共查询到18条相似文献,搜索用时 296 毫秒
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在桁架式深吃水立柱式平台(Truss Spar)运输作业的浮卸过程中,半潜驳船不断压载下潜直到Truss Spar平台自浮后拖离驳船。针对浮卸作业的双浮体状态,提出Truss Spar平台在与半潜驳船发生接触情况下的载荷计算方案并进行结构应力水平评估。基于三维势流理论及SESAM软件,考虑平台及半潜驳船双浮体之间的水动力相互影响,首先对双浮体系统进行频域下求解,得到波浪诱导载荷;然后在时域下求解波浪中双浮体的运动方程及产生的接触力;最后将这两种载荷下的结构强度分析结果进行线性叠加,得到Truss Spar平台在波浪诱导载荷及接触力联合作用下结构应力水平。对比不同波浪方向及周期下的接触力结果,研究Spar平台结构整体应力水平及高应力区域位置特点,对总体强度水平进行评估。 相似文献
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基于细长体水动力模型比较了Truss Spar平台在波流联合作用下运动响应预报的三种方法。分别采用波流耦合、速度叠加及力叠加计算Truss Spar平台在波流联合作用下的水动力载荷,根据流场水质点运动规律和Truss Spar外部形状特点,分段高效计算水动力载荷。利用Runge-Kutta-Fehlberg方法求解刚体非线性运动方程得Truss Spar在波流场中的运动响应。研究结果表明力叠加法所预报的Truss Spar纵荡和纵摇运动明显大于其他两种方法的相应运动响应预报结果,而波流耦合法与速度叠加法所预报的纵荡与纵摇运动响应幅值相当,三种方法所预报的垂荡运动响应的大小取决于具体波流参数。 相似文献
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均匀流中深水系泊Truss Spar平台涡激运动试验研究 总被引:1,自引:0,他引:1
在工程中广泛应用的Truss Spar平台自诞生之初就为涡激运动问题所困扰,对其运动特性及抑制方法的机理性研究始终都在进行。采用截断系泊系统水池模型试验对设计中的Truss Spar平台在均匀流中的涡激运动响应进行了研究,分析了有无侧板平台的运动轨迹以及不同速度及流向角来流对平台运动的平衡位置的影响。在影响平台涡激运动特性的重要因素中,选取折合速度及流向角分别加以研究,分析了幅值在锁定区间中的变化规律,验证了减涡侧板对涡激运动良好的抑制作用,并对热点问题进行了探讨。为进一步研究Spar平台的涡激运动特性奠定了基础。 相似文献
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Truss Spar平台垂荡响应频域分析 总被引:10,自引:0,他引:10
利用已有水动力试验和数值模拟结果及Morison方程,简化估计了Truss Spar平台垂荡方向水动力贡献,快速有效地预报了平台极端海况下的垂荡响应.在频域内分别采用数值迭代计算和粘滞阻尼线性化方法得到了平台在不同数量垂荡板配置下的垂荡响应幅值算子.在墨西哥湾、西非和中国南海等3种不同地区极端海况以及墨西哥湾工作状态海况下计算了平台的响应极值,分析发现平台波频垂荡响应对入射波浪周期非常敏感.采用JONSWAP波能谱得到了Truss Spar平台垂荡响应谱.通过比较和参数分析,验证了平台在设计上的合理性与实际海况下良好的垂荡运动性能. 相似文献
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KK型管节点是自升式平台桁架式桩腿中的一种管节点,其应力集中系数是影响桩腿疲劳寿命的重要参数。应力集中系数与管节点的几何形式密切相关,为分析KK型管节点应力集中系数对几何参数的敏感性,利用ANSYS软件对某KK型管节点进行几何参数化建模,利用有限元数值模拟方法对各工况下的热点应力进行分析,并分别计算各相应工况下的名义应力,然后将热点应力与名义应力相比得到不同几何参数下的热点应力集中系数。对计算结果进行整理分析,得到了KK型管节点应力集中系数对无量纲几何参数的敏感性规律。结果表明,应力集中系数与撑杆受力状态、管节点结构形式有关,在满足结构布置、建造工艺和其他安全性指标的前提下,分析结果能够为KK型管节点的结构设计和疲劳分析提供技术支撑。 相似文献
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以某新型深水半潜式钻井平台为分析对象,依据三维绕射理论计算单位波幅下波浪诱导载荷,通过建立三维有限元模型计算完成了热点应力响应。运用热点应力的谱分析法计算得到危险节点的疲劳寿命,并进一步分析了各个短期海况和不同浪向对节点总的疲劳损伤度的贡献。研究结果表明,危险节点的疲劳寿命都满足设计寿命要求;在各种中低海况下,疲劳损伤主要来自于平均跨零周期在6 s附近,有义波高转大的短期海况;平台关键连接部位的疲劳损伤主要是在横浪和斜浪状态下产生的,并且对某单一方向的波浪非常敏感。此研究对该类型平台的连接处结构设计和疲劳分析方法有参考意义。 相似文献
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随机波浪下Truss Spar平台垂荡运动时域分析 总被引:4,自引:2,他引:2
研究Truss Spar平台在随机波浪下的垂荡运动特性。采用ITTC双参数谱,考虑绕射作用,数值计算了平台所受的随机波浪力。利用已有的水动力试验和数值模拟结果及Morison方程,估计了Truss Spar平台垂荡方向的附加质量和粘滞阻尼大小。考虑非线性阻尼和瞬时波面的影响,运用Runge-Kutta数值迭代算法,比较了不同随机波浪参数对平台运动响应的影响,特别是波浪特征周期接近垂荡固有周期时。结果表明,当波浪特征周期接近平台垂荡固有周期时,平台产生大幅垂荡运动,频域的运动分析结果比时域结果偏小。 相似文献
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Economy and ice-resistance are two factors that must be considered in the design of offshore oil platforms in the Bohai Gulf. This paper focuses on the optimal design of ice-resistant offshore jacket platforms in the Bohai Gulf in consideration of fatigue life of tubular joints, with the minimum initial weight and satisfying dynamic properties. An efficient fatigue analysis procedure based on spectral analysis is proposed, in which a hybrid finite element model is adopted to simulate the jacket platform and the tubular joints, and the pseudo-excitation method is used to calculate the power spectral density of the hot spot stress. Finally, a practical jacket platform with an ice-breaking cone in the Bohai Gulf is optimized, and the results demonstrate that the fatigue life of tubular joints could be improved and the weight of jackets decreased simultaneously. 相似文献
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Chen Tieyun Zhang Huiyuan Professor Shanghai Jiao Tong University Shanghai
Doctor of Engineering Shenzhen Shipbuilding Trading Co. LTD. 《中国海洋工程》1993,(1)
- Stress concentration analysis of multiplanar tubular DT joints plays an important role in the fatigue design of offshore platforms. A semi-analytic method for stress analysis under the condition of any loads is briefly introduced in the paper. Nineteen multiplanar tubular DT joints with one of two braces of the same dimension subjected to axial loads and out- of- plane bending moments are computed for parametric stress analysis by using the present method. The influence of geometrical parameters on the stresses of multiplanar tubular DT joints is discussed and compared with corresponding uniplanar T joints. The regression formulae for the stress at hot spot of multiplanar DT joints are found by modification of SCF of corresponding uniplanar T joints. The parametric formulae for the maximum stress by superposition. Finally, the influences of stiffening effect and load-interaction effect on the maximum stress of DT joints are discussed. 相似文献
