【作者】 王东军；

【导师】 黄一；

【作者基本信息】 大连理工大学 ， 轮机工程， 2005， 硕士

【摘要】 固定式海洋平台结构分析涉及载荷、基础、应力等多个方面的研究,其工作量是非常庞大的。目前可用于固定式海洋平台结构分析的专用软件有StruCAD*3D,SACS等,但它们的功能总是局限的。而通用有限元软件又缺乏用于海洋平台结构分析的专用模块,因而,结合现有的有限元分析软件,开发相应的专用分析模块,应用于海洋平台的结构分析研究是非常有意义的。另外,管节点是海洋平台结构的关键部位,同时也是导致结构整体失效破坏的最薄弱环节,海洋平台的失事很多都是由于管节点发生疲劳损伤并进一步导致不安定断裂所致,为此管节点的疲劳评估及断裂性能研究也显得尤为重要。 本文的主要工作包括三个方面:首先对波浪理论及桩土分析理论做了研究,在此基础上结合ANSYS结构分析软件开发了载荷计算模块、桩基分析模块,并验证了其正确性:利用上述计算程序,建立了BZ-281平台结构分析模型,根据平台所处海域的波浪资料,对BZ-281平台进行了64种工况下的结构分析,结合谱疲劳分析方法对平台作了疲劳评估;最后通过研究裂纹体网格剖分特点,提出了一种创建裂纹体有限元模型的简便方法,根据该方法建立了一系列含表面裂纹的平板结构模型,研究了裂纹前缘的单元边长L与裂纹深度a之比对裂纹尖端应力强度因子计算结果的影响,并将本文方法的计算结果与Newman-Raju公式计算结果作了比较。 大量计算及分析表明本文编写的结构分析程序模块可以应用于工程实际,从而实现了钢质导管架平台结构分析模型化;同时通过对BZ-281平台进行的疲劳分析,得出了该平台可以继续安全使用的结论。另外,本文提出的用ANSYS软件生成裂纹体有限元模型的简便方法,丰富了裂纹体模型的生成方法,给应力强度因子研究带来了方便。更多还原

【Abstract】 Structural assessment for a fixed platform involves geometry modeling, environmental loads calculation as well as soil-pile interactive simulation, etc. The preprocess is tedious and time-consuming. There are some specialized software packages for the ocean structural analysis, for example, StruCAD*3D, SUCS, however, their function are always limited. On the contrary, most of general purposed commercial FE software packages have powerful functions but without the specialized modules. It’s necessary to develop some special modules for the general purposed FE software packages to satisfy our unique requirements in ocean platform structural analysis. In addition, the tubular joints are the most important but the weakest members of ocean platform. Fatigue and fracture at tubular joints are recognised as the predominant factors which contribute to the fixed platform failures; consequently, it is compelling to further understand the fatigue and fracture mechanism of tubular joints on fixed platforms.The main work of this article includes three aspects: first, wave load module and pile-soil interactive module were developed under the ANSYS environment; meanwhile, the validity of these modules was checked. Second, an FE model of BZ-281 platform was established and stress distributions were obtained under 64 wave load cases according to the long-term wave distribution, then, the fatigue life was assessed in spectrum method. Third, a convenient automatically mesh generation method for the crack model was put forward after studying the mesh characteristic of cracked bodies. Then, the effect of ratio of the element size(L) to the crack length(a) on Stress Intensity Factors were discussed and compared with Newman-Raju formula.The result shows that the developed modules can be applied in practice. And the BZ-281 platform can be reused after fatigue assessment. In addition, the method recommend in this article for meshing cracked bodies , which extends the way to build crack model, brings convenience for stress intensity factors research.更多还原