共查询到18条相似文献,搜索用时 925 毫秒
1.
2.
3.
4.
5.
对于深水管道,止屈器起到了很好的防止屈曲传播的作用,但是在卷管法安装中,管道在上卷和退卷的过程中将产生塑性变形,而由于止屈器导致的管道壁厚几何不连续性将使局部管段的变形增大,可能加剧塑性变形的影响。针对这个问题,建立ABAQUS非线性有限元模型模拟管道安装过程,研究上述问题对卷管、铺管中管道性能的影响并作参数敏感性分析。结果表明:壁厚所致几何不连续性的存在导致卷管安装时管道局部曲率和应变明显增大;增加回拉力可降低上述不连续性的影响,但管道残余椭圆度也将增加;增大卷筒半径或减小管道直径将使不连续性的影响降低;增大管道壁厚可降低不连续性的影响,但会增加建造成本。文章研究结论可为卷管法安装中管道设计提供理论指导。 相似文献
6.
对于深水管道,止屈器起到了很好的防止屈曲传播的作用,但是在卷管法安装中,管道在上卷和退卷的过程中将产生塑性变形,而由于止屈器导致的管道壁厚几何不连续性将使局部管段的变形增大,可能加剧塑性变形的影响。针对这个问题,建立ABAQUS非线性有限元模型模拟管道安装过程,研究上述问题对卷管铺管中管道性能的影响并作参数敏感性分析。结果表明,壁厚所致几何不连续性的存在导致卷管安装时管道局部曲率及应变明显增大;回拉力、管径与卷筒直径之比及管道壁厚等参数也将产生影响。另外,增加回拉力可降低上述不连续性的影响,但管道残余椭圆度也将增加;增大卷筒半径(或减小管道直径)将使不连续性的影响降低;增大管道壁厚可降低不连续性影响,但随之建造成本也将增加。本文研究结论可为卷管法安装中管道设计提供理论指导。 相似文献
7.
由于复合材料具有高比强度、设计性强、扰腐蚀性能好等优点,而广泛应用于海洋立管中,但是复合材料立管设计还不够成熟。本文为探究提高复合材料立管抗面压屈曲能力的方法,研究了复合材料结构参数对复合材料立管抗面压屈曲能力的影响,发现铺层数和铺层角对其抗面压屈曲能力有较大影响。其后对复合材料立管增加止屈器,结果表明止屈器可以较大幅度提高其抗面压屈曲能力。对今后研究复合材料立管抗屈曲能力提供一定的指导意义。 相似文献
8.
9.
10.
11.
Rigid–plastic solutions for the steady-state, quasi-static buckle propagation pressure in corroded pipelines are derived and compared to finite element predictions (ABAQUS). The corroded pipeline is modeled as an infinitely long, cylindrical shell with a section of reduced thickness that is used to describe the corrosion. A five plastic hinge mechanism is used to describe plastic collapse of the corroded pipeline. Closed-form expressions are given for the buckle propagation pressure as a function of the amount of corrosion in an X77 steel pipeline. Buckles that propagate down the pipeline are caused by either global or snap-through buckling, depending on the amount of corrosion. Global buckling occurs when the angular extent of the corrosion is greater than 90°. When the angular extent is less than 90° and the corrosion is severe, snap-through buckling takes place. The buckle propagation pressure and the corresponding collapse modes also compare well to finite element predictions. 相似文献
12.
《Marine Structures》2005,18(1):43-61
Solutions for the steady-state buckle propagation modes and pressures in a corroded pipeline subjected to external hydrostatic pressure are presented. The buckle propagation pressure of a corroded pipeline is obtained analytically with a rigid-plastic analysis and numerically from finite element analysis (ABAQUS). Both the rigid-plastic analysis and ABAQUS program reveal symmetric and anti-symmetric buckling modes, depending on the depth and angular extent of the corrosion. Snap-through and global buckling of the pipeline are also distinguished in both solutions. The rigid-plastic solutions for buckle propagation pressure and corresponding collapse modes are found to be within 15% with numerical solutions. 相似文献
13.
Sandwich pipe (SP) combining high-strength performance and thermal insulation has been considered an effective solution for oil and gas transportation in ultra-deepwater. Strain hardening cementitious composite (SHCC) is well known for its capacity to withstand both tensile load and external hydrostatic pressure. The sandwich pipe considered in the research is constituted of concentric steel pipes with SHCC annular layer. In the present research work, the SHCC was manufactured, and full scale sandwich pipes were assembled. Intact and damaged specimens were submitted to controlled external pressure in a hyperbaric chamber to obtain the collapse and propagation pressures, respectively. Modeling and simulation of the buckle propagation of the SPs were correlated with the experimental results. The results show that sandwich pipe with SHCC core has an excellent structural strength under high external pressure in both intact and damaged conditions. Moreover, the results also show that the interaction between the annular and the inner/outer pipes provides a significant contribution to the buckling resistance under propagation pressure. 相似文献
14.
