Failure Analysis of Composite Repaired Pipelines with an Inclined Crack under Static Internal Pressure

The aim of the present work is to study the efficiency of the glass fiber reinforced polymer patch for repairing cracked steel pipe subjected to internal pressure. The effect of fiber orientation, [0°]8s, [90°]8s, and [0°/90°]4s, of bonded composite repair on reducing J-integral of stationary crack with different inclination angles (θ) is studied using the 3-D finite element method, FEM. Extended-FEM has been adopted to simulate the crack growth of different inclined stationary cracks in steel pipe subjected to internal pressure. It has been found that, the growing crack emanated from inclined stationary crack switched its path to be under pure mode I. The crack initiation pressure of inclined stationary crack in steel pipe with composite repair is higher than that of pipe without composite repair. The composite repair reduced the value of J-integral of stationary crack in steel pipe. This reduction is strongly affected by the crack length and θ of the stationary crack and it is fairly affected by the fiber orientation.