Fatigue Crack Propagation Analysis of Repaired Pipes With Composite Patch Under Cyclic Pressure

Abstract

The pipes in offshore and marine structures are mainly made of low-strength structural steels such as A537 steel and are subjected to the effects of both corrosive medium and cyclic loading caused by many factors. Reinforcement and repair of components using composite patches can be used for piping to reduce the stress intensity factors at the crack-front of a corrosion fatigue crack. In this paper 3D finite element analyses in general mixed-mode fracture condition are performed to study the crack growth behavior of repaired pipes subjected to internal cyclic pressure. The required formulations, crack growth modeling, and remeshing are automatically handled by developing an ANSYS parametric design language (APDL) program. For this purpose an offshore pipe made of low-strength steel containing an initial fatigue corrosion crack repaired by glass/epoxy composite patch is considered. A parametric study will be performed to find the effects of patch thickness on fatigue crack growth life extension and crack-front shape of the repaired pipes.