考虑大变形的含缺陷海洋管道非线性涡激振动研究

发布时间：2018-01-16 18:44

本文关键词：考虑大变形的含缺陷海洋管道非线性涡激振动研究　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着海洋油气资源的开发,海洋管道作为海洋油气资源最主要的运输方式,其安全性问题日益受到重视。海洋管道悬跨段在海流、波浪等海洋环境荷载的作用下容易发生涡激振动,引起管线的疲劳破坏。同时,由于长期处于恶劣的服役环境中,海洋管道普遍处于带缺陷工作状态,但现有海洋管道的涡激振动分析中未曾考虑到这一现状。因此,开展含缺陷管道的全寿命安全分析具有十分重要的理论和实际意义。本文主要研究内容包括:(1)基于梁理论,采用考虑结构大变形的非线性有限元方法,考虑管道轴向初张力及管内热油温度场引起的轴力对结构几何刚度的贡献,建立了海洋管道的结构模型;采用非线性涡激振动时域荷载模型来模拟作用在管道上的涡激力,用于同时考虑流场与管道在顺流和横流向的耦合作用;采用增量形式的时域积分法求解该非线性振动模型,通过算例,验证了该计算方法的准确性,并分析了顶张式海洋立管及海底管道悬跨段的涡激振动响应,为后续缺陷管道涡激振动响应研究提供了准确的理论方法。(2)采用非线性流固耦合振动计算方法,计算了含腐蚀缺陷管道的涡激振动响应,并与完整管的响应对比,并分析了不同腐蚀深度和位置对响应的影响,给出了含腐蚀缺陷管道涡激振动响应的预测方法,为含缺陷管道的疲劳寿命评估提供参考理论。(3)基于应变能释放理论和线性断裂力学理论,推导了管类结构在轴力、剪力、扭矩和弯矩作用下由非贯穿直裂纹所引入的附加局部柔度矩阵方程,建立了非贯穿直裂纹三维有限元模型,通过算例验证了模型的正确性。结合非线性涡激振动计算方法,对含裂纹缺陷管道的非线性涡激振动响应进行了分析,并给出了预测含裂纹管道涡激振动响应的方法。(4)基于弹性力学基本理论,采用状态空间法建立了考虑层间弱界面的三维管道模型,计算了不同程度弱界面对管道结构自振特性的影响,为含缺陷管道的涡激振动分析提供了新的思路。
[Abstract]:With the development of offshore oil and gas resources, offshore pipeline as the most important mode of transportation of offshore oil and gas resources, its safety has been paid more and more attention. Under the action of wave and other marine environmental loads, vortex-induced vibration is easy to occur, which leads to the fatigue damage of pipeline. Meanwhile, because of the long time in the bad service environment, the offshore pipeline is generally in the working state with defects. However, this situation has not been taken into account in the analysis of vortex-induced vibration of existing offshore pipelines. It is of great theoretical and practical significance to carry out life safety analysis of pipeline with defects. The main research contents in this paper include: 1) based on beam theory, nonlinear finite element method considering large deformation of structure is adopted. Considering the contribution of the axial initial tension and the axial force caused by the thermal oil temperature field to the geometric stiffness of the structure, the structural model of the offshore pipeline is established. The nonlinear vortex-induced vibration time-domain load model is used to simulate the vortex-induced forces acting on the pipeline, which is used to consider the coupling effect of the flow field and the pipeline in the downstream and the transverse direction at the same time. An incremental time domain integral method is used to solve the nonlinear vibration model. An example is given to verify the accuracy of the method. The vortex-induced vibration response of the top tensioned riser and submarine pipeline is analyzed. This paper provides an accurate theoretical method for the subsequent study of the vortex-induced vibration response of the pipeline with corrosion. The nonlinear fluid-structure coupled vibration calculation method is used to calculate the vortex-induced vibration response of the pipeline with corrosion defects. The effect of different corrosion depth and location on the response is analyzed, and the prediction method of the vortex-induced vibration response of the pipeline with corrosion defects is given. Based on the theory of strain energy release and linear fracture mechanics, the axial force and shear force of pipe structure are derived. Under the action of torque and bending moment, the additional local flexibility matrix equation introduced by the non-penetrating straight crack is introduced, and the three-dimensional finite element model of the non-penetrating straight crack is established. A numerical example is given to verify the correctness of the model, and the nonlinear vortex-induced vibration response of a cracked pipe is analyzed in combination with the nonlinear vortex-induced vibration calculation method. The method of predicting the vortex-induced vibration response of cracked pipes is presented. Based on the basic theory of elasticity, a three-dimensional pipeline model considering the weak interface between layers is established by using the state space method. The influence of weak interface on the natural vibration characteristics of pipeline structure is calculated, which provides a new idea for the analysis of vortex-induced vibration of pipeline with defects.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P756.2

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