含裂纹损伤FPSO结构的剩余极限强度研究

发布时间：2018-01-26 18:28

本文关键词： FPSO 剩余极限强度试验研究非线性有限元分析穿透裂纹加筋板　出处：《江苏科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：船舶与海洋工程结构在服役期间发生的灾难性断裂事故不仅严重危害了工作人员的人身安全,而且会造成巨大的经济损失。因此海洋工程设计师开始探求新的船舶与海洋工程结构设计思想,正确评估其结构极限强度,尤其是具有裂纹缺陷影响的钢结构剩余极限强度的研究引起了船舶及海洋工程领域学者的极大兴趣。本文针对含裂纹加筋板在压缩载荷下的剩余极限强度、屈曲模式及裂纹应力强度因子做了系统的分析总结,综合考察了不同裂纹参数,载荷参数以及初始变形缺陷对加筋板剩余压缩极限强度的影响,并在此基础上对含裂纹FPSO复杂结构的剩余极限强度进行了初步探讨。具体研究内容如下:(1)采用试验法对含裂纹损伤加筋板的压缩剩余极限强度进行研究。设计六种典型的穿透裂纹损伤加筋板,对试件进行轴向压缩试验。通过改变模型裂纹尺寸、位置及倾角参数,观测试验数据,探讨了不同裂纹参数影响下的加筋板破坏特点和对剩余极限强度影响。试验结果表明,不同的裂纹长度以及裂纹位置改变加筋板结构承载力的分布,影响结构应力应变场,进而改变其失效崩溃模式;初始缺陷对结构的剩余极限强度的影响也不容忽视。(2)探讨一种数值与试验相结合的受裂纹损伤加筋板结构极限强度研究方法。采用非线性有限元分析法,考虑初始变形缺陷下对受轴向压缩载荷的含穿透裂纹加筋板的极限强度进行分析,分别探讨存在初始变形缺陷,裂纹位置、长度不同时加筋板结构应力分布特性及屈曲变形模式,并与试验结果进行对比分析,结果较为吻合。并计算裂纹加筋板裂纹尖端应力强度因子,使用K判据判断裂纹是否扩展,探讨加载过程中裂纹尖端的应力场的变化。(3)为研究含裂纹损伤加筋板剩余极限强度的边界影响,以单条筋双跨加筋板和三条筋双跨加筋板为研究对象,采用非线性有限元法开展其极限强度分析。考虑结构的初始变形缺陷,对比分析承受轴向压缩、同时承受轴向压缩和侧向压力联合作用时加筋板的剩余极限强度,给出不同裂纹位置和裂纹长度加筋板剩余承载力的变化规律。结果表明,单条加筋板的剩余极限强度偏小,三条加筋模型的计算结果更接近于真实情况,边界对于含裂纹损伤加筋板结构的极限强度分析模型影响较大。侧向压力的存在相当于增加了主板的转动约束,改变了整个加筋板结构的应力响应,降低了结构的极限强度。(4)研究裂纹对FPSO船体结构的极限强度的影响。采用非线性有限元法对FPSO船体结构进行分析,比较单跨距和三跨距完整船体结构的极限弯矩,在此基础上,得到在中拱/中垂状态下,裂纹在甲板、舱底以及两处同时存在裂纹时FPSO结构的应力、应变分布以及极限弯矩变化规律。
[Abstract]:The cataclysmic fracture of ship and marine engineering structure during service not only seriously endangers the personal safety of the staff. And will cause huge economic losses, so the marine engineering designers began to explore a new ship and marine engineering structure design ideas, the correct evaluation of the ultimate strength of the structure. In particular, the study of residual ultimate strength of steel structures with crack defects has aroused great interest of the scholars in the field of ship and marine engineering. In this paper, the residual ultimate strength of stiffened plates with cracks under compression load is studied. The buckling mode and crack stress intensity factor are systematically analyzed and summarized. The effects of different crack parameters, load parameters and initial deformation defects on the residual compressive ultimate strength of stiffened plates are comprehensively investigated. On this basis, the residual ultimate strength of FPSO structures with cracks is preliminarily discussed. The specific research contents are as follows: 1). The compressive residual ultimate strength of stiffened plates with crack damage is studied by means of experimental method. Six typical stiffened plates with crack penetrating damage are designed. The axial compression test was carried out on the specimen. The experimental data were observed by changing the model crack size, position and dip angle parameters. The failure characteristics of stiffened plate under different crack parameters and its influence on residual ultimate strength are discussed. The experimental results show that different crack length and crack location change the distribution of bearing capacity of stiffened plate structure. The stress and strain field of the structure is affected and the failure collapse mode is changed. The influence of initial defects on the residual ultimate strength of the structure can not be ignored. (2) A numerical and experimental method for studying the ultimate strength of cracked stiffened plate structures is discussed. The nonlinear finite element analysis method is used. Considering the initial deformation defect, the ultimate strength of the stiffened plate with penetrating crack under axial compression load is analyzed, and the initial deformation defect and crack location are discussed respectively. The stress distribution characteristics and buckling mode of stiffened plate structure with different length are compared with the experimental results and the stress intensity factor at crack tip of stiffened plate is calculated. The K criterion is used to judge whether the crack is propagating or not, and the change of stress field at the crack tip during loading is discussed as the boundary influence of residual ultimate strength of cracked stiffened plate. The ultimate strength analysis of single-stiffened double-span stiffened plate and three-stiffened double-span stiffened plate is carried out by nonlinear finite element method. Considering the initial deformation defects of the structure, the axial compression is comparatively analyzed. At the same time, the residual ultimate strength of stiffened plates subjected to axial compression and lateral pressure is obtained, and the variation law of residual bearing capacity of stiffened plates with different crack positions and crack lengths is given. The residual ultimate strength of the single stiffened plate is small, and the calculation results of the three stiffened plates are closer to the real situation. The boundary has a great influence on the ultimate strength analysis model of the stiffened plate structure with crack. The existence of lateral pressure is equivalent to increasing the rotation constraint of the main plate and changing the stress response of the whole stiffened plate structure. The influence of crack on the ultimate strength of FPSO hull structure is studied. The nonlinear finite element method is used to analyze the FPSO hull structure. On the basis of comparing the ultimate bending moments of single-span and three-span intact hull structures, the stresses of FPSO structures with cracks in deck, bilge and two places are obtained under the condition of mid-arch / mid-vertical. Strain distribution and variation of ultimate bending moment.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U661.43;U674.38

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