氢致鼓泡缺陷压力管道力学行为分析及剩余强度评价研究

发布时间：2018-02-20 07:12

  本文关键词： 氢致鼓泡 应力强度因子 J积分 剩余强度　出处：《重庆科技学院》2017年硕士论文　论文类型：学位论文

【摘要】：氢致鼓泡缺陷是输气管道中较常见的一种管道缺陷,输气管道一旦出现氢致鼓泡缺陷而不及时处理,很容易造成管道失效,从而带来经济损失和人员伤亡。鉴于此,本文建立氢致鼓泡裂纹的有限元模型,计算不同工况下氢致鼓泡裂纹的断裂参量并判断裂纹开裂扩展的趋势;模拟氢致鼓泡裂纹的扩展状态,探索氢致鼓泡在管道内扩展的一般规律;最后计算缺陷管道的剩余强度,以确保输气管道的安全运行。本课题的研究具有重要的工程实际意义及一定的理论价值。本文首先利用ABAQUS有限元软件建立了氢致鼓泡管道的有限元模型;根据建立的有限元模型计算不同工况下的断裂参量并得出了规律:随着鼓泡裂纹的椭圆率(b/a)、内压(P)、氢压(Pq)、裂纹长度(a)的增大,对应的断裂参量增大,同时裂纹扩展的可能性也增大;随着鼓泡裂纹深度(h)的增加,对应的断裂参量减小,说明越靠近管道内壁面的鼓泡越有扩展的危险。其次,通过对竹渠线管道鼓泡的扩展模拟验证了有限元模型的正确性,通过对不同情况下鼓泡裂纹的扩展模拟发现:在管道直径、内压及裂纹初始直径一定时,氢压越大鼓泡高度和直径就越大,且鼓泡高度、鼓泡直径与氢压的关系为二次抛物线函数关系。对两个鼓泡的管道进行模拟发现:当两个鼓泡之间的距离小于半径为5 mm的圆周范围以内时,必须考虑两个鼓泡的相互作用,当两个鼓泡之间相隔的距离大于半径为60 mm的圆周范围以外时,两个鼓泡的相互作用比较微弱,可以只选取其中一个鼓泡进行模拟计算。在次,经过计算得出了t=20℃、30℃、100℃、200℃ 时氢压-总浓度的关系图,也得出了DN=200、350、500、650、800 mm时氢压-鼓泡高度、氢压-鼓泡直径的关系图。根据管道中浓度计算出鼓泡处总氢浓度可以得出鼓泡处的氢压强度值,由此可以根据趋势图查出此氢压下的鼓泡高度及鼓泡直径值,从而计算出该情况下的剩余强度。最后,运用有限元法对不同氢压下氢致鼓泡管道的剩余强度进行了计算与评价,得出了不同氢压下缺陷管道的剩余强度值。
[Abstract]:Hydrogen bubble defect is a common pipeline defect in gas transmission pipeline. Once hydrogen bubble defect occurs in gas pipeline without timely treatment, it is easy to cause pipeline failure, resulting in economic losses and casualties. In this paper, the finite element model of hydrogen-induced bubbling crack is established, the fracture parameters of hydrogen-induced bubbling crack under different working conditions are calculated and the tendency of crack crack propagation is judged, the propagation state of hydrogen-induced bubbling crack is simulated, To explore the general rules of hydrogen induced bubbling in the pipeline, and finally to calculate the residual strength of the defective pipe, In order to ensure the safe operation of gas transmission pipeline, the research of this subject has important practical significance and certain theoretical value. Firstly, the finite element model of hydrogen induced bubbling pipeline is established by using ABAQUS finite element software. According to the established finite element model, the fracture parameters under different working conditions are calculated and the rules are obtained: the corresponding fracture parameters increase with the increase of the ellipse ratio of bubbling crack (b / a), the internal pressure (P), the hydrogen pressure (PQ), and the crack length (a). At the same time, the possibility of crack growth is also increasing, and with the increase of bubble crack depth, the corresponding fracture parameters decrease, which indicates that the blistering near the inner surface of the pipe is more dangerous. Secondly, The correctness of the finite element model is verified by the simulation of the bubble propagation of the bamboo canal pipeline. The simulation of bubble crack propagation under different conditions shows that when the pipe diameter, internal pressure and the initial diameter of the crack are fixed, the results are as follows: (1) when the pipe diameter, internal pressure and initial diameter of the crack are fixed, The greater the hydrogen pressure, the bigger the bubble height and diameter, and the higher the bubble height, The relationship between bubble diameter and hydrogen pressure is a quadratic parabola function. It is found that the interaction of two bubbles must be considered when the distance between two bubbles is less than the circumference range of 5 mm radius. When the distance between two bubbles is larger than a radius of 60 mm, the interaction between the two bubbles is weak, only one of the bubbles can be selected for simulation. The relationship diagram of hydrogen pressure-total concentration at 30 鈩，

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