基于塑性模型的钢悬链立管疲劳分析（英文）

The most critical issue in the steel catenary riser design is to evaluate the fatigue damage in the touchdown zone accurately. Appropriate modeling of the riser-soil resistance in the touchdown zone can lead to significant cost reduction by optimizing design. This paper presents a plasticity model that can be applied to numerically simulate riser-soil interaction and evaluate dynamic responses and the fatigue damage of a steel catenary riser in the touchdown zone. Utilizing the model, numerous riser-soil elements are attached to the steel catenary riser finite elements, in which each simulates local foundation restraint along the riser touchdown zone. The riser-soil interaction plasticity model accounts for the behavior within an allowable combined loading surface. The model will be represented in this paper, allowing simple numerical implementation. More importantly, it can be incorporated within the structural analysis of a steel catenary riser with the finite element method. The applicability of the model is interpreted theoretically and the results are shown through application to an offshore 8.625″ steel catenary riser example. The fatigue analysis results of the liner elastic riser-soil model are also shown. According to the comparison results of the two models, the fatigue life analysis results of the plasticity framework are reasonable and the horizontal effects of the riser-soil interaction can be included.     

柔性立管整体分析(英文)

The mechanical performance of a flexible riser is more outstanding than other risers in violent environmental conditions. Based on the lumped mass method, a steep wave flexible riser configuration attached to a Floating Production Storage and Offloading (FPSO) has been applied to a global analysis in order to acquire the static and dynamic behavior of the flexible riser. The riser was divided into a series of straight massless line segments with a node at each end. Only the axial and torsional properties of the line were modeled, while the mass, weight, and buoyancy were all lumped to the nodes. Four different buoyancy module lengths have been made to demonstrate the importance of mode selection, so as to confirm the optimum buoyancy module length. The results in the sensitivity study show that the flexible riser is not very sensitive to the ocean current, and the buoyancy module can reduce the Von Mises stress and improve the mechanical performance of the flexible riser. Shorter buoyancy module length can reduce the riser effective tension in a specific range of the buoyancy module length when other parameters are constant, but it can also increase the maximum curvature of the riser. As a result, all kinds of the riser performances should be taken into account in order to select the most appropriate buoyancy module length.     

集束塔式立管总体强度分析(英文)

Bundled hybrid offset riser (BHOR) global strength analysis, which is more complex than single line offset riser global strength analysis, was carried out in this paper. At first, the equivalent theory is used to deal with BHOR, and then its global strength in manifold cases was analyzed, along with the use of a three-dimensional nonlinear time domain finite element program. So the max bending stress, max circumferential stress, and max axial stress in the BHOR bundle main section (BMS) were obtained, and the values of these three stresses in each riser were obtained through the "stress distribution method". Finally, the Max Von Mises stress in each riser was given and a check was made whether or not they met the demand. This paper provides a reference for strength analysis of the bundled hybrid offset riser and some other bundled pipelines.     

钢质悬链线立管与海床土体相互作用的数值模拟

对海洋钢悬链线立管(SCR)与土体的相互作用研究越来越得到业界的重视,不同计算方法得到的结果准确性如何尚未做过对比分析.文章采用有限元法和有限差分法对管—土的相互作用进行了数值计算.在有限差分法中采用弹簧单元,在有限元法中采用接触单元模拟悬链线立管与海床土体的相互作用,得到端部施加不同位移载荷下的立管弯矩、土体反力、触底点位置并与实验结果作比较.分析了端部位移载荷大小对触地点(TDP)位置及对土体反力的影响.文中采用的方法在模拟静态端部位移加载下的管—土相互作用与实验结果吻合较好.为进一步模拟循环载荷下管—土相互作用奠定了基础.     

深水钢悬链线立管(SCR)安装分析研究

海管(立管)是海底生产系统和浮武装置之间的关键连接.随着海洋油气开发水深的不断增加,对海管(立管)自身以及辅助施工设备的性能都提出了更高要求,施工及正常作业的安全保证愈加重要.基于立管分析软件Orcaflex,针对项目中的SCR立管进行了安装分析,并依据规范进行应力、应变校核,可为深水安装分析及方案的确定提供一定的技术参考和理论支持.     