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Wang Gnanghai Chen Bozhen Senior Research Engineer China Ship Scientific Research Center 《中国海洋工程》1992,(1)
In China, a nationwide research program on fatigue behaviour of tubular joints made of China-made platform steel was carried out from 1983 to 1990, which was set by the Tubular Joint Research Committee for Offshore Structures (TJCOS) of China. This paper gives an outline of the basic properties of the China-made platform steel and fatigue test of tubular joints, including test specimens, test particulars and test results. A p-S-N curve based on the test results was established which reveals that the fatigue strength of tubular joints is fairly good. The thickness effect and effect of corrosion on fatigue strength in sea water are briefly discussed. 相似文献
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Gu Hongxin Chen Tieyun Senior Engineer Marine Design Research Institute of China Shanghai Professor Shanghai Jiao Tong University Shanghai 《中国海洋工程》1991,(3)
"The effect of interaction of loads on the ultimate static strength of tubular joints of offshore fixed platforms, is a practical problem. But there is still absence of rigorous theory to explain available experimental data and empirical criteria for the static strength of tubular joints. The idea of yield at hot spot of tubular joints is introduced in this paper. The interaction equations of plastic capacity for the tubular joints under combined loads (two and three different kinds) are derived. Thereafter the Yura's test data and empirical criteria of ultimate static strength for the tubular joints can be explained. The idea of classification of category of loads in accordance with experimental data and the present theory is suggested. Finally, the improved ultimate capacity equations for tubular joints are recommended. The physical significance of the coefficient of plastic reservation Qp is discussed. 相似文献
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Recently, a mesh-size insensitive structural stress definition (Battelle structural stress method) has been proposed. This method gives a stress state at a weld toe with a relatively coarse mesh, such as up to 2t (t=plate thickness) or irregular mesh shapes. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of a weld toe. In this present study, a fatigue strength assessment was carried out for a side shell connection of a container vessel using both the hot spot stress and the structural stress methods. A consistent approach to computing extrapolated hot spot stress for design purposes based on converged hot spot stresses is described and current fatigue guidance is evaluated. Fatigue strength predicted by the two methods, i.e. hot spot stress and structural stress approaches, at hot spot locations of a typical ship structure are compared and discussed. 相似文献
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Accurate prediction of the offshore structure motion response and associate mooring line tension is important in both technical applications and scientific research. In our study, a truss spar platform, operated in Gulf of Mexico, is numerically simulated and analyzed by an in-house numerical code ‘COUPLE'. Both the platform motion responses and associated mooring line tension are calculated and investigated through a time domain nonlinear coupled dynamic analysis. Satisfactory agreement between the simulation and corresponding field measurements is in general reached, indicating that the numerical code can be used to conduct the time-domain analysis of a truss spar interacting with its mooring and riser system. Based on the comparison between linear and nonlinear results, the relative importance of nonlinearity in predicting the platform motion response and mooring line tensions is assessed and presented. Through the coupled and quasi-static analysis, the importance of the dynamic coupling effect between the platform hull and the mooring/riser system in predicting the mooring line tension and platform motions is quantified. These results may provide essential information pertaining to facilitate the numerical simulation and design of the large scale offshore structures. 相似文献
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The procedure of assessment of structural fatigue strength of an offshore floating production and storage and offloading unit(FPSO) in this paper. The emphasis is placed on the long-term prediction of wave induced loading, the refined finite element model for hot spot stress calculation, the combination of stress components, and fatigue damage assessment based on S-N curve. 相似文献