含内腐蚀缺陷—裂纹管道的应力强度因子与承压能力研究

发布时间：2018-04-28 02:44

本文选题：应力强度因子 + 腐蚀缺陷-裂纹　；参考：《西南石油大学》2017年硕士论文

【摘要】：随着油气管道服役时间的增加,管道内部不可避免地会产生腐蚀缺陷,削弱管道的静态和动态抗力。由于应力集中,腐蚀缺陷处很可能会起源裂纹,进一步影响管道的性能。论文主要研究了含腐蚀缺陷-裂纹管道的应力强度因子和承压能力的变化规律,比研究单一的腐蚀缺陷或裂纹所产生的影响更具有现实意义。有关管道腐蚀缺陷和裂纹的研究较多,而对于腐蚀缺陷-裂纹的研究则非常少。基于管道内腐蚀缺陷的产生机理和断裂力学理论,文中主要研究不同类型裂纹的不同参数对应的应力强度因子和极限承压能力的影响规律。本文的主要研究工作包括:1、腐蚀缺陷-轴向裂纹研究:采用有限元法计算了缺陷-轴向裂纹的应力强度因子,结果表明:保持其他参数不变时,随着轴向裂纹的相对深度的增大,应力强度因子的大小关系为多缺陷-轴向裂纹单缺陷-轴向裂纹双缺陷-轴向裂纹;随着管道内压的增大,应力强度因子的大小关系为双缺陷-轴向裂纹单缺陷-轴向裂纹多缺陷-轴向裂纹。2、不同腐蚀缺陷-裂纹应力强度因子研究:应用扩展有限元法求解了三维点蚀缺陷-径向裂纹和均匀腐蚀缺陷下的环向裂纹、矩形状裂纹的应力强度因子,结果表明应力强度因子随着裂纹相对深度和管道内压的增大而增大,随着管道壁厚增加而减小。3、形状因子F的计算:根据仿真结果和应力强度因子求解公式,推导出了不同类型裂纹所对应的形状因子与裂纹的相对深度以及管道壁厚之间的关系式,并验证了形状因子拟合式的正确性。4、管道承压能力研究:以数值模拟和局部塑性失效准则为基础,计算含腐蚀缺陷-裂纹管道的最大承压能力,并得出了同一内压下裂纹的临界深度,同一深度下管道的失效压力。5、管道承压能力评价方法:采用不同评价方法计算不同长度缺陷-裂纹的失效压力,得出DNVRP-F101评价结果偏高;ASME B31G评价结果则显得保守;而改进B31G方法、RPA方法及有限元法与Choi回归公式法的计算结果较为接近,对管道承压能力的评价比较可靠。
[Abstract]:With the increase of service time of oil and gas pipeline, corrosion defects will inevitably occur inside the pipeline, which will weaken the static and dynamic resistance of the pipeline. Due to the stress concentration, the corrosion defects may cause cracks, which will further affect the performance of the pipeline. In this paper, the variation of stress intensity factor and pressure bearing capacity of pipes with corrosion defects and cracks is studied, which is more practical than that of single corrosion defects or cracks. There are many researches on corrosion defects and cracks in pipelines, but very few on corrosion defects and cracks. Based on the mechanism of corrosion defects in pipeline and the theory of fracture mechanics, this paper mainly studies the influence law of stress intensity factor and ultimate bearing capacity of different types of crack parameters. The main research work in this paper includes: 1, corrosion defect axial crack study: the stress intensity factor of defect axial crack is calculated by finite element method. The results show that the stress intensity factor is constant when other parameters are kept unchanged. With the increase of the relative depth of the axial crack, the relationship of the stress intensity factor is as follows: multiple defects, single defect of the axial crack, double defect of the axial crack and axial crack, and with the increase of the internal pressure of the pipe, The relation of stress intensity factor is double defect, axial crack, single defect, axial crack, axial crack, axial crack. The stress intensity factor of different corrosion defect and crack is studied. The expanded finite element method is used to solve the three-dimensional pitting corrosion. Defects-radial cracks and toroidal cracks under uniform corrosion defects, The results show that the stress intensity factor increases with the increase of the relative depth of the crack and the internal pressure of the pipe. With the increase of pipe wall thickness, the calculation of shape factor F: based on the simulation results and the formula of stress intensity factor, The relationship between the shape factors corresponding to different types of cracks, the relative depth of cracks and the wall thickness of pipes is derived. The correctness of the fitting formula of shape factor. 4. The study of pipeline bearing capacity. Based on numerical simulation and local plastic failure criterion, the maximum pressure bearing capacity of pipeline with corrosion defect and crack is calculated. The critical depth of the crack under the same internal pressure, the failure pressure of the pipeline at the same depth, and the evaluation method of the pipeline bearing capacity are obtained. Different evaluation methods are used to calculate the failure pressure of the crack with different length. It is concluded that the evaluation results of DNVRP-F101 are higher than that of B31G, while the results of improved B31G method and finite element method are close to those of Choi regression formula, and the evaluation of pipeline bearing capacity is more reliable.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O346.1

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