The effects of non-symmetrical corrosion defects (about the major or minor axis of the ellipse) on the collapse modes and collapse pressures of subsea pipelines are studied using the Finite Element (FE) method. The corrosion defects are represented by a groove of a given length, width, and depth which is created by the “element death” technology. Parametric studies are conducted and the influences of corrosion location angle, length, width, and depth on the collapse pressure are discussed. Several significant and interesting results are achieved: (1) The collapse modes are mainly affected by the corrosion location angle, width, and depth; (2) The collapse pressure of a pipe may increase as the corrosion length, width, or depth increases when the corrosion location angle is small; (3) The longer the corrosion length, the larger the effect of corrosion location angle on the collapse pressure; (4) For collapses controlled by corrosion defect (0.3≤h/t ≤ 0.7), the relationship between the collapse pressure and corrosion location angle follows a simple cosine function. For collapses controlled by the ovality (h/t < 0.3), the relationship can be expressed by the combination of straight-line and cosine function. 相似文献
15.
The understanding and study of the mechanical behavior of submarine pipes have significant relevance in ocean exploration, allowing the application of these structures in adverse conditions. In this sense, protecting the tube's internal surface is vital for the transportation of corrosive materials, threatening structural integrity. Usually, the external surface is at constant hydrostatic pressure, leading to possible structural failure if the project does not consider all failure modes. Within the framework of Metallurgically Cladded Pipes (MCP) and Mechanically Lined Pipes (MLP), Corrosion-Resistant Alloys (CRAs) are inserted in the internal surface of pipelines. However, they are not typically deemed in the structural analysis as an integrant part of the mechanical resistance for the external load. This work presents an initial analytical proposal to calculate the collapse pressure of concentric tubes incorporating the rigidity provided by the CRA. Tied or frictionless numerical models are assumed to describe the interaction between the two bodies at the interface region. These two scenarios establish the upper and lower boundaries for cases where friction is part of the problem. The methodology applies a least-square minimization function based on nonlinear finite element simulations to extract analytical expressions that estimate the collapse pressure. An effort is made to reduce the number of sensitive parameters involved in the analytical proposals and minimize the complexity of the formulation. This process allows the analyst to visualize which parameters are more relevant in various scenarios. Nevertheless, the main goal is to evaluate how the variables are coupled and develop a methodology that can be adapted to reproduce the analyst's necessities. 相似文献
16.
Corrosion defect is considered to be one of the major critical damages of subsea pipelines, which can result in a considerable loss in the collapse capacity of thick-walled pipes in deep waters. In this paper, collapse experiments on 13 small-scale seamless steel tubes with varying sizes of elliptical and rectangular corrosion defects were carried out in a sealed hyperbaric chamber. The collapse pressure and deformed configurations were obtained, with four types of collapse trajectories identified. A numerical framework was established to simulate the collapse event using ABAQUS, and decent consistency of the collapse pressure and collapsed configurations was observed between numerical and experimental results. Then, the collapse pressure of thick-walled pipes with a single elliptical corrosion defect was studied parametrically, covering different defect sizes, geometric characteristics, and material properties. Based on the extensive numerical analysis, a reasonable empirical formula was developed to estimate the collapse pressure of thick-walled steel pipes with various elliptical corrosion defects and material properties. 相似文献
17.
Sandwich pipes have been studied as one option to overcome the high pressure problems in deep and ultra-deep waters. They have become a possible alternative solution for submarine infrastructure due to its thermal insulation capacity. This contribute to preventing the pipeline from clogging due to the difference in temperature between reservoir fluids and water at the bottom of the sea. The pipelines in ultra-deepwater are continually exposed to severe operating conditions, such as the effect of high levels of external pressure that can cause local deformation or even collapse of the pipe. Thus, a greater understanding of the mechanical behavior of sandwich pipes is required. This paper presents a FEM-based evaluation of friction and initial imperfection effects on sandwich pipes local buckling. The non-linear evaluation was carried out in FEM of local buckling of two sandwich pipes, with polypropylene and cement as filled annular material. The influence of initial imperfections and the degree of friction, between the annular material and the steel pipes, as well as geometric variations of the pipe were considered. The numerical simulations results indicate a capacity to withstand ultra-deep waters collapsing pressures, around 3000 m, either for polypropylene or cement filled annular material model. In addition, the results indicate that the collapse pressure is inversely proportional to the increase in annular thickness and directly proportional to the decrease in friction which have an impact and contribution on the carrying capacity of the sandwich pipe. Further research will consider a design of experiments analysis of reported effects for different diameter-to-thickness ratios. 相似文献
18.
Nonlinear finite element (FE) collapse pressure predictions are compared to experimental results for submarine pressure hull test specimens with and without artificial corrosion and tested to collapse under external hydrostatic pressure. The accuracy of FE models, and their sensitivity to modeling and solution procedures, are investigated by comparing FE simulations of the experiments using two different model generators and three solvers. The standard FE methodology includes the use of quadrilateral shell elements, nonlinear mapping of measured geometric imperfections, and quasi-static incremental analyses including nonlinear material and geometry. The FE models are found to be accurate to approximately 11%, with 95% confidence, regardless of the model generator and solver that is used. Collapse pressure predictions for identical FE models obtained using each of the three solvers agree within 2.8%, indicating that the choice of FE solver does not significantly affect the predicted collapse pressure. The FE predictions are found to be more accurate for corroded than for undamaged models, and neglecting the shell eccentricity that arises due to one-sided shell thinning is found to significantly decrease the resulting accuracy of the FE model. 相似文献