管土作用下的钢悬链线立管动力响应及其疲劳分析

钢悬链线立管的疲劳分析得到越来越多的重视,尤其是其与海床土体相互作用引起的疲劳。本文根据 Aubeny提出的管土作用模型以及 Bridge提出的土体吸力模型,采用有限元方法,在考虑其与海床土体相互作用的基础上,分析了钢悬链线立管在不同载况作用下的动力响应及疲劳损伤。分析发现,钢悬链线立管上触地点和悬挂点处的疲劳损伤更为显著;洋流载荷对立管疲劳损伤的影响随着水深的增加而减弱;土体吸力的存在,会增大触地段尤其是触地点附近的疲劳损伤;立管触地点附近的疲劳损伤与土体刚度呈正相关。     

管土作用下的钢悬链线立管动力响应及其疲劳分析

钢悬链线立管的疲劳分析得到越来越多的重视,尤其是其与海床土体相互作用引起的疲劳。本文根据Aubeny提出的管土作用模型以及Bridge提出的土体吸力模型,采用有限元方法,在考虑其与海床土体相互作用的基础上,分析了钢悬链线立管在不同载况作用下的动力响应及疲劳损伤。分析发现,钢悬链线立管上触地点和悬挂点处的疲劳损伤更为显著;洋流载荷对立管疲劳损伤的影响随着水深的增加而减弱;土体吸力的存在,会增大触地段尤其是触地点附近的疲劳损伤;立管触地点附近的疲劳损伤与土体刚度呈正相关。     

船模在简谐激励存在时的运行模态分析(英文)

A ship is operated under an extremely complex environment, and waves and winds are assumed to be the stochastic excitations. Moreover, the propeller, host and mechanical equipment can also induce the harmonic responses. In order to reduce structural vibration, it is important to obtain the modal parameters information of a ship. However, the traditional modal parameter identification methods are not suitable since the excitation information is difficult to obtain. Natural excitation technique-eigensystem realization algorithm (NExT-ERA) is an operational modal identification method which abstracts modal parameters only from the response signals, and it is based on the assumption that the input to the structure is pure white noise. Hence, it is necessary to study the influence of harmonic excitations while applying the NExT-ERA method to a ship structure. The results of this research paper indicate the practical experiences under ambient excitation, ship model experiments were successfully done in the modal parameters identification only when the harmonic frequencies were not too close to the modal frequencies.     

深水钢悬链线立管顺流向非线性动力分析

深水钢悬链线立管在外部流体作用下的动力响应在立管的性能优化设计中是非常重要的.文章考虑了深水钢悬链线立管轴向大应变的特性以及弯曲刚度和内流的影响,利用Hamilton原理和拉格朗日应变理论建立了立管的二维动力学模型.将外部流体的非线性作用力用Morison方程表示,通过Hermite插值函数对动力学方程进行离散,采用平均加速度法求解立管的动力响应.探讨了外部流体的非线性作用力对海洋立管顺流向动力响应的影响以及不同流速和拖曳力系数与海洋立管共振响应幅值的关系.     

深水SCR立管触地区域管土作用研究进展

钢悬链线立管作为一种全新的深水立管系统已经在国外多个项目中应用,总结了有关深水钢悬链线立管触地区域管土相互作用的研究进展,主要包括STRIDE和CAluSIMA工业合作计划的研究数据和其他的相关论文,能够为国内深水钢悬链线立管的研究提供参考.     

