of the articulated cargo ship. Some slight differences were observed, but generally the calculated results showed the same trends as the experimental values.     

超大型海洋浮式结构物动力特性研究综述

对于超大型海洋浮式结构物的研究正日益受到重视。在研制超大型海洋浮式结构过程中需要解决的一项最具挑战性的关键技术问题是它在海洋环境中的动力特性预报方法。国内外许多人士都对这一问题正在开展研究。本文对这一领域的研究现状作一回顾，为进一步开展深入研究提供基础。     

航行船舶的三维非线性水弹性分析

基于Wu提出的浮体二阶水弹性理论[1],研究大浪中航行船舶的非线性水弹性响应,给出了数值方法和计算结果.在二阶水弹性分析中,主要考虑了大角度刚体转动和瞬时湿表面变化引起的非线性水动力.根据三维线性水弹性理论[2],采用移动脉动源格林函数和Kelvin定常兴波假定,求解了对二阶水动力做主要贡献的一阶速度势及响应.最后以航行于不规则波中的小水线面双体船为例,讨论了航速和定常兴波流场对水弹性响应的影响,并对线性和非线性响应的预报结果进行了比较.     

拱肋内倾角对钢管混凝土提篮拱桥车桥动力响应的影响

为考虑拱肋内倾角对大跨度钢管混凝土拱桥的动力特性及车辆走形性的影响,以某主跨为240 m的钢管混凝土提篮拱桥为例,运用结构动力学以及有限元原理,分别建立了3种不同内倾角度(7.5°,8.5°,9.5°)下的桥梁动力分析模型和车辆模型,由动力学势能不变值原理"与形成矩阵的"对号入座"法则建立空间振动方程,并对3种情况下的车桥耦合空间响应进行了计算分析。研究结果表明:桥梁横向自振频率随拱肋内倾角的增加而明显增大;竖向自振振动频率随内倾角度的增大而减小;列车通过桥梁时,不同内倾角度下拱顶竖向位移和加速度的变化很小,而横向位移、横向加速度均随着内倾角度的增大而减小;车辆的动力响应对内倾角的变化不敏感。     

双曲面球型减隔震支座曲线连续梁桥的减隔震

针对某3跨门式桥墩轨道交通曲线连续梁桥,采用其桥址<地震安全性评价报告>提供的3条地震动时程曲线,应用SAP2000有限元软件,分析未隔震和双曲面球型减隔震支座隔震条件下的罕遇地震响应,进行双曲面球型减隔震支座曲线连续梁桥的减隔震研究.研究结果表明,曲线连续梁桥各桥墩的内力响应受响应内力方向与地震动输入方向火角的影响;仅固定墩切向隔震时,固定墩的切向内力大幅减少,弯矩和剪力分别减小约70%和50%,但各墩的径向内力均有增加,最大增幅约达10%,不能满足桥梁的抗震要求;固定墩切向和径向双向、滑动墩径向隔震时,固定墩的切向和径向内力均大幅减少,弯矩和剪力分别降低约73%和49%,同时各滑动墩的径向内力也大幅降低40%～60%,减震效果明显.     

Dynamic Responses of Long-Span Transmission Tower-Line System Subjected to Broken Wires

A macroscopic finite element modeling approach was proposed to calculate the vibration of a tower-line system subjected to broken wires with software ANSYS/LS-DYNA. In the finite element model, not only the nonlinearity of wires and suspension insulators are considered, but also the support towers are included. The incremental and iterative approaches are combined by applying the unbalanced loads incrementally during each iteration cycle. The approach was illustrated with an example of a Hanjiang-River long-span transmission line system subjected to a shield wire and a conductor failure, respectively. The analysis results showed that the proposed dynamic simulation approach can demonstrate the kinetic process of the tower-line system subjected to wire ruptures: The frequencies of line components were lower and densely distributed, but the frequencies of tower components were higher and sparsely distributed. Anyhow, the dynamic effects of wire ruptures on tower-line system could not be ignored in analysis of tower-line system subjected wire failures.     

一型小水线面双体船的水动力性能与结构设计

简要介绍了中国船舶重工集团公司(CSIS)建立和发展的一种小水线面双体船(SWATH)优化设计工程技术系统.主要包括SWATH船型的概念设计、主尺度与线型优化、有效功率预报、纵向运动稳定性校验及稳定鳍设计、耐波性预报、结构载荷评估、波浪中的船体结构动、静响应分析等有关设计、预报与评估的系统方法.并以一型1500吨级小水线面双体型海洋调查船设计和评估为例对有关设计方法进行了说明和验证,在该船设计中,采用线性和非线性三维水弹性理论来预报载荷与评估在波浪中航行船体的结构安全性,同时在中国船舶科学研究中心(CSSRC)的拖曳水池与耐波性水池中进行了阻力与自航、耐波性与操纵性、波浪载荷等船模拖曳及自航试验.文中还给出了该船有关优化设计及模型试验结果.