纤维复合材料修复缺陷管道的失效分析

Failure analysis of defective pipelines repaired with fiber composites

为准确预测纤维复合材料修复缺陷管道的极限失效压力,基于管道钢材料、填充胶层和复合材料的极限失效状态,建立修复后缺陷管道的极限失效数值模型.以缺陷深度、轴向长度、环向长度以及修复层数来表征不同的修复工况,对不同的修复工况进行非线性数值分析.结果表明：对于未修复缺陷管道在单调递增内压力作用下,缺陷区域等效应力曲线可分为线弹性、塑性屈服和刚度退化三个阶段,且腐蚀程度对管道极限承压能力的影响极为显著;复合材料修复层在管道缺陷区域屈服后均能很好地抑制缺陷处的径向膨胀,起到加固修复作用,但对于同一缺陷工况,不同修复层数呈现出不同的失效模式,修复层数对复合材料修复性能具有显著影响;在相同修复层数下,修复后缺陷管道的极限承压能力随缺陷深度的增大呈较大的下降趋势,缺陷轴向长度和环向长度对复合材料修复性能的影响极为有限,但轴向和环向长度较大的缺陷管道其修复后的极限承压能力增量较大.

To accurately predict the ultimate failure pressure of corroded pipelines reinforced with composites repair systems,a numerical model of limit failure of repaired defect pipelines was established based on the ultimate failure state of pipe steel,epoxy and fiber composites.Defect depth,axial length,circumferential length and thickness of the repaired layer were used to characterize different repair conditions.Analysis results show that the equivalent stress curve of the defect can be divided into three stages of linear elasticity,plastic yield and stiffness degradation under the monotonically increasing internal pressure.Repair conditions with different composites thickness can restrain the radial expansion well after yielding in the pipeline defect,however,for the same defect condition,different composites thickness presents different failure modes,and composites thickness has a significant effect on the performance of the repair systems.Under the same composites thickness,the ultimate bearing capacity decreases greatly with the increase of the depth of the defect zone.The axial length and circumferential length of the defect have a very limited influence on the repairing performance of the repair systems,while the ultimate bearing capacity for defective pipeline with large axial length and circumferential length increases greatly after repairing.