钢悬链式立管涡激振动疲劳损伤参数分析

针对钢悬链式立管的结构特性,采用了简化后的振动模型。先对立管进行了模态分析;再根据立管的模态特性结合环境水流参数,采用模态叠加法对立管进行了涡激振动疲劳损伤分析。分析过程中,通过改变流速大小、立管壁厚、立管外径、内部介质以及抑制立管涡激振动的螺旋列板长度等参数,对立管的涡激振动疲劳损伤进行了相应的参数分析。结果表明:立管疲劳损伤随水流速度的增大、立管外径的增大以及内部介质密度的降低呈现上升趋势,但是壁厚变化对立管疲劳损伤大小影响却不显著。     

绞吸挖泥船柔性钢桩原理及分析

柔性钢桩是减缓超大型绞吸挖泥船的定位桩在高海况下受力问题的一种系统装备。文中研究并阐述了绞吸挖泥船柔性钢桩的工作原理,根据某实船算例进行其缓冲能力的分析计算;通过梳理、分析系统各部件间的机械关系和联动机制,在MATLAB软件中建立其数学计算模型。计算结果表明:该系统性能曲线线性程度较高,预压参数对其缓冲能力影响显著,是设计中的重要参数。柔性钢桩通过油缸做功来吸收船体上部分外力,从而减缓定位桩的受力,能有效提高绞吸船在高海况下的可作业性。     

考虑沟槽深度及土体吸力影响的SCR与海床土体循环作用分析

悬链线立管与海床土体的相互作用对立管的疲劳寿命影响很大,而管土作用的机理又十分复杂,海底沟槽以及海床土体吸力都会对立管力学特性产生影响,文章以Aubeny等提出的管土作用完整P-y曲线为基础,在有限元分析软件ANSYS中采用非线性弹簧模拟海床土体,计算中考虑了土体吸力;模拟了三种位移幅值下管土循环作用时沟槽深度的变化,分析了沟槽段各点弯矩及应力随深度的变化规律,同时对比了三种情况下管道最深点的弯矩及应力随加载时间的变化关系,为进一步分析管土循环作用提供了参考。     

操作与悬挂工况下的深海立管有限元分析

近年来,在深海进行油气开发的技术进展日新月异,全世界的海洋工程公司都在用更新的科技手段努力向更深的海域拓展,向深海进军已经成为了整个海洋行油工业的总体趋势.作为连接、平台设备和海底的重要设备,深海海洋立管的设计和使川也越来越趋向标准化.该文以某深海立管为例,从操作工况和悬挂工况两个方面探讨了钻井立管的整体分析中遇到的主要问题并进行了相关的校核.该文的具体上作包括计算了立管在钻探模态下的旋转角度和应力分布,确定了操作半径、浮箱数日等要素,并根据API规范进行了校核.根据计算的结果可以看出,所选的立管在恶劣海况下的操作半径相对较小,而确定的浮箱数略多,相关结论对立管的初步设计具有较好的参考意义.     

柔性连接装置约束下的相邻浮体动力响应分析

许多海上工程作业中会出现两个或多个浮体相邻作业的情形,如海洋平台组块双船浮托安装等.在波浪作用下,相邻多浮体会发生水动力干扰现象,在特定条件下引起强烈的间隙共振,产生的巨大波浪力会对浮体造成破坏.相邻多浮体之间往往会存在柔性连接,需要考虑多浮体水动力干扰及机柔性连接构件的约束力对浮体运动响应的耦合作用,以及约束力本身对刚性或柔性连接构件的影响.因此,需要建立多浮体耦合的水动力-结构动力模型研究相互连接的海上浮式结构在复杂环境载荷下的动力响应.本文以双船浮托安装作业为背景,开发耦合的水动力-结构动力模型分析平台组块在双船拖运过程中的复杂动力响应.通过结合动态子结构法和静凝聚法,考虑连接构件的柔度,将连接构件的质量和刚度凝聚到构件与双船的连接点处.结合多浮体频域水动力分析,研究双船在柔性构件约束下和复杂水动力干扰共同作用下的运动响应.     

船用离心泵内部流场数值分析和性能预测

通过对船用离心泵内流场三维不可压湍进行数值模拟,揭示了泵内流道的压力及速度分布规律,根据泵内流道的压力及速度分布规律,对泵进行水力优化设计,同时对船用离心泵的性能进行预测．