Using XFEM Technique to Predict the Effect of Default on the Damage of Steel Pipe Reduced-Connection Under Bending and Pressure Loading

Over the years of service and by effect of their typical geometries, pressurized tubular structures assembled by a connection of an elbow or a reduced Tee or other, are much more stressed compared to straight tubes at significant normal and tangential stresses. With the presence of faults, these connections are subsequently largely responsible for their damage. Damage to an X60 Grade 8 ”x4” steel tube Reduced Tee connection element under oriented loading and internal pressure with or without the presence of a defect was investigated in this work. Because of these advantages and in order to present the propagation of a crack, we opted for the use of the XFEM technique (extend finite element method). Numerical prediction using the ABAQUS compute code set out to assess dependent parameters such as location and type of fault as well as mode and accumulated load level. Indeed, the loading mode clearly showed a large difference between the response down to the level of damage. These results are presented by curves which present both the response of a structure in force-displacement and the crack propagation (initiation and critical length). The default location in the structure at the connection joint is oriented according to the loading mode. The different situations analyzed affect all possible cases that the element of the reduced Tee may undergo. The type of defect is related by its location according to the thickness in the form of a metal tear. This damage analysis shows that the parameters studied in the structure clearly condition the level and mode of failure as well as their response to damage.