环焊缝缺陷复合材料修复结构的抗弯性能分析

Analysis of bending properties of structures repaired by composite materials with girth weld defects

为了研究复合材料修复方法对环焊缝缺陷抗弯曲载荷的修复效果,采用低氢焊条手工电弧焊(SMAW)+自保护药芯焊丝半自动焊(FCAW)焊接工艺制备了X80钢级管道(管径1016 mm,壁厚18.4 mm)环焊缝,采用电火花(EDM)加工了双台阶环焊缝根部裂纹(长度350 mm,深度9 mm),并采用真空辅助树脂传递模塑成型工艺(VARI)制备了性能优异的E级高强双向玻璃纤维织物+环氧树脂的复合材料修复结构,开展了全尺寸四点弯曲试验,对比了修复前后含缺陷环焊缝的弯曲载荷抗力。结果表明:试验所用复合材料修复结构(厚度40 mm,长度1000 mm)提升环焊缝的抗弯曲载荷能力约为管材实测屈服强度的21%,对含缺陷环焊缝的抗弯曲能力提升有限。研究结果对于指导环焊缝缺陷修复策略的制定具有借鉴意义。

In order to research and determine the repair effect of composite material repair method against bending load of girth weld defects,the girth weld of X80 pipeline(pipe diameter 1016 mm,wall thickness 18.4 mm)was prepared by low hydrogen electrode shielded manual arc welding(SMAW)+self-protected flux-cored wire semi-automatic welding(FCAW)welding process,and the root crack(length 350 mm,depth 9 mm)of double-step girth weld was processed by electrical discharge machining(EDM).A composite material structure of grade E high-strength two-way fiberglass fabric+epoxy resin with excellent properties was prepared by vacuum-assisted resin injection(VARI),and a full-scale four-point bending test was carried out to compare the bending load resistance of the defective girth weld before and after repair.The results show that the bending load resistance of the girth weld enhanced by the test composite structure(thickness 40 mm,length 1000 mm)is about 21%of the measured yield strength of the pipe,which has limited capability for enhancement of bending resistance.The research results have a reference significance for guiding the formulation of repair strategies for girth weld defects.